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Better Builds with Maven
The How-to Guide for Maven 2.0
John Casey Vincent Massol Brett Porter Carlos Sanchez Jason van Zyl
Better Builds with Maven. The How-to Guide for Maven 2.0
© 2006 Mergere, Inc. The contents of this publication are protected by U.S. copyright law and international treaties. Unauthorized reproduction of this publication or any portion of it is strictly prohibited. While every precaution has been taken in the preparation of this book, the publisher and the authors assume no responsibility for errors or omissions, or for damages resulting from the use of information contained in this book or from the use of programs and source code that may accompany it. In no event shall the publisher and the authors be liable for any loss of profit or any other commercial damage caused or alleged to have been caused directly or indirectly by this book. Printed: June 2006 in the USA Version 1.0.1
I'm very lucky to have been able to write this book with the core Maven team. They are all great developers and working with them on Maven since 2002 has been an endless source of discoveries and enlightening. Jason van Zyl and I were initially supposed to write half of the book but we soon realized that there was a substantial amount of work to be done on the code to stabilize Maven and the plugins before we could write about it. This is when Brett Porter, Carlos Sanchez and John D. Casey stepped up to the plate and jumped on board to help us. They ended up writing a big portion of the book and improving the overall book's quality by several folds. Thank you guys! We owe you. I'd like to thank Jason of course who's guided Maven all those years and who's had the foresight and courage to rewrite Maven 2 from scratch, taking into account all learnings from the past. A special thank goes to Jesse McConnell who's helped me a lot to write the J2EE chapter and especially the Web Services part. Thanks also to all our reviewers who provided great feedback and fixed our errors. They are all part of the vibrant Maven community whether as committers or contributors. In no special order, I'd like to thank Stephane Nicoll, Napoleon Esmundo C. Ramirez, Felipe Leme, Jerome Lacoste, Bill Dudney and David Blevins. A big thank to Mergere which sponsored this book and a company I admire for really understanding open source. Thanks to Winston Damarillo and Gordon King for making this book possible and thanks to Natalie Burdick for driving it relentlessly to completion, which is not a small feat when you have to manage a bunch of hardcore open source developers who continually lapse into coding when they should be writing instead! Delivering a quality book would not have been possible without the professional help of Lisa Malgeri and Elena Renard who did all layouts, copy editing and more generally transformed our technical prose into proper and readable English. Thank you to Joakim Erdfelt for the graphical images in our Figures. A huge thank to Pivolis for allowing me to work part time on the book even though the return on investment was far from being guaranteed! Once more Francois Hisquin and Jean-Yves Grisi have proved that they have their employees' satisfaction at heart. Last but not least, all my love goes to my wife Marie-Albane and my 3 young kids who kept loving me unfalteringly even though I spent a good portion of our play-time to write this book. Vincent Massol
I'd like to start by thanking everyone who has been involved in the Maven community over the years, for sticking with it through some of the early development and for holding the development team to a higher standard. Maven is the cumulative work of nearly 40 committers and an even larger number of contributors who've taken the time to give feedback, contribute ideas, answer questions, test features, and submit fixes. Jason van Zyl deserves particular credit and has my constant admiration for having the foresight to start the project and for continuing to stick unwaveringly to his vision throughout its development. I'd also like to thank Paul Russell and the development team during my time at Fairfax Digital, for trusting my judgment to use Maven on our projects, and without whom I would never have been able to get involved in the project in the first place. Both I and the Maven project owe you all a debt of gratitude. I'm grateful to have had the opportunity to finally write a book about Maven, and to do so with such a number of my talented friends and colleagues. To the authors Jason, Vincent, John and Carlos congratulations on a job well done. To Natalie Burdick, for her dedication to see this through, despite having all of the least enjoyable tasks of keeping the development on track, doing additional copy editing and organizing its release. To Lisa Malgeri and Elena Renard, for their copy editing, formatting and development of the book's template, whose work made this book as professional and polished as it is. I'm very thankful to the team at Mergere and Simula Labs for not only sponsoring the development of the book and making it available free of charge, but for the opportunity to work in such a tremendous environment. It is a rare thing to be able to work with such a friendly group of people that are among the brightest in their field, doing what you enjoy and being able to see your our own personal vision realized. Personally, I'd like to say how much I appreciate all of my family, friends, and those of St Paul's Anglican church for all of their care,support, help and encouragement in everything that I do. My most heartfelt thanks and all of my love go to my wife Laura, for loving me as I am despite all my flaws, for her great patience and sacrifice in allowing me to work at all hours from home, and for leaving her native Michigan to live in a bizarre foreign land. I continue to hope that it was for me and not just because of the warmer climate. Brett Porter
I'd like to thank my family for their continuous support. and the teammates during my time at Softgal. Finally. Brett and Carlos iii . Thanks also to all the people in Galicia for that delicious food I miss so much when traveling around the world. Lester Ecarma. David Blevins. Tim O'Brien. John. Bill Dudney. Vincent. Jerome Lacoste. Emmanuel Venisse and John Tolentino. Felipe Leme. Allan Ramirez. Ramirez. All of us would like to thank Lisa Malgeri. Ruel Loehr.I would like to thank professor Fernando Bellas for encouraging my curiosity about the open source world. It is much appreciated. for accepting my crazy ideas about open source. Carlos Sanchez Many thanks to Jesse McConnell for his contributions to the book. Also. Napoleon Esmundo C. Elena Renard and Joakim Erdfelt for their many contributions to the book. Chris Berry. Abel Rodriguez. Fabrice Bellingard. Jason. Mark Hobson. we would like to thank all the reviewers who greatly enhanced the content and quality of this book: Natalie Burdick. especially my parents and my brother for helping me whenever I needed. Stephane Nicoll.
Inc.About the Authors Vincent Massol has been an active participant in the Maven community as both a committer and a member of the Project Management Committee (PMC) since Maven's early days in 2002. where he is the technical director of Pivolis. He created his own company. specializing in open source consulting. and today a large part of John's job focus is to continue the advancement of Maven as a premier software development tool. Brett became increasingly involved in the project's development. When he's not working on Maven. and is a Member of the Apache Software Foundation. and working on his house. he is a co-author of JUnit in Action. financial. Jason van Zyl: As chief architect and co-founder of Mergere. Jason van Zyl focuses on improving the Software Development Infrastructure associated with medium to large scale projects. as well as to various Maven plugins. Brett has become involved in a variety of other open source projects. Carlos Sanchez received his Computer Engineering degree in the University of Coruña. Inc. and started early in the open source technology world. John enjoys amateur astrophotography. Spain.0 and 2. Additionally. He is grateful to work and live in the suburbs of Sydney. and in 2005. Vincent lives and works in Paris. supporting both European and American companies to deliver pragmatic solutions for a variety of business problems in areas like e-commerce. which has led to the founding of the Apache Maven project. of course. He continues to work directly on Maven and serves as the Chair of the Apache Maven Project Management Committee. where he hopes to be able to make the lives of other developers easier. This is Vincent's third book.. Build management and open source involvement have been common threads throughout his professional career. He enjoys cycling and raced competitively when he was younger. John Casey became involved in the Maven community in early 2002. Florida with his wife. published by O'Reilly in 2005 (ISBN 0-596-00750-7). when he began looking for something to make his job as Ant "buildmeister" simpler. a company which specializes in collaborative offshore software development using Agile methodologies. He was invited to become a Maven committer in 2004. he founded the Jakarta Cactus project-a simple testing framework for server-side Java code and the Cargo project-a J2EE container manipulation framework. In addition to his work on Maven. Vincent has directly contributed to Maven's core. John was elected to the Maven Project Management Committee (PMC). John lives in Gainesville. CSSC. software development. Australia. iv .0 major releases. Brett Porter has been involved in the Apache Maven project since early 2003. published by Manning in 2003 (ISBN 1-930-11099-5) and Maven: A Developer's Notebook. joining the Maven Project Management Committee (PMC) and directing traffic for both the 1. Immediately hooked. telecommunications and. discovering Maven while searching for a simpler way to define a common build process across projects. his focus in the Maven project has been the development of Maven 2. Emily. Brett is a co-founder and the Director of Engineering at Mergere.. Since 2004. roasting coffee.
.... 16 1.............................................................. 20 Standard directory layout for projects..................1..........31 2.................................................................... What is Maven?......................................................................................................... Introducing Maven.............................. 25 Local Maven repository...............6....................................................................................................................................................................................................... Summary.............. Preventing Filtering of Binary Resources...............5................................................ 12 1...............57 3.......... 22 Standard naming conventions................................................1.............................. 49 3................................................................................... Preparing to Use Maven............................. Filtering Classpath Resources....................................... Using Maven Plugins..................................................................................7.................................................... 23 Maven's build life cycle.. 16 1................................. 17 1....................................................6. 30 2...........................................................................2. 33 2............ Creating Applications with Maven.................................................. Compiling Application Sources............... Maven's Origins....25 1..............................................................6............................................ Using Snapshots.......... 37 2.............................................................2.........................................3.... Setting Up an Application Directory Structure............................... 48 3......... 32 2......... 29 2............................................................................................3.55 3...... 23 1..........................1.. Handling Test Classpath Resources.. 18 1..................................................................................................22 1.......................................... Maven's Benefits.................4.....3......... 36 2....................................................................................................... Getting Started with Maven......................... 41 2......3.........................................................58 v ................. Handling Classpath Resources...................................................................1.....................................1............................................................................................................................................6................................................2...........40 2... 50 3....8............................................................................ Convention Over Configuration........... 50 3.........................2........................................1......Table of Contents Preface.....5.............................................................................................................................................2.................................. 23 Maven's project object model (POM).....................................................................................................................................................................1.............. Using Project Inheritance... Maven Overview................................................3.........................2.....................................6.............................. Maven's Principles.................................................................. Compiling Test Sources and Running Unit Tests....4..... 15 1............................................4..... Resolving Dependency Conflicts and Using Version Ranges.................................................................................................. Packaging and Installation to Your Local Repository............ 20 1............................................................. 45 2.................................... Declarative Execution...........................2....................... 43 2...............1............................................2....................................2.................... 26 Locating dependency artifacts.. Coherent Organization of Dependencies..................................................................... 28 1..................................................................................3...................................... Creating Your First Maven Project..2..............................................................................................................................1...................21 One primary output per project............53 3................................... Introduction......... What Does Maven Provide?.................................................................................................... Reuse of Build Logic........... Managing Dependencies......................................47 2.............
......................4...............................1........................9......................94 4.........3.......................................................... Building a Web Application Project..................................................................129 5....................................4.......2............................................................................................................................................................................ Building an EJB Project...................................... 77 4.............................1............................................................. 90 4...... 66 3..................................................... 117 4... 132 5...........................................................................................................2.....................9..............9.............3......................................................3...................... Building J2EE Applications..108 4.............................. BuildInfo Example: Notifying Other Developers with an Ant Mojo........................ Deploying with an External SSH..................................7...........................2....................................................................................... A Note on the Examples in this Chapter.......................9.......2.................................................................................. 114 4.............................................5............................................................. 67 3......... Introduction............................................................................................ 69 3................................. 68 3...................7......... 67 3............................. The Plugin Framework.. 133 5........ 78 4.............................. 133 Using the archetype plugin to generate a stub plugin project....................66 3.......4............................................ 126 5................................................................................ 139 The Ant target.................. 129 The plugin descriptor...............9.. Using Profiles........................... 139 vi .....................................................................9............................................. 130 Choose your mojo implementation language............................................................... Testing J2EE Application.................................................5........................4.................................................................................................................................................................11.. Improving Web Development Productivity..............................................................................128 Accessing build information....................................................................................................................................................2..................................................................................................1.........3................. 138 5.............. 124 5.........................1..................................................................100 4............ Deploying your Application................................. Organizing the DayTrader Directory Structure................. Introducing the DayTrader Application........133 The mojo.....................................................................1........................................................................................... Building an EJB Module With Xdoclet................................................................... 62 3.................................................................. 126 5.......................................................................... Introduction..........3..............................................................10.......... 134 The plugin POM....................11.......................................10......................6....................... 75 4.82 4....... 86 4....................................... Summary.................................................................. Summary........125 5.... 105 4................... Deploying EJBs... 61 3........................127 5......................136 Binding to the life cycle..........................................................................................................9............... A Review of Plugin Terminology.................................................................................4....................................................... Building an EAR Project.. Developing Your First Mojo......................................8.............8....................................... BuildInfo Example: Capturing Information with a Java Mojo .......... Deploying with SSH2............ Utilizing the Build Life Cycle.......................................................................................... 96 4................................................ Deploying with FTP.......................................................... Bootstrapping into Plugin Development.................. 137 The output....... 69 3.................. Deploying a J2EE Application..........3.......... Deploying with SFTP...................... 127 Participation in the build life cycle.................................... 77 4......3.......................................... Developing Custom Maven Plugins........................................................................ Creating a Web Site for your Application...... 76 4..........................................13........................................................14............................................................................... Deploying to the File System............................................................................................ Plugin Development Tools.............3......... Deploying Web Applications. 132 5...... Building a Web Services Client Project.............................12..........................................................
...................................197 7...........................................................................................................3................. 194 7.................. Migrating to Maven..............2......... Creating a Shared Repository...................................................11......................................................... 203 7.........................195 7... 187 6..................... Viewing Overall Project Health.................................................................................................... Creating POM files..................................231 8........................................... Monitoring and Improving the Health of Your Dependencies................. 229 8..237 vii .....9....................................................................................... 146 5...................................... Creating Reference Material................5.................. Advanced Mojo Development.........................................................10......................... 215 7.. The Issues Facing Teams.....................................................................................................................................200 7................................................... 223 7.......... Accessing Project Sources and Resources......................... Configuration of Reports..................... 228 8....... What Does Maven Have to do With Project Health?....... Accessing Project Dependencies.....................................................................................................................................3............................................................................... Adding Reports to the Project Web site........5......................................................................................220 7..........................................................4................................................................................................................ 139 Modifying the plugin POM for Ant mojos......... 158 6.............5........ Where to Begin?................................................ 172 6.............. Attaching Artifacts for Installation and Deployment.......5....................................................................................................................................1........................5.....................3......................................................The mojo metadata file... Creating a Standard Project Archetype................................................................. Continuous Integration with Continuum.........................................................................1..7..................................................2....151 Note on testing source-roots and resources........................ 159 6...................8..........................................................................................2....... Choosing Which Reports to Include..8......12............................................................190 6................................................................................................................. 144 Injecting the project dependency set......................149 Accessing the source-root list.... Team Collaboration with Maven....................................................................................................................................................6......................................................... 164 6...................9....3................................... Monitoring and Improving the Health of Your Source Code.............................7................................................................1...............1..................................... Team Dependency Management Using Snapshots......................................................... 161 6.. 143 5........................................................................ 194 6. 170 6................... 141 Binding the notify mojo to the life cycle...............................4.......................................144 Requiring dependency resolution........................................................................... 147 Adding a source directory to the build. 196 7.......................... Summary.......... Summary........................................... 227 8................................. Creating an Organization POM...................................................... 154 5.............................................................182 6...6............................... Cutting a Release..........................................1..................................... Introducing the Spring Framework..........2................. How to Set up a Consistent Developer Environment............................................................................................ Introduction............................................................ Separating Developer Reports From User Documentation....... 156 6..........................6...................................... 153 5............................................... Summary............................................................... 229 8.................... Monitoring and Improving the Health of Your Releases........................ 144 5...................... Monitoring and Improving the Health of Your Tests......................... 157 6......................... 175 6...................................... 206 7................................................................ 150 Accessing the resource list........5. Assessing Project Health with Maven...........1.............................. 148 Adding a resource to the build..... 145 BuildInfo example: logging dependency versions..........................................
. 275 viii ..................1.................1........................................................... 261 A...........6............................................................................. Referring to Test Classes from Other Modules... Testing.... 245 8................... 258 A............................................241 8.......................................................................................................... Standard Directory Structure....5..................................................... Maven's Default Build Life Cycle..3...........................................................................4....3.............................2..... 261 Plugin metadata..... Ant Metadata Syntax.............................................270 B........................................8.................................................. The default Life Cycle....................................................................4.................... Using Ant Tasks From Inside Maven.............................................................................................................. 252 A................1............................................................................................................. Some Special Cases......................................... Non-redistributable Jars..................................................................... Complex Expression Roots..........2...2............................................ Simple Expressions......................................1....................................6.........................2............ 243 8.................. 244 8.. 251 8...................................... 251 Appendix A: Resources for Plugin Developers.........................................................................................1.........................5.......................................... Summary.................2............................................................................................................................................. Maven's Life Cycles............................................265 Field-level annotations........................... 257 Life-cycle phases.............1......................................8.....................................2........................................... 241 8..................................................5...................................................................................................................................... 265 Class-level annotations..1................................ Restructuring the Code...............1........................................................................237 8......................7................... 256 A..................... Compiling............................................................................................................. 273 Index......................................................................................... 266 A.......253 A.......261 Plugin descriptor syntax............2.......................258 Default Life Cycle Bindings................................................................................................ 244 8............................. 245 8.......6.............................................................................................................. 260 A................ 248 8......................................................................... 259 A...................................................................... The site Life Cycle..................................................................................5..................................................... 259 A.................................253 Bindings for the jar packaging...... 257 A................................................. 250 8................................................................................... 272 Bibliography.....................6..................................................... 266 Appendix B: Standard Conventions....................................... 258 Life-cycle phases......................................................2.. Other Modules...........................................6.......................................................................... 269 B.......................................... Java Mojo Metadata: Supported Javadoc Annotations...................................3................................................................................... The Expression Resolution Algorithm............................................................................................................................................ Building Java 5 Classes...............................................................................................................6................257 Default life-cycle bindings.......................... Maven's Super POM.......................2.............................................................................................................6....3...1.....................................2................................................ Avoiding Duplication...................6........................................ 253 Life-cycle phases............................................................. 271 B.................................... 255 Bindings for the maven-plugin packaging............ Compiling Tests............................................... Mojo Parameter Expressions.............2................ Running Tests..4......... The clean Life Cycle................................................................................................................................5.... 250 8..
..........259 Table A-6: A summary of the valid root objects for plugin parameter expressions................256 Table A-3: The clean life-cycle bindings for the jar packaging..................................................................................................................................................... 265 Table A-8: Field-level annotations.......................................................................................99 Table 5-1: Life-cycle bindings for jar packaging.................. 165 Table 6-2: Report highlights............................. 258 Table A-5: Primitive expressions supported by Maven's plugin parameter....................................................................................... 82 Table 4-2: WAR plugin configuration properties..........................................................................................255 Table A-2: A summary of the additional mojo bindings............................................................................... 270 Table B-2: Phases in Maven's life cycle.............................260 Table A-7: A summary of class-level javadoc annotations....................................................................................................................................................................170 Table 6-3: Built-in Checkstyle configurations.................................................................................266 Table B-1: Standard directory layout for maven project content........................................ 272 ix ........................................................................................................... 60 Table 3-3: Site descriptor............................................................................................................153 Table 6-1: Project Web site content types..................................................................................................................................... 72 Table 4-1: Axis generated classes................................................................................................................................128 Table 5-2: Key differences between compile-time and test-time mojo activities............................................ 257 Table A-4: The site life-cycle bindings for the jar packaging.....................................................................................................................................List of Tables Table 3-1: Module packaging types............................................................................................................... 52 Table 3-2: Examples of version ranges.................................................................................................................181 Table A-1: The default life-cycle bindings for the jar packaging......................................................................................................................
......................................108 Figure 4-12: Directory structure of the ear module showing the Geronimo deployment plan.............................................................................................................................................................. 42 Figure 3-1: Proficio directory structure............................................. 79 Figure 4-3: Modules split according to a server-side vs client-side directory organization...............................................................................166 Figure 6-4: The directory layout with a user guide.......80 Figure 4-4: Nested directory structure for the EAR......................... 172 Figure 6-7: An example PMD report....................................117 Figure 4-14: Directory structure for the functional-tests module................................................. 27 Figure 1-2: General pattern for the repository layout..................................................................................................... 187 Figure 6-12: The dependency convergence report........ 52 Figure 3-3: Version parsing....................51 Figure 3-2: Proficio-stores directory......................................................................................... 33 Figure 2-2: Directory structure after adding the resources directory........................................................................................................................................................ 179 Figure 6-9: An example Checkstyle report..................................................................................119 Figure 6-1: The reports generated by Maven................................................................................159 Figure 6-2: The Surefire report..................... 60 Figure 3-4: The site directory structure...........................................................................................80 Figure 4-5: Directory structure of the wsappclient module.......................................................................................................................................................................................160 Figure 6-3: The initial setup......................... 41 Figure 2-4: Directory structure after adding test resources..................................................................................................................75 Figure 4-1: Architecture of the DayTrader application............................................... 74 Figure 3-6: The sample generated site........................................................82 Figure 4-6: Directory structure for the DayTrader ejb module...............................................................................................................................................................................................................................................................168 Figure 6-6: An example source code cross reference......................114 Figure 4-13: The new functional-tests module amongst the other DayTrader modules ............................................................................................................................. 190 x .....28 Figure 2-1: Directory structure after archetype generation............................................................................................................................................................................................................................................................96 Figure 4-9: DayTrader JSP registration page served by the Jetty6 plugin.. 102 Figure 4-11: Directory structure of the ear module................................................................................................................................................List of Figures Figure 1-1: Artifact movement from remote to local repository................................................................................................... 167 Figure 6-5: The new Web site...........................................................................86 Figure 4-7: Directory structure for the DayTrader ejb module when using Xdoclet.......................................................................................................................................................................................................................................................... 102 Figure 4-10: Modified registration page automatically reflecting our source change.....................189 Figure 6-13: An example Clirr report.................................................................................................................................................................................................................................................................................................. 175 Figure 6-8: An example CPD report.................................................................................... 183 Figure 6-11: An example dependency report......................... 70 Figure 3-5: The target directory.......... EJB and Web modules................. 40 Figure 2-3: Directory structure of the JAR file created by Maven..........................................................................77 Figure 4-2: Module names and a simple flat directory structure............................................................................................................................................ 28 Figure 1-3: Sample directory structure............. 91 Figure 4-8: Directory structure for the DayTrader web module showing some Web application resources.............................180 Figure 6-10: An example Cobertura report.........................................................................
......................................................... 210 Figure 7-4: Schedule configuration. 231 Figure 8-3: A tiger module directory.......................................................................................................................................................................221 Figure 8-1: Dependency relationship between Spring modules.......................................................... 218 Figure 7-7: Archetype directory layout....................................................................... 246 Figure 8-5: Dependency relationship......................................................................................................................................................209 Figure 7-3: Summary page after projects have built...................................................................................................... 212 Figure 7-5: Adding a build definition for site deployment.......................... 230 Figure 8-2: A sample spring module directory............... 247 xi ........................... with all modules....... 207 Figure 7-2: Add project screen shot...............................................................................................Figure 7-1: The Continuum setup screen.....................................................................................................................................................................................................................213 Figure 7-6: Continuum configuration....................................................................... 246 Figure 8-4: The final directory structure.........................................................................................................................................................................
this guide endeavors to provide a quick solution for the need at hand. Maven works equally well for small and large projects.0.Preface Preface Welcome to Better Builds with Maven. This guide is intended for Java developers who wish to implement the project management and comprehension capabilities of Maven 2 and use it to make their day-to-day work easier and generally help with the comprehension of any Java-based project. but Maven shines in helping teams operate more effectively by allowing team members to focus on what the stakeholders of a project require -leaving the build infrastructure to Maven! This guide is not meant to be an in-depth and comprehensive resource but rather an introduction. Perhaps. it does not take long to realize those benefits. reading this book will take you longer. Better Builds With Maven 12 . an indispensable guide to understand and use Maven 2. For users more familiar with Maven (including Maven 1. For first time users. which provides a wide range of topics from understanding Maven's build platform to programming nuances. As you will soon find. We hope that this book will be useful for Java project managers as well. Maven 2 is a product that offers immediate value to many users and organizations.x). it is recommended that you step through the material in a sequential fashion.
Creating Applications with Maven. you will be able to take an existing Ant-based build. Migrating to Maven. and compiling and packaging it. reporting tools. Developing Custom Maven Plugins. The first two chapters are geared toward a new user of Maven 2. Chapter 6 discusses project monitoring issues and reporting. In this chapter. explains a migration path from an existing build in Ant to Maven. and document for reuse the artifacts that result from a software project. Chapter 3. you will be able to keep your current build working. From there. and install those JARs in your local repository using Maven. shows how to create the build for a full-fledged J2EE application. create JARs. they discuss what Maven is and get you started with your first Maven project. Better Builds With Maven 13 . looks at Maven as a set of practices and tools that enable effective team communication and collaboration. At this stage you'll pretty much become an expert Maven user. and how to use Maven to generate a Web site for your project. Chapter 6. split it into modular components if needed. Chapter 8. you will be revisiting the Proficio application that was developed in Chapter 3. illustrates Maven's best practices and advanced uses by working on a real-world example application. Assessing Project Health with Maven. Introducing Maven. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. Finally. WAR. You will learn how to use Maven to ensure successful team development. discusses Maven's monitoring tools. Chapter 7. These tools aid the team to organize. In this chapter you will learn to set up a directory structure for a typical application and the basics of managing the application's development with Maven. you should be up and running with Maven. At the same time. After reading this chapter.Preface Organization Here is how the book is organized. EJB. Team Collaboration with Maven. After reading this second chapter. compile and test the code. Chapter 5 focuses on developing plugins for Maven. Getting Started with Maven. Building J2EE Applications. Chapter 7 discusses using Maven in a team development environment and Chapter 8 shows you how to migrate Ant builds to Maven. Chapter 4 shows you how to build a J2EE application and deploy it. Chapter 2. Chapter 4. Chapter 5. and learning more about the health of the project. and how to use Maven to deploy J2EE archives to a container. goes through the background and philosophy behind Maven and defines what Maven is. visualize. Chapter 1. It starts by describing fundamentals. focuses on the task of writing custom plugins. Chapter 3 builds on that and shows you how to build a real-world project. Web Services). it discusses the various ways that a plugin can interact with the Maven build environment and explore some examples. the chapter covers the tools available to simplify the life of the plugin developer. EAR. shows how to use Maven to build J2EE archives (JAR. gives detailed instructions on creating your first project.
On this page you will be able to view all errata that have been submitted for this book and posted by Maven editors.mergere. So if you have Maven 2. You can also click the Submit Errata link on this page to notify us of any errors that you might have found.mergere. To find the errata page for this book.com. Then. errata.Preface Errata We have made every effort to ensure that there are no errors in the text or in the code. click the Book Errata link. However.com. go to http://library. Simply email the information to community@mergere. We'll check the information and. we are human.com and locate the title in the title lists. Better Builds With Maven 14 . so occasionally something will come up that none of us caught prior to publication. How To Contact Us We want to hear about any errors you find in this book. Once at the site. We offer source code for download. and technical support from the Mergere Web site at http://library. if appropriate. click the Get Sample Code link to obtain the source code for the book. on the book details page. How To Download the Source Code All of the source code used in this book is available for download at http://library. then you're ready to go.mergere.0 installed. post an update to the book's errata page and fix the problem in subsequent editions of the book.com.
but not any simpler. Introducing Maven Introducing Maven This chapter covers: An overview of Maven • Maven's objectives • Maven's principles: • Convention over configuration • Reuse of build logic • Declarative execution • Coherent organization of dependencies • Maven's benefits • Things should be made as simple as possible.Albert Einstein Better Builds With Maven 15 . .1.
You may have been expecting a more straightforward answer. Maven can be the build tool you are looking for. and a piece of software used to manage and describe projects. From compilation. a repository format. testing. Maven provides the necessary abstractions that encourage reuse and take much of the work out of project builds.1. Maven 2. Too often technologists rely on abstract phrases to capture complex topics in three or four words. Maven Overview Maven provides a comprehensive approach to managing software projects. to documentation. distribution. This book focuses on the core tool produced by the Maven project. Don't worry. In addition to solving straightforward. It's the most obvious three-word definition of Maven the authors could come up with. and software. It provides a framework that enables easy reuse of common build logic for all projects following Maven's standards. you can stop reading now and skip to Chapter 2.1. 1. they will usually ask "What exactly is Maven?". first-order problems such as simplifying builds. If Maven isn't a "project management framework". When someone wants to know what Maven is. but this doesn't tell you much about Maven. and deploying project artifacts. It defines a standard life cycle for building. If you are reading this introduction just to find something to tell your manager1. but the term project management framework is a meaningless abstraction that doesn't do justice to the richness and complexity of Maven. Maven and the technologies related to the Maven project are beginning to have a transformative effect on the Java community. and many developers who have approached Maven as another build tool have come away with a finely tuned build system.Introducing Maven 1. What is Maven? Maven is a project management framework. documentation. If you are interested in a fuller. The Maven project at the Apache Software Foundation is an open source community which produces software tools that understand a common declarative Project Object Model (POM). standards. it will prime you for the concepts that are to follow. a framework that greatly simplifies the process of managing a software project. Perhaps you picked up this book because someone told you that Maven is a build tool. what is it? Here's one attempt at a description: Maven is a set of standards." Better Builds With Maven 16 . While you are free to use Maven as "just another build tool". to view it in such limited terms is akin to saying that a web browser is nothing more than a tool that reads hypertext. to team collaboration. and they expect a short. "Well it is a build tool or a scripting framework" Maven is more than three boring.1. to distribution. uninspiring words. richer definition of Maven read this introduction. Revolutionary ideas are often difficult to convey with words. 1 You can tell your manager: "Maven is a declarative project management tool that decreases your overall time to market by effectively leveraging your synergies. It simultaneously reduces your headcount and leads to remarkable operational efficiencies. Maven also brings with it some compelling second-order benefits. It is a combination of ideas. sound-bite answer. and with repetition phrases such as project management and enterprise software start to lose concrete meaning. and it is impossible to distill the definition of Maven to simply digested sound-bites. and the deployment process.
but different communities were creating different build systems of varied complexity and there was no reuse of build logic between projects. you will wonder how you ever developed without it. Once you get up to speed on the fundamentals of Maven. Etc. developers were building yet another build system.Introducing Maven As more and more projects and products adopt Maven as a foundation for project management. the barrier to entry for a project with a difficult build system was extremely high. Developers within the Turbine project could freely move between subcomponents. The build process for Tomcat was different from the build process used by Struts. It is a set of standards and an approach as much as it is a piece of software. the Codehaus community started to adopt Maven 1 as a foundation for project management. and it immediately sparked interest as a sort of Rosetta Stone for software project management. There were some common themes to each separate build. and Web site generation. projects such as Jakarta Taglibs had (and continue to have) a tough time attracting developer interest because it could take an hour to configure everything in just the right way. and started focusing on component development. The same effect extended to testing. and not just a replacement for Ant. Maven is not just a build tool. generating documentation. If developers spent time understanding how one project was built. they would not have to go through this process again when they moved on to the next project. 1. generating metrics and reports. Using Maven has made it easier to add external dependencies and publish your own components. Soon after the creation of Maven other projects. Make files and Ant are alternatives to Maven. and deploying. this copy and paste approach to build reuse reached a critical tipping point at which the amount of work required to maintain this collection of build systems was distracting from the central task of developing high-quality software. and package. Maven is about the application of patterns in order to facilitate project management through the reuse of common build strategies. Many people come to Maven familiar with Ant so it's a natural association. It is the next step in the evolution of how individuals and organizations collaborate to create software systems. test. People stopped figuring out creative ways to compile. the Turbine developers used a different approach to site generation than the developers of Jakarta Commons. Whereas Ant provides a toolbox for scripting builds. It is a way of approaching a set of software as a collection of interdependent components which can be described in a common format. Instead of focusing on creating good component libraries or MVC frameworks.1. it becomes easier to build relationships between projects and to build systems that navigate and report on these relationships. knowing clearly how they all worked just by understanding how one of them worked. distribution. such as Jakarta Commons. In addition. So to answer the original question: Maven is many things to many people. Maven's Origins Maven was borne of the practical desire to make several projects at the Apache Software Foundation (ASF) work in the same. every project at the ASF had a different approach to compilation.2. Maven entered the scene by way of the Turbine project. Maven's standards and central repository have defined a new naming system for projects. This lack of a common approach to building software meant that every new project tended to copy and paste another project's build system. The ASF was effectively a series of isolated islands of innovation. If you followed the Maven Way. Prior to Maven. Better Builds With Maven 17 . but Maven is an entirely different creature from Ant. Ultimately. Maven's standard formats enable a sort of "Semantic Web" for programming projects. your project gained a build by default. predictable way.
install) is effectively delegated to the POM and the appropriate plugins. and easier to comprehend. Maven's ability to standardize locations for source files. more maintainable. if your project currently relies on an existing Ant build script that must be maintained. and you gain access to expertise and best-practices of an entire industry. the car provides a known interface. An individual Maven project's structure and contents are declared in a Project Object Model (POM). test. 1. and much more transparent. referred to as "building the build". you can apply it to all projects. if you've learned how to drive a Jeep.1. assemble. and to retrieve project dependencies from a shared storage area makes the building process much less time consuming. and output. Much of the project management and build orchestration (compile. to provide a common layout for project documentation. Plugins allow developers to call existing Ant scripts and Make files and incorporate those existing functions into the Maven build life cycle. you can easily drive a Camry.3. Developers can build any given project without having to understand how the individual plugins work (scripts in the Ant world). The key value to developers from Maven is that it takes a declarative approach rather than developers creating the build process themselves. Maven allows developers to declare goals and dependencies and rely on Maven's default structures and plugin capabilities to build the project. When you purchase a new car. existing Ant scripts and Make files can be complementary to Maven and used through Maven's plugin architecture. and the software tool named Maven is just a secondary side-effect of this model. What Does Maven Provide? It provides a comprehensive model that can be applied to all software projects. You describe your project using Maven's model. and if you can apply a testing plugin to one project. Maven provides a useful abstraction in the same way an automobile provides an abstraction most of us are familiar with. which forms the basis of the entire Maven system. Maven takes a similar approach to software projects: if you can build one Maven project you can build them all. documentation.Introducing Maven However. Given the highly inter-dependent nature of projects in open source. Maven provides a common project "language". more reusable. Projects and systems that use this standard declarative approach tend to be more transparent. Maven provides you with: A comprehensive model for software projects • Tools that interact with this Declarative Model • Better Builds With Maven 18 .
• • • Without these characteristics. The definition of this term from the American Heritage dictionary captures the meaning perfectly: "Marked by an orderly.Maven is built upon a foundation of reuse. and aesthetically consistent relation of parts. home-grown build system. Maintainability .Introducing Maven Organizations and projects that adopt Maven benefit from: • Coherence . When code is not reused it is very hard to create a maintainable system.Maven lowers the barrier to reuse not only of build logic but of components. As a result you end up with a lack of shared knowledge along with the commensurate degree of frustration among team members. Agility . logical. When using Maven it is easier to create a component and integrate it into a multi-project build. When you adopt Maven you are effectively reusing the best practices of an entire industry. It is easier for developers to jump between different projects without a steep learning curve that accompanies a custom. there is little chance anyone is going to comprehend the project as a whole. This is a natural effect when processes don't work the same way for everyone. Maven projects are more maintainable because they have fewer surprises and follow a common model.Organizations that adopt Maven can stop building the build. When everyone is constantly searching to find all the different bits and pieces that make up a project.Maven allows organizations to standardize on a set of best practices. Without visibility it is unlikely one individual will know what another has accomplished and it is likely that useful code will not be reused. it is improbable that multiple individuals will work productively together on a project. Because Maven projects adhere to a standard model they are less opaque." Reusability . Better Builds With Maven 19 . and start focusing on the application.
Rails does.2. you gain an immense reward in terms of productivity that allows you to do more. but the use of these sensible default strategies is encouraged and should be strayed from only when absolutely necessary. sooner.Introducing Maven 1.2. This is not to say that you can't override them. Convention Over Configuration One of the central tenets of Maven is to provide sensible default strategies for the most common tasks so that you don't have to think about these mundane details. We have a ton of examples like that. This chapter will examine each of these principles in detail and these principles will be demonstrated in action in the following chapter when you create your first Maven project. It eschews placing the old ideals of software in a primary position. One characteristic of opinionated software is the notion of "convention over configuration". With Rails. If you follow basic conventions. and better at the application level. This notion is known as "convention over configuration" and has been popularized by the Ruby on Rails (ROR) community and specifically encouraged by ROR's creator David Heinemeier Hansson who summarizes the notion as follows: "Rails is opinionated software."2 2 O'Reilly interview with DHH Better Builds With Maven 20 . One of those ideals is flexibility. which all add up to make a huge difference in daily use. and I believe that's why it works. the notion that we should try to accommodate as many approaches as possible. As mentioned earlier Maven creates a sense of structure so that problems can be approached in terms of this structure. Maven's Principles According to Christopher Alexander "patterns help create a shared language for communicating insight and experience about problems and their solutions". you're rewarded by not having to configure that link. The following principles were inspired by Christopher Alexander's idea of creating a shared language: Convention over configuration • Declarative execution • Reuse of build logic • Coherent organization of dependencies • Maven provides a shared language for software development projects. Each of these principles allows developers to talk about their projects at a higher level of abstraction allowing more effective communication and allowing team members to get on with the important work of creating value at the application level. Well. that we shouldn't pass judgment on one form of development over another. such as classes are singular and tables are plural (a person class relates to a people table). The class automatically knows which table to use for persistence. you trade flexibility at the infrastructure level to gain flexibility at the application level. 1.1. If you are happy to work along the golden path that I've embedded in Rails.
generated output.Introducing Maven David Heinemeier Hansson articulates very well what Maven has aimed to accomplish since its inception (note that David Heinemeier Hansson in no way endorses the use of Maven. and you will make it easier to communicate about your project. and documentation. makes it easier to communicate to others. when you do this. It is a very simple idea but it can save you a lot of time. Standard directory layout for projects The first convention used by Maven is a standard directory layout for project sources. You can override any of Maven's defaults to create a directory layout of your choosing. These components are generally referred to as project content. and this is what Maven provides for you. or deploying. you will be able to adapt your project to your customized layout at a cost. Using standard conventions saves time. There are three primary conventions that Maven employs to promote a familiar development environment: Standard directory layout for projects • The concept of a single Maven project producing a single output • Standard naming conventions • Let's elaborate on each of these points in the following sections. project resources. All of these things should simply work. Better Builds With Maven 21 . In this case. he probably doesn't even know what Maven is and wouldn't like it if he did because it's not written in Ruby yet!). If you have no choice in the matter due to organizational policy or integration issues with existing systems you might be forced to use a directory structure that diverges from Maven's defaults. configuration files. even if you only look at a few new projects a year that's time better spent on your application. and allows you to create value in your applications faster with less effort. You shouldn't need to spend a lot of time getting your development infrastructure functioning. increased complexity of your project's POM. Follow the standard directory layout. With Maven you slot the various pieces in where it asks and Maven will take care of almost all of the mundane aspects for you. If you do have a choice then why not harness the collective knowledge that has built up as a result of using this convention? You will be able to look at other projects and immediately understand the project layout. you will be able to navigate within any Maven project you encounter in the future. You don't want to spend time fiddling with building. First time users often complain about Maven forcing you to do things a certain way and the formalization of the directory structure is the source of most of the complaints. but. You will see clear examples of the standard directory structure in the next chapter but you can also take a look in Appendix B for a full listing of the standard conventions. Maven encourages a common arrangement of project content so that once you are familiar with the standard locations. If this saves you 30 minutes for each new project you look at. generating documentation. you need to ask yourself if the extra configuration that comes with customization is really worth it.
is much easier to reuse. and some shared utility code. The intent behind the naming conventions employed by Maven is that you can tell exactly what you are looking at by. or concern. A simple example of the naming convention might be commons-logging-1. in a separate JAR file. which should be identified and separated to cope with complexity and to achieve the required engineering quality factors such as adaptability. This is illustrated in the Coherent Organization of Dependencies section.2 of Commons Logging. and a project for the shared utility code. It's happened to all of us and it doesn't have to. In this scenario the code contained in each separate project has a different role to play. The conventions provide clarity and immediate comprehension. If the JAR were named commonslogging. If you have placed all the sources together in a single project. maintainability. Better Builds With Maven 22 . the boundaries between our three separate concerns can easily become blurred and a simple desire to reuse the utility code could prove to be difficult. Maven pushes you to think clearly about the separation of concerns when setting up your projects because modularity leads to reuse. easy to see manner. looking at it. the server code. well. You could produce a single JAR file which contained all the compiled classes. It is immediately obvious that this is version 1.jar you would not really have any idea what version of Commons Logging you were dealing with and in a lot of cases not even the manifest in the JAR gives any indication.Introducing Maven One primary output per project The second convention used by Maven is the concept of a Maven project producing one primary output. Having the utility code in a separate project.jar are inherently flawed because there will come a time when something is misplaced and you'll track down a ClassNotFound exception which resulted from the wrong version of a JAR file being used. This is important if there are multiple projects involved. To illustrate this point consider a set of sources for a client/server-based application that contained the client code. a project for the server portion of the application. It doesn't make much sense to exclude pertinent information when you have it at hand to use. The separation of concerns (SoC) principle states that a given problem involves different kinds of concerns. a set of conventions really. because the naming convention keeps them separate in a logical. and they should be separated.2. later in this chapter. is a standard naming convention for directories and a standard naming convention for the primary output of a project. extendibility and reusability. but Maven would encourage you to have three separate projects: a project for the client portion of the application.2. Standard naming conventions The third convention. Systems that cannot cope with information rich artifacts like commons-logging-1.jar.
Maven's project object model (POM) Maven is project-centric by design. Maven encourages a separation of concerns because it promotes reuse. a plugin for creating Javadocs. and many others.Introducing Maven 1.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>184.108.40.206. Better Builds With Maven 23 . and the answer lies in Maven's implicit use of its Super POM.3. test.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. specifically from the plugin configurations contained in the POM. will ask how this is possible using a 15 line file. You. a plugin for running tests.0</modelVersion> <groupId>com. One important concept to keep in mind is that everything accomplished in Maven is the result of a plugin executing. Even from this short list of examples you can see that a plugin in Maven has a very specific role to play in the grand scheme of things. and the POM is Maven's description of a single project. 1. The POM below is an example of what you could use to build and test a project. It's a very good and essential question in fact.2. Declarative Execution Everything in Maven is driven in a declarative fashion using Maven's Project Object Model (POM) and specifically the plugin configurations contained in the POM. Maven is useless . being the observant reader.the POM is Maven's currency.2. It is the POM that drives execution in Maven and this approach can be described as model driven execution. The POM is an XML document and looks like the following (very) simplified example: <project> <modelVersion>4. Maven can be thought of as a framework which coordinates the execution of plugins in a well defined way. Reuse of Build Logic As you have already learned. The execution of Maven's plugins is coordinated by Maven's build life cycle in a declarative fashion with inputs from Maven's Project Object Model (POM). In Maven there is a plugin for compiling source code. Maven puts this principle into practice by encapsulating build logic into coherent modules called plugins.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM will allow you to compile. Plugins are the key building blocks for everything in Maven. a plugin for creating JARs. and generate basic documentation.mycompany. Without POM.
This element indicates the version of the artifact generated by the project. and during the build process for your project.apache.This element indicates the unique base name of the primary artifact being generated by this project. EAR. • • packaging . The groupId is one of the key identifiers of a project and is typically based on the fully qualified domain name of your organization. but also indicates a specific life cycle to use as part of the build process.This element indicates the package type to be used by this artifact (JAR. or other projects that use it as a dependency. all objects have the implicit parent of java.Object class. The Super POM can be rather intimidating at first glance so if you wish to find out more about it you can refer to Appendix B.This element indicates the unique identifier of the organization or group that created the project.lang. Maven goes a long way to help you with version management and you will often see the SNAPSHOT designator in a version. but still displays the key elements every POM contains. • version .html. WAR. Additional artifacts such as source bundles also use the artifactId as part of their file name. Better Builds With Maven 24 . modelVersion . etc. which indicates that a project is in a state of development.).<extension> (for example.jar).This element provides a basic description of your project. In Java. The life cycle is a topic dealt with later in the chapter. • • url .Object.This required element indicates the version of the object model this POM is using. WAR.org/maven-model/maven.plugins is the designated groupId for all Maven plugins. artifactId .This element indicates where the project's site can be found. For example org. The default value for the packaging element is jar so you do not have to specify this in most cases. This is often used in Maven's generated documentation. The POM shown above is a very simple POM.xml files. in Maven all POMs have an implicit parent which is Maven's Super POM.Introducing Maven Maven's Super POM carries with it all the default conventions that Maven encourages. A typical artifact produced by Maven would have the form <artifactId>-<version>.apache. just keep in mind that the selected packaging of a project plays a part in customizing the build life cycle. • • project . description .0. For a complete reference of the elements available for use in the POM please refer to the POM reference at http://maven. The POM contains every important piece of information about your project.lang.maven. but it is mandatory in order to ensure stability when Maven introduces new features or other model changes.This is the top-level element in all Maven pom. Likewise. This not only means that the artifact produced is a JAR. and is the analog of the Java language's java. myapp-1. or EAR. • name .This element indicates the display name used for the project. The key feature to remember is the Super POM contains important default information so you don't have to repeat this information in the POMs you create. The version of the model itself changes very infrequently. • groupId . For now.
artifacts and repositories work. or goals.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.0. and repositories. For example. generate-sources. you tell Maven that you want to compile.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. which is for Junit: <project> <modelVersion>4. 1. The actions you need to have performed are stated at a high level and Maven deals with the details behind the scenes. and compile phases will execute. or install. testing. The standard build life cycle consists of many phases and these can be thought of as extension points. Coherent Organization of Dependencies We are now going to delve into how Maven resolves dependencies and discuss the intimately connected concepts of dependencies. compilation.2. installation. the validate. Maven plugins provide reusable build logic that can be slotted into the standard build life cycle. Better Builds With Maven 25 .mycompany. packaging. When you need to add some functionality to the build life cycle you do so with a plugin. In "Maven-speak" an artifact is a specific piece of software.7 Using Maven Plugins for an example of customizing the Maven build. If you tell Maven to compile. It is important to note that each phase in the life cycle will be executed up to and including the phase you specify. or package. well-trodden path: preparation. but you may be asking yourself "Where does that dependency come from?" and "Where is the JAR?" The answers to those questions are not readily apparent without some explanation of how Maven dependencies. Any time you need to customize the way your project builds you either employ the use of an existing plugin or create a custom plugin for the task at hand. See Chapter 2. initialize. the build life cycle consists of a series of phases where each phase can perform one or more actions. If you recall. generate-resources. process-sources. The path that Maven moves along to accommodate an infinite variety of projects is called the build life cycle.4. artifacts.8.Introducing Maven Maven's build life cycle Software projects generally follow a similar. which is straightforward. related to that phase.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM states that your project has a dependency on JUnit. In Maven. For example. In Maven you do day-to-day work by invoking particular phases in this standard build life cycle.0</modelVersion> <groupId>com. our example POM has a single dependency listed. the compile phase invokes a certain set of goals to compile a set of classes. or test.
Maven transports it from that remote repository to your local repository for general use.jar: Better Builds With Maven 26 . Maven needs to know what repository to look in as well as the dependency's coordinates. A dependency is uniquely identified by the following identifiers: groupId. Maven has two types of repositories: local and remote. but when a declared dependency is not present in your local repository Maven searches all the remote repositories it has access to in an attempt to find what's missing. we can describe the process of dependency management as Maven reaching out into the world. Your project doesn't require junit-3.1 of the junit artifact produced by the junit group.jar.1. SAR. the most common artifact is a JAR file. you stop focusing on a collection of JAR files. artifactId and version. within the context of your project. In the POM you are not specifically telling Maven where the dependencies are physically. it depends on version 3. Maven tries to satisfy that dependency by looking in all of the remote repositories that are available. If a matching artifact is located. Local Maven repository When you install and run Maven for the first time your local repository will be created and populated with artifacts as a result of dependency requests. You must have a local repository in order for Maven to work. Dependency Management is one of the most easily understood and powerful features in Maven.Introducing Maven In Java.m2/repository. Maven usually interacts with your local repository. Read the following sections for specific details about where Maven searches for these dependencies.8. and providing this dependency to your software project. grabbing a dependency.1. When a dependency is declared. but a Java artifact could also be a WAR. A dependency is a reference to a specific artifact that resides in a repository. for artifacts that match the dependency request. Maven creates your local repository in ~/. By default. you are simply telling Maven what a specific project expects. instead you deal with logical dependencies. Maven takes the dependency coordinates you provide in a POM. The following folder structure shows the layout of a local Maven repository that has a few locally installed dependency artifacts such as junit-3. In order for Maven to attempt to satisfy a dependency.8. There is more going on behind the scenes. or EAR file. At a basic level.8. With Maven. but the key concept is that Maven dependencies are declarative. and it supplies these coordinates to its own internal dependency mechanisms.
In theory a repository is just an abstract storage mechanism.jar artifact that landed in your local repository. Above you can see the directory structure that is created when the JUnit dependency is resolved. On the next page is the general pattern used to create the repository layout: Better Builds With Maven 27 .Introducing Maven Figure 1-1: Artifact movement from remote to local repository Take a closer look at one of the artifacts that appeared in your local repository.8. but in practice the repository is a directory structure in your file system. We'll stick with our JUnit example and examine the junit-3. so you understand how the layout works.1.
apache. it will be fetched from a remote repository.org/maven2. the artifact is downloaded and installed in your local repository. Maven will attempt to find the artifact with a groupId of "junit".8. Locating dependency artifacts When satisfying dependencies. By default. If this file is not present. First.1.maven.1/junit-3.ibiblio.x then you would end up with a directory structure like the following: Figure 1-3: Sample directory structure In the first directory listing you can see that Maven artifacts themselves are stored in a directory structure that corresponds to Maven's groupId of org. for example.8.1" in ~/. Maven will attempt to download an artifact from each remote repository in the order defined in your POM.y. Once the dependency is satisfied.jar. Better Builds With Maven 28 . If your project's POM contains more than one remote repository. Maven will generate a path to the artifact in your local repository.8.m2/repository/junit/junit/3.Introducing Maven Figure 1-2: General pattern for the repository layout If the groupId is a fully qualified domain name (something Maven encourages) such as z. and a version of "3. Maven attempts to locate a dependency's artifact using the following process. Maven will attempt to fetch an artifact from the central Maven repository at http://www. artifactId of "junit".
you simply changed some configuration. if ever. it simplifies the process of development. it doesn't scale easily to support an application with a great number of small components. be a part of your thought process. While this approach works for a few projects.6 of the Spring Framework. Each project relies upon a specific artifact via the dependencies listed in a POM. there is no need to store the various spring JAR files in your project. To summarize. Before Maven. Using Maven is more than just downloading another JAR file and a set of scripts. in doing so. and they don't deserve to be versioned in an SCM.1. and. In other words. Maven is a framework. every project with a POM that references the same dependency will use this single copy installed in your local repository. rather than imposing one. and you would add these dependencies to your classpath. you would check in the 10-20 JAR files your project relies upon into a lib directory.jar for each project that needs it. Better Builds With Maven 29 . active open-source community that produces software focused on project management. Your local repository is one-stop-shopping for all artifacts that you need regardless of how many projects you are working on. With Maven. Like the engine in your car or the processor in your laptop. If you were coding a web application. all project referencing this dependency share a single copy of this JAR. Maven is also a vibrant. You don't have to worry about whether or not it's going to work.0 JARs to every project. and Maven is software. you don't have to jump through hoops trying to get it to work.Introducing Maven From this point forward. Maven provides such a technology for project management. Storing artifacts in your SCM along with your project may seem appealing but it is incompatible with the concept of small. shielding you from complexity and allowing you to focus on your specific task. modular project arrangements. and it is a trivial process to upgrade all of your ten web applications to Spring 2. Declare your dependencies and let Maven take care of details like compilation and testing classpaths. Maven is a set of standards.0 by change your dependency declarations.3. a useful technology just works. it is the adoption of processes that allow you to take your software development to the next level. you don't store a copy of junit3. Maven's Benefits A successful technology takes away a burden. it should rarely. 1. the common pattern in most project was to store JAR files in a project's subdirectory. Dependencies are not your project's code. Instead of adding the Spring 2. if your project has ten web applications which all depend on version 1. in the background.2. Maven is a repository.8.
.2. The terrible temptation to tweak should be resisted unless the payoff is really noticeable.Jon Bentley and Doug McIlroy Better Builds With Maven 30 . not battalions of special cases. Getting Started with Maven Getting Started with Maven This chapter covers: • • • • • • • Preparing to use Maven Creating your first project Compiling application sources Compiling test sources and running unit tests Packaging an installation to your local repository Handling classpath resources Using Maven plugins The key to performance is elegance.
it is assumed that you are a first time Maven user and have already set up Maven on your local system. If you have not set up Maven yet.mycompany.com</host> <port>8080</port> <username>your-username</username> <password>your-password</password> </proxy> </proxies> </settings> If Maven is already in use at your workplace. then you should be all set to create your first Maven project.xml file. create a <your-homedirectory>/. <settings> <mirrors> <mirror> <id>maven. ask your administrator if there if there is an internal Maven proxy.xml file will be explained in more detail in the following chapter and you can refer to the Maven Web site for the complete details on the settings. then you will have to set up Maven to understand that. To do this.m2/settings.com</id> <name>My Company's Maven Proxy</name> <url>http://maven. Better Builds With Maven 31 . If there is an active Maven proxy running.Getting Started with Maven 2. Preparing to Use Maven In this chapter. then please refer to Maven's Download and Installation Instructions before continuing. The settings. Depending on where your machine is located. so for now simply assume that the above settings will work. Create a <your-home-directory>/.mycompany.xml file with the following content: <settings> <proxies> <proxy> <active>true</active> <protocol>http</protocol> <host>proxy. then note the URL and let Maven know you will be using a proxy. If you are behind a firewall. it may be necessary to make a few more preparations for Maven to function correctly.xml file with the following content. Now you can perform the following basic check to ensure Maven is working correctly: mvn -version If Maven's version is displayed. Maven requires network access.com/maven2</url> <mirrorOf>central</mirrorOf> </mirror> </mirrors> </settings> In its optimal mode.mycompany.m2/settings.1.
0</modelVersion> <groupId>com.0.2.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.Getting Started with Maven 2. To create the Quick Start Maven project.8.mycompany. An archetype is defined as an original pattern or model from which all other things of the same kind are made.1</version> <scope>test</scope> </dependency> </dependencies> </project> At the top level of every project is your pom.app \ -DartifactId=my-app You will notice a few things happened when you executed this command. and this directory contains your pom. Better Builds With Maven 32 . First. you will use Maven's Archetype mechanism.mycompany. This chapter will show you how the archetype mechanism works.xml. please refer to the Introduction to Archetypes. Creating Your First Maven Project To create your first project. After the archetype generation has completed you will notice that the following directory structure has been created. you will notice that a directory named my-app has been created for the new project. but if you would like more information about archetypes. and it in fact adheres to Maven's standard directory layout discussed in Chapter 1.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven.apache.xml file. which looks like the following: <project> <modelVersion>4. In Maven. an archetype is a template of a project.xml file you know you are dealing with a Maven project. Whenever you see a directory structure which contains a pom. execute the following: C:\mvnbook> mvn archetype:create -DgroupId=com.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. which is combined with some user input to produce a fullyfunctional Maven project.
note that manifest in this one simple command are Maven's four foundational principles: Convention over configuration • Reuse of build logic • Declarative execution • Coherent organization of dependencies • These principles are ingrained in all aspects of Maven. but the following analysis of the simple compile command shows you the four principles in action and makes clear their fundamental importance in simplifying the development of a project. ${basedir}. Compiling Application Sources As mentioned in the introduction. in one fell swoop.3. and deploying the project (source files. you will compile your application sources using the following command: C:\mvnbook\my-app> mvn compile Better Builds With Maven 33 . documenting. Change into the <my-app> directory. at a very high level. in a declarative way. Now that you have a POM. but later in the chapter you will see how the standard directory layout is employed for other project content. configuration files. various descriptors such as assembly descriptors. some application sources. In this first stage you have Java source files only. you are ready to build your project. and so on). testing. you tell Maven what you need.Getting Started with Maven Figure 2-1: Directory structure after archetype generation The src directory contains all of the inputs required for building. in order to accomplish the desired task. Before you issue the command to compile the application sources. and some test sources. Then. 2. The <my-app> directory is the base directory. the site. for the my-app project.
Although you now know that the compiler plugin was used to compile the application sources. Even the simplest of POMs knows the default location for application sources. This default value (though not visible in the POM above) was. but there is very little reason to do so. Instead. is target/classes. in the first place? You might be guessing that there is some background process that maps a simple command to a particular plugin. application sources are placed in src/main/java. The same holds true for the location of the compiled classes which.Getting Started with Maven After executing this command you should see output similar to the following: [INFO-------------------------------------------------------------------[INFO] Building Maven Quick Start Archetype [INFO] task-segment: [compile] [INFO]------------------------------------------------------------------[INFO] artifact org. now you know how Maven finds application sources. The standard compiler plugin. how was Maven able to decide to use the compiler plugin. So. Better Builds With Maven 34 . in fact. override this default location. The next question is. if you poke around the standard Maven installation.plugins:maven-compiler-plugin: checking for updates from central .maven. How did Maven know where to look for sources in order to compile them? And how did Maven know where to put the compiled classes? This is where Maven's principle of "convention over configuration" comes into play. you won't find the compiler plugin since it is not shipped with the Maven distribution.. [INFO] [resources:resources] . You can. how was Maven able to retrieve the compiler plugin? After all. is the tool used to compile your application sources.. inherited from the Super POM. [INFO] artifact org. Maven downloads plugins when they are needed. what Maven uses to compile the application sources. In fact.. of course. along with its default configuration. [INFO] [compiler:compile] Compiling 1 source file to c:\mvnbook\my-app\target\classes [INFO]------------------------------------------------------------------[INFO] BUILD SUCCESSFUL [INFO]------------------------------------------------------------------[INFO] Total time: 3 minutes 54 seconds [INFO] Finished at: Fri Sep 23 15:48:34 GMT-05:00 2005 [INFO] Final Memory: 2M/6M [INFO]------------------------------------------------------------------- Now let's dissect what actually happened and see where Maven's four principles come into play with the execution of this seemingly simple command..plugins:maven-resources-plugin: checking for updates from central . By default.apache. and how Maven invokes the compiler plugin.. there is a form of mapping and it is called Maven's default build life cycle. What actually compiled the application sources? This is where Maven's second principle of "reusable build logic" comes into play..apache. This means you don't have to state this location at all in any of your POMs. by default. if you use the default location for application sources.maven. The same build logic encapsulated in the compiler plugin will be executed consistently across any number of projects.
it took almost 4 minutes with a broadband connection). or where your output should go. it won't download anything new. Maven will download all the plugins and related dependencies it needs to fulfill the command. the compiled classes were placed in target/classes. The next time you execute the same command again. If you're a keen observer you'll notice that using the standard conventions makes the POM above very small. As you can see from the output. Maven will execute the command much quicker. because Maven already has what it needs. Therefore. which is specified by the standard directory layout. and eliminates the requirement for you to explicitly tell Maven where any of your sources are. By following the standard Maven conventions you can get a lot done with very little effort! Better Builds With Maven 35 .Getting Started with Maven The first time you execute this (or any other) command. From a clean installation of Maven this can take quite a while (in the output above.
plugins:maven-surefire-plugin: checking for updates from central .maven.. programmers always write and execute their own unit tests *nudge nudge. This implies that all prerequisite phases in the life cycle will be performed to ensure that testing will be successful. Failures: 0. [INFO] [surefire:test] [INFO] Setting reports dir: C:\Test\Maven2\test\my-app\target/surefire-reports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running com. Time elapsed: 0 sec Results : [surefire] Tests run: 1. Errors: 0.Getting Started with Maven 2.apache. Use the following simple command to test: C:\mvnbook\my-app> mvn test After executing this command you should see output similar to the following: [INFO]------------------------------------------------------------------[INFO] Building Maven Quick Start Archetype [INFO] task-segment: [test] [INFO]------------------------------------------------------------------[INFO] artifact org. Failures: 0.app. Again.mycompany. Errors: 0 [INFO]------------------------------------------------------------------[INFO] BUILD SUCCESSFUL [INFO]------------------------------------------------------------------[INFO] Total time: 15 seconds [INFO] Finished at: Thu Oct 06 08:12:17 MDT 2005 [INFO] Final Memory: 2M/8M [INFO]------------------------------------------------------------------- Better Builds With Maven 36 . simply tell Maven you want to test your sources.AppTest [surefire] Tests run: 1. Compiling Test Sources and Running Unit Tests Now that you're successfully compiling your application's sources.all classes are up to date [INFO] [resources:testResources] [INFO] [compiler:testCompile] Compiling 1 source file to C:\Test\Maven2\test\my-app\target\test-classes .. you probably have unit tests that you want to compile and execute as well (after all.. [INFO] [resources:resources] [INFO] [compiler:compile] [INFO] Nothing to compile .4.. wink wink*).
remember that it isn't necessary to run this every time. compile the tests. The directory <your-homedirectory>/. you'll want to move on to the next logical step. you'll want to install the artifact (the JAR file) you've generated into your local repository. Now. and execute the tests. execute the following command: C:\mvnbook\my-app> mvn install Better Builds With Maven 37 . This is how Maven knows to produce a JAR file from the above command (you'll read more about this later). Now that you can compile the application sources. Maven compiles the main code (all these classes are up-to-date. how to package your application. Take a look in the the target directory and you will see the generated JAR file. These are the dependencies and plugins necessary for executing the tests (recall that it already has the dependencies it needs for compiling and won't download them again). you will notice the packaging element is set to jar. • If you simply want to compile your test sources (but not execute the tests). 2.m2/repository is the default location of the repository.Getting Started with Maven Some things to notice about the output: Maven downloads more dependencies this time. mvn test will always run the compile and test-compile phases first. as well as all the others defined before it. It can then be used by other projects as a dependency.5. To install. since we haven't changed anything since we compiled last). Packaging and Installation to Your Local Repository Making a JAR file is straightforward and can be accomplished by executing the following command: C:\mvnbook\my-app> mvn package If you take a look at the POM for your project. you can execute the following command: C:\mvnbook\my-app> mvn test-compile However. • Before compiling and executing the tests.
java • Conversely. this covers the majority of tasks users perform. the following tests are included: **/*Test. For projects that are built with Maven. Better Builds With Maven 38 . Errors: 0 [INFO] [jar:jar] [INFO] Building jar: <dir>/my-app/target/my-app-1. Failures: 0.AppTest [surefire] Tests run: 1.jar to <localrepository>\com\mycompany\app\my-app\1.0-SNAPSHOT\my-app-1. the following tests are excluded: **/Abstract*Test.0-SNAPSHOT. there is far more functionality available to you from Maven without requiring any additions to the POM.0-SNAPSHOT.app. and if you've noticed. testing.Getting Started with Maven Upon executing this command you should see the following output: [INFO]------------------------------------------------------------------[INFO] Building Maven Quick Start Archetype [INFO] task-segment: [install] [INFO]------------------------------------------------------------------[INFO] [resources:resources] [INFO] [compiler:compile] Compiling 1 source file to <dir>/my-app/target/classes [INFO] [resources:testResources] [INFO] [compiler:testCompile] Compiling 1 source file to <dir>/my-app/target/test-classes [INFO] [surefire:test] [INFO] Setting reports dir: <dir>/my-app/target/surefire-reports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running com.java • **/Abstract*TestCase.001 sec Results : [surefire] Tests run: 1.java • **/*TestCase. Of course.jar [INFO] [install:install] [INFO] Installing c:\mvnbook\my-app\target\my-app-1. to get any more functionality out of an Ant build script. building.0-SNAPSHOT. as it currently stands. Time elapsed: 0. everything done up to this point has been driven by an 18-line POM. Failures: 0.java • You have now completed the process for setting up. By default. Errors: 0. packaging.mycompany. and installing a typical Maven project.jar [INFO]------------------------------------------------------------------[INFO] BUILD SUCCESSFUL [INFO]------------------------------------------------------------------[INFO] Total time: 5 seconds [INFO] Finished at: Tue Oct 04 13:20:32 GMT-05:00 2005 [INFO] Final Memory: 3M/8M [INFO]------------------------------------------------------------------- Note that the Surefire plugin (which executes the test) looks for tests contained in files with a particular naming convention. In contrast.java • **/Test*. you must keep making error-prone additions.
Or. there are a great number of Maven plugins that work out of the box. This chapter will cover one in particular.Getting Started with Maven So. Without any work on your part. Perhaps you'd like to generate an IntelliJ IDEA descriptor for the project: C:\mvnbook\my-app> mvn idea:idea This can be run over the top of a previous IDEA project. simply execute the following command: C:\mvnbook\my-app> mvn site There are plenty of other stand-alone goals that can be executed as well. this POM has enough information to generate a Web site for your project! Though you will typically want to customize your Maven site. In this case. given Maven's re-usable build logic? With even the simplest POM. what other functionality can you leverage. it will update the settings rather than starting fresh. alternatively you might like to generate an Eclipse descriptor: C:\mvnbook\my-app> mvn eclipse:eclipse Better Builds With Maven 39 . if you're pressed for time and just need to create a basic Web site for your project. so it is fresh. as it is one of the highly-prized features in Maven. for example: C:\mvnbook\my-app> mvn clean This will remove the target directory with the old build data before starting.
Handling Classpath Resources Another common use case which requires no changes to the POM shown previously. That is where you place any resources you wish to package in the JAR. For this common task. Figure 2-2: Directory structure after adding the resources directory You can see in the preceding example that there is a META-INF directory with an application.properties file within that directory. In the example following.6. is the packaging of resources into a JAR file. simply by placing those resources in a standard directory structure. you need to add the directory src/main/resources. Maven again uses the standard directory layout.Getting Started with Maven 2. The rule employed by Maven is that all directories or files placed within the src/main/resources directory are packaged in your JAR with the exact same structure. starting at the base of the JAR. you can package resources within JARs. If you unpacked the JAR that Maven created you would see the following: Better Builds With Maven 40 . This means that by adopting Maven's standard conventions.
except place resources in the src/test/resources directory. You can create your own manifest if you choose. as well as a pom. but the properties can be utilized using the standard Java APIs. At this point you have a project directory structure that should look like the following: Better Builds With Maven 41 .MF. Then run mvn install and examine the jar file in the target directory. simply create the resources and META-INF directories and create an empty file called application. Handling Test Classpath Resources To add resources to the classpath for your unit tests. If you would like to try this example. One simple use might be to retrieve the version of your application. 2.properties file is there in the META-INF directory.xml and pom. but Maven will generate one by default if you don't.properties file.6.properties files are packaged up in the JAR so that each artifact produced by Maven is self-describing and also allows you to utilize the metadata in your own application. The pom.xml and pom.xml inside. You will also notice some other files there like META-INF/MANIFEST.Getting Started with Maven Figure 2-3: Directory structure of the JAR file created by Maven The original contents of src/main/resources can be found starting at the base of the JAR and the application. Operating on the POM file would require you to use Maven utilities.1. These come standard with the creation of a JAR in Maven. follow the same pattern as you do for adding resources to the JAR. should the need arise.
properties" )....] To override the manifest file yourself.maven.Getting Started with Maven Figure 2-4: Directory structure after adding test resources In a unit test.] // Retrieve resource InputStream is = getClass().apache. // Do something with the resource [..MF</manifestFile> </archive> </configuration> </plugin> Better Builds With Maven 42 .getResourceAsStream( "/test.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <configuration> <archive> <manifestFile>META-INF/MANIFEST. you can use the follow configuration for the maven-jarplugin: <plugin> <groupId>org. you could use a simple snippet of code like the following for access to the resource required for testing: [.
So ${project.Getting Started with Maven 2. you can filter your resource files dynamically by putting a reference to the property that will contain the value into your resource file using the syntax ${<property name>}.version} refers to the version of the project. To have Maven filter resources when copying.apache. ${project.8. Filtering Classpath Resources Sometimes a resource file will need to contain a value that can be supplied at build time only.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.xml.1</version> <scope>test</scope> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> </project> You'll notice that the build. In fact.xml.mycompany.xml.build. whose values will be supplied when the resource is filtered as follows: # application. which weren't there before.0.name} application.name} refers to the name of the project. resources. All of this information was previously provided as default values and now must be added to the pom.version=${project.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven. when the built project is packaged. To continue the example.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. any element in your POM is available when filtering resources.finalName} refers to the final name of the file created. and resource elements have been added. The property can be either one of the values defined in your pom.name=${project. the POM has to explicitly state that the resources are located in the src/main/resources directory.properties application.xml: <project> <modelVersion>4. To reference a property defined in your pom. and ${project. or a system property.2.6.0</modelVersion> <groupId>com.properties file. create an src/main/resources/application. In addition. a value defined in the user's settings.version} Better Builds With Maven 43 . the property name uses the names of the XML elements that define the value. a property defined in an external properties file. To accomplish this in Maven. simply set filtering to true for the resource directory in your pom.xml to override the default value for filtering and set it to true.
.] Then.value=hello! Next.properties application.properties</filter> </filters> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> [.value property in an external file.properties file under target/classes.filter...xml file: [.properties. you can execute the following command (process-resources is the build life cycle phase where the resources are copied and filtered): mvn process-resources The application.properties application. all you need to do is add a reference to this external file in your pom.version} message=${my. add a reference to this new file in the pom. create an external properties file and call it src/main/filters/filter.filter.filter. As an alternative to defining the my.name=Maven Quick Start Archetype application.properties: # filter.version=${project.0-SNAPSHOT To reference a property defined in an external file.] <build> <filters> <filter>src/main/filters/filter.name} application. First.value} The next execution of the mvn process-resources command will put the new property value into application.properties file as follows: # application..version=1.properties my. which will eventually go into the JAR looks like this: # application.xml and you'd get the same effect (notice you don't need the references to src/main/filters/filter. you could have defined it in the properties section of your pom.Getting Started with Maven With that in place.properties either): Better Builds With Maven 44 .name=${project.xml. add a reference to this property in the application.
prop=${command. change the application.prop=hello again" 2.properties java.0.filter. If you had a src/main/resources/images that you didn't want to be filtered.apache. with filtering disabled.home). then you would create one resource entry that handled the filtering of resources with an exclusion on the resources you wanted unfiltered.Getting Started with Maven <project> <modelVersion>4.filter.1</version> <scope>test</scope> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> <properties> <my. for example image files.line.line. and an inclusion of your images directory.3.properties file will contain the values from the system properties. Preventing Filtering of Binary Resources Sometimes there are classpath resources that you want included in your JAR.8. mvn process-resources "-Dcommand. when you execute the following command (note the definition of the command.6.version} command.version=${java.prop property on the command line).app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.line. The build element would look like the following: Better Builds With Maven 45 .0</modelVersion> <groupId>com.prop} Now. but you do not want them filtered.value>hello</my. In addition you would add another resource entry. the application.line.value> </properties> </project> Filtering resources can also retrieve values from system properties. either the system properties built into Java (like java.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven.properties file to look like the following: # application.mycompany.version or user.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. or properties defined on the command line using the standard Java -D parameter. This is most often the case with binary resources. To continue the example.
. <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> <excludes> <exclude>images/**</exclude> </excludes> </resource> <resource> <directory>src/main/resources</directory> <includes> <include>images/**</include> </includes> </resource> </resources> </build> .. </project> Better Builds With Maven 46 .Getting Started with Maven <project> ...
or settings.. To illustrate the similarity between plugins and dependencies.. Better Builds With Maven 47 . <build> <plugins> <plugin> <groupId>org. but if you find something has changed . This plugin will be downloaded and installed automatically.apache. In the above case.maven. the groupId and version elements have been shown. This is as simple as adding this following to your POM: <project> .0 sources. If you do not specify a version then Maven will attempt to use the latest released version of the specified plugin. If you do not specify a groupId. </project> You'll notice that all plugins in Maven 2 look very similar to a dependency.apache. then Maven will default to looking for the plugin with the org. you may want to configure the Java compiler to allow JDK 5.7.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2. if it is not present on your local system.codehaus.Getting Started with Maven 2. The configuration element applies the given parameters to every goal from the compiler plugin.5</target> </configuration> </plugin> </plugins> </build> . For the most part. but in most cases these elements are not required. you must include additional Maven plugins.plugins or the org. in much the same way that a dependency would be handled.0</version> <configuration> <source>1. but you may want to specify the version of a plugin to ensure reproducibility. You can specify an additional groupId to search within your POM.and in some ways they are.. the compiler plugin is already used as part of the build process and this just changes the configuration. or configure parameters for the plugins already included in the build. to customize the build for a Maven project. Using Maven Plugins As noted earlier in the chapter..xml.maven. This is often the most convenient way to use a plugin. plugin developers take care to ensure that new versions of plugins are backward compatible so you are usually OK with the latest release.mojo groupId label. For example.you can lock down a specific version.5</source> <target>1.
you have gained access to every single project using Maven. By learning how to build a Maven project.maven. use the following command: mvn help:describe -DgroupId=org. You should also have some insight into how Maven handles dependencies and provides an avenue for customization using Maven plugins. use the mvn help:describe command. In seventeen pages. you should be up and running with Maven. Better Builds With Maven 48 . If you were just looking for a build tool. You might need to refer to the next chapter for more information about customizing your build to fit your project's unique needs.apache. 2.8.plugins \ -DartifactId=maven-compiler-plugin -Dfull=true You can also find out what plugin configuration is available by using the Maven Plugin Reference section at http://maven. and packaging a project. If you are interested in learning how Maven builds upon the concepts introduced in the Introduction and the practical tools introduced in Chapter 2. If someone throws a Maven project at you. read on. testing a project.org/plugins/ and navigating to the plugin and goal you are using. If you want to see the options for the maven-compiler-plugin shown previously. You've learned a new language and you've taken Maven for a test drive. you've seen how you can use Maven to build your project. compiling a project. Summary After reading this second chapter.Getting Started with Maven If you want to find out what the plugin's configuration options are.apache. you could safely stop reading this book now. you'll know how to exercise the basic features of Maven: creating a project. The next few chapters provide you with the tools to customize Maven's behavior and use Maven to manage interdependent software projects.
Berard Better Builds With Maven 49 .3.Edward V. . Creating Applications with Maven Creating Applications with Maven This chapter covers: • • • • • • • • • • Setting Up an Application Directory Structure Using Project Inheritance Managing Dependencies Using Snapshots Using Version Ranges Managing Plugins Utilizing the Build Life Cycle Using Profiles Deploying your Application Creating a Web Site for your Application Walking on water and developing software from a specification are easy if both are frozen.
a necessary goal for every software development project. The application that you are going to create is called Proficio. Proficio has a very simple memory-based store and a simple XStream-based store. more manageable and comprehensible parts. The only real criterion to which to adhere is that your team has a single convention. you will see that the Proficio sample application is made up of several modules: Proficio Model: The data model for the Proficio application. goal. • Proficio Core: The implementation of the API. • • Proficio CLI: The code which provides a command line interface to Proficio. So. Concerns are the primary motivation for organizing and decomposing software into smaller. The interfaces for the APIs of major components. you can see in the modules element all the modules that make up the Proficio application. lets start by discussing the ideal directory structure for Proficio. The guiding principle in determining how best to decompose your application is called the Separation of Concerns (SoC). In this chapter. 3. • Proficio Stores: The module which itself houses all the store modules. task. and they clearly understand that convention. and modular builds. As such. or purpose. Introduction In the second chapter you stepped though the basics of setting up a simple project. Now you will delve in a little deeper. you are going to learn about some of Maven's best practices and advanced uses by working on a small application to manage frequently asked questions (FAQ). each of which addresses one or more concerns. This setup is typically referred to as a multi-module build and this is how it looks in the top-level Proficio POM: Better Builds With Maven 50 . In examining the top-level POM for Proficio. and operate on the pieces of software that are relevant to a particular concept. which enable code reusability. These are default naming conventions that Maven uses. which consists of a set of interfaces. which really means a reference to another POM. A module is a reference to another Maven project. which is Latin for "help". using a real-world example.Creating Applications with Maven 3.1. but you are free to name your modules in any fashion your team decides. The natural outcome of this practice is discrete and coherent components. encapsulate. In doing so you will be guided through the specifics of setting up an application and managing that structure. SoC refers to the ability to identify. • Proficio API: The application programming interface for Proficio. like the store. are also kept here. which consists of all the classes that will be used by Proficio as a whole. it is important to keep in mind that Maven emphasizes the practice of discrete.2. and can easily identify what a particular module does simply by looking at its name. coherent. Setting Up an Application Directory Structure In setting up the directory structure for Proficio.
0</modelVersion> <groupId>org.org</url> .apache.. You should take note of the packaging element...x these were commonly referred to as multi-project builds and some of this vestigial terminology carried over to the Maven 2. If you were to look at Proficio's directory structure you would see the following: Figure 3-1: Proficio directory structure Better Builds With Maven 51 . For an application that has multiple modules it is very common that you will release all the modules together and so it makes sense that all the modules have a common application version.proficio</groupId> <artifactId>proficio</artifactId> <packaging>pom</packaging> <version>1. the packaging must be set to value of pom: this tells Maven that you're going to be walking through a set of modules in a structure similar to the example being covered here.. <modules> <module>proficio-model</module> <module>proficio-api</module> <module>proficio-core</module> <module>proficio-stores</module> <module>proficio-cli</module> </modules> . which has a value of pom.maven. Currently there is some variance on the Maven web site when referring to directory structures that contain more than one Maven project. For POMs that contain modules. In Maven 1.0-SNAPSHOT</version> <name>Maven Proficio</name> <url>http://maven. but the Maven team is now trying to consistently refer to these setups as multimodule builds.0-SNAPSHOT. </project> An important feature to note in the POM above is the value of the version element.apache. It is recommended that you specify the application version in the top-level POM and use that version across all the modules that make up your application.0.Creating Applications with Maven <project> <modelVersion>4. which you can see is 1.x documentation.
apache.0-SNAPSHOT</version> </parent> <modelVersion>4.maven. which is the proficio-stores module.proficio</groupId> <artifactId>proficio</artifactId> <version>1. Looking at the module names is how Maven steps into the right directory to process the POM located there. If you take a look at the POM for the proficio-stores module you will see a set of modules contained there: <project> <parent> <groupId>org.0.0</modelVersion> <artifactId>proficio-stores</artifactId> <name>Maven Proficio Stores</name> <packaging>pom</packaging> <modules> <module>proficio-store-memory</module> <module>proficio-store-xstream</module> </modules> </project> Examine the directory structure inside the proficio-stores directory and you will see the following: Figure 3-2: Proficio-stores directory Better Builds With Maven 52 . but the interesting thing here is that we have another project with a packaging type of pom.Creating Applications with Maven You may have noticed that the module elements in the POM match the names of the directories that you see above in the Proficio directory structure. Let's take a quick look at the modules and examine the packaging for each of them: Table 3-1: Module packaging types Module Packaging proficio-api proficio-cli proficio-core proficio-model proficio-stores jar jar jar jar pom The packaging type in most cases is the default of jar.
. If you look at the top-level POM for Proficio. This is the snippet in each of the POMs that lets you draw on the resources stated in the specified toplevel POM and from which you can inherit down to any level you wish . 3. note specifically there is no visible dependency declaration for JUnit: Better Builds With Maven 53 . you will see that in the dependencies section there is a declaration for JUnit version 3..proficio</groupId> <artifactId>proficio</artifactId> <version>1..all in a single place.1. Let's examine a case where it makes sense to put a resource in the top-level POM. <parent> <groupId>org. in any of your child POMs.Creating Applications with Maven Whenever Maven sees a POM with a packaging of type pom Maven knows to look for a set of modules and to then process each of those modules... just as has been done with Proficio's multiple storage mechanisms. So. The dependency is stated as following: <project> . </project> What specifically happens for each child POM. by stating the dependency in the top-level POM once.apache..0-SNAPSHOT</version> </parent> . Being the observant user. In this case the assumption being made is that JUnit will be used for testing in all our child projects. So. state your deployment information. Using Project Inheritance One of the most powerful features in Maven is project inheritance. You can nest sets of projects like this to any level.maven. <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. is that each one inherits the dependencies section of the top-level POM. if you take a look at the POM for the proficio-core module you will see the following. using our top-level POM for the sample Proficio application. Using project inheritance allows you to do things like state your organizational information.. or state your common dependencies . organizing your projects in groups according to concern..enabling you to add resources where it makes sense in the hierarchy of your projects. which are all placed in one directory. you never have to declare this dependency again.8. you have probably taken a peek at all the POMs in each of the projects that make up the Proficio project and noticed the following at the top of each of the POMs: .8.3.1</version> <scope>test</scope> </dependency> </dependencies> .
<dependencies> .. <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3..0-SNAPSHOT</version> </parent> <modelVersion>4.proficio</groupId> <artifactId>proficio-api</artifactId> </dependency> <dependency> <groupId>org.0</modelVersion> <artifactId>proficio-core</artifactId> <packaging>jar</packaging> <name>Maven Proficio Core</name> <dependencies> <dependency> <groupId>org.8. which in turn inherits from the Super POM. Better Builds With Maven 54 .plexus</groupId> <artifactId>plexus-container-default</artifactId> </dependency> </dependencies> </project> In order for you to see what happens during the inheritance process you will need to use the handy mvn help:effective-pom command.proficio</groupId> <artifactId>proficio</artifactId> <version>1.apache..maven. </project> You will have noticed that the POM that you see when using the mvn help:effective-pom is bigger than you expected.1</version> <scope>test</scope> </dependency> . take a look at the resulting POM you will see the JUnit version 3. So in this case. This command will show you the final result for a target POM.1 dependency: <project> ....codehaus. After you move into the proficio-core module and run the command.apache. But remember from Chapter 2 that the Super POM sits at the top of the inheritance hierarchy.8. </dependencies> .0.maven.Creating Applications with Maven <project> <parent> <groupId>org. Looking at the effective POM includes everything and is useful to view when trying to figure out what is going on when you are having problems. the proficio-core project inherits from the toplevel Proficio project...
When you write applications which consist of multiple.Creating Applications with Maven 3. you use the dependency management section in the top-level POM of an application. <dependencyManagement> <dependencies> <dependency> <groupId>org.proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project.apache. In order to manage. which is the application version..0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> .. across all of your projects are in alignment so that your testing accurately reflects what you will deploy as your final result.proficio</groupId> <artifactId>proficio-core</artifactId> <version>${project. to end up with multiple versions of a dependency on the classpath when your application executes. individual projects.. versions of dependencies across several projects. You want to make sure that all the versions.version}</version> </dependency> <dependency> <groupId>org.. You don't want. To illustrate how this mechanism works. or align.apache. as the results can be far from desirable.version} specification is the version specified by the top-level POM's version element. Better Builds With Maven 55 . it is likely that some of those projects will share common dependencies.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1.codehaus.version}</version> </dependency> <dependency> <groupId>org. so that the final application works correctly.maven. Managing Dependencies When you are building applications you have many dependencies to manage and the number of dependencies only increases over time. Maven's strategy for dealing with this problem is to combine the power of project inheritance with specific dependency management elements in the POM. making dependency management difficult to say the least.maven. When this happens it is critical that the same version of a given dependency is used for all your projects.version}</version> </dependency> <dependency> <groupId>org.maven.apache.4. </project> Note that the ${project. let's look at the dependency management section of the Proficio top-level POM: <project> . for example. of all your dependencies.
The dependencies element contained within the dependencyManagement element is used only to state the preference for a version and by itself does not affect a project's dependency graph. whereas the top-level dependencies element does affect the dependency graph. The dependencyManagement declares a stated preference for the 1. There is an important distinction to be made between the dependencies element contained within the dependencyManagment element and the top-level dependencies element in the POM.0-SNAPSHOT (stated as ${project..proficio</groupId> <artifactId>proficio-model</artifactId> </dependency> </dependencies> </project> The version for this dependency is derived from the dependencyManagement element which is inherited from the Proficio top-level POM.Creating Applications with Maven As you can see within the dependency management section we have several Proficio dependencies and a dependency for the Plexus IoC container.maven.apache.. you will see a single dependency declaration and that it does not specify a version: <project> . <dependencies> <dependency> <groupId>org.version}) for proficio-model so that version is injected into the dependency above. If you take a look at the POM for the proficio-api module. to make it complete. Better Builds With Maven 56 . The dependencies stated in the dependencyManagement only come into play when a dependency is declared without a version.
A snapshot in Maven is an artifact which has been prepared using the most recent sources available.maven.version}</version> </dependency> <dependency> <groupId>org..codehaus.apache.5. Snapshot dependencies are assumed to be changing.maven. but you can use the -U command line option to force the search for updates..proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project. Better Builds With Maven 57 . it is usually the case that each of the modules are in flux. By default Maven will look for snapshots on a daily basis.0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> . or you may be doing some refactoring.0-SNAPSHOT</version> <dependencyManagement> <dependencies> <dependency> <groupId>org.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project. Using Snapshots While you are developing an application with multiple modules. When you specify a non-snapshot version of a dependency Maven will download that dependency once and never attempt to retrieve it again. If you look at the top-level POM for Proficio you will see a snapshot version specified: <project> .apache. Controlling how snapshots work will be explained in detail in Chapter 7. so Maven will attempt to update them.version}</version> </dependency> <dependency> <groupId>org.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1.Creating Applications with Maven 3. Your build system needs to be able to deal easily with this real-time flux. and this is where Maven's concept of a snapshot comes into play.. Your APIs might be undergoing some change or your implementations are undergoing change and are being fleshed out. <version>1. </project> Specifying a snapshot version for a dependency means that Maven will look for new versions of that dependency without you having to manually specify a new version..
0-SNAPSHOT (selected for compile) plexus-utils:1. the version selected is the one declared "nearest" to the top of the tree .4 (selected for compile) classworlds:1..1 (selected for test) plexus-container-default:1. local scope test wins) proficio-api:1.9 in Chapter 6).0-SNAPSHOT (selected for compile) proficio-model:1. To manually resolve conflicts. For example. In Maven 2.that is.1 be used. and to allow Maven to calculate the full dependency graph. plexus-utils occurs twice. Maven must choose which version to provide. you can remove the incorrect version from the tree. if you run mvn -X test on the proficio-core module. you can exclude the dependency from the graph by adding an exclusion to the dependency that introduced it. A dependency in the POM being built will be used over anything else. this has limitations: The version chosen may not have all the features required by the other dependency. Resolving Dependency Conflicts and Using Version Ranges With the introduction of transitive dependencies in Maven 2. In this example. see section 6. and more importantly ways to avoid it as the author of a reusable library. To ensure this.6. However. • If multiple versions are selected at the same depth. and Proficio requires version 1. to compile. there are ways to manually resolve these conflicts as the end user of a dependency.8. as the graph grows.1-alpha-2 (selected for compile) junit:3. the output will contain something similar to: proficio-core:1.1 (selected for compile) Once the path to the version has been identified. it is inevitable that two or more artifacts will require different versions of a particular dependency. or you can override both with the correct version.0-alpha-9 (selected for compile) plexus-utils:1. However. then the result is undefined. In this case.8.Creating Applications with Maven 3. modify the plexus-container-default dependency in the proficio-core/pom.1 (not setting.0. • While further dependency management features are scheduled for the next release of Maven at the time of writing.0-SNAPSHOT junit:3. the least number of dependencies that were traversed to get this version.xml file as follows: Better Builds With Maven 58 . it became possible to simplify your own POM by only including the dependencies you need directly. Removing the incorrect version requires identifying the source of the incorrect version by running Maven with the -X flag (for more information on how to do this..0.
<dependencies> <dependency> <groupId>org.regardless of whether another dependency introduces it.. This ensures that Maven ignores the 1. You'll notice here that the runtime scope is used.. for stability it would always be declared in the current POM as a dependency . In fact. but it is possible to improve the quality of your own dependencies to reduce the risk of these issues occurring with your own build artifacts.0-alpha-9</version> <exclusions> <exclusion> <groupId>org. Maven has no knowledge about what versions will definitely work. <dependency> <groupId>org.1 version is used instead. Neither of these solutions is ideal. Maven assumes that all versions are valid and uses the "nearest dependency" technique described previously to determine which version to use.1.codehaus.plexus</groupId> <artifactId>plexus-utils</artifactId> <version>1. This is achieved using version ranges instead.Creating Applications with Maven .. for a library or framework. However.. This is extremely important if you are publishing a build. However.1.plexus</groupId> <artifactId>plexus-utils</artifactId> </exclusion> </exclusions> </dependency> . but that other versions may be acceptable.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1. The reason for this is that it distorts the true dependency graph. a WAR file).. as shown above for plexus-utils. the dependency is used only for packaging. the dependency should be specified as follows: Better Builds With Maven 59 .0. In this case.codehaus. This is because in this situation. is to include it directly in the POM.codehaus. as follows: . not for compilation. so that the 1.1</version> <scope>runtime</scope> </dependency> </dependencies> . so in the case of a conflict with another dependency. you may require a feature that was introduced in plexus-utils version 1. that will be used widely by others. When a version is declared as 1..1. which will accumulate if this project is reused as a dependency itself.. this approach is not recommended unless you are producing an artifact that is bundling its dependencies and is not used as a dependency itself (for example.. if it were required for compilation. this indicates that the preferred version of the dependency is 1. The alternate way to ensure that a particular version of a dependency is used.4 version of plexus-utils in the dependency graph.
However.3 (inclusive) Greater than or equal to 1. while the build number is an increment after release to indicate patched builds. then the next nearest will be tested.Creating Applications with Maven <dependency> <groupId>org. minor and bug fix releases. If the nearest version does not match. rc1).2. you also need to avoid being too specific. and table 3-2 shows some of the values that can be used. and so on. To understand how ranges work.codehaus. a version is broken down into five parts: the major.3] [1. it is possible to make the dependency mechanism more reliable for your builds and to reduce the number of exception cases that will be required. This means that the latest version. Better Builds With Maven 60 . Finally. if none of them match.) Less than or equal to 1. or there were no conflicts originally.1. then the qualifier and finally a build number.1. the version that is used must fit the range given.1.0 Between 1.plexus</groupId> <artifactId>plexus-utils</artifactId> <version>[1. but less than 2. while the nearest dependency technique will still be used in the case of a conflict. that is greater than or equal to 1.1). The notation used above is set notation. beta-1. In the current version scheme. In a regular version.5 Any version.0 Greater than or equal to 1. the snapshot (as shown above) is a special case where the qualifier and build number are both allowed. you can provide only the qualifier.). Figure 3-3: Version parsing As you can see.1. the version you are left with is [1. or only the build number. Table 3-2: Examples of version ranges Range Meaning (. except 1.2 and 1.0.)</version> </dependency> What this means is that.0. it is necessary to understand how versions are compared. It is intended that the qualifier indicates a version prior to release (for example.0] [1. You can see how a version is partitioned by Maven in figure 3-1. the build will fail.1 By being more specific through the use of version ranges.1.) (. alpha-1.5.(1.1. will be retrieved from the repository.1.0) [1.2. If two ranges in a dependency graph do not intersect at all.
A version that also contains a build number is considered newer than a version without a build number.7. Plugins in Maven are created with a specific task in mind. the generate-sources phase.first by major version. through the use of a separate repository.if the major versions were equal . So. typically. This will ensure that the beta versions are used in a range only if the project has declared the snapshot (or development) repository explicitly.2-beta-1 exist. If you look at the POM for the proficio-model you will see the plugins element with a configuration for the Modello plugin: Better Builds With Maven 61 . <repository> . second . and the versions 1. However. For example: .). In those cases. this can be configured perrepository to be on a more regular interval. Because all of these elements are considered part of the version.1. A version that contains a qualifier is always considered newer than a version without a qualifier. This mechanism is identical to that of the snapshots that you learned in section 3. or forced from the command line using the -U option for a particular Maven execution. then 1.Creating Applications with Maven With regard to ordering. 1. Maven's default build life cycle will suffice for a great number of projects without any augmentation but. the Modello plugin is used to generate the Java sources for Proficio's data model. and finally. Maven accommodates this requirement by allowing the declaration of a plugin. or release betas as milestones along the way.2-beta-1 will be selected. which means the plugin is bound to a specific phase in the default life cycle. you should deploy them to a snapshot repository as is discussed in Chapter 7 of this book. Utilizing the Build Life Cycle In Chapter 2 Maven was described as a framework that coordinates the execution of its plugins in a well defined way or path. the repository is checked once a day for updates to the versions of artifacts in use. the ranges do not differentiate. which binds itself to a standard phase in Maven's default life cycle. so to avoid such a situation. 1. by build number. fourth by qualifier (using string comparison). If it will be configured for a particular repository. the versions will not match this syntax. the two versions are compared entirely as strings. the elements are considered in sequence to determine which is newer . In some cases.2-beta-1 is newer than 1.. if you use the range [1. Whether you use snapshots until the final release. A final note relates to how version updates are determined when a range is in use.by minor version. all projects have different requirements and it is sometimes necessary to augment the life cycle to satisfy these requirements. which is actually Maven's default build life cycle. Often this is not desired. the updatePolicy value (which is in minutes) is changed for releases. For example.2-beta.2-beta.. you must structure your releases accordingly.1 and 1.2 is newer than 1..6.. for example. Proficio has a requirement to generate Java sources from a model. <releases> <updatePolicy>interval:60</updatePolicy> </releases> </repository> 3. In Proficio. for example. By default. of course. third by bug fix version.
so you need to specify which goal in the plugin you wish to run. building with different JVMs.0-SNAPSHOT</version> </parent> <modelVersion>4.0</version> <packageWithVersion>false</packageWithVersion> <model>src/main/mdo/proficio. and are meant to be used in complementary sets to give equivalent-but-different parameters for a set of target environments (providing.0-alpha-5</version> <executions> <execution> <goals> <goal>java</goal> </goals> </execution> </executions> <configuration> <version>1.0.0</modelVersion> <artifactId>proficio-model</artifactId> <packaging>jar</packaging> <name>Proficio Model</name> <build> <plugins> <plugin> <groupId>org. and production environments). Profiles modify the POM at build time. testing with different databases. the path of the application server root in the development. testing. A plugin in Maven may have several goals. Using Profiles Profiles are Maven's way of letting you create environmental variations in the build life cycle to accommodate things like building on different platforms. but here you see an additional executions element. by specifying the goal in the executions element.Creating Applications with Maven <project> <parent> <groupId>org.mdo</model> </configuration> </plugin> </plugins> </build> </project> This is very similar to the declaration for the maven-compiler-plugin that you saw in Chapter 2. but sometimes you simply have to take into consideration variation across systems and this is why profiles were introduced in Maven. for example. Better Builds With Maven 62 . and can be activated in several ways. or referencing the local file system.maven. 3.modello</groupId> <artifactId>modello-maven-plugin</artifactId> <version>1.8.0. Profiles are specified using a subset of the elements available in the POM itself (plus one extra section).codehaus.proficio</groupId> <artifactId>proficio</artifactId> <version>1. Typically you try to encapsulate as much as possible in the POM to ensure that builds are portable.apache.
profile2 install Profiles can be activated in the Maven settings. which consists of: defaultGoal resources • testResources • finalName • • There are several ways that you can activate profiles: • Profiles can be specified explicitly using the -P CLI option. For example: <settings> . each containing a profile-id. no profiles other than those specified in the option argument will be activated.xml • The POM itself • In any of the above three profile sites.... You can define profiles in one of the following three places: The Maven settings file (typically <your -home-directory>/. you can still preserve build portability with profiles. For example: mvn -Pprofile1. </settings> • Profiles can be triggered automatically based on the detected state of the build environment. this 63 Better Builds With Maven . called profiles. but used behind the scenes) modules reporting dependencyManagement distributionManagement A subset of the build element. This option takes an argument that contains a comma-delimited list of profile-ids. This section takes a list of activeProfile elements. you can define the following elements: • • • • • • • • • repositories pluginRepositories dependencies plugins properties (not actually available in the main POM.xml file as well. Note that you must have defined the profiles in your settings. Currently.Creating Applications with Maven As such. profiles can easily lead to differing build results from different members of your team.xml) • A file in the the same directory as the POM. used properly. However. via the activeProfiles section.. • <profiles> <profile> <id>profile1</id> . When this option is specified...m2/settings. </profile> </profiles> <activeProfiles> <activeProfile>profile1</activeProfile> </activeProfiles> . These activators are specified via an activation section in the profile itself.
Better Builds With Maven 64 . the presence of a system property. <profile> <id>profile1</id> .4.4</jdk> </activation> </profile> This activator will trigger the profile when the JDK's version starts with "1.4"). "1.. <activation> <property> <name>debug</name> </property> </activation> </profile> This will activate the profile when the system property "debug" is specified with any value.4. <profile> <id>profile1</id> . you are going to use them to create tailored assemblies: an assembly of Proficio which uses the memory-based store and an assembly of Proficio which uses the XStream-based store. The assemblies will be created in the proficio-cli module and the profiles used to control the creation of our tailored assemblies are defined there as well.. "1..0_08". or the value of a system property. <activation> <property> <name>environment</name> <value>test</value> </property> </activation> </profile> This last example will activate the profile when the system property "environment" is specified with the value "test". "1..4" (eg. Here are some examples: <profile> <id>profile1</id> .2_07"...Creating Applications with Maven detection is limited to prefix-matching of the JDK version. <activation> <jdk>1. Now that you are familiar with profiles.
..Profiles for the two assemblies to create for deployment --> <profiles> <!-. <!-.Profile which creates an assembly using the xstream based store --> <profile> <id>xstream</id> <build> <plugins> <plugin> <artifactId>maven-assembly-plugin</artifactId> <configuration> <descriptors> <descriptor>src/main/assembly/assembly-store-xstream.Creating Applications with Maven If you take a look at the POM for the proficio-cli module you will see the profile definitions: <project> .Profile which creates an assembly using the memory based store --> <profile> <id>memory</id> <build> <plugins> <plugin> <artifactId>maven-assembly-plugin</artifactId> <configuration> <descriptors> <descriptor>src/main/assembly/assembly-store-memory.xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>xstream</name> </property> </activation> </profile> </profiles> </project> Better Builds With Maven 65 .xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>memory</name> </property> </activation> </profile> <!-.
jar file..9. If you wanted to create the assembly using the memory-based store you would execute the following: mvn -Dmemory clean assembly:assembly If you wanted to create the assembly using the XStream-based store you would execute the following: mvn -Dxstream clean assembly:assembly Both of the assemblies are created in the target directory and if you use the jar tvf command on the resulting assemblies you will see that the memory-based assembly only contains the proficiostore-memory-1.9. 3. It should be noted that the examples below depend on other parts of the build having been executed beforehand so it might be useful to run mvn install at the top level of the project to ensure that needed components are installed into the local repository. 3. This is a very simple example but illustrates how you can customize the execution of the life cycle using profiles to suit any requirement you might have. Currently Maven supports several methods of deployment. SSH2 deployment.. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>file://${basedir}/target/deploy</url> </repository> </distributionManagement> .0-SNAPSHOT. Deploying your Application Now that you have an application assembly. Here are some examples of how to configure your POM via the various deployment mechanisms.jar file and the XStream-based store only contains the proficio-store-xstream-1.Creating Applications with Maven You can see there are two profiles: one with an id of memory and another with an id of xstream. you'll want to share it with as many people as possible! So. which would typically be your top-level POM so that all child POMs can inherit this information. You will also notice that the profiles are activated using a system property. </project> Better Builds With Maven 66 . and external SSH deployment.1. In order to deploy you need to correctly configure your distributionManagement element in your POM.0-SNAPSHOT. In each of these profiles you are configuring the assembly plugin to point at the assembly descriptor that will create a tailored assembly. it is now time to deploy your application assembly. SFTP deployment. including simple file-based deployment. Deploying to the File System To deploy to the file system you would use something like the following: <project> . FTP deployment...
3.com/deploy</url> </repository> </distributionManagement> . </project> Better Builds With Maven 67 .yourcompany.yourcompany.Creating Applications with Maven 3.com/deploy</url> </repository> </distributionManagement> .9.9. Deploying with SFTP To deploy to an SFTP server you would use something like the following: <project> .....2. Deploying with SSH2 To deploy to an SSH2 server you would use something like the following: <project> . <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scp://sshserver.. </project> 3.... <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>sftp://ftpserver.
but also a build extension.0-alpha-6</version> </extension> </extensions> </build> . the first three methods illustrated are included with Maven. <project> ...9.4.Creating Applications with Maven 3. which does the work of moving your files to the remote server. so only the distributionManagement element is required. but to use an external SSH command to deploy you must configure not only the distributionManagement element..maven. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scpexe://sshserver. Better Builds With Maven 68 . </project> The build extension specifies the use of the Wagon external SSH provider.wagon</groupId> <artifactId>wagon-ssh-external</artifactId> <version>1. Deploying with an External SSH Now.apache. Wagon is the general purpose transport mechanism used throughout Maven.com/deploy</url> </repository> </distributionManagement> <build> <extensions> <extension> <groupId>org.yourcompany..
0-alpha-6</version> </extension> </extensions> </build> .com/deploy</url> </repository> </distributionManagement> <build> <extensions> <extension> <groupId>org. testing and deploying Proficio. simply execute the following command: mvn deploy 3. </project> Once you have configured your POM accordingly. For applications like Proficio it is recommended that you create a source directory at the top-level of the directory structure to store the resources that are used to generate the web site..apache. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>ftp://ftpserver.. Deploying with FTP To deploy with FTP you must also specify a build extension. Creating a Web Site for your Application Now that you have walked though the process of building.yourcompany.maven..wagon</groupId> <artifactId>wagon-ftp</artifactId> <version>1.10.5. If you take a look you will see that we have something similarly the following: Better Builds With Maven 69 .. To deploy to an FTP server you would use something like the following: <project> .9. and you are ready to initiate deployment. it is time for you to see how a standard web site is created for an application.Creating Applications with Maven 3.
which is a less complex version of the full DocBook format.Creating Applications with Maven Figure 3-4: The site directory structure Everything that you need to generate the site resides within the src/site directory. • The DocBook Simple format. which is a popular Wiki markup format. • The FML format. Maven supports a number of different documentation formats to accommodate various needs and preferences. which is a simple XML format used widely at Apache. Within the src/site directory. there is a subdirectory for each of the supported documentation formats that you are using for your site and the very important site descriptor. which is a wiki-like format that allows you to write simple. which is the FAQ format. A simple XML format for managing FAQs. which is another popular Wiki markup format. structured documents (like this) very quickly. • The DocBook format. • The APT format (Almost Plain Text). • Better Builds With Maven 70 . A full reference of the APT Format is available. Currently the most well supported formats available are: The XDOC format. • Maven also has limited support for: The Twiki format. • The Confluence format.
0-SNAPSHOT</version> </skin> <publishDate format="dd MMM yyyy" /> <body> <links> <item name="Apache" href="http://www.html"/> </menu> <menu name="About Proficio"> <item name="What is Proficio?" href="/what-is-maven.apache.apache. but you should become familiar with the site descriptor as it is used to: • • • • • • • Configure the appearance of the banner Configure the skin used for the site Configure the format of the publish date Configure the links displayed below the banner Configure additional information to be fed into the <head/> element of the generated pages Configure the menu items displayed in the navigation column Configure the appearance of project reports If you look in the src/site directory of the Proficio application and look at the site descriptor you will see the following: <project name="Proficio"> <bannerLeft> <name>Proficio</name> <href>http://maven.html"/> </menu> ${reports} </body> </project> Better Builds With Maven 71 .org/"/> <item name="Maven" href="http://maven.Creating Applications with Maven We will look at a few of the more well supported formats further on in the chapter.org/"/> <item name="Continuum" href="http://maven.apache.org/continuum"/> </links> <head> <meta name="faq" content="proficio"/> </head> <menu name="Quick Links"> <item name="Features" href="/maven-features.apache.org/images/apache-maven project.png</src> </bannerRight> <skin> <groupId>org.apache.apache.org/</href> </bannerLeft> <bannerRight> <name>Proficio</name> <src>http://maven.skins</groupId> <artifactId>maven-default-skin</artifactId> <version>1.maven.
which can be used for images. often you will want to customize the projects reports that are created and displayed in your web site. The format of the publish date is that of the SimpleDateFormat class in Java. by default. The link elements control the references that are displayed below the banner and take a simple name and href. or script snippets for activating tools like Google Analytics. The menu elements control the list of menus and their respective menu items that are displayed in the navigation column of the site.Creating Applications with Maven This is a fairly standard site descriptor. You do so by configuring the plugin as follows: Better Builds With Maven 72 . href and optional src element. have the standard project information reports generated and displayed automatically for you. The reports created and displayed are controlled in the build/reports element in the POM. The head element allows you to insert anything in the head element of generated pages. This element looks very much like a dependency (the same mechanism is used to retrieve the skin) and controls which skin is used for the site. The standard project information reports consist of the following: • • • • • • • Dependencies Report Mailing Lists Report Continuous Integration Report Source Repository Report Issue Tracking Report Project Team Report License Even though the standard reports are very useful. You may want to be more selective about the reports that you generate and to do so you need to list each report that you want to include as part of the site generation. but you should know about the specifics of each of the elements in the site descriptor: Table 3-3: Site descriptor Site Descriptor Element Description bannerLeft and bannerRight skin publishDate body/links body/head These elements take a name. The inclusion of the ${reports} reference controls whether the project reports are displayed in the web site. You may wish to add metadata. If you simply include the ${reports} reference in your site descriptor you will. You might exclude ${reports} reference for a site that consists purely of user documentation for example. You can have any number of menu items each containing any number of links. body/menu body/${reports} One of the most popular features of Maven are the standard reports that can be produced with little effort.
.Creating Applications with Maven <project> . You can do so by executing the following command: mvn site Better Builds With Maven 73 .. how the site descriptor works.apache.maven...... and how to configure reports it's time for you to generate the site. </project> Now that you have a good grasp on what formats are supported.. <reporting> . </reporting> . <plugins> <plugin> <groupId>org.plugins</groupId> <artifactId>maven-project-info-reports-plugin</artifactId> <reportSets> <reportSet> <reports> <report>dependencies</report> <report>project-team</report> <report>mailing-list</report> <report>cim</report> <!-Issue tracking report will be omitted <report>issue-tracking</report> --> <report>license</report> <report>scm</report> </reports> </reportSet> </reportSets> </plugin> </plugins> .
Creating Applications with Maven After executing this command you will end up with a directory structure (generated inside the target directory) with the generated content that looks like this: Figure 3-5: The target directory If you look at the generated site with your browser this is what you will see: Better Builds With Maven 74 .
augmenting your site to view quality metrics. Keeping in mind this simple rule you can add any resources you wish to your site. and how to create a simple Web site for your application. Better Builds With Maven 75 . If you remember the directory structure for the the sources of our site you will have noticed the src/site/resources directory and that it contains an images directory and as you can see in the directory listing above it is located within the images directory of the generated site.11. You should now have a grasp of how project inheritance works. 3. Summary In this chapter you have learned to setup a directory structure for a typical application and learned the basics of managing the application's development with Maven. how to deploy your application. how to manage your application's dependencies. You are now prepared to move on and learn about more advanced application directory structures like the J2EE example you will see in Chapter 4 and more advanced uses of Maven like creating your own plugins.Creating Applications with Maven Figure 3-6: The sample generated site If you have resources like images or PDFs that you want to be able to reference in your documents you can use the src/site/resources to store them and when the site is generated the content of src/site/resources will be copied to the top-level directory of the site. how to make small modifications to Maven's build life cycle. and using Maven in a collaborative environment.
Web Services) Setting up in-place Web development Deploying J2EE archives to a container Automating container start/stop Keep your face to the sun and you will never see the shadows. . Building J2EE Applications Building J2EE Applications This chapter covers: • • • • • Organizing the directory structure Building J2EE archives (EJB. EAR.Helen Keller Better Builds With Maven 76 . WAR.4.
1.Building J2EE Applications 4. Through this example. The functional goal of the DayTrader application is to buy and sell stock. 4. and Web applications.4 application and as a test bed for running performance tests. Whether you are using the full J2EE stack with EJBs or only using Web applications with frameworks such as Spring or Hibernate. Introducing the DayTrader Application DayTrader is a real world application developed by IBM and then donated to the Apache Geronimo project. Introduction J2EE (or Java EE as it is now called) applications are everywhere. Figure 4-1: Architecture of the DayTrader application Better Builds With Maven 77 .2. you'll learn how to automate configuration and deployment of J2EE application servers. and its architecture is shown in Figure 4-1. As a consequence the Maven community has developed plugins to cover every aspect of building J2EE applications. Web services. This chapter will take you through the journey of creating the build for a full-fledged J2EE application called DayTrader. Its goal is to serve as both a functional example of a full-stack J2EE 1. it's likely that you are using J2EE in some of your projects. EJBs. This chapter demonstrates how to use Maven on a real application to show how to address the complex issues related to automated builds. you'll learn how to build EARs. You'll learn not only how to create a J2EE build but also how to create a productive development environment (especially for Web application development) and how to deploy J2EE modules into your container. As importantly.
and Message-Driven Beans (MDB) to send purchase orders and get quote changes. Looking again at Figure 4-1. • • • A typical "buy stock" use case consists of the following steps that were shown in Figure 4-1: 1. buy or sell a stock. The Trade Session is a stateless session bean that offers the business services such as login. The EJB layer is where the business logic is. The Trade Broker calls the Trade Session bean which in turn calls the CMP entity beans to mark the order as "completed". It uses container-managed persistence (CMP) entity beans for storing the business objects (Order. using Web services. The user is notified of the completed order on a subsequent request. logout. Organizing the DayTrader Directory Structure The first step to organizing the directory structure is deciding what build modules are required. Better Builds With Maven 78 . • A module producing a WAR which will contain the Web application. and a JMS Server for interacting with the outside world. Once this happens the Trade Broker MDB is notified 6. you can see that the following modules will be needed: A module producing an EJB which will contain all of the server-side EJBs.Building J2EE Applications There are 4 layers in the architecture: • The Client layer offers 3 ways to access the application: using a browser. 4.Quote and AccountProfile). The Data layer consists of a database used for storing the business objects and the status of each purchase. and using the Quote Streamer. 2. • A module producing a JAR that will contain the Quote Streamer client application. 4. The Quote Streamer is a Swing GUI application that monitors quote information about stocks in real-time as the price changes. 5. 3. Asynchronously the order that was placed on the queue is processed and the purchase completed. get a stock quote. It uses servlets and JSPs. The creation of the "open" order is confirmed for the user. The user gives a buy order (by using the Web client or the Web services client). This EAR will be used to easily deploy the server code into a J2EE container. The Web layer offers a view of the application for both the Web client and the Web services client. Holding.3. Account. The order is then queued for processing in the JMS Message Server. cancel an order. The easy answer is to follow Maven's artifact guideline: one module = one main artifact. This request is handled by the Trade Session bean. • A module producing another JAR that will contain the Web services client application. and so on. A new "open" order is saved in the database using the CMP Entity Beans. Thus you simply need to figure out what artifacts you need. • In addition you may need another module producing an EAR which will contain the EJB and WAR produced from the other modules.
Figure 4-2 shows these modules in a flat directory structure. if you needed to physically locate the WARs in separate servlet containers to distribute the load. you may want to split the WAR module into 2 WAR modules: one for the browser client and one for the Web services client. it is better to find functional names for modules. For example. However..the module containing the Web application streamer . If there isn't a strong need you may find that managing several modules can be more cumbersome than useful.. it is usually easier to choose names that represent a technology instead.. Let's discuss the pros and cons of each layout. Creating Applications with Maven. For the DayTrader application the following names were chosen: • • • • • ejb .. It is possible to come up with more.the module containing the Web services client application ear . This file also contains the list of modules that Maven will build when executed from this directory (see the Chapter 3.xml file contains the POM elements that are shared between all of the modules. The next step is to give these modules names and map them to a directory structure.the module containing the EJBs web . It is flat because you're locating all the modules in the same directory.the module producing the EAR which packages the EJBs and the Web application There are two possible layouts that you can use to organize these modules: a flat directory structure and a nested one. it is important to split the modules when it is appropriate for flexibility. for more details): [. Best practices suggest to do this only when the need arises. Figure 4-2: Module names and a simple flat directory structure The top-level daytrader/pom. As a general rule. For example.] Better Builds With Maven 79 .the module containing the client side streamer application wsappclient . On the other hand.Building J2EE Applications Note that this is the minimal number of modules required.] <modules> <module>ejb</module> <module>web</module> <module>streamer</module> <module>wsappclient</module> <module>ear</module> </modules> [.
For example. the ejb and web modules are nested in the ear module. as shown in Figure 4-4. Figure 4-4: Nested directory structure for the EAR.xml file containing the shared POM elements and the list of modules underneath. This makes sense as the EAR artifact is composed of the EJB and WAR artifacts produced by the ejb and web modules. However.Building J2EE Applications This is the easiest and most flexible structure to use. Figure 4-3: Modules split according to a server-side vs client-side directory organization As before. and is the structure used in this chapter. if you have many modules in the same directory you may consider finding commonalities between them and create subdirectories to partition them. not nested within each other. Having this nested structure clearly shows how nested modules are linked to their parent. each directory level containing several modules contains a pom. The other alternative is to use a nested directory structure. you might separate the client side modules from the server side modules in the way shown in Figure 4-3. In this case. Note that in this case the modules are still separate. EJB and Web modules Better Builds With Maven 80 .
. Depending on the target deployment environment the Assembler may package things differently: one EAR for one environment or two EARs for another environment where a different set of machines are used. Now run mvn -N install in daytrader/ in order to install the parent POM in your local repository and make it available to all modules: C:\dev\m2book\code\j2ee\daytrader>mvn -N install [INFO] Scanning for projects. EJB project. For example.xml to C:\[.. A flat layout is more neutral with regard to assembly and should thus be preferred. starting with the wsappclient module after we take care of one more matter of business. etc. so before we move on to developing these sub-projects we need to install the parent POM into our local repository so it can be further built on..xml of the project.Building J2EE Applications However. You'd need to consider the three modules as one project. In addition. In those cases using a nested directory structure should be avoided. the ejb or web modules might depend on a utility JAR and this JAR may be also required for some other EAR. We are now ready to continue on with developing the sub-projects! Better Builds With Maven 81 . [INFO] --------------------------------------------------------------------[INFO] Building DayTrader :: Performance Benchmark Sample [INFO] task-segment: [install] [INFO] --------------------------------------------------------------------[INFO] [site:attach-descriptor] [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\pom. The Assembler has a pool of modules and its role is to package those modules for deployment. but then you'll be restricted in several ways. the three modules wouldn't be able to have different natures (Web application project. the nested strategy doesn't fit very well with the Assembler role as described in the J2EE specification.m2\repository\org\apache\geronimo\samples\daytrader\daytrader\1. • It doesn't allow flexible packaging. Now that you have decided on the directory structure for the DayTrader application.]\. Or the ejb module might be producing a client EJB JAR which is not used by the EAR. • These examples show that there are times when there is not a clear parent for a module. you're going to create the Maven build for each module. it has several drawbacks: Eclipse users will have issues with this structure as Eclipse doesn't yet support nested projects. EAR project).0\daytrad er-1. For example..0.pom. but by some client-side application. even though the nested directory structure seems to work quite well here. The modules we will work with from here on will each be referring to the parent pom.
We start our building process off by visiting the Web services portion of the build since it is a dependency of later build stages. and Maven's ability to integrate toolkits can make them easier to add to the build process. As the name suggests.Building J2EE Applications 4. As you may notice. see http://ws.apache. For example. Building a Web Services Client Project Web Services are a part of many J2EE applications.org/axis/java/).html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL. the Maven plugin called Axis Tools plugin takes WSDL files and generates the Java files needed to interact with the Web services it defines.org/axis/java/userguide. the plugin uses the Axis framework (http://ws.apache.4. and this will be used from DayTrader's wsappclient module. which is the default used by the Axis Tools plugin: Figure 4-5: Directory structure of the wsappclient module Better Builds With Maven 82 . Axis generates the following: Table 4-1: Axis generated classes WSDL clause Java class(es) generated For each entry in the type section For each port type For each binding For each service A Java class A holder if this type is used as an in-out/out parameter A Java interface A stub class A service interface A service implementation (the locator) For more details on the generation process. the WSDL files are in src/main/wsdl. Figure 4-5 shows the directory structure of the wsappclient module.
Building J2EE Applications
The location of WSDL source can be customized using the sourceDirectory property. For example:
[...] <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>axistools-maven-plugin</artifactId> <configuration> <sourceDirectory> src/main/resources/META-INF/wsdl </sourceDirectory> </configuration> [...]
In order to generate the Java source files from the TradeServices.wsdl file, the wsappclient/pom.xml file must declare and configure the Axis Tools plugin:
<project> [...] <build> <plugins> [...] <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>axistools-maven-plugin</artifactId> <executions> <execution> <goals> <goal>wsdl2java</goal> </goals> </execution> </executions> </plugin> </plugins> </build> </project>
Note that there's no need to define a phase in the execution element as the wsdl2java goal is bound to the generate-sources phase by default. At this point if you were to execute the build, it would fail. This is because after the sources are generated, you will require a dependency on Axis and Axis JAXRPC in your pom.xml. While you might expect the Axis Tools plugin to define this for you, it is required for two reasons: it allows you to control what version of the dependency to use regardless of what the Axis Tools plugin was built against, and more importantly, it allows users of your project to automatically get the dependency transitively. Similarly, any tools that report on the POM will be able to recognize the dependency.
Better Builds With Maven
Building J2EE Applications
As before, you need to add the J2EE specifications JAR to compile the project's Java sources. Thus add the following three dependencies to your POM:
<dependencies> <dependency> <groupId>axis</groupId> <artifactId>axis</artifactId> <version>1.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>axis</groupId> <artifactId>axis-jaxrpc</artifactId> <version>1.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.apache.geronimo.specs</groupId> <artifactId>geronimo-j2ee_1.4_spec</artifactId> <version>1.0</version> <scope>provided</scope> </dependency> </dependencies>
The Axis JAR depends on the Mail and Activation Sun JARs which cannot be redistributed by Maven. Thus, they are not present on ibiblio and you'll need to install them manually. Run mvn install and Maven will fail and print the installation instructions.
Better Builds With Maven
Building J2EE Applications
After manually installing Mail and Activation, running the build with mvn install leads to:
C:\dev\m2book\code\j2ee\daytrader\wsappclient>mvn install [...] [INFO] [axistools:wsdl2java {execution: default}] [INFO] about to add compile source root [INFO] processing wsdl: C:\dev\m2book\code\j2ee\daytrader\wsappclient\ src\main\wsdl\TradeServices.wsdl [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources. [INFO] [compiler:compile] Compiling 13 source files to C:\dev\m2book\code\j2ee\daytrader\wsappclient\target\classes [INFO] [resources:testResources] [INFO] Using default encoding to copy filtered resources. [INFO] [compiler:testCompile] [INFO] No sources to compile [INFO] [surefire:test] [INFO] No tests to run. [INFO] [jar:jar] [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1.0.jar [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1.0.jar to C:\[...]\.m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-wsappclient\1.0\daytrader-wsappclient-1.0.jar [...]
Note that the daytrader-wsappclient JAR now includes the class files compiled from the generated source files, in addition to the sources from the standard source directory. The Axis Tools plugin boasts several other goals including java2wsdl that is useful for generating the server-side WSDL file from handcrafted Java classes. The generated WSDL file could then be injected into the Web Services client module to generate client-side Java files. But that's another story... The Axis Tools reference documentation can be found at http://mojo.codehaus.org/axistoolsmaven-plugin/. Now that we have discussed and built the Web services portion, lets visit EJBs next.
Better Builds With Maven
Building J2EE Applications
4.5. Building an EJB Project
Let's create a build for the ejb module.
Figure 4-6: Directory structure for the DayTrader ejb module
Figure 4-6 shows a canonical directory structure for EJB projects: Runtime Java source code in src/main/java. • Runtime classpath resources in src/main/resources. More specifically, the standard ejbjar.xml deployment descriptor is in src/main/resources/META-INF/ejb-jar.xml. Any container-specific deployment descriptor should also be placed in this directory.
• •
Unit tests in src/test/java and classpath resources for the unit tests in src/test/resources. Unit tests are tests that execute in isolation from the container. Tests that require the container to run are called integration tests and are covered at the end of this chapter.
Better Builds With Maven
Building J2EE Applications
Now, take a look at the content of this project's pom.xml file:
<project> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.apache.geronimo.samples.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.0</version> </parent> <artifactId>daytrader-ejb</artifactId> <name>Apache Geronimo DayTrader EJB Module</name> <packaging>ejb</packaging> <description>DayTrader EJBs</description> <dependencies> <dependency> <groupId>org.apache.geronimo.samples.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <version>1.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.geronimo.specs</groupId> <artifactId>geronimo-j2ee_1.4_spec</artifactId> <version>1.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1.0.3</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean.class</clientExclude> </clientExcludes> </configuration> </plugin> </plugins> </build> </project>
As you can see, you're extending a parent POM using the parent element. This is because the DayTrader build is a multi-module build and you are gathering common POM elements in a parent daytrader/pom.xml file. If you look through all the dependencies you should see that we are ready to continue with building and installing this portion of the build.
Better Builds With Maven
Building J2EE Applications The ejb/pom. • Lastly.class and **/package.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean. You should note that you're using a provided scope instead of the default compile scope. the pom. it still needs to be listed in the POM so that the code can be compiled.html. This is achieved by specifying a dependency element on the J2EE JAR. **/*CMP. However.apache.xml file is is a standard POM file except for three items: • You need to tell Maven that this project is an EJB project so that it generates an EJB JAR when the package phase is called. Fortunately. The reason is that this dependency will already be present in the environment (being the J2EE application server) where your EJB will execute. this JAR is not redistributable and as such cannot be found on ibiblio.class</clientExclude> </clientExcludes> </configuration> </plugin> The EJB plugin has a default set of files to exclude from the client EJB JAR: **/*Bean. Better Builds With Maven 88 . This is done by specifying: <packaging>ejb</packaging> • As you're compiling J2EE code you need to have the J2EE specifications JAR in the project's build classpath. You make this clear to Maven by using the provided scope. By default the EJB plugin does not generate the client JAR. this prevents the EAR module from including the J2EE JAR when it is packaged. Even though this dependency is provided at runtime. You could instead specify a dependency on Sun's J2EE JAR. so you must explicitly tell it to do so: <plugin> <groupId>org.maven. **/*Session.xml contains a configuration to tell the Maven EJB plugin to generate a Client EJB JAR file when mvn install is called. The Client will be used in a later examples when building the web module.class. the Geronimo project has made the J2EE JAR available under an Apache license and this JAR can be found on ibiblio.class.
Building J2EE Applications
In this example, you need to override the defaults using a clientExclude element because it happens that there are some required non-EJB files matching the default **/*Bean.class pattern and which need to be present in the generated client EJB JAR. Thus you're specifying a pattern that only excludes from the generated client EJB JAR all EJB implementation classes located in the ejb package (**/ejb/*Bean.class). Note that it's also possible to specify a list of files to include using clientInclude elements. You're now ready to execute the build. Relax and type mvn install:
C:\dev\m2book\code\j2ee\daytrader\ejb>mvn install [INFO] Scanning for projects... [INFO] ----------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [install] [INFO] ----------------------------------------------------------[INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources. [INFO] [compiler:compile] Compiling 49 source files to C:\dev\m2book\code\j2ee\daytrader\ejb\target\classes [INFO] [resources:testResources] [INFO] Using default encoding to copy filtered resources. [INFO] [compiler:testCompile] Compiling 1 source file to C:\dev\m2book\code\j2ee\daytrader\ejb\target\testclasses [INFO] [surefire:test] [INFO] Setting reports dir: C:\dev\m2book\code\j2ee\daytrader\ejb\target/surefirereports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running org.apache.geronimo.samples.daytrader.FinancialUtilsTest [surefire] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0,02 sec Results : [surefire] Tests run: 1, Failures: 0, Errors: 0 [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1.0 [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.0.jar [INFO] Building ejb client daytrader-ejb-1.0-client [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.0-client.jar [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.0.jar to C:\[...]\.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ejb\1.0\daytrader-ejb-1.0.jar [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.0-client.jar to C:\[...]\.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ejb\1.0\daytrader-ejb-1.0-client.jar
Better Builds With Maven
Building J2EE Applications
Maven has created both the EJB JAR and the client EJB JAR and installed them in your local Maven repository. The EJB plugin has several other configuration elements that you can use to suit your exact needs. Please refer to the EJB plugin documentation on http://maven.apache.org/plugins/maven-ejb-plugin/. Early adopters of EJB3 may be interested to know how Maven supports EJB3. At the time of writing, the EJB3 specification is still not final. There is a working prototype of an EJB3 Maven plugin, however in the future it will be added to the main EJB plugin after the specification is finalized. Stay tuned!
4.6. Building an EJB Module With Xdoclet
If you've been developing a lot of EJBs (version 1 and 2) you have probably used XDoclet to generate all of the EJB interfaces and deployment descriptors for you. Using XDoclet is easy: by adding Javadoc annotations to your classes, you can run the XDoclet processor to generate those files for you. When writing EJBs it means you simply have to write your EJB implementation class and XDoclet will generate the Home interface, the Remote and Local interfaces, the container-specific deployment descriptors, and the ejb-jar.xml descriptor. Note that if you're an EJB3 user, you can safely skip this section – you won't need it!
Better Builds With Maven
Building J2EE Applications
Here's an extract of the TradeBean session EJB using Xdoclet:
/** * Trade Session EJB manages all Trading services * * @ejb.bean * display-name="TradeEJB" * name="TradeEJB" * view-type="remote" * impl-class-name= * "org.apache.geronimo.samples.daytrader.ejb.TradeBean" * @ejb.home * generate="remote" * remote-class= * "org.apache.geronimo.samples.daytrader.ejb.TradeHome" * @ejb.interface * generate="remote" * remote-class= * "org.apache.geronimo.samples.daytrader.ejb.Trade" * […] */ public class TradeBean implements SessionBean { […] /** * Queue the Order identified by orderID to be processed in a * One Phase commit […] * * @ejb.interface-method * view-type="remote" * @ejb.transaction * type="RequiresNew" *[…] */ public void queueOrderOnePhase(Integer orderID) throws javax.jms.JMSException, Exception […]
To demonstrate XDoclet, create a copy of the DayTrader ejb module called ejb-xdoclet. As you can see in Figure 4-7, the project's directory structure is the same as in Figure 4-6, but you don't need the ejb-jar.xml file anymore as it's going to be generated by Xdoclet.
Figure 4-7: Directory structure for the DayTrader ejb module when using Xdoclet
Better Builds With Maven
Building J2EE Applications
The other difference is that you only need to keep the *Bean.java classes and remove all of the Home, Local and Remote interfaces as they'll also get generated. Now you need to tell Maven to run XDoclet on your project. Since XDoclet generates source files, this has to be run before the compilation phase occurs. This is achieved by using the Maven XDoclet plugin and binding it to the generate-sources life cycle phase. Here's the portion of the pom.xml that configures the plugin:
<plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>xdoclet-maven-plugin</artifactId> <executions> <execution> <phase>generate-sources</phase> <goals> <goal>xdoclet</goal> </goals> <configuration> <tasks> <ejbdoclet verbose="true" force="true" ejbSpec="2.1" destDir= "${project.build.directory}/generated-sources/xdoclet"> <fileset dir="${project.build.sourceDirectory}"> <include name="**/*Bean.java"></include> <include name="**/*MDB.java"></include> </fileset> <homeinterface/> <remoteinterface/> <localhomeinterface/> <localinterface/> <deploymentdescriptor destDir="${project.build.outputDirectory}/META-INF"/> </ejbdoclet> </tasks> </configuration> </execution> </executions> </plugin>
The XDoclet plugin is configured within an execution element. This is required by Maven to bind the xdoclet goal to a phase. The plugin generates sources by default in ${project.build.directory}/generated-sources/xdoclet (you can configure this using the generatedSourcesDirectory configuration element). It also tells Maven that this directory contains sources that will need to be compiled when the compile phase executes. Finally, in the tasks element you use the ejbdoclet Ant task provided by the XDoclet project (for reference documentation see http://xdoclet.sourceforge.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.html). In practice you can use any XDoclet task (or more generally any Ant task) within the tasks element, but here the need is to use the ejbdoclet task to instrument the EJB class files. In addition, the XDoclet plugin will also trigger Maven to download the XDoclet libraries from Maven's remote repository and add them to the execution classpath.
Better Builds With Maven
Building J2EE Applications
Executing mvn install now automatically executes XDoclet and compiles the generated files:
C:\dev\m2book\code\j2ee\daytrader\ejb-xdoclet>mvn install […] [INFO] [xdoclet:xdoclet {execution: default}] [INFO] Initializing DocletTasks!!! [INFO] Executing tasks 10 janv. 2006 16:53:50 xdoclet.XDocletMain start INFO: Running <homeinterface/> Generating Home interface for 'org.apache.geronimo.samples.daytrader.ejb.TradeBean'. […] INFO: Running <remoteinterface/> Generating Remote interface for 'org.apache.geronimo.samples.daytrader.ejb.TradeBean'. […] 10 janv. 2006 16:53:50 xdoclet.XDocletMain start INFO: Running <localhomeinterface/> Generating Local Home interface for 'org.apache.geronimo.samples.daytrader.ejb.AccountBean'. […] 10 janv. 2006 16:53:51 xdoclet.XDocletMain start INFO: Running <localinterface/> Generating Local interface for 'org.apache.geronimo.samples.daytrader.ejb.AccountBean'. […] 10 janv. 2006 16:53:51 xdoclet.XDocletMain start INFO: Running <deploymentdescriptor/> Generating EJB deployment descriptor (ejb-jar.xml). […] [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1.0 […]
You might also want to try XDoclet2. It's based on a new architecture but the tag syntax is backwardcompatible in most cases. There's also a Maven 2 plugin for XDoclet2 at http://xdoclet.codehaus.org/Maven2+Plugin. However, it should be noted that XDoclet2 is a work in progress and is not yet fully mature, nor does it boast all the plugins that XDoclet1 has.
Better Builds With Maven
. Deploying EJBs Now that you know how to build an EJB project.codehaus.log</log> [. you will need to have Maven start the container automatically.] See http://cargo..zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> </plugin> </plugins> </build> If you want to debug Cargo's execution. you will learn how to deploy it. Better Builds With Maven 94 . Maven 1.org/Debugging for full details. In the container element you tell the Cargo plugin that you want to use JBoss 4.log</output> <log>${project.codehaus. Ant. stopping.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <zipUrlInstaller> <url>http://internap.x (containerId element) and that you want Cargo to download the JBoss 4.] <plugin> <groupId>org. Netbeans. you can use the log element to specify a file where Cargo logs will go and you can also use the output element to specify a file where the container's output will be dumped. Maven 2.net/ sourceforge/jboss/jboss-4. in the Testing J2EE Applications section of this chapter. Later. IntelliJ IDEA.directory}/cargo..Building J2EE Applications 4.) for performing various actions on containers such as starting. To do so you're going to use the Maven plugin for Cargo. The location where Cargo should install JBoss is a user-dependent choice and this is why the ${installDir} property was introduced. It offers generic APIs (Java.2. In order to build this project you need to create a Profile where you define the ${installDir} property's value. For example: <container> <containerId>jboss4x</containerId> <output>${project.build. First. etc. Edit the ejb/pom.7..0.sourceforge. you will also learn how to test it automatically. In this example.dl.directory}/jboss4x.0.2 distribution from the specified URL and install it in ${installDir}. Let's discover how you can automatically start a container and deploy your EJBs into it. Cargo is a framework for manipulating containers.build.xml file and add the following Cargo plugin configuration: <build> <plugins> [. the JBoss container will be used. configuring them and deploying modules to them.
[INFO] Searching repository for plugin with prefix: 'cargo'. you can define a profile in the POM. That's it! JBoss is running.2</home> That's all you need to have a working build and to deploy the EJB JAR into JBoss. or in a settings. activated by default and in which the ${installDir} property points to c:/apps/cargo-installs.xml file.0. It's also possible to tell Cargo that you already have JBoss installed locally. Better Builds With Maven 95 . it detects that the Maven project is producing an EJB from the packaging element and it automatically deploys it when the container is started. [INFO] [talledLocalContainer] JBoss 4.xml file. and the EJB JAR has been deployed. in a settings.2 starting. Nor should the content be shared with other Maven projects at large.xml file defines a profile named vmassol.2 started on port [8080] [INFO] Press Ctrl-C to stop the container. In this case. then start JBoss and deploy the EJB JAR by running mvn cargo:start (or mvn package cargo:start to do it all at once): C:\dev\m2book\code\j2ee\daytrader\ejb>mvn cargo:start [INFO] Scanning for projects. the EJB JAR should first be created.0. [INFO] ----------------------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [cargo:start] [INFO] ----------------------------------------------------------------------[INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4...2] [INFO] [talledLocalContainer] JBoss 4. For example: <home>c:/apps/jboss-4. Of course. in a profiles. as the content of the Profile is user-dependent you wouldn't want to define it in the POM.. Thus the best place is to create a profiles. so run mvn package to generate it.0. In that case replace the zipURLInstaller element with a home element. The Cargo plugin does all the work: it provides a default JBoss configuration (using port 8080 for example).Building J2EE Applications As explained in Chapter 3..xml file..0..xml file in the ejb/ directory: <profilesXml> <profiles> <profile> <id>vmassol</id> <properties> <installDir>c:/apps/cargo-installs</installDir> </properties> </profile> </profiles> <activeProfiles> <activeProfile>vmassol</activeProfile> </activeProfiles> </profilesXml> This sample profiles.
let's focus on building the DayTrader web module. especially if you are on a slow connection.codehaus. deploying on a remote machine.8. to stop the container call mvn cargo:stop.org/Maven2+plugin. Check the documentation at http://cargo. The layout is the same as for a JAR module (see the first two chapters of this book). JSPs. Subsequent calls will be fast as Cargo will not download JBoss again. If the container was already started and you wanted to just deploy the EJB. the first time you execute cargo:start it will take some time. 4. you would run the cargo:deploy goal. Finally. (see Figure 4-8). etc. and more. Cargo has many other configuration options such as the possibility of using an existing container installation. except that there is an additional src/main/webapp directory for locating Web application resources such as HTML pages. Figure 4-8: Directory structure for the DayTrader web module showing some Web application resources Better Builds With Maven 96 .Building J2EE Applications As you have told Cargo to download and install JBoss. Building a Web Application Project Now. modifying various container parameters. WEB-INF configuration files.
Depending on the main EJB JAR would also work.samples.Building J2EE Applications As usual everything is specified in the pom. for example to prevent coupling.0</version> <scope>provided</scope> </dependency> </dependencies> </project> You start by telling Maven that it's building a project generating a WAR: <packaging>war</packaging> Next.xml: <dependency> <groupId>org.geronimo.4_spec</artifactId> <version>1.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1.xml.samples. Therefore.0</version> </parent> <artifactId>daytrader-web</artifactId> <name>DayTrader :: Web Application</name> <packaging>war</packaging> <description>DayTrader Web</description> <dependencies> <dependency> <groupId>org. The reason you are building this web module after the ejb module is because the web module's servlets call the EJBs.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1. the servlets only need the EJB client JAR in their classpath to be able to call the EJBs.0</modelVersion> <parent> <groupId>org.geronimo.specs</groupId> <artifactId>geronimo-j2ee_1. you need to add a dependency on the ejb module in web/pom. It's always cleaner to depend on the minimum set of required classes.samples.apache. you specify the required dependencies.xml file: <project> <modelVersion>4.apache. Therefore. This is because the servlets are a client of the EJBs. but it's not necessary and would increase the size of the WAR file.geronimo. This is why you told the EJB plugin to generate a client JAR earlier on in ejb/pom.apache.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1.0.apache.geronimo.0</version> <type>ejb-client</type> </dependency> <dependency> <groupId>org. Better Builds With Maven 97 .0</version> <type>ejb-client</type> </dependency> Note that you're specifying a type of ejb-client and not ejb.
0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. An alternative is to use the uberwar goal from the Cargo Maven Plugin (see http://cargo. The configuration is very simple because the defaults from the WAR plugin are being used.0.0\daytrader-web-1. and files such as web. allowing the aggregation of multiple WAR files..0.war Better Builds With Maven 98 . The final dependency listed is the J2EE JAR as your web module uses servlets and calls EJBs.m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-web\1.Building J2EE Applications If you add a dependency on a WAR..codehaus. it's a good practice to use the default conventions as much as possible. the Geronimo J2EE specifications JAR is used with a provided scope (as seen previously when building the EJB). As seen in the introduction.]\. However. As you know. When it generates your WAR. it recursively adds your module's dependencies.0.xml. unless their scope is test or provided.0 [INFO] Assembling webapp daytrader-web in C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.org/Merging+WAR+files).war to C:\[. Maven 2 supports transitive dependencies. Running mvn install generates the WAR and installs it in your local repository: C:\dev\m2book\code\j2ee\daytrader\web>mvn install [.. then the WAR you generate will be overlaid with the content of that dependent WAR. Again.... This is why we defined the J2EE JAR using a provided scope in the web module's pom.war [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.xml file and reduces maintenance.0.xml won't be merged. only files not in the existing Web application will be added.war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. Otherwise it would have surfaced in the WEB-INF/lib directory of the generated WAR. as it reduces the size of the pom.] [INFO] [war:war] [INFO] Exploding webapp.
xml file found in ${warSourceDirectory}/WEBINF/web.finalName} For the full list. Specify where to find the web. Name of the generated WAR.org/plugins/maven-war-plugin/.build.apache. Better Builds With Maven 99 . warSourceIncludes/war All files are included SourceExcludes warName ${project. see the reference documentation for the WAR plugin at http://maven.xml Location of Web application resources to include in the WAR. Specify the files to include/exclude from the generated WAR.Building J2EE Applications Table 4-2 lists some other parameters of the WAR plugin that you may wish to configure.xml file. Table 4-2: WAR plugin configuration properties Configuration property Default value Description warSourceDirectory webXml ${basedir}/src/main/webapp The web.
There are two plugins that can alleviate this problem: the Cargo plugin and the Jetty6 plugin. You execute the Jetty6 plugin by typing mvn jetty6:run: Better Builds With Maven 100 . Fortunately.9. Improving Web Development Productivity If you're doing Web development you know how painful it is to have to package your code in a WAR and redeploy it every time you want to try out a change you made to your HTML. and it adds the compiled classes in target/classes to its execution classpath.mortbay.geronimo.0</version> <scope>provided</scope> </dependency> </dependencies> </plugin> […] The scanIntervalSeconds configuration property tells the plugin to monitor for changes every 10 seconds.xml file. JSP or servlet code.xml file: […] <build> <plugins> <plugin> <groupId>org.Building J2EE Applications 4. Add the following to the web/pom. the web.specs</groupId> <artifactId>geronimo-j2ee_1. Since the Web application earlier declared that the specification must be provided through the provided scope. the plugin reloads the Web application in Jetty. The plugin is configured by default to look for resource files in src/main/webapp.apache. The Jetty6 plugin creates a custom Jetty6 configuration that is wired to your source tree. You'll discover how to use the Jetty6 plugin in this section as you've already seen how to use the Cargo plugin in a previous section.jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> <scanIntervalSeconds>10</scanIntervalSeconds> </configuration> <dependencies> <dependency> <groupId>org. adding this dependency to the plugin adds it to the classpath for Jetty.xml file. If any change is detected. the src/main/webapp tree. Thus any recompilation in your IDE will trigger a redeploy of your Web application in Jetty. providing an extremely fast turnaround time for development. Let's try the Jetty6 plugin on the DayTrader web module. A typical usage for this plugin is to develop the source code in your IDE and have the IDE configured to compile classes in target/classes (this is the default when the Maven IDE plugins are used to set up your IDE project). The reason for the dependency on the J2EE specification JAR is because Jetty is a servlet engine and doesn't provide the EJB specification JAR. The plugin monitors the source tree for changes. including the pom. the project dependencies and the compiled classes and classpath resources in target/classes. Maven can help.4_spec</artifactId> <version>1.
Open a browser with the http://localhost:8080/daytrader-web/register. but then the fun examples won't work!..SimpleLogger@1242b11 via org.log.0.xml [INFO] Classes located at: C:\dev\m2book\code\j2ee\daytrader\ web\target\classes [INFO] tmp dir for webapp will be C:\dev\m2book\code\j2ee\daytrader\web\target\jetty-tmp [INFO] Starting Jetty Server .log . resource base= C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Finished configuring web.impl.jetty.mortbay.nio.0... [INFO] No connectors configured. Better Builds With Maven 101 .SelectChannelConnector listening on 8080 with maxIdleTime 30000 0 [main] INFO org..Logging to org.Started SelectChannelConnector @ 0.Building J2EE Applications C:\dev\m2book\code\j2ee\daytrader\web>mvn jetty6:run […] [INFO] [jetty6:run] [INFO] Configuring Jetty for project: Apache Geronimo DayTrader Web Module [INFO] Webapp source directory is: C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] web. using defaults: org.xml.0:8080 [INFO] Starting scanner at interval of 10 seconds. Maven pauses as Jetty is now started and may be stopped at anytime by simply typing Ctrl-C.slf4j.jsp URL as shown in Figure 4-9 to see the Web application running.mortbay.xml file located at: C:\dev\m2book\code\j2ee\daytrader\ web\src\main\webapp\WEB-INF\web. [INFO] Finished setting up classpath [INFO] Started configuring web.mortbay.log .Slf4jLog [INFO] Context path = /daytrader-web [INFO] Webapp directory = C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Setting up classpath . As you can see.xml 681 [main] INFO org.mortbay. Your Web application has been deployed and the plugin is waiting. listening for changes.
search for "10000" and replace it with "90000" (a much better starting amount!): <TD colspan="2" align="right">$<B> </B><INPUT size="20" type="text" name="money" value='<%= money==null ? "90000" : money %>'></TD> Now simply refresh your browser (usually the F5 key) and the new value will appear as shown in Figure 4-10: Figure 4-10: Modified registration page automatically reflecting our source change Better Builds With Maven 102 .jsp. In practice it's easier to deploy a full EAR as you'll see below. Edit web/src/main/webapp/register. In order to make it work you'd need to have your EJB container started with the DayTrader code deployed in it. Now let's try to modify the content of this JSP by changing the opening account balance. The reason is that we have only deployed the Web application here. but the EJBs and all the back end code has not been deployed.Building J2EE Applications Figure 4-9: DayTrader JSP registration page served by the Jetty6 plugin Note that the application will fail if you open a page that calls EJBs.
properties</config> </userRealm> </userRealms> </configuration> </plugin> You can also configure the context under which your Web application is deployed by using the contextPath configuration element. Now imagine that you have an awfully complex Web application generation process. It's also possible to pass in a jetty.HashUserRealm"> <name>Test Realm</name> <config>etc/realm.org/jetty6/mavenplugin/index. possibly generating some files. By default the plugin uses the module's artifactId from the POM. Fortunately there's a solution.mortbay. you would use: <plugin> <groupId>org.xml configuration file using the jettyConfig configuration element. The strategy above would not work as the Jetty6 plugin would not know about the custom actions that need to be executed to generate a valid Web application. and so on.html.mortbay. Better Builds With Maven 103 .jetty. For example if you wanted to run Jetty on port 9090 with a user realm defined in etc/realm.nio.properties. In that case anything in the jetty.Building J2EE Applications That's nifty.mortbay. isn't it? What happened is that the Jetty6 plugin realized the page was changed and it redeployed the Web application automatically. For a reference of all configuration options see the Jetty6 plugin documentation at http://jetty.jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> […] <connectors> <connector implementation= "org. The Jetty container automatically recompiled the JSP when the page was refreshed.security.jetty. There are various configuration parameters available for the Jetty6 plugin such as the ability to define Connectors and Security realms.SelectChannelConnector"> <port>9090</port> <maxIdleTime>60000</maxIdleTime> </connector> </connectors> <userRealms> <userRealm implementation= "org. that you have custom plugins that do all sorts of transformations to Web application resource files.xml file will be applied first.mortbay.
Started SelectChannelConnector @ 0.Logging to org.slf4j. Better Builds With Maven 104 . WEB-INF/web.mortbay. Then it deploys the unpacked Web application located in target/ (whereas the jetty6:run-war goal deploys the WAR file).. To demonstrate..xml and pom.] [INFO] [war:war] [INFO] Exploding webapp.0.. for example) or when the pom..xml.Building J2EE Applications The WAR plugin has an exploded goal which produces an expanded Web application in the target directory.war [INFO] [jetty6:run-exploded] [INFO] Configuring Jetty for project: DayTrader :: Web Application [INFO] Starting Jetty Server .0. Then the plugin deploys the WAR file to the Jetty server and it performs hot redeployments whenever the WAR is rebuilt (by calling mvn package from another window. • jetty6:run-exploded: The plugin runs the package phase as with the jetty6:run-war goal. execute mvn jetty6:run-exploded goal on the web module: C:\dev\m2book\code\j2ee\daytrader\web>mvn jetty6:run-exploded [. Calling this goal ensures that the generated Web application is the correct one. The Jetty6 plugin also contains two goals that can be used in this situation: • jetty6:run-war: The plugin first runs the package phase which generates the WAR file.log .log .. The plugin then watches the following files: WEB-INF/lib.mortbay.mortbay.. any change to those files results in a hot redeployment.0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1..xml file is modified. 0 [main] INFO org.0 [INFO] Assembling webapp daytrader-web in C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. [INFO] Scan complete at Wed Feb 15 11:59:00 CET 2006 [INFO] Starting scanner at interval of 10 seconds. [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1.0.0:8080 [INFO] Scanning .0.log.SimpleLogger@78bc3b via org.. WEB-INF/classes.Slf4jLog [INFO] Context path = /daytrader-web 2214 [main] INFO org.impl.
Listeners completed.port element has been introduced to show how to configure the containers to start on port 8280 instead of the default 8080 port. This is very useful if you have containers already running your machine and you don't want to interfere with them.. No more excuses! 4..xml file and add the Cargo configuration: <plugin> <groupId>org.servlet. Stopping webapp . First. This example uses the Cargo Maven plugin to deploy to any container supported by Cargo (see http://cargo.... Those properties will be defined in a Profile.. You're now ready for productive web development.10.codehaus.org/Containers).port>8280</cargo. There are two differences though: • • Two new properties have been introduced (containerId and url) in order to make this build snippet generic. 105 Better Builds With Maven .port> </properties> </configuration> </configuration> </plugin> As you can see this is a configuration similar to the one you have used to deploy your EJBs in the Deploying EJBs section of this chapter. Restarting webapp .cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>${containerId}</containerId> <zipUrlInstaller> <url>${url}</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <configuration> <properties> <cargo. Scanning ...codehaus.servlet. Restart completed.Building J2EE Applications As you can see the WAR is first assembled in the target directory and the Jetty plugin is now waiting for changes to happen.servlet. so now the focus will be on deploying a packaged WAR to your target container. edit the web module's pom. Deploying Web Applications You have already seen how to deploy a Web application for in-place Web development in the previous section. If you open another shell and run mvn package you'll see the following in the first shell's console: [INFO] [INFO] [INFO] [INFO] [INFO] [INFO] [INFO] [INFO] Scan complete at Wed Feb 15 12:02:31 CET 2006 Calling scanner listeners . This is very useful when you're developing an application and you want to verify it works on several containers.. A cargo.. Reconfiguring webapp .
xml file: [.apache.30 starting...0.....0.] [INFO] [cargo:start] [INFO] [talledLocalContainer] Tomcat 5.zip</url> </properties> </profile> </profiles> </project> You have defined two profiles: one for JBoss and one for Tomcat and the JBoss profile is defined as active by default (using the activation element). starts the JBoss container and deploys the WAR into it: C:\dev\m2book\code\j2ee\daytrader\web>mvn install cargo:start [..2.Building J2EE Applications As seen in the Deploying EJBs section the installDir property is user-dependent and should be defined in a profiles... [INFO] [talledLocalContainer] JBoss 4. Thus.zip</url> </properties> </profile> <profile> <id>tomcat5x</id> <properties> <containerId>tomcat5x</containerId> <url>http://www.30/bin/ jakarta-tomcat-5..0.0.2] [INFO] [talledLocalContainer] JBoss 4.] [INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4..2 started on port [8280] [INFO] Press Ctrl-C to stop the container.xml file.org/dist/jakarta/tomcat-5/v5.sourceforge.0.dl..0.2 starting.0. You could add as many profiles as there are containers you want to execute your Web application on. add the following profiles to the web/pom.net/sourceforge/jboss/jboss4. Executing mvn install cargo:start generates the WAR. However. the containerId and url properties should be shared for all users of the build.] </build> <profiles> <profile> <id>jboss4x</id> <activation> <activeByDefault>true</activeByDefault> </activation> <properties> <containerId>jboss4x</containerId> <url>http://ovh.30. To deploy the WAR using Tomcat tell Maven to execute the tomcat5x profile by typing mvn cargo:start -Ptomcat5x: C:\dev\m2book\code\j2ee\daytrader\web>mvn cargo:start -Ptomcat5x [. [INFO] [CopyingLocalDeployer] Deploying Better Builds With Maven 106 .
To deploy the DayTrader's WAR to a running JBoss server on machine remoteserver and executing on port 80.30 started on port [8280] [INFO] Press Ctrl-C to stop the container.. once this is verified you'll want a solution to deploy your WAR into an integration platform.hostname>${remoteServer}</cargo.servlet. All the properties introduced need to be declared inside the POM for those shared with other users and in the profiles. • Several configuration properties (especially a user name and password allowed to deploy on the remote JBoss container) to specify all the details required to perform the remote deployment.port>${remotePort}</cargo..cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <type>remote</type> </container> <configuration> <type>runtime</type> <properties> <cargo..remote.password> </properties> </configuration> </configuration> </plugin> When compared to the configuration for a local deployment above. One solution is to have your container running on that integration platform and to perform a remote deployment of your WAR to it.0.codehaus.username>${remoteUsername}</cargo.. Better Builds With Maven 107 .codehaus.remote.xml file (or the settings.remote.0. the changes are: A remote container and configuration type to tell Cargo that the container is remote and not under Cargo's management.xml: <plugin> <groupId>org.port> <cargo.. Note that there was no need to specify a deployment URL as it is computed automatically by Cargo. This is useful for development and to test that your code deploys and works. you would need the following Cargo plugin configuration in web/pom.hostname> <cargo.remote. [INFO] [talledLocalContainer] Tomcat 5.username> <cargo.war] to [C:\[.Building J2EE Applications [C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.xml file) for those user-dependent..password>${remotePassword}</cargo. • Check the Cargo reference documentation for all details on deployments at http://cargo.org/Deploying+to+a+running+container.]\Temp\cargo\50866\webapps].servlet. However.
.0</modelVersion> <parent> <groupId>org.xml file (see Figure 4-11).Building J2EE Applications 4. The ear module's directory structure can't be any simpler.11. Start by defining that this is an EAR project by using the packaging element: <project> <modelVersion>4. It's time to package the server module artifacts (EJB and WAR) into an EAR for convenient deployment..daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.xml file. Figure 4-11: Directory structure of the ear module As usual the magic happens in the pom.0</version> </parent> <artifactId>daytrader-ear</artifactId> <name>DayTrader :: Enterprise Application</name> <packaging>ear</packaging> <description>DayTrader EAR</description> Better Builds With Maven 108 . Building an EAR Project You have now built all the individual modules.geronimo.samples. it solely consists of a pom.0.apache.
samples.apache.0</version> <type>ejb</type> </dependency> <dependency> <groupId>org. rar. par. and EJB modules. the EAR plugin supports the following module types: ejb.0</version> </dependency> </dependencies> Finally.geronimo. ejb-client. It is also necessary to tell the EAR plugin which of the dependencies are Java modules. the description to use. define all of the dependencies that need to be included in the generated EAR: <dependencies> <dependency> <groupId>org. ejb3.geronimo.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1.0</version> </dependency> <dependency> <groupId>org.apache.0</version> <type>war</type> </dependency> <dependency> <groupId>org. jar.geronimo. Better Builds With Maven 109 .daytrader</groupId> <artifactId>daytrader-web</artifactId> <version>1. you need to configure the Maven EAR plugin by giving it the information it needs to automatically generate the application.Building J2EE Applications Next.xml deployment descriptor file.geronimo.samples.samples. At the time of writing. and the J2EE version to use. sar and wsr.apache.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <version>1. Web modules.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <version>1. war.apache.samples. This includes the display name to use.
maven.xml file.samples. Better Builds With Maven 110 .Building J2EE Applications By default. it is often necessary to customize the inclusion of some dependencies such as shown in this example: <build> <plugins> <plugin> <groupId>org.samples.plugins</groupId> <artifactId>maven-ear-plugin</artifactId> <configuration> <displayName>Trade</displayName> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <version>1.apache.apache.geronimo. all dependencies are included.apache.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <javaModule> <groupId>org. By default. only EJB client JARs are included when specified in the Java modules list. the contextRoot element is used for the daytrader-web module definition to tell the EAR plugin to use that context root in the generated application. However.4</version> <modules> <javaModule> <groupId>org. with the exception of those that are optional.apache.samples. or those with a scope of test or provided.geronimo.daytrader</groupId> <artifactId>daytrader-web</artifactId> <contextRoot>/daytrader</contextRoot> </webModule> </modules> </configuration> </plugin> </plugins> </build> </project> Here.geronimo.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <webModule> <groupId>org. You should also notice that you have to specify the includeInApplicationXml element in order to include the streamer and wsappclient libraries into the EAR.
. Run mvn install in daytrader/streamer..geronimo.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <includeInApplicationXml>true</includeInApplicationXml> <bundleDir>lib</bundleDir> </javaModule> In order not to have to repeat the bundleDir element for each Java module definition you can instead use the defaultJavaBundleDir element: [.samples.apache.] <defaultBundleDir>lib</defaultBundleDir> <modules> <javaModule> [.] There are some other configuration elements available in the EAR plugin which you can find out by checking the reference documentation on http://maven.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <includeInApplicationXml>true</includeInApplicationXml> <bundleDir>lib</bundleDir> </javaModule> <javaModule> <groupId>org..geronimo..samples. The streamer module's build is not described in this chapter because it's a standard build generating a JAR.. However the ear module depends on it and thus you'll need to have the Streamer JAR available in your local repository before you're able to run the ear module's build.apache.] </javaModule> [.org/plugins/maven-ear-plugin. For example.Building J2EE Applications It is also possible to configure where the JARs' Java modules will be located inside the generated EAR.apache. if you wanted to put the libraries inside a lib subdirectory of the EAR you would use the bundleDir element: <javaModule> <groupId>org.. Better Builds With Maven 111 .
samples.jar] [INFO] Copying artifact [ejb-client:org.0] to[daytrader-ejb-1.0-client.0.daytrader: daytrader-wsappclient:1.0.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ear\1.apache.0] to [daytrader-wsappclient-1.ear [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1.daytrader: daytrader-web:1.0] to [daytrader-web-1.geronimo. [INFO] [ear:ear] [INFO] Copying artifact [jar:org.geronimo.0.0\daytrader-ear-1.MF .Generating one [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1.0.0.jar] [INFO] Copying artifact [war:org.apache.daytrader: daytrader-ejb:1..jar] [INFO] Copying artifact [jar:org.samples.Building J2EE Applications To generate the EAR.daytrader: daytrader-streamer:1.xml [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources.0.apache.daytrader: daytrader-ejb:1.samples.apache. run mvn install: C:\dev\m2book\code\j2ee\daytrader\ear>mvn install […] [INFO] [ear:generate-application-xml] [INFO] Generating application.samples.ear Better Builds With Maven 112 .0] to [daytrader-streamer-1.geronimo.war] [INFO] Copying artifact [ejb:org.jar] [INFO] Could not find manifest file: C:\dev\m2book\code\j2ee\daytrader\ear\src\main\application\ META-INF\MANIFEST.ear to C:\[.apache.0] to [daytrader-ejb-1.geronimo..samples.]\.geronimo.0.
sun.0" encoding="UTF-8"?> <application xmlns="http://java.xsd" version="1.xml to prove that it has everything you need: <?xml version="1.0.w3.0.com/xml/ns/j2ee" xmlns:xsi="http://www. Better Builds With Maven 113 .jar</java> </module> <module> <web> <web-uri>daytrader-web-1.0.com/xml/ns/j2ee http://java.com/xml/ns/j2ee/application_1_4.jar</ejb> </module> </application> This looks good.Building J2EE Applications You should review the generated application.sun.jar</java> </module> <module> <java>daytrader-wsappclient-1.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.0.4"> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <display-name>Trade</display-name> <module> <java>daytrader-streamer-1.war</web-uri> <context-root>/daytrader</context-root> </web> </module> <module> <ejb>daytrader-ejb-1. The next section will demonstrate how to deploy this EAR into a container.
You'll need to use the JDK 1. as shown on Figure 4-2. Geronimo is somewhat special among J2EE containers in that deploying requires calling the Deployer tool with a deployment plan. However. you'll deploy the DayTrader EAR into Geronimo.Building J2EE Applications 4. Deploying EARs follows the same principle. A plan is an XML file containing configuration information such as how to map CMP entity beans to a specific database. Figure 4-12: Directory structure of the ear module showing the Geronimo deployment plan How do you perform the deployment with Maven? One option would be to use Cargo as demonstrated earlier in the chapter.4 for this section and the following.xml. store the deployment plan in ear/src/main/deployment/geronimo/plan. In this example. how to map J2EE resources in the container. Geronimo also supports having this deployment descriptor located within the J2EE archives you are deploying. it is recommended that you use an external plan file so that the deployment configuration is independent from the archives getting deployed. etc.xml configuration snippet: Better Builds With Maven 114 . enabling the Geronimo plan to be modified to suit the deployment environment. To get started.12. You would need the following pom. The DayTrader application does not deploy correctly when using the JDK 5 or newer. Like any other container. Deploying a J2EE Application You have already learned how to deploy EJBs and WARs into a container individually.
home}/bin/deployer.build. This plugin can execute any process.13 Testing J2EE Applications).mojo</groupId> <artifactId>exec-maven-plugin</artifactId> <configuration> <executable>java</executable> <arguments> <argument>-jar</argument> <argument>${geronimo. Even though it's recommended to use a specific plugin like the Cargo plugin (as described in 4.build.codehaus.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www. or when Cargo doesn't support the container you want to deploy into. Modify the ear/pom.org/dist/geronimo/1.Building J2EE Applications <plugin> <groupId>org.finalName}.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <deployer> <deployables> <deployable> <properties> <plan>${basedir}/src/main/deployment/geronimo/plan.xml </argument> </arguments> </configuration> </plugin> Better Builds With Maven 115 .codehaus. in this section you'll learn how to use the Maven Exec plugin.ear </argument> <argument> ${basedir}/src/main/deployment/geronimo/plan.apache. learning how to use the Exec plugin is useful in situations where you want to do something slightly different.directory}/${project.0/ geronimo-tomcat-j2ee-1.xml</plan> </properties> </deployable> </deployables> </deployer> </configuration> </plugin> However. You'll use it to run the Geronimo Deployer tool to deploy your EAR into a running Geronimo container.jar</argument> <argument>--user</argument> <argument>system</argument> <argument>--password</argument> <argument>manager</argument> <argument>deploy</argument> <argument> ${project.xml to configure the Exec plugin: <plugin> <groupId>org.0.
As you've seen in the EJB and WAR deployment sections above and in previous chapters it's possible to create properties that are defined either in a properties section of the POM or in a Profile. the Exec plugin will transform the executable and arguments elements above into the following command line: java -jar c:/apps/geronimo-1.xml file: <profiles> <profile> <id>vmassol</id> <properties> <geronimo. start your preinstalled version of Geronimo and run mvn exec:exec: C:\dev\m2book\code\j2ee\daytrader\ear>mvn exec:exec [.home property that has not been defined anywhere.jar [INFO] [INFO] `-> daytrader-wsappclient-1. As the location where Geronimo is installed varies depending on the user.home> </properties> </profile> </profiles> At execution time.xml or settings.0-SNAPSHOT.0-tomcat</geronimo. put the following profile in a profiles.] [INFO] [exec:exec] [INFO] Deployed Trade [INFO] [INFO] `-> daytrader-web-1.war [INFO] [INFO] `-> daytrader-ejb-1.ear C:\dev\m2book\code\j2ee\daytrader\ear/src/main/deployment/geronimo/plan. Better Builds With Maven 116 .0-SNAPSHOT.xml First.0-SNAPSHOT..jar –user system –password manager deploy C:\dev\m2book\code\j2ee\daytrader\ear\target/daytrader-ear-1.0..Building J2EE Applications You may have noticed that you're using a geronimo.jar [INFO] [INFO] `-> TradeDataSource [INFO] [INFO] `-> TradeJMS You can now access the DayTrader application by opening your browser to http://localhost:8080/daytrader/.0-SNAPSHOT.home>c:/apps/geronimo-1.0-tomcat/bin/deployer.jar [INFO] [INFO] `-> daytrader-streamer-1.
Testing J2EE Application In this last section you'll learn how to automate functional testing of the EAR built previously. so you can define a profile to build the functional-tests module only on demand. you should first stop it.0-tomcat\bin>deploy stop geronimo/daytrader-derby-tomcat/1. modify the daytrader/pom. Functional tests can take a long time to execute.xml file as follows: Better Builds With Maven 117 . by creating a new execution of the Exec plugin or run the following: C:\apps\geronimo-1.xml so that it's built along with the others. Since Geronimo 1.13. At the time of writing. For example. Figure 4-13: The new functional-tests module amongst the other DayTrader modules You need to add this module to the list of modules in the daytrader/pom.0 comes with the DayTrader application bundled. Maven only supports integration and functional testing by creating a separate module.0/car If you need to undeploy the DayTrader version that you've built above you'll use the "Trade" identifier instead: C:\apps\geronimo-1.0-tomcat\bin>deploy undeploy Trade 4. To achieve this.Building J2EE Applications You will need to make sure that the DayTrader application is not already deployed before running the exec:exec goal or it will fail. create a functional-tests module as shown in Figure 4-12.
xml. Figure 4-1 shows how it is organized: Functional tests are put in src/it/java. take a look in the functional-tests module itself. • Better Builds With Maven 118 . This means that running mvn install will not build the functional-tests module.Building J2EE Applications <modules> <module>ejb</module> <module>web</module> <module>streamer</module> <module>wsappclient</module> <module>ear</module> </modules> <profiles> <profile> <id>functional-test</id> <activation> <property> <name>enableCiProfile</name> <value>true</value> </property> </activation> <modules> <module>functional-tests</module> </modules> </profile> </profiles> For more information on the ciProfile configuration. • The Geronimo deployment Plan file is located in src/deployment/geronimo/plan. see Chapter 7. but running mvn install -Pfunctional-test will. • Classpath resources required for the tests are put in src/it/resources (this particular example doesn't have any resources). Now.
Building J2EE Applications
Figure 4-14: Directory structure for the functional-tests module
As this module does not generate an artifact, the packaging should be defined as pom. However, the compiler and Surefire plugins are not triggered during the build life cycle of projects with a pom packaging, so these need to be configured in the functional-tests/pom.xml file:
Better Builds With Maven
Building J2EE Applications
<project> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.apache.geronimo.samples.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.0-SNAPSHOT</version> </parent> <artifactId>daytrader-tests</artifactId> <name>DayTrader :: Functional Tests</name> <packaging>pom</packaging> <description>DayTrader Functional Tests</description> <dependencies> <dependency> <groupId>org.apache.geronimo.samples.daytrader</groupId> <artifactId>daytrader-ear</artifactId> <version>1.0-SNAPSHOT</version> <type>ear</type> <scope>provided</scope> </dependency> [...] </dependencies> <build> <testSourceDirectory>src/it</testSourceDirectory> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <executions> <execution> <goals> <goal>testCompile</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <executions> <execution> <phase>integration-test</phase> <goals> <goal>test</goal> </goals> </execution> </executions> </plugin> [...] </plugins> </build> </project>
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Building J2EE Applications
As you can see there is also a dependency on the daytrader-ear module. This is because the EAR artifact is needed to execute the functional tests. It also ensures that the daytrader-ear module is built before running the functional-tests build when the full DayTrader build is executed from the toplevel in daytrader/. For integration and functional tests, you will usually utilize a real database in a known state. To set up your database you can use the DBUnit Java API (see http://dbunit.sourceforge.net/). However, in the case of the DayTrader application, Derby is the default database configured in the deployment plan, and it is started automatically by Geronimo. In addition, there's a DayTrader Web page that loads test data into the database, so DBUnit is not needed to perform any database operations. You may be asking how to start the container and deploy the DayTrader EAR into it. You're going to use the Cargo plugin to start Geronimo and deploy the EAR into it. As the Surefire plugin's test goal has been bound to the integration-test phase above, you'll bind the Cargo plugin's start and deploy goals to the preintegration-test phase and the stop goal to the postintegration-test phase, thus ensuring the proper order of execution. Start by adding the Cargo dependencies to the functional-tests/pom.xml file:
<project> [...] <dependencies> [...] <dependency> <groupId>org.codehaus.cargo</groupId> <artifactId>cargo-core-uberjar</artifactId> <version>0.8</version> <scope>test</scope> </dependency> <dependency> <groupId>org.codehaus.cargo</groupId> <artifactId>cargo-ant</artifactId> <version>0.8</version> <scope>test</scope> </dependency> </dependencies>
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Then create an execution element to bind the Cargo plugin's start and deploy goals:
<build> <plugins> [...] <plugin> <groupId>org.codehaus.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <wait>false</wait> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www.apache.org/dist/geronimo/1.0/ geronimo-tomcat-j2ee-1.0.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> <executions> <execution> <id>start-container</id> <phase>pre-integration-test</phase> <goals> <goal>start</goal> <goal>deploy</goal> </goals> <configuration> <deployer> <deployables> <deployable> <groupId>org.apache.geronimo.samples.daytrader</groupId> <artifactId>daytrader-ear</artifactId> <type>ear</type> <properties> <plan>${basedir}/src/deployment/geronimo/plan.xml</plan> </properties> <pingURL>http://localhost:8080/daytrader</pingURL> </deployable> </deployables> </deployer> </configuration> </execution> [...]
The deployer element is used to configure the Cargo plugin's deploy goal. It is configured to deploy the EAR using the Geronimo Plan file. In addition, a pingURL element is specified so that Cargo will ping the specified URL till it responds, thus ensuring that the EAR is ready for servicing when the tests execute.
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Building J2EE Applications
Last, add an execution element to bind the Cargo plugin's stop goal to the post-integration-test phase:
[...] <execution> <id>stop-container</id> <phase>post-integration-test</phase> <goals> <goal>stop</goal> </goals> </execution> </executions> </plugin> </plugins> </build> </project>
The functional test scaffolding is now ready. The only thing left to do is to add the tests in src/it/java. An alternative to using Cargo's Maven plugin is to use the Cargo Java API directly from your tests, by wrapping it in a JUnit TestSetup class to start the container in setUp() and stop it in tearDown(). You're going to use the HttpUnit testing framework (http://httpunit.sourceforge.net/) to call a Web page from the DayTrader application and check that it's working. Add the JUnit and HttpUnit dependencies, with both defined using a test scope, as you're only using them for testing:
<dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>httpunit</groupId> <artifactId>httpunit</artifactId> <version>1.6.1</version> <scope>test</scope> </dependency>
Better Builds With Maven
add a JUnit test class called src/it/java/org/apache/geronimo/samples/daytrader/FunctionalTest.samples. public class FunctionalTest extends TestCase { public void testDisplayMainPage() throws Exception { WebConversation wc = new WebConversation(). Errors: 0.. WebRequest request = new GetMethodWebRequest( "http://localhost:8080/daytrader").apache.14. Summary You have learned from chapters 1 and 2 how to build any type of application and this chapter has demonstrated how to build J2EE applications.framework. the http://localhost:8080/daytrader URL is called to verify that the returned page has a title of "DayTrader": package org. In the class.531 sec [INFO] [cargo:stop {execution: stop-container}] 4.Building J2EE Applications Next. and more.apache.geronimo.java. } } It's time to reap the benefits from your build. import junit.FunctionalTest [surefire] Tests run: 1.samples. type mvn install and relax: C:\dev\m2book\code\j2ee\daytrader\functional-tests>mvn install [. how to gather project health information from your builds. Change directory into functional-tests. At this stage you've pretty much become an expert Maven user! The following chapters will show even more advanced topics such as how to write Maven plugins.. response.geronimo.] [INFO] [cargo:start {execution: start-container}] [INFO] [cargo:deploy {execution: start-container}] [INFO] [surefire:test {execution: default}] [INFO] Setting reports dir: C:\dev\m2book\code\j2ee\daytrader\functionaltests\target/surefire-reports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running org. import com.httpunit.getResponse(request). In addition you've discovered how to automate starting and stopping containers. assertEquals("DayTrader". Better Builds With Maven 124 . deploying J2EE archives and implementing functional tests. Time elapsed: 0.daytrader. how to effectively set up Maven in a team.*. Failures: 0.getTitle()).daytrader.meterware. WebResponse response = wc.*.
Richard Feynman Better Builds With Maven 125 . .5. and resources from a plugin Attaching an artifact to the project For a successful technology. Developing Custom Maven Plugins Developing Custom Maven Plugins This chapter covers: • • • • • How plugins execute in the Maven life cycle Tools and languages available to aid plugin developers Implementing a basic plugin using Java and Ant Working with dependencies. for Nature cannot be fooled. reality must take precedence over public relations. source directories.
and is defined as a set of task categories. This chapter will focus on the task of writing custom plugins. Finally. Additionally. Each mojo can leverage the rich infrastructure provided by Maven for loading projects. or even at the web sites of third-party tools offering Maven integration by way of their own plugins (for a list of some additional plugins available for use. and organizing and running plugins. Better Builds With Maven 126 . From there. refer to the Plugin Matrix. A mojo is the basic unit of work in the Maven application. well-defined order. It executes an atomic build task that represents a single step in the build process. resolving dependencies. and more. resolving project dependencies. Correspondingly.1. In this case. For example. called phases. it may be necessary to write a custom plugin to integrate these tasks into the build life cycle. With most projects. such as integration with external tools and systems. the maven-compiler-plugin incorporates two mojos: compile and testCompile. The actual functional tasks. Maven is actually a platform that executes plugins within a build life cycle. This ordering is called the build life cycle. plugins provide a grouping mechanism for multiple mojos that serve similar functions within the build life cycle. Such supplemental plugins can be found at the Apache Maven project the loosely affiliated CodeHaus Mojo project. or work. Just like Java packages.Developing Custom Maven Plugins 5. of the build process are executed by the set of plugins associated with the phases of a project's build life-cycle. but also extending a project's build to incorporate new functionality. However. it is still likely that a plugin already exists to perform this task. the plugins provided "out of the box" by Maven are enough to satisfy the needs of most build processes (see Appendix A for a list of default plugins used to build a typical project). they are packaged together into a plugin. Introduction As described in Chapter 2. Recall that a mojo represents a single task in the build process. Packaging these mojos inside a single plugin provides a consistent access mechanism for users. if your project requires tasks that have no corresponding plugin. executing all the associated mojos at each phase of the build. the common theme for these tasks is the function of compiling code. 5. in order to perform the tasks necessary to build a project. When Maven executes a build. This association of mojos to phases is called binding and is described in detail below. When a number of mojos perform related tasks. let's begin by reviewing the terminology used to describe a plugin and its role in the build. it will discuss the various ways that a plugin can interact with the Maven build environment and explore some examples. Maven's core APIs handle the "heavy lifting" associated with loading project definitions (POMs). A Review of Plugin Terminology Before delving into the details of how Maven plugins function and how they are written. injecting runtime parameter information. It starts by describing fundamentals. This makes Maven's plugin framework extremely important as a means of not only building a project. Even if a project requires a special task to be performed. allowing shared configuration to be added to a single section of the POM. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. it enables these mojos to share common code more easily. the chapter will cover the tools available to simplify the life of the plugin developer. it traverses the phases of the life cycle in order. the build process for a project is comprised of set of mojos executing in a particular.2.
While Maven does in fact define three different lifecycles. A discussion of all three build life cycles can be found in Appendix A. using the plugin executions section of the project's POM. Such mojos may be meant to check out a project from version control. Maven also provides a welldefined procedure for building a project's sources into a distributable archive. Understanding this framework will enable you to extract the Maven build-state information that each mojo requires. Using Maven's parameter injection infrastructure.3. mojos have a natural phase binding which determines when a task should execute within the life cycle. you will also need a good understanding of how plugins are structured and how they interact with their environment. the ordered execution of Maven's life cycle gives coherence to the build process. Better Builds With Maven 127 .1. Most mojos fall into a few general categories. As a plugin developer. These mojos are meant to be used by way of direct invocation. 5. Think of these mojos as tangential to the the Maven build process. before a mojo can execute. However. which correspond to the phases of the build life cycle. since they often perform tasks for the POM maintainer. As a result. and parameter resolution and injection. it may still require that certain activities have already been completed. successive phases can make assumptions about what work has taken place in the previous phases. In some cases. including a well-defined build life cycle. it is important to provide the appropriate phase binding for your mojos. plus much more. The Plugin Framework Maven provides a rich framework for its plugins. or aid integration with external development tools. dependency management. Together. 5. to ensure compatibility with other plugins. parameter injection and life-cycle binding form the cornerstone for all mojo development. sequencing the various build operations. and as such. While mojos usually specify a default phase binding. Using the life cycle. in addition to determining its appropriate phase binding.Developing Custom Maven Plugins Together with phase binding. Binding to a phase of the Maven life cycle allows a mojo to make assumptions based upon what has happened in the preceding phases. the discussion in this chapter is restricted to the default life cycle.3. they can be bound to any phase in the life cycle. which is used for the majority of build activities (the other two life cycles deal with cleaning a project's work directory and generating a project web site). you must understand the mechanics of life-cycle phase binding and parameter injection. Therefore. a given mojo can even be bound to the life cycle multiple times during a single build. a mojo can pick and choose what elements of the build state it requires in order to execute its task. Bootstrapping into Plugin Development In addition to understanding Maven's plugin terminology. Indeed. so be sure to check the documentation for a mojo before you re-bind it. Each execution can specify a separate phase binding for its declared set of mojos. or even create the directory structure for a new project. will not have a life-cycle phase binding at all since they don't fall into any natural category within a typical build process. a mojo may be designed to work outside the context of the build life cycle. Since phase bindings provide a grouping mechanism for mojos within the life cycle.
Indeed. Only those mojos with tasks to perform are executed during this build. none of the mojos from the maven-resources-plugin will be executed. the jar mojo from the maven-jarplugin will harvest these class files and archive them into a jar file. The testCompile mojo from the maven-compiler-plugin will compile the test sources. Instead. and much more. Maven's plugin framework ensures that almost anything can be integrated into the build life cycle. many more plugins can be used to augment the default life-cycle definition. each of the resource-related mojos will discover this lack of non-code resources and simply opt out without modifying the build in any way. Better Builds With Maven 128 .Developing Custom Maven Plugins Participation in the build life cycle Most plugins consist entirely of mojos that are bound at various phases in the life cycle according to their function in the build process. Depending on the needs of a given project. consider a very basic Maven build: a project with source code that should be compiled and archived into a jar file for redistribution. Then. Maven will execute a default life cycle for the 'jar' packaging. generation of the project's website. then two additional mojos will be triggered to handle unit testing. Since our hypothetical project has no "non-code" resources. but until now they had nothing to do and therefore. If this basic Maven project also includes source code for unit tests. at least two of the above mojos will be invoked. then the test mojo from the maven-surefire-plugin will execute those compiled tests. did not execute. These mojos were always present in the life-cycle definition. This level of extensibility is part of what makes Maven so powerful. During this build process. is often as important as the modifications made during execution itself. First. As a specific example of how plugins work together through the life cycle. The 'jar' packaging definition assigns the following life-cycle phase bindings: Table 5-1: Life-cycle bindings for jar packaging Life-cycle Phase Mojo Plugin process-resources compile process-test-resources test-compile test package install deploy resources compile testResources testCompile test jar install deploy maven-resources-plugin maven-compiler-plugin maven-resources-plugin maven-compiler-plugin maven-surefire-plugin maven-jar-plugin maven-install-plugin maven-deploy-plugin When you command Maven to execute the package phase of this life cycle. In good mojo design. determining when not to execute. validation of project content. the compile mojo from the maven-compiler-plugin will compile the source code into binary class files in the output directory. providing functions as varied as deployment into the repository system. This is not a feature of the framework. but a requirement of a well-designed mojo.
in addition to any programmatic modifications made by previous mojo executions. Environment information – which is more static. and the resulting value is injected into the mojo. a mojo that applies patches to the project source code will need to know where to find the project source and patch files. whether it is required for the mojo's execution. and the mechanism for injecting the parameter value into the mojo instance. until now you have not seen exactly how a life-cycle binding occurs. they require information about the state of the current build. whether it is editable. the set of parameters the mojo declares. That is to say. the life-cycle phase to which the mojo should be bound. a mojo can keep its dependency list to a bare minimum. see Appendix A. This information comes in two categories: • • Project information – which is derived from the project POM. Using the correct parameter expressions. The descriptor is an XML file that informs Maven about the set of mojos that are contained within the plugin. and once resolved. under the path /META-INF/maven/plugin. the expression associated with a parameter is resolved against the current build state.Developing Custom Maven Plugins Accessing build information In order for mojos to execute effectively. Within this descriptor. each declared mojo parameter includes information about the various expressions used to resolve its value. assuming the patch directory is specified as mojo configuration inside the POM. For example. For the complete plugin descriptor syntax. how do you instruct Maven to instantiate a given mojo in the first place? The answers to these questions lie in the plugin descriptor. This mojo would retrieve the list of source directories from the current build information using the following expression: ${project. The Maven plugin descriptor is a file that is embedded in the plugin jar archive. The plugin descriptor Though you have learned about binding mojos to life-cycle phases and resolving parameter values using associated expressions.and machine-level Maven settings.compileSourceRoots} Then. how do you instruct Maven to inject those values into the mojo instance? Further. using a language-appropriate mechanism. Maven allows mojos to specify parameters whose values are extracted from the build state using expressions. and more. and consists of the user. thereby avoiding traversal of the entire build-state object graph. To gain access to the current build state. how do you associate mojo parameters with their expression counterparts. see Appendix A. along with any system properties that were provided when Maven was launched. At runtime. It contains information about the mojo's implementation class (or its path within the plugin jar). and what methods Maven uses to extract mojo parameters from the build state. the expression to retrieve that information might look as follows: ${patchDirectory} For more information about which mojo expressions are built into Maven.xml. Better Builds With Maven 129 .
However. This framework generates both plugin documentation and the coveted plugin descriptor. • Of course.3. These plugindevelopment tools are divided into the following two categories: • The plugin extractor framework – which knows how to parse the metadata formats for every language supported by Maven. Using Java. Writing a plugin descriptor by hand demands that plugin developers understand low-level details about the Maven plugin framework – details that the developer will not use. By abstracting many of these details away from the plugin developer. except when configuring the descriptor. it uses a complex syntax. to generate the plugin descriptor). it consists of a framework library which is complemented by a set of provider libraries (generally. the format used to write a mojo's metadata is dependent upon the language in which the mojo is implemented.verbose}" default-value="false" */ private boolean verbose. The clean mojo also defines the following: /** * Be verbose in the debug log-level? * * @parameter expression="${clean. Maven provides plugin tools to parse mojo metadata from a variety of formats. and orchestrates the process of extracting metadata from mojo implementations. and direct invocations (as from the command line). the clean mojo in the maven-cleanplugin provides the following class-level javadoc annotation: /** * @goal clean */ public class CleanMojo extends AbstractMojo This annotation tells the plugin-development tools the mojo's name. one per supported mojo language). To accommodate the extensive variability required from the plugin descriptor. the mavenplugin-plugin simply augments the standard jar life cycle mentioned previously as a resourcegenerating step (this means the standard process of turning project sources into a distributable jar archive is modified only slightly. POM configurations. Maven's plugindevelopment tools remove the burden of maintaining mojo metadata by hand. so it can be referenced from lifecycle mappings. adding any other plugin-level metadata through its own configuration (which can be modified in the plugin's POM). Plugin Development Tools To simplify the creation of plugin descriptors. 5.Developing Custom Maven Plugins The plugin descriptor is very powerful in its ability to capture the wiring information for a wide variety of mojos. This is where Maven's plugin development tools come into play. This metadata is embedded directly in the mojo's source code where possible. Better Builds With Maven 130 . The maven-plugin-plugin – which uses the plugin extractor framework. Maven's development tools expose only relevant specifications in a format convenient for a given plugin's implementation language. For example. this flexibility comes at a price. it's a simple case of providing special javadoc annotations to identify the properties and parameters of the mojo. In short. and its format is specific to the mojo's implementation language.2.
If you choose to write mojos in another language. Better Builds With Maven 131 . it might seem counter-intuitive to initialize the default value of a Java field using a javadoc annotation. The second specifies that this parameter can also be configured from the command line as follows: -Dclean. it's a good idea to consistently specify the parameter's default value in the metadata. rather than in the Java field initialization code. like Ant. it specifies that this parameter can be configured from the POM using: <configuration> <verbose>false</verbose> </configuration> You may notice that this configuration name isn't explicitly specified in the annotation. namely the java. * * @parameter default-value="${project. For instance. it's impossible to initialize the Java field with the value you need.verbose=false Moreover. see Appendix A. especially when you could just declare the field as follows: private boolean verbose = false. At first.build. In this case. Remember. expression and default-value. Since the plugin tools can also generate documentation about plugins based on these annotations.io.Developing Custom Maven Plugins Here. The first specifies that this parameter's default value should be set to false. consider the following field annotation from the resources mojo in the maven-resources-plugin: /** * Directory containing the classes. This parameter annotation also specifies two attributes. this value is resolved based on the POM and injected into this field. For a complete list of javadoc annotations available for specifying mojo metadata. it's implicit when using the @parameter annotation. then the mechanism for specifying mojo metadata such as parameter definitions will be different.outputDirectory}" */ private File classesDirectory. the annotation identifies this field as a mojo parameter. When the mojo is instantiated. However. But consider what would happen if the default value you wanted to inject contained a parameter expression.File instance. which references the output directory for the current project. these annotations are specific to mojos written in Java. the underlying principles remain the same.
3. During the early phases of such a migration. the examples in this chapter will focus on a relatively simple problem space: gathering and publishing information about a particular build. Ant-based plugins can consist of multiple mojos mapped to a single build script. In these cases. it also provides good alignment of skill sets when developing mojos from scratch. when translating a project build from Ant to Maven (refer to Chapter 8 for more discussion about migrating from Ant to Maven). This is especially important during migration. Therefore. Since Java is currently the easiest language for plugin development.3. For many mojo developers. Maven can wrap an Ant build target and use it as if it were a mojo. Maven currently supports mojos written in Java. Java is the language of choice. To facilitate these examples. you risk confusing the issue at hand – namely. and minimizes the number of dependencies you will have on Maven's core APIs. A Note on the Examples in this Chapter When learning how to interact with the different aspects of Maven from within a mojo. Since it provides easy reuse of third-party APIs from within your mojo. mojo mappings and parameter definitions are declared via an associated metadata file. Such information might include details about the system environment. Ant. the particular feature of the mojo framework currently under discussion. Plugin parameters can be injected via either field reflection or setter methods. Otherwise. This relieves you of the burden associated with traversing a large object graph in your code. Maven can accommodate mojos written in virtually any language. Whatever language you use. You can install it using the following simple command: mvn install Better Builds With Maven 132 . In addition. this chapter will also provide an example of basic plugin development using Ant. This pairing of the build script and accompanying metadata file follows a naming convention that allows the mavenplugin-plugin to correlate the two files and create an appropriate plugin descriptor. Maven lets you select pieces of the build state to inject as mojo parameters. due to the migration value of Ant-based mojos when converting a build to Maven. However. or any combination thereof. which is used to read and write build information metadata files. and because many Maven-built projects are written in Java. called buildinfo.Developing Custom Maven Plugins Choose your mojo implementation language Through its flexible plugin descriptor format and invocation framework. this technique also works well for Beanshell-based mojos. and so on. This project can be found in the source code that accompanies this book. the specific snapshot versions of dependencies used in the build. Since Beanshell behaves in a similar way to standard Java. individual mojos each mapped to separate scripts. and Beanshell. For example. To make Ant scripts reusable. you will need to work with an external project. in certain cases you may find it easier to use Ant scripts to perform build tasks. 5. this chapter will focus primarily on plugin development in this language. it's important to keep the examples clean and relatively simple. Simple javadoc annotations give the plugin processing plugin (the maven-plugin-plugin) the instructions required to generate a descriptor for your mojo. it is often simpler to wrap existing Ant build targets with Maven mojos and bind them to various phases in the life cycle.
for the purposes of debugging. since this plugin doesn't currently have an associated web site. This information should capture relevant details about the environment used to build the Guinea Pig artifacts.4. it's helpful to use the archetype plugin to create a simple stub project. • Better Builds With Maven 133 . called Guinea Pig. To generate a stub plugin project for the buildinfo plugin.4. a default profile injects a dependency on a windows-specific library. you'll find a basic POM and a sample mojo.plugins \ -DartifactId=maven-buildinfo-plugin \ -DarchetypeGroupId=org. which will be deployed to the Maven repository system.name is set to the value Linux (for more information on profiles.Developing Custom Maven Plugins 5.1.mergere. If you have a test dependency which contains a defect. if the system property os. this dependency is used only during testing. Capturing this information is key. BuildInfo Example: Capturing Information with a Java Mojo To begin. In addition to simply capturing build-time information.mvnbook. When this profile is not triggered. writing your custom mojo is simple. refer to Chapter 3). and has no impact on transitive dependencies for users of this project.maven. Developing Your First Mojo For the purposes of this chapter. the values of system properties used in the build are clearly very important.0-alpha-4 This will create a project with the standard layout under a new subdirectory called mavenbuildinfo-plugin within the current working directory. For simplicity.archetypes \ -DarchetypeArtifactId=maven-archetype-mojo \ -DarchetypeVersion=1. consider a case where the POM contains a profile. Therefore. This development effort will have the task of maintaining information about builds that are deployed to the development repository. Once you have the plugin's project structure in place. you will need to modify the POM as follows: Change the name element to Maven BuildInfo Plugin. you will look at the development effort surrounding a sample project. which will be triggered by the value of a given system property – say.apache. Inside. For the purposes of this plugin. which allows the build to succeed in that environment. 5. this profile adds a new dependency on a Linux-specific library. then the value of the triggering system property – and the profile it triggers – could reasonably determine whether the build succeeds or fails. and this dependency is injected by one of the aforementioned profiles. you will need to disseminate the build to the rest of the development team. Here. Using the archetype plugin to generate a stub plugin project To jump-start the process of writing a new plugin. • Remove the url element. since it can have a critical effect on the build process and the composition of the resulting Guinea Pig artifacts. it makes sense to publish the value of this particular system property in a build information file so that others can see the aspects of the environment that affected this build. eventually publishing it alongside the project's artifact in the repository for future reference (refer to Chapter 7 for more details on how teams use Maven). When triggered. simply execute the following: mvn archetype:create -DgroupId=com.
Developing Custom Maven Plugins You will modify the POM again later.] /** * Write environment information for the current build to file.split( ". you should remove the sample mojo. i < keys.outputFile}" defaultvalue="${project.length.trim(). Properties sysprops = System.version}buildinfo. if ( systemProperties != null ) { String[] keys = systemProperties." ).artifactId}-${project.MISSING_INFO_PLACEHOLDER ). } buildInfo. fairly simple Java-based mojo: [.getProperties(). * @parameter expression="${buildinfo.java.xml" * @required */ private File outputFile. for ( int i = 0. BuildInfoConstants. under the following path: src/main/java/org/codehaus/mojo/MyMojo. Finally. i++ ) { String key = keys[i]..outputDirectory}/${project. String value = sysprops. since you will be creating your own mojo from scratch. value ). * @parameter expression="${buildinfo..build. It can be found in the plugin's project directory.getProperty( key. /** * The location to write the buildinfo file. public void execute() throws MojoExecutionException { BuildInfo buildInfo = new BuildInfo(). The mojo You can handle this scenario using the following. this simple version will suffice for now.systemProperties}" */ private String systemProperties. as you know more about your mojos' dependencies. * This is a comma-delimited list. However. * @goal extract * @phase package */ public class WriteBuildInfoMojo extends AbstractMojo { /** * Determines which system properties are added to the file.addSystemProperty( key. } Better Builds With Maven 134 .
In the class-level javadoc comment. you have several field-level javadoc comments. Using the expression attribute. e ). Aside from the class-level comment.Developing Custom Maven Plugins try { } } BuildInfoUtils. the expression attribute allows you to specify a list of system properties on-the-fly. Using the @parameter annotation by itself.version. } catch ( IOException e ) { throw new MojoExecutionException( "Error writing buildinfo XML file. However. In general. When you invoke this mojo. it's worthwhile to take a closer look at the javadoc annotations. Each offers a slightly different insight into parameter specification. you will use this name. with no attributes. consider the parameter for the systemProperties variable: /** * @parameter expression="${buildinfo. outputFile ). In this case.user.systemProperties}" */ This is one of the simplest possible parameter specifications. tells the plugin tools to treat this class as a mojo named extract. Therefore. so they will be considered separately.dir Better Builds With Maven 135 . @goal. attaching to the package phase also gives you the best chance of capturing all of the modifications made to the build state before the jar is produced. which are used to specify the mojo's parameters.writeXml( buildInfo. you can specify the name of this parameter when it's referenced from the command line. The second annotation tells Maven where in the build life cycle this mojo should be executed. In this case. you're collecting information from the environment with the intent of distributing it alongside the main project artifact in the repository.getMessage(). so it will be ready to attach to the project artifact. you may want to allow a user to specify which system properties to include in the build information file. This is where the expression attribute comes into play. there are two special annotations: /** * @goal extract * @phase package */ The first annotation. will allow this mojo field to be configured using the plugin configuration specified in the POM. Reason: " + e.systemProperties=java. it makes sense to execute this mojo in the package phase. } While the code for this mojo is fairly straightforward. as follows: localhost $ mvn buildinfo:extract \ -Dbuildinfo. First.
as execution without an output file would be pointless. This mapping is a slightly modified version of the one used for the jar packaging.xml" * * @required */ In this case. as follows: <project> <modelVersion>4.mergere. you want the mojo to use a certain value – calculated from the project's information – as a default value for this parameter. The plugin POM Once the mojo has been written. using several expressions to extract project information on-demand. the mojo cannot function unless it knows where to write the build information file. In addition.outputFile}" defaultvalue="${project. To ensure that this parameter has a value.plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <version>1.version}buildinfo. which simply adds plugin descriptor extraction and generation to the build process. Note the dependency on the buildinfo project. Better Builds With Maven 136 . However.0</modelVersion> <groupId>com.0. * * @parameter expression="${buildinfo.mvnbook.outputDirectory}/${project.apache. the complexity is justified. Take another look: /** * The location to write the buildinfo file. the mojo uses the @required annotation.artifactId}-${project. which provides the parsing and formatting utilities for the build information file.shared</groupId> <artifactId>buildinfo</artifactId> <version>1. If this parameter has no value when the mojo is configured.0-SNAPSHOT</version> </dependency> </dependencies> </project> This POM declares the project's identity and its two dependencies. In this example.0</version> </dependency> <dependency> <groupId>com. you can see why the normal Java field initialization is not used.mergere.maven</groupId> <artifactId>maven-plugin-api</artifactId> <version>2. note the packaging – specified as maven-plugin – which means that this plugin build will follow the maven-plugin life-cycle mapping. the outputFile parameter presents a slightly more complex example of parameter annotation.mvnbook.build.0-SNAPSHOT</version> <packaging>maven-plugin</packaging> <dependencies> <dependency> <groupId>org.Developing Custom Maven Plugins Finally. Also. The default output path is constructed directly inside the annotation. the build will fail with an error. you can construct an equally simple POM which will allow you to build the plugin. since you have more specific requirements for this parameter.
Developing Custom Maven Plugins Binding to the life cycle Now that you have a method of capturing build-time environmental information... Better Builds With Maven 137 . which you can do by adding the configuration of the new plugin to the Guinea Pig POM. </plugins> . </build> The above binding will execute the extract mojo from your new maven-buildinfo-plugin during the package phase of the life cycle.name system property. so that every build triggers it.version</systemProperties> </configuration> <goals> <goal>extract</goal> </goals> </execution> </executions> </plugin> ..name...java.mvnbook. This involves modification of the standard jar life-cycle. The easiest way to guarantee this is to bind the extract mojo to the life cycle. you need to ensure that every build captures this information.plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> <configuration> <systemProperties>os. as follows: <build> . and capture the os..mergere. <plugins> <plugin> <groupId>com.
0-SNAPSHOT-buildinfo. you should see output similar to the following: [. and both of these properties can have profound effects on binary compatibility..name> <java..name>Linux</os. build the buildinfo plugin with the following commands: > C:\book-projects\maven-buildinfo-plugin > mvn clean install Next.0" encoding="UTF-8"?><buildinfo> <systemProperties> <os.version> </systemProperties> </buildinfo> While the name of the OS may differ.] [INFO] [INFO] [INFO] [INFO] [. test the plugin by building Guinea Pig with the buildinfo plugin bound to its life cycle as follows: > C:\book-projects\guinea-pig > mvn package When the Guinea Pig build executes.. Better Builds With Maven 138 . there should be a file named: guinea-pig-1..version>1. the output of of the generated build information is clear enough.xml In the file. you can build the plugin and try it out! First. you will find information similar to the following: <?xml version="1. Your mojo has captured the name of operating system being used to execute the build and the version of the jvm.Developing Custom Maven Plugins The output Now that you have a mojo and a POM.4</java.] [buildinfo:extract {execution:extract}] ------------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------------- Under the target directory.
it's simpler to use Ant. and the dozens of well-tested. and should look similar to the following: <project> <target name="notify-target"> <mail from="maven@localhost" replyto="${listAddr}" subject="Build Info for Deployment of ${project. The corresponding metadata file will be called notify. To ensure these project properties are in place within the Ant Project instance. you need to share it with others in your team when the resulting project artifact is deployed.xml. which is associated to the build script using a naming convention. it might be enough to send a notification e-mail to the project development mailing list. and how. The Ant target To leverage the output of the mojo from the previous example – the build information file – you can use that content as the body of the e-mail. In this example. metadata for an Ant mojo is stored in a separate file. "deployment" is defined as injecting the project artifact into the Maven repository system. you just need to write a mojo definition to wire the new target into Maven's build process. After writing the Ant target to send the notification e-mail.Developing Custom Maven Plugins 5.xml. mature tasks available for build script use (including one specifically for sending e-mails). the build script was called notify. Your new mojo will be in a file called notify. From here. it's a simple matter of specifying where the email should be sent. you'll notice that this mojo expects several project properties. such a task could be handled using a Java-based mojo and the JavaMail API from Sun. Information like the to: address will have to be dynamic. Of course.2. However. For now. given the amount of setup and code required. so that other team members have access to it. therefore. The mojo metadata file Unlike the prior Java examples. simply declare mojo parameters for them.name}" mailhost="${mailHost}" mailport="${mailPort}" messagefile="${buildinfo.build.4. BuildInfo Example: Notifying Other Developers with an Ant Mojo Now that some important information has been captured. It's important to remember that in the Maven world.mojos. it should be extracted directly from the POM for the project we're building.build.xml and should appear as follows: Better Builds With Maven 139 .outputFile}"> <to>${listAddr}</to> </mail> </target> </project> If you're familiar with Ant.
Better Builds With Maven 140 . you will see many similarities. upon closer examination.name}</defaultValue> <required>true</required> <readonly>true</readonly> </parameter> <parameter> <name>mailHost</name> <expression>${mailHost}</expression> <defaultValue>localhost</defaultValue> <required>false</required> </parameter> <parameter> <name>mailPort</name> <expression>${mailPort}</expression> <defaultValue>25</defaultValue> <required>false</required> </parameter> </parameters> </mojo> </mojos> </pluginMetadata> At first glance.Developing Custom Maven Plugins <pluginMetadata> <mojos> <mojo> <call>notify-target</call> <goal>notify</goal> <phase>deploy</phase> <description><![CDATA[ Email environment information from the current build to the development mailing list when the artifact is deployed.artifactId}${project.directory}/${project.build.version}-buildinfo.xml </defaultValue> <required>true</required> <readonly>false</readonly> </parameter> <parameter> <name>listAddr</name> <required>true</required> </parameter> <parameter> <name>project.outputFile</name> <defaultValue> ${project. however. ]]></description> <parameters> <parameter> <name>buildinfo.name</name> <defaultValue>${project. the contents of this file may appear different than the metadata used in the Java mojo.
In this example. notice that this mojo is bound to the deploy phase of the life cycle. metadata specify a list of parameters for the mojo. As with the Java example.0. Fortunately. In Java.or Beanshell-based mojos with no additional configuration. However. because you're going to be sending e-mails to the development mailing list. expression. parameters are injected as properties and references into the Ant Project instance. and more. you will have to add support for Ant mojo extraction to the maven-plugin-plugin. Modifying the plugin POM for Ant mojos Since Maven 2. Any build that runs must be deployed for it to affect other development team members. As with the Java example.0 shipped without support for Ant-based mojos (support for Ant was added later in version 2. mojo-level metadata describes details such as phase binding and mojo name.Developing Custom Maven Plugins First of all. This allows developers to generate descriptors for Java. Instead. and parameter flags such as required are still present.String. The expression syntax used to extract information from the build state is exactly the same. The maven-plugin-plugin ships with the Java and Beanshell provider libraries which implement the above interface. The maven-plugin-plugin is a perfect example.lang. to develop an Ant-based mojo. In an Antbased mojo however. its value is injected as a project reference. in order to capture the parameter's type in the specification. each with its own information like name. some special configuration is required to allow the maven-plugin-plugin to recognize Ant mojos. you'd have to add a <type> element alongside the <name> element. but expressed in XML. otherwise. The rule for parameter injection in Ant is as follows: if the parameter's type is java. so it's pointless to spam the mailing list with notification e-mails every time a jar is created for the project. all of the mojo's parameter types are java.String (the default). parameter injection takes place either through direct field assignment. then its value is injected as a property. the overall structure of this file should be familiar. If one of the parameters were some other object type. Also. Maven allows POM-specific injection of plugin-level dependencies in order to accommodate plugins that take a framework approach to providing their functionality. the notification e-mails will be sent only when a new artifact becomes available in the remote repository. When this mojo is executed. the difference here is the mechanism used for this injection. by binding the mojo to the deploy phase of life cycle. or through JavaBeans-style setXXX() methods. Maven still must resolve and inject each of these parameters into the mojo. This is an important point in the case of this mojo.lang. default value. Finally. Better Builds With Maven 141 . with its use of the MojoDescriptorExtractor interface from the maven-plugin-tools-api library. a more in-depth discussion of the metadata file for Ant mojos is available in Appendix A. since you now have a good concept of the types of metadata used to describe a mojo. This library defines a set of interfaces for parsing mojo descriptors from their native format and generating various output from those descriptors – including plugin descriptor files.2).
] </project> Additionally.2</version> </dependency> <dependency> <groupId>ant</groupId> <artifactId>ant</artifactId> <version>1.] </dependencies> The first of these new dependencies is the mojo API wrapper for Ant build scripts.2</version> </dependency> </dependencies> </plugin> </plugins> </build> [.0.. you will need to add a dependency on the maven-plugin-tools-ant library to the maven-plugin-plugin using POM configuration as follows: <project> [. and it is always necessary for embedding Ant scripts as mojos in the Maven build process.. quite simply. since the plugin now contains an Ant-based mojo.maven</groupId> <artifactId>maven-plugin-tools-ant</artifactId> <version>2..5</version> </dependency> [..apache. it will be quite difficult to execute an Ant-based plugin. the specifications of which should appear as follows: <dependencies> [.] <dependency> <groupId>org. The second new dependency is..apache.] <build> <plugins> <plugin> <artifactId>maven-plugin-plugin</artifactId> <dependencies> <dependency> <groupId>org.Developing Custom Maven Plugins To accomplish this. Better Builds With Maven 142 .6...0.. a dependency on the core Ant library (whose necessity should be obvious). If you don't have Ant in the plugin classpath.maven</groupId> <artifactId>maven-script-ant</artifactId> <version>2. it requires a couple of new dependencies.
and send them to the Guinea Pig development mailing list in the deploy phase. it will also extract the relevant environmental details during the package phase. which supplies the listAddr parameter value.. execute the following command: > mvn deploy The build process executes the steps required to build and deploy a jar . Even its configuration is the same. In order to tell the notify mojo where to send this e-mail. notification happens in the deploy phase only.] </plugins> </build> The existing <execution> section – the one that binds the extract mojo to the build – is not modified.. a new section for the notify mojo is created. and these two mojos should not execute in the same phase (as mentioned previously). This is because an execution section can address only one phase of the build life cycle.] <plugins> <plugin> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> [. you should add a configuration section to the new execution section.. Instead..codehaus.except in this case. Now. Again. Better Builds With Maven 143 ... because non-deployed builds will have no effect on other team members. Adding a life-cycle binding for the new Ant mojo in the Guinea Pig POM should appear as follows: <build> [.] </execution> <execution> <id>notify</id> <goals> <goal>notify</goal> </goals> <configuration> <listAddr>firstname.lastname@example.com Custom Maven Plugins Binding the notify mojo to the life cycle Once the plugin descriptor is generated for the Ant mojo.org</listAddr> </configuration> </execution> </executions> </plugin> [. it behaves like any other type of mojo to Maven.
. The following sections do not build on one another. since the dependency resolution process is what populates the set of artifacts that make up the project's dependencies). Maven makes it easy to inject a project's dependencies. if you want to know how to develop plugins that manage dependencies. To enable a mojo to work with the set of artifacts that comprise the project's dependencies.dependencies}" * @required * @readonly */ private java. This annotation tells Maven not to allow the user to configure this parameter directly. namely it disables configuration via the POM under the following section: <configuration> <dependencies>. In addition. this declaration has another annotation.</dependencies> </configuration> Better Builds With Maven 144 . and artifact attachments. this is specified via a mojo parameter definition and should use the following syntax: /** * The set of dependencies required by the project * @parameter default-value="${project.5. As with all declarations.util.Developing Custom Maven Plugins 5. it must tell Maven that it requires access to that set of artifacts. • Injecting the project dependency set As described above.. which might not be as familiar: @readonly. However. and how to annotate the mojo with a name and a preferred phase binding.1.5. Fortunately. then read on! 5. This declaration should be familiar to you. • Second. Accessing Project Dependencies Many mojos perform tasks that require access to a project's dependencies. the mojo must tell Maven that it requires the project's dependencies be resolved (this second requirement is critical. the compile mojo in the maven-compiler-plugin must have a set of dependency paths in order to build the compilation classpath. only the following two changes are required: First. For example.Set dependencies. since it defines a parameter with a default value that is required to be present before the mojo can execute. However. the test mojo in the maven-surefire-plugin requires the project's dependency paths so it can execute the project's unit tests with a proper classpath. The next examples cover more advanced topics relating to mojo development. if the mojo works with a project's dependencies. Advanced Mojo Development The preceding examples showed how to declare basic mojo parameters. project source code and resources. and are not required for developing basic mojos. the mojo must tell Maven that it requires the project dependency set.
encapsulating all others). you'll know that one of its major problems is that it always resolves all project dependencies before invoking the first goal in the build (for clarity. this is a direct result of the rigid dependency resolution design in Maven 1. If a mojo doesn't need access to the dependency list. Returning to the example. Maven provides a mechanism that allows a mojo to specify whether it requires the project dependencies to be resolved. the @readonly annotation functions to force users to configure the POM.x. any dependencies specific to the test scope will remain unresolved. Maven will resolve only the dependencies that satisfy the requested scope. Requiring dependency resolution Having declared a parameter that injects the projects dependencies into the mojo. Maven 2. it will force all of the dependencies to be resolved (test is the widest possible scope. Maven 2 will not resolve project dependencies until a mojo requires it. If you've used Maven 1. at which scope.] So. However. the mojo is missing one last important step. Maven encounters another mojo that declares a requirement for test-scoped dependencies. your mojo must declare that it needs them. if later in the build process. and if so. direct configuration could result in a dependency being present for compilation. If the project's dependencies aren't available. Therefore. rather than configuring a specific plugin only. but being unavailable for testing. if your mojo needs to work with the project's dependencies. so you configure this parameter by modifying that section directly. Even then.. Consider the case where a developer wants to clean the project directory using Maven 1. Failure to do so will cause an empty set to be injected into the mojo's dependencies parameter. Better Builds With Maven 145 . the build process doesn't incur the added overhead of resolving them. To gain access to the project's dependencies. Maven 2 addresses this problem by deferring dependency resolution until the project's dependencies are actually required.0 uses the term 'mojo' as roughly equivalent to the Maven 1.Developing Custom Maven Plugins It also disables configuration via system properties.x term 'goal').. "How exactly can I configure this parameter?" The answer is that the mojos parameter value is derived from the dependencies section of the POM. In other words. you may be wondering.x. the clean process will fail – though not because the clean goal requires the project dependencies. It's important to note that your mojo can require any valid dependency scope to be resolved prior to its execution. If this parameter could be specified separately from the main dependencies section. In this case. such as: -Ddependencies=[. users could easily break their builds – particularly if the mojo in question compiled project source code. if a mojo declares that it requires dependencies for the compile scope. it will have to tell Maven to resolve them. Rather.
Developing Custom Maven Plugins
You can declare the requirement for the test-scoped project dependency set using the following class-level annotation:
/** * @requiresDependencyResolution test [...] */
Now, the mojo should be ready to work with the dependency set.
BuildInfo example: logging dependency versions
Turning once again to the maven-buildinfo-plugin, you will want to log the versions of the dependencies used during the build. This is critical when the project depends on snapshot versions of other libraries. In this case, knowing the specific set of snapshots used to compile a project can lend insights into why other builds are breaking. For example, one of the dependency libraries may have a newer snapshot version available. To that end, you'll add the dependency-set injection code discussed previously to the extract mojo in the maven-buildinfo-plugin, so it can log the exact set of dependencies that were used to produce the project artifact. This will result in the addition of a new section in the buildinfo file, which enumerates all the dependencies used in the build, along with their versions – including those dependencies that are resolved transitively. Once you have access to the project dependency set, you will need to iterate through the set, adding the information for each individual dependency to your buildinfo object. The code required is as follows:
if ( dependencies != null && !dependencies.isEmpty() ) { for ( Iterator it = dependencies.iterator(); it.hasNext(); ) { Artifact artifact = (Artifact) it.next(); ResolvedDependency rd = new ResolvedDependency(); rd.setGroupId( artifact.getGroupId() ); rd.setArtifactId( artifact.getArtifactId() ); rd.setResolvedVersion( artifact.getVersion() ); rd.setOptional( artifact.isOptional() ); rd.setScope( artifact.getScope() ); rd.setType( artifact.getType() ); if ( artifact.getClassifier() != null ) { rd.setClassifier( artifact.getClassifier() ); } } buildInfo.addResolvedDependency( rd );
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Developing Custom Maven Plugins
When you re-build the plugin and re-run the Guinea Pig build, the extract mojo should produce the same buildinfo file, with an additional section called resolvedDependencies that looks similar to the following:
<resolvedDependencies> <resolvedDependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <resolvedVersion>3.8.1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>test</scope> </resolvedDependency> [...] <resolvedDependency> <groupId>com.mergere.mvnbook.guineapig</groupId> <artifactId>guinea-pig-api</artifactId> <resolvedVersion>1.0-20060210.094434-1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>compile</scope> </resolvedDependency> [...] </resolvedDependencies>
The first dependency listed here, junit, has a static version of 3.8.1. This won't add much insight for debuggers looking for changes from build to build, but consider the next dependency: guinea-pigapi. This dependency is part of the example development effort, and is still listed with the version 1.0-alpha-SNAPSHOT in the POM. The actual snapshot version used for this artifact in a previous build could yield tremendous insight into the reasons for a current build failure, particularly if the newest snapshot version is different. If you were using a snapshot version from the local repository which has not been deployed, the resolvedVersion in the output above would be 1.0-alpha-SNAPSHOT. This is because snapshot time-stamping happens on deployment only.
5.5.2. Accessing Project Sources and Resources
In certain cases, it's possible that a plugin may be introduced into the build process when a profile is activated. If this plugin adds resources like images, or new source code directories to the build, it can have dramatic effects on the resulting project artifact. For instance, when a project is built in a JDK 1.4 environment, it may be necessary to augment a project's code base with an additional source directory. Once this new source directory is in place, the compile mojo will require access to it, and other mojos may need to produce reports based on those same source directories. Therefore, it's important for mojos to be able to access and manipulate both the source directory list and the resource definition list for a project.
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Developing Custom Maven Plugins
Adding a source directory to the build
Although the POM supports only a single sourceDirectory entry, Maven's concept of a project can accommodate a whole list of directories. This can be very useful when plugins generate source code, or simply need to augment the basic project code base. Maven's project API bridges this gap, allowing plugins to add new source directories as they execute. It requires access to the current MavenProject instance only, which can be injected into a mojo using the following code:
/** * Project instance, used to add new source directory to the build. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project;
This declaration identifies the project field as a required mojo parameter that will inject the current MavenProject instance into the mojo for use. As in the prior project dependencies discussion, this parameter also adds the @readonly annotation. This annotation tells Maven that users cannot modify this parameter, instead, it refers to a part of the build state that should always be present (a more in-depth discussion of this annotation is available in section 3.6, Chapter 3 of this book). The current project instance is a great example of this; any normal build will have a current project, and no other project contains current state information for this build. It is possible that some builds won't have a current project, as in the case where the mavenarchetype-plugin is used to create a stub of a new project. However, mojos require a current project instance to be available, unless declared otherwise. Maven will fail the build if it doesn't have a current project instance and it encounters a mojo that requires one. So, if you expect your mojo to be used in a context where there is no POM – as in the case of the archetype plugin – then simply add the class-level annotation: @requiresProject with a value of false, which tells Maven that it's OK to execute this mojo in the absence of a POM. Once the current project instance is available to the mojo, it's a simple matter of adding a new source root to it, as in the following example: project.addCompileSourceRoot( sourceDirectoryPath ); Mojos that augment the source-root list need to ensure that they execute ahead of the compile phase. The generally-accepted binding for this type of activity is in the generate-sources life-cycle phase. Further, when generating source code, the accepted default location for the generated source is in: ${project.build.directory}/generated-sources/<plugin-prefix> While conforming with location standards like this is not required, it does improve the chances that your mojo will be compatible with other plugins bound to the same life cycle.
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Developing Custom Maven Plugins
Adding a resource to the build
Another common practice is for a mojo to generate some sort of non-code resource, which will be packaged up in the same jar as the project classes. This could be a descriptor for binding the project artifact into an application framework, as in the case of Maven itself and the components.xml file found in all maven artifacts. Many different mojo's package resources with their generated artifacts such as web.xml files for servlet engines, or wsdl files for web services. Whatever the purpose of the mojo, the process of adding a new resource directory to the current build is straightforward and requires access to the MavenProject and MavenProjectHelper:
/** * Project instance, used to add new source directory to the build. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project;
This declaration will inject the current project instance into the mojo, as discussed previously. However, to simplify adding resources to a project, the mojo also needs access to the MavenProjectHelper component. This component is part of the Maven application, which means it's always present; so your mojo simply needs to ask for it. The project helper component can be injected as follows:
/** * project-helper instance, used to make addition of resources * simpler. * @component */ private MavenProjectHelper helper;
Right away, you should notice something very different about this parameter. Namely, that it's not a parameter at all! In fact, this is what Maven calls a component requirement (it's a dependency on an internal component of the running Maven application). To be clear, the project helper is not a build state; it is a utility. Component requirements are simple to declare; in most cases, the unadorned @component annotation – like the above code snippet – is adequate. Component requirements are not available for configuration by users. Normally, the Maven application itself is well-hidden from the mojo developer. However, in some special cases, Maven components can make it much simpler to interact with the build process. For example, the MavenProjectHelper is provided to standardize the process of augmenting the project instance, and abstract the associated complexities away from the mojo developer. It provides methods for attaching artifacts and adding new resource definitions to the current project. A complete discussion of Maven's architecture – and the components available – is beyond the scope of this chapter; however, the MavenProjectHelper component is worth mentioning here, as it is particularly useful to mojo developers.
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Developing Custom Maven Plugins
With these two objects at your disposal, adding a new resource couldn't be easier. Simply define the resources directory to add, along with inclusion and exclusion patterns for resources within that directory, and then call a utility method on the project helper. The code should look similar to the following:
String directory = "relative/path/to/some/directory"; List includes = Collections.singletonList("**/*"); List excludes = null; helper.addResource(project, directory, includes, excludes);
The prior example instantiates the resource's directory, inclusion patterns, and exclusion patterns as local variables, for the sake of brevity. In a typical case, these values would come from other mojo parameters, which may or may not be directly configurable. Again, it's important to understand where resources should be added during the build life cycle. Resources are copied to the classes directory of the build during the process-resources phase. If your mojo is meant to add resources to the eventual project artifact, it will need to execute ahead of this phase. The most common place for such activities is in the generate-resources life-cycle phase. Again, conforming with these standards improves the compatibility of your plugin with other plugins in the build.
Accessing the source-root list
Just as some mojos add new source directories to the build, others must read the list of active source directories, in order to perform some operation on the source code. The classic example is the compile mojo in the maven-compiler-plugin, which actually compiles the source code contained in these root directories into classes in the project output directory. Other examples include javadoc mojo in the maven-javadoc-plugin, and the jar mojo in the maven-source-plugin. Gaining access to the list of source root directories for a project is easy; all you have to do is declare a single parameter to inject them, as in the following example:
/** * List of source roots containing non-test code. * @parameter default-value="${project.compileSourceRoots}" * @required * @readonly */ private List sourceRoots;
Similar to the parameter declarations from previous sections, this parameter declaration states that Maven does not allow users to configure this parameter directly; instead, they have to modify the sourceDirectory element in the POM, or else bind a mojo to the life-cycle phase that will add an additional source directory to the build. The parameter is also required for this mojo to execute; if it's missing, the entire build will fail.
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addSourceRoot( makeRelative( sourceRoot ) ).Developing Custom Maven Plugins Now that the mojo has access to the list of project source roots. in order to incorporate list of source directories to the buildinfo object.iterator(). let's learn about how a mojo can access the list of resources used in a build. it's better to bind it to a later phase like package if capturing a complete picture of the project is important. By the time the mojo gains access to them. for eventual debugging purposes. since compile is the phase where source files are converted into classes. binding to any phase later than compile should be acceptable. it can be bound to any phase in the life cycle. it will add a corresponding section to the buildinfo file that looks like the following: <sourceRoots> <sourceRoot>src/main/java</sourceRoot> <sourceRoot>some/custom/srcDir</sourceRoot> </sourceRoots> Since a mojo using this code to access project source-roots does not actually modify the build state in any way. This involves subtracting ${basedir} from the source-root paths.hasNext(). which copies all non-code resources to the output directory for inclusion in the project artifact. You've already learned that mojos can modify the list of resources included in the project artifact. it. ) { String sourceRoot = (String) it. then this profile would dramatically alter the resulting project artifact when activated. If a certain profile injects a supplemental source directory into the build (most likely by way of a special mojo binding). Remember. it could be critically important to track the list of source directories used in a particular build. In order to make this information more generally applicable.next(). When you add this code to the extract mojo in the maven-buildinfo-plugin. it can iterate through them. Accessing the resource list Non-code resources complete the picture of the raw materials processed by a Maven build. source roots are expressed as absolute file-system paths. One thing to note about this code snippet is the makeRelative() method. To be clear. } buildInfo. any reference to the path of the project directory in the local file system should be removed. In this case however. as in the case of the extract mojo. now. Returning to the buildinfo example. This is the mechanism used by the resources mojo in the maven-resources-plugin. Therefore. Better Builds With Maven 151 . However. you need to add the following code: for ( Iterator it = sourceRoots. applying whatever processing is necessary. binding this mojo to an early phase of the life cycle increases the risk of another mojo adding a new source root in a later phase. the ${basedir} expression refers to the location of the project directory in the local file system.
getDirectory(). it. Just like the source-root injection parameter. It's necessary to revert resource directories to relative locations for the purposes of the buildinfo plugin. it is important that the buildinfo file capture the resource root directories used in the build for future reference. mojos must be smart enough to cast list elements as org. ) { Resource resource = (Resource) it. since the ${basedir} path won't have meaning outside the context of the local file system. Since mojos can add new resources to the build programmatically. if an activated profile introduces a mojo that generates some sort of supplemental framework descriptor. it can mean the difference between an artifact that can be deployed into a server environment and an artifact that cannot. and can be accomplished through the following code snippet: if ( resources != null && !resources.Developing Custom Maven Plugins Much like the source-root list. which in fact contain information about a resource root. Since the resources list is an instance of java. along with some matching rules for the resource files it contains. In this case.addResourceRoot( makeRelative( resourceRoot ) ). For instance. The parameter appears as follows: /** * List of Resource objects for the current build.util. and excludes. * @parameter default-value="${project. capturing the list of resources used to produce a project artifact can yield information that is vital for debugging purposes.Resource instances.model.resources}" * @required * @readonly */ private List resources. includes. by trimming the ${basedir} prefix. you'll notice the makeRelative() method.4 environment that doesn't support Java generics.hasNext(). } As with the prior source-root example. and Maven mojos must be able to execute in a JDK 1. the resources list is easy to inject as a mojo parameter. the user has the option of modifying the value of the list by configuring the resources section of the POM. It's also important to note that this list consists of Resource objects. Better Builds With Maven 152 . this parameter is declared as required for mojo execution and cannot be edited by the user. containing * directory. This method converts the absolute path of the resource directory into a relative path. It's a simple task to add this capability.next(). to avoid any ambiguity. All POM paths injected into mojos are converted to their absolute form first.maven. String resourceRoot = resource. Therefore.iterator(). As noted before with the dependencies parameter.List. } buildInfo. allowing direct configuration of this parameter could easily produce results that are inconsistent with other resource-consuming mojos.apache.isEmpty() ) { for ( Iterator it = resources.
addTestResource() ${project. a corresponding activity can be written to work with their test-time counterparts. Note on testing source-roots and resources All of the examples in this advanced development discussion have focused on the handling of source code and resources. This chapter does not discuss test-time and compile-time source roots and resources as separate topics. which may be executed during the build process. Table 5-2: Key differences between compile-time and test-time mojo activities Activity Change This To This Add testing source root Get testing source roots Add testing resource Get testing resources project. collecting the list of project resources has an appropriate place in the life cycle.addCompileSourceRoot() ${project.testResources} Better Builds With Maven 153 . The concepts are the same. only the parameter expressions and method names are different. It's important to note however.Developing Custom Maven Plugins Adding this code snippet to the extract mojo in the maven-buildinfo-plugin will result in a resourceRoots section being added to the buildinfo file. This ensures that any resource modifications introduced by mojos in the build process have been completed.addTestSourceRoot() ${project.testSourceRoots} helper. that for every activity examined that relates to source-root directories or resource definitions. the key differences are summarized in the table below. Like the vast majority of activities. any mojo seeking to catalog the resources used in the build should execute at least as late as the process-resources phase. which must be processed and included in the final project artifact.compileSourceRoots} helper. due to the similarities. instead. That section should appear as follows: <resourceRoots> <resourceRoot>src/main/resources</resourceRoot> <resourceRoot>target/generated-resources/xdoclet</resourceRoot> </resourceRoots> Once more.addResource() ${project.resources} project. Since all project resources are collected and copied to the project output directory in the processresources phase. it's worthwhile to discuss the proper place for this type of activity within the build life cycle.
produces a derivative artifact. which will make the process of attaching the buildinfo artifact a little easier: /** * This helper class makes adding an artifact attachment simpler. and only serves to describe the latest build. it can be referenced like any other artifact. like sources or javadoc. by using the classifier element for that dependency section within the POM. Attaching Artifacts for Installation and Deployment Occasionally.2 for a discussion about MavenProjectHelper and component requirements. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project. Better Builds With Maven 154 . mojos produce new artifacts that should be distributed alongside the main project artifact in the Maven repository system. can provide valuable information to the development team. First. When a mojo. The MavenProject instance is the object with which your plugin will register the attachment with for use in later phases of the lifecycle. for historical reference. Therefore. this classifier must also be specified when declaring the dependency for such an artifact.5. and even the buildinfo file produced in the examples throughout this chapter. an extra piece of code must be executed in order to attach that artifact to the project artifact. See Section 5. For convenience you should also inject the following reference to MavenProjectHelper. since it provides information about how each snapshot of the project came into existence. While an e-mail describing the build environment is transient. Including an artifact attachment involves adding two parameters and one line of code to your mojo.3.5. in that they are never distributed without the project artifact being distributed.Developing Custom Maven Plugins 5. Doing so guarantees that attachment will be distributed when the install or deploy phases are run. which sets it apart from the main project artifact in the repository. Once an artifact attachment is deposited in the Maven repository. to which we want to add an attached artifact. javadoc bundles. Maven treats these derivative artifacts as attachments to the main project artifact. * @component */ private MavenProjectHelper helper. which is still missing from the maven-buildinfo-plugin example. Classic examples of attached artifacts are source archives. Usually. the distribution of the buildinfo file via Maven's repository will provide a more permanent record of the build for each snapshot in the repository. This extra step. you'll need a parameter that references the current project instance as follows: /** * Project instance. an artifact attachment will have a classifier. These artifacts are typically a derivative action or side effect of the main build process. or set of mojos.
you can test it by re-building the plugin. It identifies the file as being produced by the the maven-buildinfoplugin. and route that message to other development team members on the project development mailing list. However. If you build the Guinea Pig project using this modified version of the maven-buildinfo-plugin.0-SNAPSHOT-buildinfo. From the prior examples.0-SNAPSHOT dir guinea-pig-core-1.jar guinea-pig-core-1. By specifying an extension of "xml". the maven-buildinfo-plugin can also generate an e-mail that contains the buildinfo file contents. outputFile ). These values represent the artifact extension and classifier.pom Now.0-SNAPSHOT. This serves to attach meaning beyond simply saying. the process of attaching the generated buildinfo file to the main project artifact can be accomplished by adding the following code snippet: helper. By specifying the "buildinfo" classifier. "xml". there are also two somewhat cryptic string values being passed in: "xml" and "buildinfo". Now that you've added code to distribute the buildinfo file. when the project is deployed. it can attach the buildinfo file to the main project artifact so that it's distributed whenever Maven installs or deploys the project. then running Maven to the install life-cycle phase on our test project. Better Builds With Maven 155 .Developing Custom Maven Plugins Once you include these two fields in the extract mojo within the maven-buildinfo-plugin. the maven-buildinfo-plugin is ready for action. Finally. you're telling Maven that the file in the repository should be named using a. you should see the buildinfo file appear in the local repository alongside the project jar.xml guinea-pig-core-1.xml extension. as follows: > > > > mvn install cd C:\Documents and Settings\jdcasey\. It can extract relevant details from a running build and generate a buildinfo file based on these details. "buildinfo".attachArtifact( project. as opposed to another plugin in the build process which might produce another XML file with different meaning. the meaning and requirement of project and outputFile references should be clear. From there. "This is an XML file". you're telling Maven that this artifact should be distinguished from other project artifacts by using this value in the classifier element of the dependency declaration. respectively.m2\repository cd org\codehaus\guineapig\guinea-pig-core\1.0-SNAPSHOT.
which can extract relevant parts of the build state in order to perform a custom build-process task – even to the point of altering the set of source-code directories used to build the project. it's unlikely to be a requirement unique to your project. only a tiny fraction of which are a part of the default lifecycle mapping. you can integrate almost any tool into the build process.6. Using the plugin mechanisms described in this chapter. Better Builds With Maven 156 . chances are good that you can find a plugin to address this need at the Apache Maven project. Working with project dependencies and resources is equally as simple. Using the default lifecycle mapping. Many plugins already exist for Maven use. reporting. developing a custom Maven plugin is an easy next step. Summary In its unadorned state. please consider contributing back to the Maven community by providing access to your new plugin. Since the build process for a project is defined by the plugins – or more accurately. So. Whether they be code-generation. Maven can build a basic project with little or no modification – thus covering the 80% case. It is in great part due to the re-usable nature of its plugins that Maven can offer such a powerful build platform. or verification steps. Maven represents an implementation of the 80/20 rule. or the project web site of the tools with which your project's build must to integrate. the mojos – that are bound to the build life cycle. If your project requires special handling. enabling you to attach custom artifacts for installation or deployment. remember that whatever problem your custom-developed plugin solves. in certain circumstances. you've learned that it's a relatively simple to create a mojo. Mojo development can be as simple or as complex (to the point of embedding nested Maven processes within the build) as you need it to be. If not. you've also learned how a plugin generated file can be distributed alongside the project artifact in Maven's repository system. Finally. In this chapter. the Codehaus Mojo project. Maven can integrate these custom tasks into the build process through its extensible plugin framework. there is a standardized way to inject new behavior into the build by binding new mojos at different life-cycle phases. a project requires special tasks in order to build successfully. However.Developing Custom Maven Plugins 5. However. if you have the means.
it is an art.Samuel Butler Better Builds With Maven 157 . Assessing Project Health with Maven Assessing Project Health with Maven This chapter covers: • • • • • How Maven relates to project health Organizing documentation and developer reports Selecting the right tools to monitor the health of your project How to incorporate reporting tools Tips for how to use tools more effectively Life is not an exact science.6. .
To begin. it was pointed out that Maven's application of patterns provides visibility and comprehensibility.determining how well the code works. because if the bar is set too high. you'll learn how to use a number of these tools effectively. how well it is tested. and how well it adapts to change. In this chapter. It is these characteristics that assist you in assessing the health of your project. and learning more about the health of the project. Through the POM. unzip the Code_Ch06-1. Project vitality . the project will meet only the lowest standard and go no further.Assessing Project Health with Maven 6. if the build fails its checks? The Web site also provides a permanent record of a project's health. Maven takes all of the information you need to know about your project and brings it together under the project Web site. What Does Maven Have to do With Project Health? In the introduction. Maven can analyze. This is unproductive as minor changes are prioritized over more important tasks.finding out whether there is any activity on the project. many of the reports illustrated can be run as part of the regular build in the form of a "check" that will fail the build if a certain condition is not met. and whether the conditions for the checks are set correctly. and what the nature of that activity is. which everyone can see at any time. For this reason.1. In this chapter. relate. This is important. It provides additional information to help determine the reasons for a failed build. Maven has access to the information that makes up a project. you will be revisiting the Proficio application that was developed in Chapter 3. But. why have a site. and using a variety of tools.zip file into C:\mvnbook or your selected working directory. if the bar is set too low. Conversely. Better Builds With Maven 158 . there will be too many failed builds. It is important not to get carried away with setting up a fancy Web site full of reports that nobody will ever use (especially when reports contain failures they don't want to know about!). new tools that can assess its health are easily integrated. The code that concluded Chapter 3 is also included in Code_Ch06-1. and then run mvn install from the proficio subdirectory to ensure everything is in place. The next three sections demonstrate how to set up an effective project Web site. When referring to health. to get a build to pass. there are two aspects to consider: • • Code quality . Because the POM is a declarative model of the project.zip for convenience as a starting point. and display that information in a single place.
These reports provide a variety of insights into the quality and vitality of the project. having these standard reports means that those familiar with Maven Web sites will always know where to find the information they need.2. you can add the Surefire report to the sample application. unless you choose to disable them. These reports are useful for sharing information with others. this menu doesn't appear as there are no reports included. review the project Web site shown in figure 6-1. adding a new report is easy.Assessing Project Health with Maven 6.xml: Better Builds With Maven 159 . For example. issue tracker. and to reference as links in your mailing lists. To start. is the focus of the rest of this chapter. Figure 6-1: The reports generated by Maven You can see that the navigation on the left contains a number of reports. and now shows how to integrate project health information. by including the following section in proficio/pom. On a new project. For newcomers to the project. The Project Info menu lists the standard reports Maven includes with your site by default. SCM. The second menu (shown opened in figure 6-1). However. Adding Reports to the Project Web site This section builds on the information on project Web sites in Chapter 2 and Chapter 3. and so on. Project Reports.
plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> </plugin> </plugins> </reporting> .html. <reporting> <plugins> <plugin> <groupId>org. C:\mvnbook\proficio\proficio-core> mvn site This can now be found in the file target/site/surefire-report. it will be inherited by all of the child modules.Assessing Project Health with Maven . and as a result. You can now run the following site task in the proficio-core directory to regenerate the site.maven.. Figure 6-2: The Surefire report Better Builds With Maven 160 .. and is shown in figure 6-2.apache. </project> This adds the report to the top level project...
. <build> <plugins> <plugin> <groupId>org. the report can also be run individually using the following standalone goal: C:\mvnbook\proficio\proficio-core> mvn surefire-report:report That's all there is to generating the report! This is possible thanks to key concepts of Maven discussed in Chapter 2: through a declarative project model. You might recall from Chapter 2 that a plugin is configured using the configuration element inside the plugin declaration in pom.. however it is added to the reporting section of the POM. For example..plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.Assessing Project Health with Maven As you may have noticed in the summary..apache. for example: .xml.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <showSuccess>false</showSuccess> </configuration> </plugin> </plugins> </reporting> .5</target> </configuration> </plugin> </plugins> </build> . Better Builds With Maven 161 . The addition of the plugin element triggers the inclusion of the report in the Web site.xml: . it is important to understand how the report configuration is handled in Maven. the report shows the test results of the project.apache.. Configuration of Reports Before stepping any further into using the project Web site. Maven knows where the tests and test results are.maven. the defaults are sufficient to get started with a useful report.. the report can be modified to only show test failures by adding the following configuration in pom. For a quicker turn around. and due to using convention over configuration.5</source> <target>1. <reporting> <plugins> <plugin> <groupId>org. as seen in the previous section.. Configuration for a reporting plugin is very similar. 6.maven.. while the configuration can be used to modify its appearance or behavior.3.
and the build. To continue with the Surefire report. you might think that you'd need to configure the parameter in both sections.directory}/surefire-reports </outputDirectory> </configuration> <executions> <execution> <phase>test</phase> <goals> <goal>report</goal> </goals> </execution> </executions> </plugin> </plugins> </build> . <build> <plugins> <plugin> <groupId>org. always place the configuration in the reporting section – unless one of the following is true: 1.maven. The reports will not be included in the site 2. To do this.Assessing Project Health with Maven If a plugin contains multiple reports. even though it is not specific to the execution.. However. some reports apply to both the site. consider if you wanted to create a copy of the HTML report in the directory target/surefirereports every time the build ran. The plugin is included in the build section to ensure that the configuration. When you configure a reporting plugin..build. they will all be included. Fortunately. Plugins and their associated configuration that are declared in the build section are not used during site generation.apache. "Executions" such as this were introduced in Chapter 3. or in addition to. is used only during the build. this isn't the case – adding the configuration to the reporting section is sufficient. what if the location of the Surefire XML reports that are used as input (and would be configured using the reportsDirectory parameter) were different to the default location? Initially. the plugin would need to be configured in the build section instead of. However.. Any plugin configuration declared in the reporting section is also applied to those declared in the build section..plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <outputDirectory> ${project. The configuration value is specific to the build stage Better Builds With Maven 162 . the reporting section: . and not site generation.
When a report is executed individually..build. Maven will use only the configuration that is specified in the plugin element itself. running mvn surefire-report:report will not use either of these configurations. Better Builds With Maven 163 .maven.apache.directory}/surefire-reports/unit </reportsDirectory> <outputName>surefire-report-unit</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> <reportSet> <id>perf</id> <configuration> <reportsDirectory> ${project. To generate two HTML reports for these results.. consider if you had run Surefire twice in your build. For example. which is the reporting equivalent of the executions element in the build section.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <reportSets> <reportSet> <id>unit</id> <configuration> <reportsDirectory> ${project. and cases where a particular report will be run more than once. <reporting> <plugins> <plugin> <groupId>org. by default all reports available in the plugin are executed once. Both of these cases can be achieved with the reportSets element. once for unit tests and once for a set of performance tests. and a list of reports to include. However. outside of any report sets. as with executions.. each time with a different configuration. there are cases where only some of the reports that the plugin produces will be required. However..directory}/surefire-reports/perf </reportsDirectory> <outputName>surefire-report-perf</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> </reportSets> </plugin> </plugins> </reporting> .xml: .build. Each report set can contain configuration.html and target/site/surefire-report-perf. you would include the following section in your pom. Running mvn site with this addition will generate two Surefire reports: target/site/surefirereport-unit.Assessing Project Health with Maven When you are configuring the plugins to be used in the reporting section.html. and that you had had generated its XML results to target/surefire-reports/unit and target/surefire-reports/perf respectively.
but quite separate to the end user documentation.xml file: . Better Builds With Maven 164 . where the end user documentation is on a completely different server than the developer information. This approach to balancing these competing requirements will vary. • The open source reusable library.maven.. While the defaults are usually sufficient. • The open source graphical application. <plugin> <groupId>org. Separating Developer Reports From User Documentation After adding a report. and most likely doesn't use Maven to generate it. add the following to the reporting section of the pom.Assessing Project Health with Maven The reports element in the report set is a required element. 6. where the developer information is available. On the entrance page there are usage instructions for Proficio. but in the navigation there are reports about the health of the project.. and an inconvenience to the developer who doesn't want to wade through end user documentation to find out the current state of a project's test coverage.. and the content's characteristics. to generate only the mailing list and license pages of the standard reports. this customization will allow you to configure reports in a way that is just as flexible as your build. which are targeted at the developers. It is also possible to include only a subset of the reports in a plugin. For example.. they must be enumerated in this list.4.plugins</groupId> <artifactId>maven-project-info-reports-plugin</artifactId> <reportSets> <reportSet> <reports> <report>mailing-list</report> <report>license</report> </reports> </reportSet> </reportSets> </plugin> . • To determine the correct balance. depending on the project. This may be confusing for the first time visitor. If you want all of the reports in a plugin to be generated. The reports in this list are identified by the goal names that would be used if they were run from the command line. who isn't interested in the state of the source code. where much of the source code and Javadoc reference is of interest to the end user. in some cases down to individual reports. there's something subtly wrong with the project Web site. each section of the site needs to be considered. Table 6-1 lists the content that a project Web site may contain. Consider the following: The commercial product. which are targeted at an end user.apache.
but usually not distributed or displayed in an application. Javadoc) that in a library or framework is useful to the end user. While there are some exceptions. The Distributed column in the table indicates whether that form of documentation is typically distributed with the project.Assessing Project Health with Maven Table 6-1: Project Web site content types Content Description Updated Distributed Separated News. For libraries and frameworks. The best compromise between not updating between releases. These are the reports discussed in this chapter that display the current state of the project to the developers. is to branch the end user documentation in the same way as source code. It is good to update the documentation on the Web site between releases. This is true of the news and FAQs. the documentation and Web site should be kept in a separate module dedicated to generating a site. This is typically true for the end user documentation. and not introducing incorrect documentation. It is also true of the project quality and vitality reports. source code references should be given a version and remain unchanged after being released. FAQs and general Web site End user documentation Source code reference material Project health and vitality reports This is the content that is considered part of the Web site rather than part of the documentation. regardless of releases. It refers to a particular version of the software. You can maintain a stable branch. Some standard reports. However. However. and to maintain only one set of documentation. as it is confusing for those reading the site who expect it to reflect the latest release. the source code reference material and reports are usually generated from the modules that hold the source code and perform the build. which are based on time and the current state of the project. This is documentation for the end user including usage instructions and guides. It is important not to include documentation for features that don't exist in the last release. This is reference material (for example. which are continuously published and not generally of interest for a particular release. Better Builds With Maven 165 . The situation is different for end user documentation. This avoids including inappropriate report information and navigation elements. the Updated column indicates whether the content is regularly updated. like mailing list information and the location of the issue tracker and SCM are updated also. The Separated column indicates whether the documentation can be a separate module or project. Yes Yes No Yes Yes No No Yes Yes No No No In the table. including the end user documentation in the normal build is reasonable as it is closely tied to the source code reference. Sometimes these are included in the main bundle. the Javadoc and other reference material are usually distributed for reference as well. and a development branch where new features can be documented for when that version is released. in most cases. that can be updated between releases without risk of including new features. and sometimes they are available for download separately. Features that are available only in more recent releases should be marked to say when they were introduced. For a single module library.
In this case. you will learn how to separate the content and add an independent project for the news and information Web site. and is not distributed with the project. the site currently contains end user documentation and a simple report. While these recommendations can help properly link or separate content according to how it will be used.mvnbook. In the following example. Figure 6-3: The initial setup The first step is to create a module called user-guide for the end user documentation. you are free to place content wherever it best suits your project. You would make it a module when you wanted to distribute it with the rest of the project. a module is created since it is not related to the source code reference material. Better Builds With Maven 166 . The resulting structure is shown in figure 6-4.Assessing Project Health with Maven This separated documentation may be a module of the main project. It is important to note that none of these are restrictions placed on a project by Maven. or maybe totally independent. which you can later add content to. The current structure of the project is shown in figure 6-3. This is done using the site archetype : C:\mvnbook\proficio> mvn archetype:create -DartifactId=user-guide \ -DgroupId=com. but make it an independent project when it forms the overall site with news and FAQs.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple This archetype creates a very basic site in the user-guide subdirectory. In Proficio.mergere.
. the URL and deployment location were set to the root of the Web site: http://library. Under the current structure.mergere.com/mvnbook/proficio. Better Builds With Maven 167 .com/mvnbook/proficio/user-guide.. In this example. the development documentation would go to that location. <distributionManagement> <site> . the development documentation will be moved to a /reference/version subdirectory so that the top level directory is available for a user-facing web site... is useful if you are maintaining multiple public versions. Previously..com/www/library/mvnbook/proficio/reference/${pom. <url> scp://mergere.. and the user guide to http://library.Assessing Project Health with Maven Figure 6-4: The directory layout with a user guide The next step is to ensure the layout on the Web site is correct. First.mergere. whether to maintain history or to maintain a release and a development preview. Adding the version to the development documentation. edit the top level pom. while optional.xml file to change the site deployment url: .version} </url> </site> </distributionManagement> .
mvnbook. There are now two sub-sites ready to be deployed: http://library. As before.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple You will not be able to deploy the Web site to the location The resulting structure is shown in figure 6-5. C:\mvnbook> mvn archetype:create -DartifactId=proficio-site \ -DgroupId=com.com/mvnbook/proficio/reference/1.com/www/library/mvnbook/proficio/user-guide </url> </site> </distributionManagement> .xml as follows: Better Builds With Maven 168 .. you can create a new site using the archetype.site</id> <url> scp://mergere. Now that the content has moved.Assessing Project Health with Maven Next.mergere. This will include news and FAQs about the project that change regularly..mergere. in the ch06-1 directory. a top level site for the project is required.com/mvnbook/proficio/user-guide/ • http://library. <distributionManagement> <site> <id>mvnbook. Figure 6-5: The new Web site You will need to add the same elements to the POM for the url and distributionManagement as were set originally for proficio/pom.com/www/library/mvnbook/proficio/user-guide It is included here only for illustrative purposes. run it one directory above the proficio directory. edit the user-guide/pom.0-SNAPSHOT/ • scp://mergere.xml file to set the site deployment url for the module: .. This time..mergere.
Better Builds With Maven 169 . Next.apt file with a more interesting news page. <url>http://library.Assessing Project Health with Maven .com/mvnbook/proficio</url> ... replace the src/site/apt/index..0-SNAPSHOT/" /> </menu> . If you deploy both sites to a server using mvn site-deploy as you learned in Chapter 3. so that link won't work even if the site is deployed..com/www/library/mvnbook/proficio</url> </site> </distributionManagement> . <menu name="Documentation"> <item name="User's Guide" href="/user-guide/" /> </menu> <menu name="Reference"> <item name="API" href="/reference/1. you will then be able to navigate through the links and see how they relate. The rest of this chapter will focus on using the developer section of the site effectively and how to build in related conditions to regularly monitor and improve the quality of your project..mergere.xml that point to the other documentation as follows: . Note that you haven't produced the apidocs directory yet.. <distributionManagement> <site> <id>mvnbook. * News * <16 Jan 2006> . like the following: ----Proficio ----Joe Blogs ----2 February 2006 ----Proficio Proficio is super.6 of this chapter..website</id> <url>scp://mergere..Proficio project started Finally. add some menus to src/site/site... You can now run mvn site in proficio-site to see how the separate site will look. Generating reference documentation is covered in section 6.0-SNAPSHOT/apidocs/" /> <item name="Developer Info" href="/reference/1.
In particular. Yes Yes ✔ ✔ ✗ Better Builds With Maven 170 . there is also a note about whether it has an associated visual report (for project site inclusion). See Chapter 7. such as Checkstyle Doesn't handle JDK 5. In some instances. and which checks to perform during the build.5. Produces a source cross reference for any Java code. the guidelines should help you to determine whether you need to use other reports. and an applicable build check (for testing a certain condition and failing the build if it doesn't pass). While these aren't all the reports available for Maven.0 features Use to enforce a standard code style. Table 6-2 covers the reports discussed in this chapter and reasons to use them. the reports that utilize unit tests often have to re-run the tests with new parameters. Team Collaboration with Maven. the performance of your build will be affected by this choice. Not useful if there are a lot of errors to be fixed – it will be slow and the result unhelpful. it is possible in the future that reports for other languages will be available. is an important decision that will determine the effectiveness of your build reports. While future versions of Maven will aim to streamline this. For each report. While this is certainly the case at present. or you can walk through all of the examples one by one. Report results and checks performed should be accurate and conclusive – every developer should know what they mean and how to address them. You may notice that many of these tools are Java-centric. Table 6-2: Report highlights Report Description Visual Check Notes ✔ ✔ ✔ ✔ ✗ Javadoc Produces an API reference from Javadoc. Choosing Which Reports to Include Choosing which reports to include. Recommended to enhance readability of the code. JXR Yes N/A Checkstyle Checks your source code against a standard descriptor for formatting issues. You can use this table to determine which reports apply to your project specifically and limit your reading to just those relevant sections of the chapter. in addition to the generic reports such as those for dependencies and change tracking.Assessing Project Health with Maven 6. Yes N/A Useful for most Java software Important for any projects publishing a public API Companion to Javadoc that shows the source code Important to include when using other reports that can refer to it. it is recommended that these checks be constrained to the continuous integration and release environments if they cause lengthy builds. and look at the output to determine which reports to use. for more information.
Recommended for all publicly released projects. Recommended for easier browsing of results. checks for duplicate source code blocks that indicates it was copy/pasted. Show the results of unit tests visually. so additional tools may be required. Simple report on outstanding tasks or other markers in source code Analyze code statement coverage during unit tests or other code execution. Yes Yes Should be used to improve readability and identify simple and common bugs. CPD Yes No ✔ ✔ Tag List Yes No ✔ ✔ ✔ ✔ ✔ ✗ Cobertura Yes Yes Surefire Report Yes Yes ✔ ✔ ✔ Dependency Examine the state of Convergence dependencies in a multiple module build Clirr Compare two versions of a JAR for binary compatibility Yes No ✔ ✔ Yes Yes ✔ ✔ Changes Produce release notes and road maps from issue tracking systems Yes N/A ✔ ✔ Better Builds With Maven 171 . Can help find snapshots prior to release.Assessing Project Health with Maven Report Description Visual Check Notes ✔ ✔ PMD Checks your source code against known rules for code smells. convenient set up Can be implemented using Checkstyle rules instead. Can also show any tests that are long running and slowing the build. Recommended for multiple module builds where consistent versions are important. Doesn't identify all missing or inadequate tests. Some overlap with Checkstyle rules Can be used to identify lazy copy/pasted code that might be refactored into a shared method. Recommended for libraries and frameworks with a public API Also important for reviewing changes to the internal structure of a project that are still exposed publicly. Avoids issues when one piece of code is fixed/updated and the other forgotten Useful for tracking TODO items Very simple. Recommended for teams with a focus on tests Can help identify untested or even unused code. Check already performed by surefire:test. Should be used for keeping teams up to date on internal projects also. Part of PMD.
html created. and. Those familiar with Javadoc will recognize the framed navigation layout. Creating Reference Material Source code reference materials are usually the first reports configured for a new project. Figure 6-6: An example source code cross reference Figure 6-6 shows an example of the cross reference. however the content pane is now replaced with a syntax-highlighted. Better Builds With Maven 172 .6.Assessing Project Health with Maven 6. crossreferenced Java source file for the selected class. Javadoc – the Java documentation tool You can get started with JXR on the example project very quickly. by running the following command: C:\mvnbook\proficio\proficio-core> mvn jxr:jxr You should now see a target/site/jxr. and one for the unit tests. This page links to the two sets of cross references: one for the main source tree. The two reports this section illustrates are: • • JXR – the Java source cross reference. The hyper links in the content pane can be used to navigate to other classes and interfaces within the cross reference. as well as to the developer of the project itself. because it is often of interest to the end user of a library or framework.
org/plugins/maven-jxr-plugin/. The end result is the familiar Javadoc output. in target/site/apidocs. However.apache... you can run it on its own using the following command: C:\mvnbook\proficio\proficio-core> mvn javadoc:javadoc Since it will be included as part of the project site.plugins</groupId> <artifactId>maven-jxr-plugin</artifactId> </plugin> . You can now run mvn site in proficio-core and see the Source Xref item listed in the Project Reports menu of the generated site. Better Builds With Maven 173 . A Javadoc report is only as good as your Javadoc! Make sure you document the methods you intend to display in the report.xml as a site report to ensure it is run every time the site is regenerated: . Unlike JXR.. Or. with most of the command line options of the Javadoc tool available. the links can be used to quickly find the source belonging to a particular exception. Now that you have a source cross reference. so an equally important piece of reference material is the Javadoc report.apache.plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> </plugin> .. <reporting> <plugins> <plugin> <groupId>org..Assessing Project Health with Maven A useful way to leverage the cross reference is to use the links given for each line number in a source file to point team mates at a particular piece of code.. and if possible use Checkstyle to ensure they are documented. see the plugin reference at http://maven.maven.apache.. <plugin> <groupId>org.xml: . you should include it in proficio/pom. however if you'd like a list of available configuration options.maven. and can be done by adding the following to proficio/pom. the default JXR configuration is sufficient. In most cases. Again. the Javadoc report is quite configurable. if you don't have the project open in your IDE. Using Javadoc is very similar to the JXR report and most other reports in Maven. many of the other reports demonstrated in this chapter will be able to link to the actual code to highlight an issue.. browsing source code is too cumbersome for the developer if they only want to know about how the API works.. Including JXR as a permanent fixture of the site for the project is simple.. </plugins> </reporting> .
when added to proficio/pom. the Javadoc plugin provides a way to produce a single set of API documentation for the entire project. Better Builds With Maven 174 .. but this would still limit the available classes in the navigation as you hop from module to module. In the online mode. this simple change will produce an aggregated Javadoc and ignore the Javadoc report in the individual modules. However. This setting must go into the reporting section so that it is used for both reports and if the command is executed separately. Now that the sample application has a complete reference for the source code.Assessing Project Health with Maven One useful option to configure is links.xml. the next section will allow you to start monitoring and improving its health.2/docs/api</link> <link>http://plexus.sun..xml by adding the following line: . ensuring that the deployed Javadoc corresponds directly to the artifact with which it is deployed for use in an IDE.plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> <configuration> <links> <link>http://java. Since it is preferred to have discrete functional pieces separated into distinct modules.. but it results in a separate set of API documentation for each library in a multi-module build. this is not sufficient. Setting up Javadoc has been very convenient. but conversely to have the Javadoc closely related.html. For example. One option would be to introduce links to the other modules (automatically generated by Maven based on dependencies.org/ref/1.apache. </configuration> .. this will link to an external Javadoc reference at a given URL.String and java.4 API documentation and the Plexus container API documentation used by Proficio: .. are linked to API documentation on the Sun website.. this setting is always ignored by the javadoc:jar goal. Edit the configuration of the existing Javadoc plugin in proficio/pom. <plugin> <groupId>org.codehaus.lang. <configuration> <aggregate>true</aggregate> ..4.0-alpha-9/apidocs</link> </links> </configuration> </plugin> .com/j2se/1. If you regenerate the site in proficio-core with mvn site again. Instead. of course!). Try running mvn clean javadoc:javadoc in the proficio directory to produce the aggregated Javadoc in target/site/apidocs/index.maven.. the following configuration. will link both the JDK 1.lang... you'll see that all references to the standard JDK classes such as java. as well as any references to classes in Plexus.Object. When built from the top level project.
sf. such as unused methods and variables. the line numbers in the report are linked to the actual source code so you can browse the issues. some source files are identified as having problems that could be addressed.7. Monitoring and Improving the Health of Your Source Code There are several factors that contribute to the health of your source code: Accuracy – whether the code does what it is expected to do • Robustness – whether the code gracefully handles exceptional conditions • Extensibility – how easily the code can be changed without affecting accuracy or requiring changes to a large amount of other code • Readability – how easily the code can be understood (in a team environment. since the JXR report was included earlier.net/) • Tag List • PMD takes a set of either predefined or user-defined rule sets and evaluates the rules across your Java source code. which is obtained by running mvn pmd:pmd. which in turn reduces the risk that its accuracy will be affected by change) • Maven has reports that can help with each of these health factors.net/) • Checkstyle (http://checkstyle. Better Builds With Maven 175 . Figure 6-7: An example PMD report As you can see. The result can help identify bugs.sf. and this section will look at three: PMD (http://pmd. and violations of a coding standard. Figure 6-7 shows the output of a PMD report on proficio-core. copy-and-pasted code. this is important for both the efficiency of other team members and also to increase the overall level of code comprehension. Also.Assessing Project Health with Maven 6.
xml.xml" /> <rule ref="/rulesets/unusedcode. by passing the rulesets configuration to the plugin.xml</ruleset> <ruleset>/rulesets/finalizers. The "unused code" rule set will locate unused private fields. you could create a rule set with all the default rules. Or.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> </plugin> .xml</ruleset> <ruleset>/rulesets/unusedcode. <plugin> <groupId>org. In either case.apache.. you may use the same rule sets in a number of projects.maven. To try this. but exclude the "unused private field" rule. if you configure these. <plugin> <groupId>org.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>/rulesets/basic.apache. The "imports" rule set will detect duplicate.xml</ruleset> </rulesets> </configuration> </plugin> ..Assessing Project Health with Maven Adding the default PMD report to the site is just like adding any other report – you can include it in the reporting section in the proficio/pom. For example.xml file: .xml</ruleset> <ruleset>/rulesets/imports. with the following content: <?xml version="1. unnecessary statements and possible bugs – such as incorrect loop variables... you must configure all of them – including the defaults explicitly. you can choose to create a custom rule set.. The "basic" rule set includes checks on empty blocks. and imports rule sets...0"?> <ruleset name="custom"> <description> Default rules. but not others. add the following to the plugin configuration you declared earlier: . Adding new rule sets is easy. The default PMD report includes the basic. to include the default rules.xml"> <exclude name="UnusedPrivateField" /> </rule> </ruleset> Better Builds With Maven 176 . You may find that you like some rules in a rule set. unused code.xml" /> <rule ref="/rulesets/imports. and the finalizer rule sets.maven. create a file in the proficio-core directory of the sample application called src/main/pmd/custom. However. no unused private field warning </description> <rule ref="/rulesets/basic. redundant or unused import declarations.. variables and parameters. For example. methods.
maven. One important question is how to select appropriate rules. basic.. change the configuration by overriding it in the proficio-core/pom. For more examples on customizing the rule sets. You'll see that the build fails with the following 3 errors: [INFO] --------------------------------------------------------------------------[INFO] Building Maven Proficio Core [INFO] task-segment: [pmd:check] [INFO] --------------------------------------------------------------------------[INFO] Preparing pmd:check [INFO] [pmd:pmd] [INFO] [pmd:check] [INFO] --------------------------------------------------------------------------[ERROR] BUILD FAILURE [INFO] --------------------------------------------------------------------------[INFO] You have 3 PMD violations. There is no point having hundreds of violations you won't fix. Start small.apache.. <reporting> <plugins> <plugin> <groupId>org.xml</ruleset> </rulesets> </configuration> </plugin> </plugins> </reporting> .sf.net/bestpractices. For PMD.sf. try the following guidelines from the Web site at http://pmd. select the rules that apply to your own project. and imports are useful in most scenarios and easily fixed. you need to make sure it stays that way..net/howtomakearuleset. From this starting. and add more as needed. Try this now by running mvn pmd:check on proficio-core.html.html: • • Pick the rules that are right for you. adding: .xml file. unusedcode. see the instructions on the PMD Web site at http://pmd..plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>${basedir}/src/main/pmd/custom. [INFO] --------------------------------------------------------------------------- Better Builds With Maven 177 . It is also possible to write your own rules if you find that existing ones do not cover recurring problems in your source code.Assessing Project Health with Maven To use this rule set. If you've done all the work to select the right rules and are correcting all the issues being discovered.
. the pmd:check goal is run in the verify phase. so that it is regularly tested.. which occurs after the packaging phase. you should include the check in the build. If you run mvn verify again. the build will succeed.maven.java file by adding a //NOPMD comment to the unused variables and method: . but recall from Configuring Reports and Checks section of this chapter that the reporting configuration is applied to the build as well. private void testMethod() // NOPMD { } . By default. </plugins> </build> You may have noticed that there is no configuration here. int j..plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> .apache.. If you need to run checks earlier. you could add the following to the execution block to ensure that the check runs just after all sources exist: <phase>process-sources</phase> To test this new setting. add the following section to the proficio/pom.Assessing Project Health with Maven Before correcting these errors. // NOPMD . // Trigger PMD and checkstyle int i. You will see that the build fails. Better Builds With Maven 178 . try running mvn verify in the proficio-core directory... // NOPMD .. fix the errors in the src/main/java/com/mergere/mvnbook/proficio/DefaultProficio. To do so. This is done by binding the goal to the build life cycle.. To correct this.xml file: <build> <plugins> <plugin> <groupId>org...
This report is included by default when you enable the PMD plugin in your reporting section. pmd:cpd-check can be used to enforce a failure if duplicate source code is found. such as Checkstyle. With this setting you can fine tune the size of the copies detected. For that reason. but mandatory in an integration environment.redhillconsulting. and it includes a list of duplicate code fragments discovered across your entire source base. There are other alternatives for copy and paste detection. This is the CPD. it can be slow and obtrusive during general development. adding the check to a profile.au/products/simian/). See Continuous Integration with Continuum section in the next chapter for information on using profiles and continuous integration. which is executed only in an appropriate environment. or to enforce a check will depend on the environment in which you are working. there is one that is in a separate report. An example report is shown in figure 6-8. and will appear as "CPD report" in the Project Reports menu.Assessing Project Health with Maven While this check is very useful. resulting in developers attempting to avoid detection by making only slight modifications. While the PMD report allows you to run a number of different rules. rather than identifying a possible factoring of the source code. Whether to use the report only. and a commercial product called Simian (http://www. Figure 6-8: An example CPD report In a similar way to the main check. can make the check optional for developers.com. the CPD report contains only one variable to configure: minimumTokenCount. This may not give you enough control to effectively set a rule for the source code. or copy/paste detection report. However. which defaults to 100. Simian can also be used through Checkstyle and has a larger variety of configuration options for detecting duplicate source code. Better Builds With Maven 179 .
html. If you need to learn more about the available modules in Checkstyle. Depending on your environment. with a link to the corresponding source line – if the JXR report was enabled. in many ways. you may choose to use it in one of the following ways: Use it to check code formatting only. and still rely on other tools for greater coverage. and rely on other tools for detecting other problems. Figure 6-9 shows the Checkstyle report obtained by running mvn checkstyle:checkstyle from the proficio-core directory.net/availablechecks. but has more recently added checks for other code issues. Some of the extra summary information for overall number of errors and the list of checks used has been trimmed from this display. the rules used are those of the Sun Java coding conventions. but Proficio is using the Maven team's code style. That's a lot of errors! By default. and then the errors are shown. It was originally designed to address issues of format and style. refer to the list on the Web site at http://checkstyle. • Use it to check code formatting and to detect other problems exclusively • This section focuses on the first usage scenario. Figure 6-9: An example Checkstyle report You'll see that each file with notices.sf. similar to PMD. warnings or errors is listed in a summary.Assessing Project Health with Maven Checkstyle is a tool that is. Better Builds With Maven 180 . • Use it to check code formatting and selected other problems.
org/plugins/maven-checkstyle-plugin/tips. add the following to the reporting section of proficio/pom.xml</configLocation> </configuration> </plugin> Table 6-3 shows the configurations that are built into the Checkstyle plugin.xml Description Reference Sun Java Coding Conventions Maven team's coding conventions Conventions from the Jakarta Turbine project Conventions from the Apache Avalon project http://java. Better Builds With Maven 181 .plugins</groupId> <artifactId>maven-checkstyle-plugin</artifactId> <configuration> <configLocation>config/maven_checks. then it is likely to be more readable and easily learned by people joining your project.html#Maven%20Code%20Style http://jakarta.sun. one or the other will be suitable for most people.xml: . the Checkstyle documentation provides an excellent reference at http://checkstyle. and to parameterize the Checkstyle configuration for creating a baseline organizational standard that can be customized by individual projects. The Checkstyle plugin itself has a large number of configuration options that allow you to customize the appearance of the report.xml config/maven_checks.apache.sf. filter the results. Before completing this section it is worth mentioning the Tag List plugin.. By default.net/config.apache.org/guides/development/guidem2-development. It is also possible to share a Checkstyle configuration among multiple projects.apache. will look through your source code for known tags and provide a report on those it finds. so to include the report in the site and configure it to use the Maven style. known as "Task List" in Maven 1.0. These checks are for backwards compatibility only. It is a good idea to reuse an existing Checkstyle configuration for your project if possible – if the style you use is common.html No longer online – the Avalon project has closed..org/turbine/common/codestandards. The built-in Sun and Maven standards are quite different. While this chapter will not go into an example of how to do this. a URL. However.html. you will need to create a Checkstyle configuration.maven.com/docs/codeconv/ http://maven.Assessing Project Health with Maven This style is also bundled with the Checkstyle plugin. This report.0 and above.html. and typically. or would like to use the additional checks introduced in Checkstyle 3. <plugin> <groupId>org. this will identify the tags TODO and @todo in the comments of your source code. if you have developed a standard that differs from these.apache. Table 6-3: Built-in Checkstyle configurations Configuration config/sun_checks.xml config/avalon_checks. The configLocation parameter can be set to a file within your build.xml config/turbine_checks. or a resource within a special dependency also. as explained at http://maven.
Setting Up the Project Web Site.. Cobertura (http://cobertura. will ignore these failures when generated to show the current test state. As you learned in section 6.mojo</groupId> <artifactId>taglist-maven-plugin</artifactId> <configuration> <tags> <tag>TODO</tag> <tag>@todo</tag> <tag>FIXME</tag> <tag>XXX</tag> </tags> </configuration> </plugin> . and Tag List are just three of the many tools available for assessing the health of your project's source code. for assessing coverage. There are additional testing stages that can occur after the packaging step to verify that the assembled package works under other circumstances. Monitoring and Improving the Health of Your Tests One of the important (and often controversial) features of Maven is the emphasis on testing as part of the production of your code. At the time of writing. or XXX in your source code. <plugin> <groupId>org. 6.codehaus... based on the theory that you shouldn't even try to use something before it has been tested. have beta versions of plugins available from the http://mojo.8. it is easy to add a report to the Web site that shows the results of the tests that have been run. PMD. To see what Cobertura is able to report.html. JavaNCSS and JDepend. it can be a useful report for demonstrating the number of tests available and the time it takes to run certain tests for a package. Better Builds With Maven 182 . however this plugin is a more convenient way to get a simple report of items that need to be addressed at some point later in time. you saw that tests are run before the packaging of the library or application for distribution. using this report on a regular basis can be very helpful in spotting any holes in the test plan. and more plugins are being added every day. Another critical technique is to determine how much of your source code is covered by the test execution.sf. run mvn cobertura:cobertura in the proficio-core directory of the sample application. This configuration will locate any instances of TODO. While you are writing your tests. or as part of the site). Failing the build is still recommended – but the report allows you to provide a better visual representation of the results. Some other similar tools.Assessing Project Health with Maven To try this plugin. add the following to the reporting section of proficio/pom. In the build life cycle defined in Chapter 2. Checkstyle. While the default Surefire configuration fails the build if the tests fail.org/ project at the time of this writing. FIXME. In addition to that.xml: .2.codehaus. It is actually possible to achieve this using Checkstyle or PMD rules.net) is the open source tool best integrated with Maven. such as FindBugs. @todo.. the report (run either on its own. Figure 6-10 shows the output that you can view in target/site/cobertura/index. Knowing whether your tests pass is an obvious and important assessment of their health.
For a source file. you'll notice the following markings: • • • Unmarked lines are those that do not have any executable code associated with them. and a line-by-line coverage analysis of each source file. For example. Unmarked lines with a green number in the second column are those that have been completely covered by the test execution.Assessing Project Health with Maven The report contains both an overall summary. in the familiar Javadoc style framed layout. a branch is an if statement that can behave differently depending on whether the condition is true or false. Each line with an executable statement has a number in the second column that indicates during the test run how many times a particular statement was run. Figure 6-10: An example Cobertura report Better Builds With Maven 183 . This includes method and class declarations. Lines in red are statements that were not executed (if the count is 0). or for which all possible branches were not executed. comments and white space.
xml: . you'll see that the cobertura. so including it in the site is simple. If you now run mvn site under proficio-core. High numbers (for example. The Cobertura report doesn't have any notable configuration.. the database used is stored in the project directory as cobertura. The Cobertura plugin also contains a goal called cobertura:check that is used to ensure that the coverage of your source code is maintained at a certain percentage.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> </plugin> . While not required.... Due to a hard-coded path in Cobertura. as well as the target directory. the report will be generated in target/site/cobertura/index.Assessing Project Health with Maven The complexity indicated in the top right is the cyclomatic complexity of the methods in the class.html.xml: . Better Builds With Maven 184 .mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> <executions> <execution> <id>clean</id> <goals> <goal>clean</goal> </goals> </execution> </executions> </plugin> </plugins> </build> . <build> <plugins> <plugin> <groupId>org. Add the following to the reporting section of proficio/pom. which measures the number of branches that occur in a particular method. there is another useful setting to add to the build section..ser. you might consider having PMD monitor it. add the following to the build section of proficio/pom.ser file is deleted.codehaus.codehaus. <plugin> <groupId>org. and is not cleaned with the rest of the project. To ensure that this happens. If you now run mvn clean in proficio-core. might indicate a method should be re-factored into simpler pieces. as it can be hard to visualize and test the large number of alternate code paths.. If this is a metric of interest.. over 10)..
. so running the check fails. and the tests are re-run using those class files instead of the normal ones (however. You would have seen in the previous examples that there were some lines not covered. If you now run mvn verify under proficio-core. as in the Proficio example. <configuration> <check> <totalLineRate>80</totalLineRate> . The Surefire report may also re-run tests if they were already run – both of these are due to a limitation in the way the life cycle is constructed that will be improved in future versions of Maven. Normally. looking through the report. If you run mvn verify again. and decide to reduce the overall average required. these are instrumented in a separate directory. This is because Cobertura needs to instrument your class files. You'll notice that your tests are run twice.. the configuration will be applied. add a configuration and another execution to the build plugin definition you added above when cleaning the Cobertura database: ..Assessing Project Health with Maven To configure this goal for Proficio.. the check passes.. However. you may decide that only some exceptional cases are untested. You can do this for Proficio to have the tests pass by changing the setting in proficio/pom.. and 100% branch coverage rate. This wouldn't be the case if it were associated with the life-cycle bound check execution. so are not packaged in your application).. The rules that are being used in this configuration are 100% overall line coverage rate. <execution> <id>check</id> <goals> <goal>check</goal> </goals> </execution> </executions> . Note that the configuration element is outside of the executions. you would add unit tests for the functions that are missing tests.. Better Builds With Maven 185 .. the check will be performed.xml: .. <configuration> <check> <totalLineRate>100</totalLineRate> <totalBranchRate>100</totalBranchRate> </check> </configuration> <executions> . This ensures that if you run mvn cobertura:check from the command line.
You may want to enforce this for each file individually as well. Choosing appropriate settings is the most difficult part of configuring any of the reporting metrics in Maven. This will allow for some constructs to remain untested. refer to the Cobertura plugin configuration reference at http://mojo. these reports work unmodified with those test types. Jester mutates the code that you've already determined is covered and checks that it causes the test to fail when run a second time with the wrong code. It behaves very similarly to Cobertura. Better Builds With Maven 186 . the easiest way to increase coverage is to remove code that handles untested. The best known commercial offering is Clover. Of course. or as the average across each package. These reports won't tell you if all the features have been implemented – this requires functional or acceptance testing.0 support is also available. In both cases. it is possible for you to write a provider to use the new tool. For more information. there is more to assessing the health of tests than success and coverage. Cobertura is not the only solution available for assessing test coverage. although not yet integrated with Maven directly. Don't set it too high.Assessing Project Health with Maven These settings remain quite demanding though. and at the time of writing experimental JUnit 4. and you can evaluate it for 30 days when used in conjunction with Maven.net). and get integration with these other tools for free. as it will discourage writing code to handle exceptional cases that aren't being tested. using lineRate and branchRate. it is worth noting that one of the benefits of Maven's use of the Surefire abstraction is that the tools above will work for any type of runner introduced.apache. Consider setting any package rates higher than the per-class rate. involve the whole development team in the decision. only allowing a small number of lines to be untested. so that they understand and agree with the choice. Surefire supports tests written with TestNG.codehaus.org/cobertura-maven-plugin. Don't set it too low. For example. using packageLineRate and packageBranchRate. To conclude this section on testing. For more information. Some helpful hints for determining the right code coverage settings are: • • • • • • Like all metrics. It is also possible to set requirements on individual packages or classes using the regexes parameter. Set some known guidelines for what type of code can remain untested. which is very well integrated with Maven as well.sf. exceptional cases – and that's certainly not something you want! The settings above are requirements for averages across the entire source tree. as it is to require that the other code be tested. as it will become a minimum benchmark to attain and rarely more. Choose to reduce coverage requirements on particular classes or packages rather than lowering them globally. It is just as important to allow these exceptions. such as handling checked exceptions that are unexpected in a properly configured system and difficult to test. may be of assistance there. If you have another tool that can operate under the Surefire framework. see the Clover plugin reference on the Maven Web site at http://maven. Tools like Jester (http://jester. and setting the total rate higher than both.org/plugins/maven-clover-plugin/. Remain flexible – consider changes over time rather than hard and fast rules. Remember. It also won't tell you whether the results of untested input values produce the correct results.
This brought much more power to Maven's dependency mechanism. Maven 2. where the dependencies of dependencies are included in a build. Monitoring and Improving the Health of Your Dependencies Many people use Maven primarily as a dependency manager. The first step to effectively maintaining your dependencies is to review the standard report included with the Maven site. Left unchecked. The result is shown in figure 6-11. used well it is a significant time saver.0 introduced transitive dependencies. and a number of other features such as scoping and version selection. but does introduce a drawback: poor dependency maintenance or poor scope and version selection affects not only your own project. If you haven't done so already. but any projects that depend on your project. While this is only one of Maven's features.html. the full graph of a project's dependencies can quickly balloon in size and start to introduce conflicts.Assessing Project Health with Maven 6. and browse to the file generated in target/site/dependencies.9. Figure 6-11: An example dependency report Better Builds With Maven 187 . run mvn site in the proficio-core directory.
0-SNAPSHOT (selected for compile) Here you can see that. The report shows all of the dependencies included in all of the modules within the project. an incorrect version. This helps ensure your build is consistent and reduces the probability of introducing an accidental incompatibility. which indicates dependencies that are in development.8. such as mvn -X package.0-SNAPSHOT junit:3. but that it is overridden by the test scoped dependency in proficio-core.0-alpha-9 (selected for compile) plexus-utils:1. The file target/site/dependencyconvergence. and must be updated before the project can be released. but more importantly in the second section it will list all of the transitive dependencies included through those dependencies. Whether there are outstanding SNAPSHOT dependencies in the build. It also includes some statistics and reports on two important factors: • Whether the versions of dependencies used for each module is in alignment.4 (selected for compile) classworlds:1. This will output the dependency tree as it is calculated. It's here that you might see something that you didn't expect – an extra dependency. local scope test wins) proficio-api:1.0. so at the time of this writing there are two features in progress that are aimed at helping in this area: • • The Maven Repository Manager will allow you to navigate the dependency tree through the metadata stored in the Ibiblio repository.1 (selected for test) plexus-container-default:1. but appears in a multi-module build only. This can be quite difficult to read. as well as comments about what versions and scopes are selected. and that plexus-container-default attempts to introduce junit as a compile dependency. here is the resolution process of the dependencies of proficio-core (some fields have been omitted for brevity): proficio-core:1.1 (not setting scope to: compile. or an incorrect scope – and choose to investigate its inclusion.Assessing Project Health with Maven This report shows detailed information about your direct dependencies. and is shown in figure 6-12.0-SNAPSHOT (selected for compile) proficio-model:1.1-alpha-2 (selected for compile) junit:3. Another report that is available is the "Dependency Convergence Report". Currently. proficio-model is introduced by proficio-api. To see the report for the Proficio project. this requires running your build with debug turned on. run mvn site from the base proficio directory. A dependency graphing plugin that will render a graphical representation of the information. For example. using indentation to indicate which dependencies introduce other dependencies.8.html will be created. This report is also a standard report. for example. • Better Builds With Maven 188 . and why.
You can control what version is actually used by declaring the dependency version in a project that packages or runs the application. Use a range of supported dependency versions. declaring the absolute minimum supported as the lower boundary. rather than using the latest available. or runtime if it is needed to bundle with or run the application but not for compiling your source code). Better Builds With Maven 189 .Assessing Project Health with Maven Figure 6-12: The dependency convergence report These reports are passive – there are no associated checks for them. try the following recommendations for your dependencies: • • • Look for dependencies in your project that are no longer used Check that the scope of your dependencies are set correctly (to test if only used for unit tests. However. they can provide basic help in identifying the state of your dependencies once you know what to find. To improve your project's health and the ability to reuse it as a dependency itself.
Better Builds With Maven 190 . this section will focus on improving the quality of the code released. Given the importance of this task. Monitoring and Improving the Health of Your Releases Releasing a project is one of the most important procedures you will perform. This is particularly the case for dependencies that are optional and unused by your project. Because existing libraries are not recompiled every time a version is changed. and more.10. 6. but there are plans for more: • • A class analysis plugin that helps identify dependencies that are unused in your current project Improved dependency management features including different mechanisms for selecting versions that will allow you to deal with conflicting versions. Figure 6-13: An example Clirr report This is particularly important if you are building a library or framework that will be consumed by developers outside of your own project. and the information released with it. Catching these before a release can eliminate problems that are quite difficult to resolve once the code is "in the wild". Two that are in progress were listed above. specification dependencies that let you depend on an API and manage the implementation at runtime. An important tool in determining whether a project is ready to be released is Clirr (http://clirr. While the next chapter will go into more detail about how Maven can help automate that task and make it more reliable. there is no verification that a library is binary-compatible – incompatibility will be discovered only when there's a failure. but it is often tedious and error prone. more tools are needed in Maven. Libraries will often be substituted by newer versions to obtain new features or bug fixes.Assessing Project Health with Maven • Add exclusions to dependencies to remove poorly defined dependencies from the tree. but then expected to continue working as they always have. An example Clirr report is shown in figure 6-13.net/).sf. Clirr detects whether the current version of a library has introduced any binary incompatibilities with the previous release.
By default. Maven currently works best if any version of an artifact is backwards compatible. the interactions between the project's own components will start behaving as if they were externally-linked. the answer here is clearly – yes..9 of proficio-api against which to compare (and that it is downloaded if you don't have it already): . the report will be generated in target/site/clirrreport. [INFO] [INFO] [INFO] [INFO] [INFO] . even if they are binary compatible.. If you run mvn site in proficio-api. to compare the current code to the 0... or a quick patch may need to be made and a new version deployed into an existing application. As a project grows.xml: .codehaus. [clirr:clirr] Comparing to version: 0. you'll notice that Maven reports that it is using version 0. You can obtain the same result by running the report on its own using mvn clirr:clirr.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <minSeverity>info</minSeverity> </configuration> </plugin> </plugins> </reporting> . If you run either of these commands.Assessing Project Health with Maven But does binary compatibility apply if you are not developing a library for external consumption? While it may be of less importance. by setting the minSeverity parameter. This is particularly true in a Maven-based environment. For example.8 release. You can change the version used with the comparisonVersion parameter. back to the first release. the Clirr report shows only errors and warnings. However. where the dependency mechanism is based on the assumption of binary compatibility between versions. Different modules may use different versions.9 ------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------- This version is determined by looking for the newest release in repository.html.8 Better Builds With Maven 191 .. This gives you an overview of all the changes since the last release.. add the following to the reporting section of proficio-api/pom. you can configure the plugin to show all informational messages. While methods of marking incompatibility are planned for future versions.. that is before the current development version. To see this in action.. <reporting> <plugins> <plugin> <groupId>org. run the following command: mvn clirr:clirr -DcomparisonVersion=0.
rather than removing or changing the original API and breaking binary compatibility.. and it can assist in making your own project more stable. on the acceptable incompatibilities.xml file. Like all of the quality metrics. then there is no point in checking the others – it will create noise that devalues the report's content in relation to the important components. </plugins> </build> . The Clirr plugin is also capable of automatically checking for introduced incompatibilities through the clirr:check goal. and later was redesigned to make sure that version 1. there is nothing in Java preventing them from being used elsewhere.. it is a good idea to monitor as many components as possible.Assessing Project Health with Maven These versions of proficio-api are retrieved from the repository. as it will be used as the interface into the implementation by other applications. to discuss and document the practices that will be used. and to check them automatically. To add the check to the proficio-api/pom. Even if they are designed only for use inside the project. it is important to agree up front. add the following to the build section: . so that fewer people are affected. you are monitoring the proficio-api component for binary compatibility changes only...zip file. It is best to make changes earlier in the development cycle. Better Builds With Maven 192 . it is almost always preferable to deprecate an old API and add a new one.codehaus. If it is the only one that the development team will worry about breaking.. However.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> . <build> <plugins> <plugin> <groupId>org. however you can see the original sources by extracting the Code_Ch06-2. The longer poor choices remain.0 would be more stable in the long run. delegating the code. This is the most important one to check. In this instance.. You'll notice there are a more errors in the report. Once a version has been released that is intended to remain binary-compatible going forward. the harder they are to change as adoption increases. since this early development version had a different API. if the team is prepared to do so.
you will see that the build fails due to the binary incompatibility introduced between the 0.. it will not pinpoint potential problems for you. Since this was an acceptable incompatibility due to the preview nature of the 0. Hopefully a future version of Clirr will allow acceptable incompatibilities to be documented in the source code. A limitation of this feature is that it will eliminate a class entirely.9 release. and ignored in the same way that PMD does. the following articles and books can be recommended: • • Evolving Java-based APIs contains a description of the problem of maintaining binary compatibility. This can be useful in getting a greater level of detail than Clirr on specific class changes. which is available at http://mojo. as well as strategies for evolving an API without breaking it. and so is most useful for browsing. While the topic of designing a strong public API and maintaining binary compatibility is beyond the scope of this book.9 preview release and the final 1. A similar tool to Clirr that can be used for analyzing changes between releases is JDiff. This allows the results to be collected over time to form documentation about known incompatibilities for applications using the library. <plugin> <groupId>org. not just the one acceptable failure.codehaus.. Note that in this instance. However. so the report still lists the incompatibility. It has a functional Maven 2 plugin. and then act accordingly. it takes a very different approach. and particularly so if you are designing a public API. you can choose to exclude that from the report by adding the following configuration to the plugin: . </plugin> This will prevent failures in the Proficio class from breaking the build in the future.. Effective Java describes a number of practical rules that are generally helpful to writing code in Java. Better Builds With Maven 193 .0 version. Built as a Javadoc doclet.org/jdiff-maven-plugin. it is listed only in the build configuration.Assessing Project Health with Maven If you now run mvn verify.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <excludes> <exclude>**/Proficio</exclude> </excludes> </configuration> . With this simple setup.codehaus. you can create a very useful mechanism for identifying potential release disasters much earlier in the development process.. taking two source trees and comparing the differences in method signatures and Javadoc annotations.
Better Builds With Maven 194 . a large amount of information was presented about a project. this focus and automated monitoring will have the natural effect of improving productivity and reducing time of delivery again. However. it should be noted that the Maven reporting API was written with these requirements in mind specifically. and as the report set stabilizes – summary reports will start to appear. Some of the reports linked to one another. Once established. they did not address all of these requirements. and incorporates the concepts learned in this chapter. How well this works in your own projects will depend on the development culture of your team.zip source archive. of the visual display is to aid in deriving the appropriate constraints to use. and few of the reports aggregated information across a multiple module build. The purpose.11. individual checks that fail the build when they're not met. However. it requires a shift from a focus on time and deadlines. 6. then. each in discrete reports. The additions and changes to Proficio made in this chapter can be found in the Code_Ch06-1. along with techniques to ensure that the build checks are now automated. and have not yet been implemented for Maven 2. These are all important features to have to get an overall view of the health of a project.xml). and run in the appropriate environment. it is important that your project information not remain passive. the Dashboard plugin). Most Maven plugins allow you to integrate rules into the build that check certain constraints on that piece of information once it is well understood. While some attempts were made to address this in Maven 1. It is important that developers are involved in the decision making process regarding build constraints. Summary The power of Maven's declarative project model is that with a very simple setup (often only 4 lines in pom. Best of all.0. regularly scheduled. as there is a constant background monitor that ensures the health of the project is being maintained. will reduce the need to gather information from various sources about the health of the project. Viewing Overall Project Health In the previous sections of this chapter. the model remains flexible enough to make it easy to extend and customize the information published on your project web site. none of the reports presented how the information changes over time other than the release announcements. but none related information from another report to itself. enforcing good. to a focus on quality. a new set of information about your project can be added to a shared Web site to help your team visualize the health of the project.0 (for example. The next chapter examines team development and collaboration. In the absence of these reports.Assessing Project Health with Maven 6. Finally. and will be used as the basis for the next chapter. so that they feel that they are achievable. In some cases.12.
Team Collaboration with Maven Team Collaboration with Maven This chapter covers: • • • • • • How Maven helps teams How to set up consistent developer environments How to set up a shared internal Maven repository Continuous Integration Creating shared organization metadata and archetypes Releasing a project Collaboration on a book is the ultimate unnatural act.Tom Clancy Better Builds With Maven 195 . .7.
CoRE is based on accumulated learnings from open source projects that have achieved successful. The Issues Facing Teams Software development as part of a team. the key to the information issue in both situations is to reduce the amount of communication necessary to obtain the required information in the first place. Even though teams may be widely distributed. further contributing to the problem. it's just as important that they don't waste valuable time researching and reading through too many information sources simply to find what they need. However. Even when it is not localized. While Maven is not tied directly to the CoRE framework. A Community-oriented Real-time Engineering (CoRE) process excels with this information challenge. faces a number of challenges to the success of the effort. in rapid. resulting in shortened development cycles. This problem gets exponentially larger as the size of the team increases. it is obvious that trying to publish and disseminate all of the available information about a project would create a near impossible learning curve and generate a barrier to productivity. and asynchronous engineering. every other member (and particularly new members). working on complex. misinterpreted. web-based communication channels and web-based project management tools. and document for reuse the artifacts that result from a software project. rapid development. This problem is particularly relevant to those working as part of a team that is distributed across different physical locations and timezones.1. iterative cycles. project information can still be misplaced. visualize. While it's essential that team members receive all of the project information required to be productive. which is enabled by the accessibility of consistently structured and organized information such as centralized code repositories. or forgotten. Better Builds With Maven 196 . Using the model of a community. although a distributed team has a higher communication overhead than a team working in a single location. and dealing with differences in opinions. will inevitably have to spend time obtaining this localized information. and that existing team members become more productive and effective. An organizational and technology-based framework. As each member retains project information that isn't shared or commonly accessible. real-time stakeholder participation. CoRE enables globally distributed development teams to cohesively contribute to high-quality software. As teams continue to grow. Many of these challenges are out of any given technology's control – for instance finding the right people for the team. it does encompass a set of practices and tools that enable effective team communication and collaboration. However. The CoRE approach to development also means that new team members are able to become productive quickly. one of the biggest challenges relates to the sharing and management of development information. CoRE emphasizes the relationship between project information and project members. but also to incorporate feedback. repeating errors previously solved or duplicating efforts already made. whether it is 2 people or 200 people. This value is delivered to development teams by supporting project transparency. These tools aid the team to organize. component-based projects despite large. the fact that everyone has direct access to the other team members through the CoRE framework reduces the time required to not only share information.Team Collaboration with Maven 7. widely-distributed teams.
In Maven. This chapter also looks at the adoption and use of a consistent development environment. To maintain build consistency.Team Collaboration with Maven As described in Chapter 6. How to Set up a Consistent Developer Environment Consistency is important when establishing a shared development environment. but also several that are typically common across users in a shared environment. the set up process for a new developer can be slow. it's a good idea to leverage Maven's two different settings files to separately manage shared and user-specific settings. error-prone and full of omissions. Better Builds With Maven 197 . while still allowing for this natural variability.m2 subdirectory of your home directory (settings in this location take precedence over those in the Maven installation directory). This file can be stored in the conf directory of your Maven installation. it will be the source of timeconsuming development problems in the future.2. The settings. the key is to minimize the configuration required by each individual developer. such as proxy settings. demonstrating how Maven provides teams with real-time information on the builds and health of a project. In Chapter 2. While one of Maven's objectives is to provide suitable conventions to reduce the introduction of inconsistencies in the build environment. Additionally. and to effectively define and declare them. In a shared development environment. such as different installation locations for software. because the environment will tend to evolve inconsistently once started that way. through the practice of continuous integration. Maven can gather and share the knowledge about the health of a project. 7. and other discrete settings such as user names and passwords. and the use of archetypes to ensure consistency in the creation of new projects. In this chapter. Without it.xml file. you learned how to create your own settings.xml file contains a number of settings that are user-specific. while an individual developer's settings are stored in their home directory. this is taken a step further. and to user-specific profiles. varying operating systems. there are unavoidable variables that remain. multiple JDK versions. these variables relate to the user and installation settings files. or in the . Common configuration settings are included in the installation directory.
Team Collaboration with Maven The following is an example configuration file that you might use in the installation directory.com/internal/</url> </repository> </repositories> <pluginRepositories> <pluginRepository> <id>internal</id> <name>Internal Plugin Repository</name> <url>http://repo.username}</username> <filePermissions>664</filePermissions> <directoryPermissions>775</directoryPermissions> </server> </servers> <profiles> <profile> <id>default-repositories</id> <repositories> <repository> <id>internal</id> <name>Internal Repository</name> <url>http://repo. <maven home>/conf/settings.xml: <settings> <proxies> <proxy> <active>true</active> <protocol>http</protocol> <host>proxy</host> <port>8080</port> </proxy> </proxies> <servers> <server> <id>website</id> <username>${website.plugins</pluginGroup> </pluginGroups> </settings> Better Builds With Maven 198 .mycompany.mycompany.mycompany.com/internal/</url> </pluginRepository> </pluginRepositories> </profile> </profiles> <activeProfiles> <activeProfile>property-overrides</activeProfile> <activeProfile>default-repositories</activeProfile> </activeProfiles> <pluginGroups> <pluginGroup>com.
home}/maven-repo). Another profile. which is typically one that has been set up within your own organization or department. with only specific properties such as the user name defined in the user's settings. These repositories are independent of the central repository in this configuration. ${user.3 for more information on setting up an internal repository. you can view the merged result by using the following help plugin command: C:\mvnbook> mvn help:effective-settings Better Builds With Maven 199 .username}.username>myuser</website. You'll notice that the local repository is omitted in the prior example. This profile will be defined in the user's settings file to set the properties used in the shared file. The plugin groups are necessary only if an organization has plugins. The active profiles listed enable the profile defined previously in every environment. The user-specific configuration is also much simpler as shown below: <settings> <profiles> <profile> <id>property-overrides</id> <properties> <website.Team Collaboration with Maven There are a number of reasons to include these settings in a shared configuration: • • • • • • If a proxy server is allowed. In Maven. See section 7.3 of this chapter for more information on creating a mirror of the central repository within your own organization. you can easily add and consistently roll out any new server and repository settings. issues with inconsistently-defined identifiers and permissions are avoided. By placing the common configuration in the shared settings. property-overrides is also enabled by default. across users. Using the basic template. The previous example forms a basic template that is a good starting point for the settings file in the Maven installation. such as ${website. While you may define a standard location that differs from Maven's default (for example. it is important that you do not configure this setting in a way that shares a local repository.username> </properties> </profile> </profiles> </settings> To confirm that the settings are installed correctly. The server settings will typically be common among a set of developers. the local repository is defined as the repository of a single user. The profile defines those common. which are run from the command line and not defined in the POM. internal repositories that contain a given organization's or department's released artifacts. it would usually be set consistently across the organization or department. See section 7. The mirror element can be used to specify a mirror of a repository that is closer to you. without having to worry about integrating local changes made by individual developers. at a single physical location.
Use an existing desktop management solution. but it is also important to ensure that the shared settings are easily and reliably installed with Maven. This internal repository is still treated as a remote repository in Maven. the next step is to establish a repository to and from which artifacts can be published and dependencies downloaded. Place the Maven installation on a read-only shared or network drive from which each developer runs the application. To set up Jetty. Change to that directory. but requires a manual procedure. organization's will typically want to set up what is referred to as an internal repository. developers must use profiles in the profiles.10-bundle. You can use an existing HTTP server for this. Now that each individual developer on the team has a consistent set up that can be customized as needed. To do this. an individual will need to customize the build of an individual project. if M2_HOME is not set. each execution will immediately be up-to-date. Retrieving an update from an SCM will easily update the configuration and/or installation. • Adjusting the path or creating symbolic links (or shortcuts) to the desired Maven executable. If necessary. just as any other external repository would be. and run: C:\mvnbook\repository> java -jar jetty-5. The following are a few methods to achieve this: • • • • Rebuild the Maven release distribution to include the shared configuration file and distribute it internally. Subversion.xml file.1. To publish releases for use across different environments within their network. Setting up an internal repository is simple. • Configuring the settings. or any number of other servers. or create a new server using Apache HTTPd.3. A new release will be required each time the configuration is changed. by one of the following methods: Using the M2_HOME environment variable to force the use of a particular installation. and when possible. doing so will prevent Maven from being available off-line. so that multiple developers and teams can collaborate effectively. easily updated. In some circumstances however. While it can be stored anywhere you have permissions.10 server bundle from the book's Web site and copy it to the repository directory. it is possible to maintain multiple Maven installations. To set up your organization's internal repository using Jetty. since not everyone can deploy to the central Maven repository. download the Jetty 5. create a new directory in which to store the files. Creating a Shared Repository Most organizations will need to set up one or more shared repositories.jar 8081 Better Builds With Maven 200 .1. located in the project directory. or other custom solution. however it applies to all projects that are built in the developer's environment. If this infrastructure is available. For an explanation of the different types of repositories. or if there are network problems. For more information on profiles. While any of the available transport protocols can be used. However.xml file covers the majority of use cases for individual developer customization. Apache Tomcat. Each developer can check out the installation into their own machines and run it from there. in this example C:\mvnbook\repository will be used. 7. see Chapter 2. or other source control management (SCM) system.Team Collaboration with Maven Separating the shared settings from the user-specific settings is helpful. the most popular is HTTP. Check the Maven installation into CVS. see Chapter 3. Jetty.
and is all that is needed to get started. However. The server is set up on your own workstation for simplicity in this example. While this isn't required. create a subdirectory called internal that will be available at http://localhost:8081/internal/. it provides faster performance (as most downloads to individual developers come from within their own network). Your repository is now set up. you can store the repositories on this single server. Use rsync to take a copy of the central repository and regularly update it. For the first repository. The repository manager can be downloaded from http://maven. configured securely and monitored to ensure it remains running at all times. as well as friendly repository browsing. However. there are a number of methods available: • • Manually add content as desired using mvn deploy:deploy-file Set up the Maven Repository Manager as a proxy to the central repository. Later in this chapter you will learn that there are good reasons to run multiple. the size of the Maven repository was 5. it is possible to use a repository on another server with any combination of supported protocols including http. scp. sftp and more. but rather than set up multiple web servers. You can create a separate repository under the same server.apache. Better Builds With Maven 201 . In addition. separate repositories. refer to Chapter 3. by avoiding any reliance on Maven's relatively open central repository. For more information. and reporting.Team Collaboration with Maven You can now navigate to http://localhost:8081/ and find that there is a web server running displaying that directory.8G. accessible location. and gives full control over the set of artifacts with which your software is built.org/repositorymanager/. This chapter will assume the repositories are running from http://localhost:8081/ and that artifacts are deployed to the repositories using the file system. searching. and keep a copy in your internal repository for others on your team to reuse. This creates an empty repository. It is deployed to your Jetty server (or any other servlet container) and provides remote repository proxies. using the following command: C:\mvnbook\repository> mkdir central This repository will be available at http://localhost:8081/central/. C:\mvnbook\repository> mkdir internal It is also possible to set up another repository (or use the same one) to mirror content from the Maven central repository. This will download anything that is not already present. To populate the repository you just created. it is common in many organizations as it eliminates the requirement for Internet access or proxy configuration. • The Maven Repository Manager (MRM) is a new addition to the Maven build platform that is designed to administer your internal repository. you will want to set up or use an existing HTTP server that is in a shared. At the time of writing. ftp.
Better Builds With Maven 202 . It is still important to declare the repositories that will be used in the top-most POM itself. and as a result. so that a project can add repositories itself for dependencies located out of those repositories configured initially. it is necessary to declare only those that contain an inherited POM. If you have multiple repositories. On the other hand. Not only is this very inconvenient.2. to configure the repository from the project level instead of in each user's settings (with one exception that will be discussed next). otherwise Maven will fail to download any dependencies that are not in your local repository.Team Collaboration with Maven When using this repository for your projects. for a situation where a developer might not have configured their settings and instead manually installed the POM.xml file. Developers may choose to use a different mirror. there are two choices: use it as a mirror. or hierarchy. if you want to prevent access to the central repository for greater control. or the original central repository directly without consequence to the outcome of the build. However. For example: <repositories> <repository> <id>central</id> <name>Internal Mirror of Central Repository</name> <url>http://localhost:8081/central/</url> </repository> </repositories> <pluginRepositories> <pluginRepository> <id>central</id> <name>Internal Mirror of Central Plugins Repository</name> <url>http://localhost:8081/central/</url> </pluginRepository> </pluginRepositories> You should not enter this into your project now. you must define a repository in a settings file and/or POM that uses the identifier central. that declares shared settings within an organization and its departments. Repositories such as the one above are configured in the POM usually. or have it override the central repository. The next section discusses how to set up an "organization POM". it would need to be declared in every POM. Usually. it must retrieve the parent from the repository. and if it's acceptable to have developers configure this in their settings as demonstrated in section 7. there is a problem – when a POM inherits from another POM that is not in the central repository. To override the central repository with your internal repository.2. as shown in section 7. it would be a nightmare to change should the repository location change! The solution is to declare your internal repository (or central replacement) in the shared settings. or to include your own artifacts in the same repository. This makes it impossible to define the repository in the parent. or had it in their source code check out. this must be defined as both a regular repository and a plugin repository to ensure all access is consistent. you should override the central repository. unless you have mirrored the central repository using one the techniques discussed previously. You would use it as a mirror if it is intended to be a copy of the central repository exclusively.
depending on the information that needs to be shared. As an example. </modules> </project> If you were to review the entire POM.org/maven-scm/</url> . Better Builds With Maven 203 .0 – that is. and is a project that.. you'd find that there is very little deployment or repositoryrelated information.0</modelVersion> <parent> <groupId>org.).maven. project inheritance can be used to assist in ensuring project consistency. Maven Continuum. consistency is important when setting up your build infrastructure. itself. Since the version of the POM usually bears no resemblance to the software.. that if your inherited projects reside in an internal repository.3. <modules> <module>maven-scm-api</module> <module>maven-scm-providers</module> .maven</groupId> <artifactId>maven-parent</artifactId> <version>1</version> </parent> <groupId>org.. You may have noticed the unusual version declaration for the parent project.xml file in the shared installation (or in each developer's home directory). or the organization as a whole.apache. This project structure can be related to a company structure. as this is consistent information.. Future versions of Maven plan to automate the numbering of these types of parent projects to make this easier. These parents (levels) may be used to define departments. the easiest way to version a POM is through sequential numbering. Creating an Organization POM As previously mentioned in this chapter. so it's possible to have one or more parents that define elements common to several projects. Any number of levels (parents) can be used. its departments. etc.apache. wherein there's the organization. there are three levels to consider when working with any individual module that makes up the Maven project. consider the Maven project itself.4. then that repository will need to be added to the settings.0.Team Collaboration with Maven 7. has a number of sub-projects (Maven. It is a part of the Apache Software Foundation. As a result. Maven SCM. and then the teams within those departments.scm</groupId> <artifactId>maven-scm</artifactId> <url>http://maven. While project inheritance was limited by the extent of a developer's checkout in Maven 1. consider the POM for Maven SCM: <project> <modelVersion>4. By declaring shared elements in a common parent POM. from section 7. To continue the Maven example.apache. the current project – Maven 2 now retrieves parent projects from the repository. which is shared across all Maven projects through inheritance. It is important to recall.
</mailingList> </mailingLists> <developers> <developer> .Team Collaboration with Maven If you look at the Maven project's parent POM.0.0</modelVersion> <parent> <groupId>org...maven</groupId> <artifactId>maven-parent</artifactId> <version>5</version> <url>http://maven..apache.apache</groupId> <artifactId>apache</artifactId> <version>1</version> </parent> <groupId>org.apache.. <mailingLists> <mailingList> <name>Maven Announcements List</name> <post>email@example.com/</url> .. you'd see it looks like the following: <project> <modelVersion>4.apache.. </developer> </developers> </project> Better Builds With Maven 204 .org</post> .
. Source control management systems like CVS and SVN (with the traditional intervening trunk directory at the individual project level) do not make it easy to store and check out such a structure. and less frequent schedule than the projects themselves. An issue that can arise.. there is no best practice requirement to even store these files in your source control management system. you can retain the historical versions in the repository if it is backed up (in the future. <distributionManagement> <repository> .. Better Builds With Maven 205 . in this case the Apache Software Foundation: <project> <modelVersion>4.org/</url> . <repositories> <repository> <id>apache. most of the elements are inherited from the organization-wide parent project.Team Collaboration with Maven The Maven parent POM includes shared elements. and deployed with their new version as appropriate. it is best to store the parent POM files in a separate area of the source control tree. modified.org/maven-snapshot-repository</url> <releases> <enabled>false</enabled> </releases> </repository> </repositories> . the Maven Repository Manager will allow POM updates from a web interface)..apache</groupId> <artifactId>apache</artifactId> <version>1</version> <organization> <name>Apache Software Foundation</name> <url>http://www. where they can be checked out. These parent POM files are likely to be updated on a different. when working with this type of hierarchy. For this reason. </repository> <snapshotRepository> ..apache..6).org/</url> </organization> <url>http://www.. </snapshotRepository> </distributionManagement> </project> The Maven project declares the elements that are common to all of its sub-projects – the snapshot repository (which will be discussed further in section 7. In fact.0.0</modelVersion> <groupId>org. Again.apache..snapshots</id> <name>Apache Snapshot Repository</name> <url>http://svn. is regarding the storage location of the source POM files. and the deployment locations.apache. such as the announcements mailing list and the list of developers that work across the whole project.
Continuous Integration with Continuum If you are not already familiar with it. however. iterative changes that can more easily support concurrent development processes. The first screen to appear will be the one-time setup page shown in figure 7-1. In this chapter. and learn how to use Continuum to build this project on a regular basis. As of Continuum 1. Better Builds With Maven 206 . For most installations this is all the configuration that's required. The examples discussed are based on Continuum 1.0.3> bin\win32\run There are scripts for most major platforms. First.0. Starting up continuum will also start a http server and servlet engine.3. ensuring that conflicts are detected earlier in a project's release life cycle. The configuration on the screen is straight forward – all you should need to enter are the details of the administration account you'd like to use.org/. continuous integration can enable a better development culture where team members can make smaller.3. continuous integration is a key element of effective collaboration. these additional configuration requirements can be set only after the previous step has been completed. as well as the generic bin/plexus. and the company information for altering the logo in the top left of the screen.Team Collaboration with Maven 7. As such.0. press Ctrl-C in the window that is running Continuum). More than just nightly builds. You can verify the installation by viewing the web site at http://localhost:8080/continuum/.tigris. some additional steps are required. you will need to install Continuum. which you can obtain for your operating system from http://subversion.5. you can run it using the following command: C:\mvnbook\continuum-1. The examples also assumes you have Subversion installed. Continuum is Maven's continuous integration and build server. continuous integration enables automated builds of your project on a regular interval. rather than close to a release.sh for use on other Unix-based platforms. and you must stop the server to make the changes (to stop the server. if you are running Continuum on your desktop and want to try the examples in this section. This is very simple – once you have downloaded it and unpacked it. however newer versions should be similar. you will pick up the Proficio example from earlier in the book.
. this is disabled as a security measure.... Value Better Builds With Maven 207 . To enable this setting.validation.. By default. edit apps/continuum/conf/application. <implementation> org. you can cut and paste field values from the following list: Field Name working-directory Working Directory Build Output Directory build-output-directory http://localhost:8080/continuum/servlet/continuum Base URL In the following examples. POM files will be read from the local hard disk where the server is running.UrlValidator </implementation> <configuration> <allowedSchemes> .Team Collaboration with Maven Figure 7-1: The Continuum setup screen To complete the Continuum setup page.plexus.formica.codehaus. since paths can be entered from the web interface..xml and verify the following line isn't commented out: . <allowedScheme>file</allowedScheme> </allowedSchemes> </configuration> .
The ciManagement section is where the project's continuous integration is defined and in the above example has been configured to use Continuum locally on port 8080... since not all of the required details were known at the time of its creation. <scm> <connection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </connection> <developerConnection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </developerConnection> </scm> . refer to http://maven...html. This requires obtaining the Code_Ch07. For instructions. You can then check out Proficio from that location...org/continuum/guides/mini/guide-configuration. If you do not have this set up on your machine.xml to correct the e-mail address to which notifications will be sent.Team Collaboration with Maven To have Continuum send you e-mail notifications. for example if it was unzipped in C:\mvnbook\svn: C:\mvnbook> svn co file://localhost/C:/mvnbook/svn/proficio/trunk \ proficio The POM in this repository is not completely configured yet. The default is to use localhost:25.. The next step is to set up the Subversion repository for the examples.com</address> </configuration> </notifier> </notifiers> </ciManagement> . you will also need an SMTP server to which to send the messages. by uncommenting and modifying the following lines: . <distributionManagement> <site> <id>website</id> <url> file://localhost/c:/mvnbook/repository/sites/proficio /reference/${project. Edit proficio/pom.version} </url> </site> </distributionManagement> .apache. and edit the location of the Subversion repository.zip archive and unpacking it in your environment. edit the file above to change the smtp-host setting. you can start Continuum again. Better Builds With Maven 208 . After these steps are completed. <ciManagement> <system>continuum</system> <url>http://localhost:8080/continuum <notifiers> <notifier> <type>mail</type> <configuration> <address>youremail@yourdomain..
The result is shown in figure 7-3. as in the Proficio example.0. This assumes that you are still running the repository Web server on localhost:8081.3 for information on how to set this up. Once you have logged in. While uploading is a convenient way to configure from your existing check out. enter the file:// URL as shown. you will enter either a HTTP URL to a POM in the repository. refer to section 7. with the following command: C:\mvnbook\proficio> mvn install You are now ready to start using Continuum. under the Continuum logo. or a Subversion HTTP server. or with another account you have since created with appropriate permissions. you can now select Maven 2. The login link is at the top-left of the screen. from the directory C:\mvnbook\repository. the builds will be marked as New and their checkouts will be queued. After submitting the URL. Once these settings have been edited to reflect your setup. commit the file with the following command: C:\mvnbook\proficio> svn ci -m 'my settings' pom. or upload from your local drive. You have two options: you can provide the URL for a POM. Continuum will return to the project summary page. When you set up your own system later.xml You should build all these modules to ensure everything is in order. you must either log in with the administrator account you created during installation. Better Builds With Maven 209 . Initially. Before you can add a project to the list. a ViewCVS installation. and each of the modules will be added to the list of projects. you will see an empty project list.Team Collaboration with Maven The distributionManagement setting will be used in a later example to deploy the site from your continuous integration environment. This will present the screen shown in figure 7-2. in Continuum 1.0+ Project from the Add Project menu. Figure 7-2: Add project screen shot This is all that is required to add a Maven 2 project to Continuum. Instead. If you return to the http://localhost:8080/continuum/ location that was set up previously.3 this does not work when the POM contains modules. If you haven't done so already. or perform other tasks.
Team Collaboration with Maven Figure 7-3: Summary page after projects have built Continuum will now build the project hourly.] public Proficio [. you might want to set up a notification to your favorite instant messenger – IRC. for example.. Jabber. In addition.java. The build in Continuum will return to the successful state.. marking the left column with an "!" to indicate a failed build (you will need to refresh the page using the Show Projects link in the navigation to see these changes).java Finally. For example. First. the build will show an "In progress" status. If you want to put this to the test. This chapter will not discuss all of the features available in Continuum. Better Builds With Maven 210 .. restore the file above to its previous state and commit it again.] Now. remove the interface keyword: [. and then fail. check the file in: C:\mvnbook\proficio\proficio-api> svn ci -m 'introduce error' \ src/main/java/com/mergere/mvnbook/proficio/Proficio. MSN and Google Talk are all supported. you should receive an e-mail at the address you configured earlier. go to your earlier checkout and introduce an error into Proficio. press Build Now on the Continuum web interface next to the Proficio API module. but you may wish to go ahead and try them. To avoid receiving this error every hour. and send an e-mail notification if there are any problems. The Build History link can be used to identify the failed build and to obtain a full output log..
it is beneficial to test against all different versions of the JDK. or local settings. In addition. clean build. but regular schedule is established for site generation. they need to be kept up-todate. If multiple branches are in development. Build all of a project's active branches. if the source control repository supports post-commit hooks. Run builds as often as possible. based on selected schedules. iterative builds are helpful in some situations. While this seems obvious. it is often ignored. Establish a stable environment. This will be constrained by the length of the build and the available resources on the build machine. operating system and other variables. Run a copy of the application continuously. Continuous integration is most effective when developers commit regularly. for example. if it isn't something already in use in other development. before the developer moves on or loses focus. • • • • • • • In addition to the above best practices. it is recommend that a separate. and your team will become desensitized to the notifications in the future. If the application is a web application. Continuum can be configured to trigger a build whenever a commit occurs. Avoid customizing the JDK. it is also important that failures don't occur due to old build state. Continuous integration will be pointless if developers repetitively ignore or delete broken build notifications. not just that the project still compiles after one or more changes occur. separate from QA and production releases. Better Builds With Maven 211 . This is another way continuous integration can help with project collaboration and communication. Run clean builds. enhancements that are planned for future versions. In Chapter 6. you learned how to create an effective site containing project information and reports about the project's health and vitality. When a failure occurs in the continuous integration environment. Though it would be overkill to regenerate the site on every commit. periodically. there are a few tips for getting the most out of the system: • Commit early. commit often. This also means that builds should be fast – long integration and performance tests should be reserved for periodic builds. This will make it much easier to detect the source of an error when the build does break. it is important that it can be isolated to the change that caused it. Continuum has preliminary support for system profiles and distributed testing. Continuum currently defaults to doing a clean build. Run comprehensive tests. run a servlet container to which the application can be deployed from the continuous integration environment.Team Collaboration with Maven Regardless of which continuous integration server you use. This can be helpful for non-developers who need visibility into the state of the application. This doesn't mean committing incomplete code. but rather keeping changes small and well tested. Continuous integration is most beneficial when tests are validating that the code is working as it always has. test and production environments. there are two additional topics that deserve special attention: automated updates to the developer web site. Fix builds as soon as possible. and profile usage. While rapid. the continuous integration environment should be set up for all of the active branches. and a future version will allow developers to request a fresh checkout. and independent of the environment being used. For these reports to be of value. but it is best to detect a failure as soon as possible. Consider a regular.
you can cut and paste field values from the following list: Field Name Site Generation Redeploy the site to the development project site during business hours 0 0 8-16 ? * MON-FRI Cron Expression Quiet Period (seconds) 0 Name Description The cron expression entered here is much like the one entered for a Unix crontab and is further described at http://www. Value Better Builds With Maven 212 . which will be configured to run every hour during business hours (8am – 4pm weekdays).com/quartz/api/org/quartz/CronTrigger. This is useful when using CVS. select Schedules. The appropriate configuration is shown in figure 7-4. Next. only the default schedule is available.. from the Administration menu on the left-hand side. It is not typically needed if using Subversion. 9:00:00. Click the Add button to add a new schedule. The "quiet period" is a setting that delays the build if there has been a commit in the defined number of seconds prior... The example above runs at 8:00:00. 16:00:00 from Monday to Friday.opensymphony.html. You will see that currently..Team Collaboration with Maven Verify that you are still logged into your Continuum instance. Figure 7-4: Schedule configuration To complete the schedule configuration. since commits are not atomic and a developer might be committing midway through a update.
In this example you will add a new build definition to run the site deployment for the entirety of the multi-module build. use the non-recursive mode instead. return to the project list.0. The project information shows just one build on the default schedule that installs the parent POM. you can cut and paste field values from the following list: Field Name Value POM filename Goals Arguments pom. but does not recurse into the modules (the -N or --non-recursive argument). there is no way to make bulk changes to build definitions. The site will be deployed to the file system location you specified in the POM. and add the same build definition to all of the modules. which will be visible from http://localhost:8081/sites/proficio/. and select the top-most project. Since this is the root of the multi-module build – and it will also detect changes to any of the modules – this is the best place from which to build the site.xml clean site-deploy --batch-mode -DenableCiProfile=true The goals to run are clean and site-deploy. Figure 7-5: Adding a build definition for site deployment To complete the Add Build Definition screen. Better Builds With Maven 213 . so you will need to add the definition to each module individually. when you first set up the Subversion repository earlier in this chapter. The Add Build Definition screen is shown in figure 7-5. To add a new build definition. click the Add button below the default build definition. on the business hours schedule. it can aggregate changes into the top-level site as required. Maven Proficio. The downside to this approach is that Continuum will build any unchanged modules.3. as well – if this is a concern.Team Collaboration with Maven Once you add this schedule. In addition to building the sites for each module. In Continuum 1.
. However. In the previous example. The checks will be run when you enable the ciProfile using mvn -DenableCiProfile=true. each build definition on the project information page (to which you would have been returned after adding the build definition) has a Build Now icon. so that if the build fails because of a failed check. Profiles are a means for selectively enabling portions of the build. In Chapter 6. you can add the test. which is essential for all builds to ensure they don't block for user input. . <profiles> <profile> <id>ciProfile</id> <activation> <property> <name>enableCiProfile</name> <value>true</value> </property> </activation> <plugins> <plugin> <groupId>org. The --non-recursive option is omitted.. the profile is enabled only when the enableCiProfile system property is set to true. since most reports continue under failure conditions. and -DenableCiProfile=true. the generated site can be used as reference for what caused the failure.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> . The meaning of this system property will be explained shortly. However. which means that Build Now from the project summary page will not trigger this build. please refer to Chapter 3. In this particular case.maven.. to ensure these checks are run. none of the checks added in the previous chapter are executed. Better Builds With Maven 214 .xml file in your Subversion checkout to that used in Chapter 6. such as the percentage of code covered in the unit tests dropping below a certain value. which can be a discouragement to using them. If you haven't previously encountered profiles. these checks delayed the build for all developers. Any of these test goals should be listed after the site-deploy goal. if you want to fail the build based on these checks as well. and that it is not the default build definition. You'll find that when you run the build from the command line (as was done in Continuum originally).apache. you'll see that these checks have now been moved to a profile. a system property called enableCiProfile was set to true. which sets the given system property. verify or integration-test goal to the list of goals. a number of plugins were set up to fail the build if certain project health checks failed. Click this for the site generation build definition.Team Collaboration with Maven The arguments provided are --batch-mode. You can see also that the schedule is set to use the site generation schedule created earlier. However. It is rare that the site build will fail. If you compare the example proficio/pom.. and view the generated site from http://localhost:8081/sites/proficio/.
but the timing and configuration can be changed depending upon your circumstances. you must build all of the modules simultaneously from a master build. How you configure your continuous integration depends on the culture of your development team and other environmental factors such as the size of your projects and the time it takes to build and test them.m2/settings. which is discussed in section 7. as well as the settings in the Maven installation. and in contrast to regular dependencies. The generated artifacts of the snapshot are stored in the local repository. The other alternative is to set this profile globally. add the following configuration to the settings. by going to the module information page. these artifacts will be updated frequently.Team Collaboration with Maven There are two ways to ensure that all of the builds added in Continuum use this profile.. and while dependency management is fundamental to any Maven build. In this section... Better Builds With Maven 215 .xml file in <maven home>/conf/settings. To enable this profile by default from these settings. if the additional checks take too much time for frequent continuous integration builds.6. indicates that the profile is always active when these settings are read. As Maven 2 is still executed as normal.xml: . 7. you will learn about using snapshots more effectively in a team environment. Team Dependency Management Using Snapshots Chapter 3 of this book discussed how to manage your dependencies in a multi-module build. for all projects in Continuum. it reads the ${user. where projects are closely related. In this case the identifier of the profile itself. Snapshots were designed to be used in a team environment as a means for sharing development versions of artifacts that have already been built. the verify goal may need to be added to the site deployment build definition. in some cases. The first is to adjust the default build definition for each module.8 of this chapter. <activeProfile>ciProfile</activeProfile> </activeProfiles> .. and clicking Edit next to the default build definition. Usually. it may be necessary to schedule them separately for each module. the team dynamic makes it critical. For example. So far in this book.home}/. it is necessary to do this for each module individually. The guidelines discussed in this chapter will help point your team in the right direction. As you saw before. in an environment where a number of modules are undergoing concurrent development. <activeProfiles> . Additionally. as discussed previously. the build involves checking out all of the dependent projects and building them yourself. or for the entire multi-module project to run the additional checks after the site has been generated... which are not changed.xml file for the user under which it is running. and how to enable this within your continuous integration environment. Projects in Maven stay in the snapshot state until they are released. at least in the version of Continuum current at the time of writing. rather than the property used to enable it. snapshots have been used to refer to the development version of an individual module.
0-20060211.3.. you'll see that the repository was defined in proficio/pom.. such as the internal repository set up in section 7.. the version used is the time that it was deployed (in the UTC timezone) and the build number. </distributionManagement> Now. though it may have been configured as part of your settings files. which can be error-prone.xml: .xml: . or to lock down a stable version by declaring the dependency version to be the specific equivalent such as 1.jar. use binary snapshots that have been already built and tested. Considering that example.. In Maven. deploy proficio-api to the repository with the following command: C:\mvnbook\proficio\proficio-api> mvn deploy You'll see that it is treated differently than when it was installed in the local repository.. locking the version in this way may be important if there are recent changes to the repository that need to be ignored temporarily. Currently. this is achieved by regularly deploying snapshots to a shared repository. it can lead to a number of problems: • • • • It relies on manual updates from developers.0-20060211. While this is not usually the case. the Proficio project itself is not looking in the internal repository for dependencies. <distributionManagement> <repository> <id>internal</id> <url>file://localhost/c:/mvnbook/repository/internal</url> </repository> .. Better Builds With Maven 216 . If you were to deploy again.131114-1. building from source doesn't fit well with an environment that promotes continuous integration. In this case. This will result in local inconsistencies that can produce non-working builds There is no common baseline against which to measure progress Building can be slower as multiple dependencies must be rebuilt also Changes developed against outdated code can make integration more difficult As you can see from these issues. The filename that is used is similar to proficio-api-1. but rather relying on the other modules to be built first. To add the internal repository to the list of repositories used by Proficio regardless of settings. <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> </repository> </repositories> . Instead. the time stamp would change and the build number would increment to 2.0SNAPSHOT.. add the following to proficio/pom.Team Collaboration with Maven While building all of the modules from source can work well and is handled by Maven inherently.. This technique allows you to continue using the latest version by declaring a dependency on 1.131114-1.
0-SNAPSHOT: checking for updates from internal .. Now. <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> . by default... However. The -U argument in the prior command is required to force Maven to update all of the snapshots in the build. Better Builds With Maven 217 .xml: . proficio-api:1. In this example. Several of the problems mentioned earlier still exist – so at this point. without having to manually intervene. making it out-of-date. You can always force the update using the -U command. It is possible to establish a policy where developers do an update from the source control management (SCM) system before committing. The settings that can be used for the update policy are never. as well as updating any version ranges. any snapshot dependencies will be checked once an hour to determine if there are updates in the remote repository. This is because the default policy is to update snapshots daily – that is. build proficio-core with the following command: C:\mvnbook\proficio\proficio-core> mvn -U install During the build. assuming that the other developers have remembered to follow the process. This causes many plugins to be checked for updates. you may also want to add this as a pluginRepository element as well.. all that is being saved is some time. this introduces a risk that the snapshot will not be deployed at all.. and interval:minutes. <repository> . However. no update would be performed.Team Collaboration with Maven If you are developing plugins. This technique can ensure that developers get regular updates.. add the following configuration to the repository configuration you defined above in proficio/pom. always.. similar to the example below (note that this output has been abbreviated): . deployed with uncommitted code. or deployed without all the updates from the SCM. and then deploy the snapshot to share with the other team members. and without slowing down the build by checking on every access (as would be the case if the policy were set to always). to see the updated version downloaded. you will see that some of the dependencies are checked for updates... to check for an update the first time that particular dependency is used after midnight local time. daily (the default).. Whenever you use the -U argument. it updates both releases and snapshots. the updates will still occur only as frequently as new versions are deployed to the repository. To see this. but you can also change the interval by changing the repository configuration. If it were omitted.
\apps\ continuum\build-output-directory C:\mvnbook\repository\internal Deployment Repository Directory http://localhost:8080/continuum/servlet/continuum Base URL Mergere Company Name http://www. Since the continuous integration server regularly rebuilds the code from a known state. you can cut and paste field values from the following list: Field Name C:\mvnbook\continuum-1.com Company URL Working Directory Value Better Builds With Maven 218 . Continuum can be configured to deploy its builds to a Maven snapshot repository automatically. Figure 7-6: Continuum configuration To complete the Continuum configuration page.\.3\bin\win32\. To deploy from your server. How you implement this will depend on the continuous integration server that you use.3\bin\win32\. it makes sense to have it build snapshots. shown in figure 7-6.Team Collaboration with Maven A much better way to use snapshots is to automate their creation. However..mergere..\. So far in this section. Log in as an administrator and go to the following Configuration screen.\apps\ continuum\working-directory Build Output Directory C:\mvnbook\continuum-1. you must ensure that the distributionManagement section of the POM is correctly configured. as well.mergere..com/_design/images/mergere_logo.. If there is a repository configured to which to deploy them. you have not been asked to apply this setting. this feature is enabled by default in a build definition. so let's go ahead and do it now.0.0. as you saw earlier.gif Company Logo http://www.
you can avoid all of the problems discussed previously. This will deploy to that repository whenever the version contains SNAPSHOT. To try this feature.Team Collaboration with Maven The Deployment Repository Directory field entry relies on your internal repository and Continuum server being in the same location. <distributionManagement> . If you are using the regular deployment mechanism (instead of using Continuum). you would add the following: ... <snapshotRepository> <id>internal. when it doesn't. With this setup. Better Builds With Maven 219 . you can enter a full repository URL such as scp://repositoryhost/www/repository/internal. you can either lock a dependency to a particular build. while you get regular updates from published binary dependencies. this separation is achieved by adding an additional repository to the distributionManagement section of your POM. Another point to note about snapshots is that it is possible to store them in a separate repository from the rest of your released artifacts. If this is not the case. This can be useful if you need to clean up snapshots on a regular interval. with an updated time stamp and build number.snapshots</id> <url>file://localhost/www/repository/snapshots</url> </snapshotRepository> </distributionManagement> . but still keep a full archive of releases. return to your console and build proficio-core again using the following command: C:\mvnbook\proficio\proficio-core> mvn -U install You'll notice that a new version of proficio-api is downloaded. when necessary.. Better yet.. and click Build Now on the Proficio API project. For example.. Once the build completes. follow the Show Projects link. if you had a snapshot-only repository in /www/repository/snapshots. and deploy to the regular repository you listed earlier. or build from source..
The replacement repository declarations in your POM would look like this: .. by hand. Better Builds With Maven 220 .snapshots</id> <url>http://localhost:8081/snapshots</url> <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> </repositories> .7.. and replacing the specific values with parameters. To get started with the archetype.. Writing an archetype is quite like writing your own project. you can create one or more of your own archetypes. the requirement of achieving consistency is a key issue facing teams. there is always some additional configuration required. There are two ways to create an archetype: one based on an existing project using mvn archetype:create-from-project.. As you saw in this chapter. While this is convenient. you can make the snapshot update process more efficient by not checking the repository that has only releases for updates. To avoid this. Beyond the convenience of laying out a project structure instantly. you have seen the archetypes that were introduced in Chapter 2 used to quickly lay down a project structure.mergere. <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> <repository> <id>internal. and the other. Creating a Standard Project Archetype Throughout this book. archetypes give you the opportunity to start a project in the right way – that is.mvnbook \ -DartifactId=proficio-archetype \ -DarchetypeArtifactId=maven-archetype-archetype The layout of the resulting archetype is shown in figure 7-7. run the following command: C:\mvnbook\proficio> mvn archetype:create \ -DgroupId=com. either in adding or removing content from that generated by the archetypes. 7. using an archetype. in a way that is consistent with other projects in your environment.Team Collaboration with Maven Given this configuration.
but it is also possible to specify files for resources. The JAR that is built is composed only of resources. The files within the archetype-resources section are Velocity templates. you'll see that the archetype is just a normal JAR project – there is no special build configuration required. For this example. the pom.xml. so everything else is contained under src/main/resources.xml at the top level.java</source> </sources> <testSources> <source>src/test/java/AppTest. The example descriptor looks like the following: <archetype> <id>proficio-archetype</id> <sources> <source>src/main/java/App. testResources. These files will be used to generate the template files when the archetype is run. and siteResources.Team Collaboration with Maven Figure 7-7: Archetype directory layout If you look at pom.java</source> </testSources> </archetype> Each tag is a list of files to process and generate in the created project.xml file looks like the following: Better Builds With Maven 221 . The example above shows the sources and test sources. and the template project in archetype-resources. There are two pieces of information required: the archetype descriptor in META-INF/maven/archetype. The archetype descriptor describes how to construct a new project from the archetype-resources provided.
Continuing from the example in section 7. Better Builds With Maven 222 . the groupId. Since the archetype inherits the Proficio parent.Team Collaboration with Maven <project xmlns="http://maven.0.apache.org/maven-v4_0_0.apache.0.mvnbook \ -DartifactId=proficio-example \ -DarchetypeGroupId=com. a previous release would be used instead).mvnbook \ -DarchetypeArtifactId=proficio-archetype \ -DarchetypeVersion=1. if omitted. so you can run the following command: C:\mvnbook\proficio\proficio-archetype> mvn deploy The archetype is now ready to be used.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven. install and deploy it like any other JAR.apache. artifactId and version elements are variables that will be substituted with the values provided by the developer running archetype:create. the archetypeVersion argument is not required at this point.mergere. since the archetype has not yet been released. To do so.0.0" xmlns:xsi="http://www. For more information on creating an archetype. go to an empty directory and run the following command: C:\mvnbook> mvn archetype:create -DgroupId=com. the required version would not be known (or if this was later development. Maven will build. Releasing a project is explained in section 7. Once you have completed the content in the archetype.org/POM/4. You now have the template project laid out in the proficio-example directory.org/POM/4.0 http://maven.0-SNAPSHOT Normally. It will look very similar to the content of the archetype-resources directory you created earlier.8.0</modelVersion> <groupId>$groupId</groupId> <artifactId>$artifactId</artifactId> <version>$version</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. now however. you will use the "internal" repository.1</version> <scope>test</scope> </dependency> </dependencies> </project> As you can see. you need to populate the template with the content that you'd like to have applied consistently to new projects. it has the correct deployment settings already. From here. However. the content of the files will be populated with the values that you provided on the command line. refer to the documentation on the Maven web site.3 of this chapter.8 of this chapter.xsd"> <modelVersion>4.w3.mergere.
Finally. Worse.8. once a release has been made. new release. without making any modifications to your project. even if the plugin is not declared in the POM.0. run the following command: c:\mvnbook\proficio> mvn release:prepare -DdryRun=true This simulates a normal release preparation. The release plugin takes care of a number of manual steps in updating the project POM. or check out the following: C:\mvnbook> svn co \ file://localhost/C:/mvnbook/svn/proficio/tags/proficio-final \ proficio To start the release process. or obtained from the development repository of the Maven project) that is implied through the build life cycle. and setting the version to the latest release (But only after verifying that your project builds correctly with that version!). You can continue using the code that you have been working on in the previous sections. such as deployment to the remote repository. This is because the prepare step is attempting to guarantee that the build will be reproducible in the future. Maven provides a release plugin that provides the basic functions of a standard release process. It is usually tedious and error prone. This is because you are using a locally installed snapshot of a plugin (either built yourself. all of the dependencies being used are releases. To demonstrate how the release plugin works. and does all of the project and source control manipulation that results in a tagged version. allowing them to be highly automated.Team Collaboration with Maven 7. This can be corrected by adding the plugin definition to your POM. if you are using a dependency that is a snapshot. and to perform standard tasks. The perform step could potentially be run multiple times to rebuild a release from a clean checkout of the tagged version. As the command runs. Accept the defaults in this instance (note that running Maven in "batch mode" avoids these prompts and will accept all of the defaults). you will be prompted for values. it happens at the end of a long period of development when all everyone on the team wants to do is get it out there. Better Builds With Maven 223 . and released as 1. updating the source control management system to check and commit release related changes. You'll notice that each of the modules in the project is considered. an error will appear. or part of the project. releases should be consistent every time they are built. Once the definition for a release has been set by a team. which often leads to omissions or short cuts. Cutting a Release Releasing software is difficult. However. other than those that will be released as part of the process (that is. the Proficio example will be revisited. you may encounter a plugin snapshot. it is usually difficult or impossible to correct mistakes other than to make another. and creating tags (or equivalent for your SCM). The prepare step is run once for a release. The prepare step ensures that there are no snapshots in the build. and snapshots are a transient build. other modules). not ready to be used as a part of a release. In some cases. The release plugin operates in two steps: prepare and perform. In this project. full of manual steps that need to be completed in a particular order.
any active profiles are explicitly activated. 3.tag file written out to each module directory. you created a profile to enable those checks conditionally. Recall from Chapter 6 that you learned how to configure a number of checks – so it is important to verify that they hold as part of the release. 4. but this might include updating the metadata in your issue tracker. when a build is run from this tag to ensure it matches the same circumstances as the release build. named pom.xml in the same directory as pom. to verify they are correct. a number of changes are made: • • • 1. Having run through this process you may have noticed that only the unit and integration tests were run as part of the test build. recall that in section 7. To do so.xml. and is set based on the values for which you were prompted during the release process. this file will be release-pom. When the final run is executed.xml. use the following plugin configuration: Better Builds With Maven 224 . there is also a release-pom.xml (both per-user and per-installation) are incorporated into the POM. Describe the SCM commit and tag operations 9.5. and this is reverted in the next POM. 6.next respectively in each module directory. This contains a resolved version of the POM that Maven will use to build from if it exists. 7. Modify all POM files in the build. or that different profiles will be applied. that resulting version ranges will be different. In this POM. you need to enable this profile during the verification step. as they will be committed to the tag Run mvn clean integration-test to verify that the project will successfully build Describe other preparation goals (none are configured by default. To include these checks as part of the release process. or that expressions would have been resolved. Describe the SCM commit operation You might like to review the POM files that are created for steps 5 and 9. the explicit version of plugins and dependencies that were used are added any settings from settings.xml. For that reason. 2. as they will be committed for the next development iteration 10. However. This is used by Maven.tag and pom.Team Collaboration with Maven To review the steps taken in this release process: Check for correct version of the plugin and POM (for example.xml and profiles. This is not the case however. Also. as these can be established from the other settings already populated in the POM in a reproducible fashion. instead of the normal POM. these changes are not enough to guarantee a reproducible build – it is still possible that the plugin versions will vary. You'll notice that the version is updated in both of these files. The SCM information is also updated in the tag POM to reflect where it will reside once it is tagged. or creating and committing an announcement file) 8.xml. including profiles from settings. the appropriate SCM settings) Check if there are any local modifications Check for snapshots in dependency tree Check for snapshots of plugins in the build Modify all POM files in the build.xml You may have expected that inheritance would have been resolved by incorporating any parent elements that are used. 5.
This is the default for the release plugin – to deploy all of the built artifacts. before running Maven from that location with the goals deploy site-deploy. because the release. If you need to start from the beginning.properties file still exists to tell the goal the version from which to release.0 If you follow the output above.] <plugin> <groupId>org. Once this is complete.properties file had been removed. you can remove that file. However. and the updated POM files are committed..maven.] Try the dry run again: C:\mvnbook\proficio> mvn release:prepare -DdryRun=true Now that you've gone through the test run and are happy with the results.apache.properties file that was created at the end of the last run. To release from an older version. the version is now 1..Team Collaboration with Maven [. This is achieved with the release:perform goal. or if the release. you'll see in your SCM the new tag for the project (with the modified files). you need to deploy the build artifacts.. or run mvn -Dresume=false release:prepare instead.. You won't be prompted for values as you were the first time – since by the default. you would run the following: C:\mvnbook\proficio> mvn release:perform -DconnectionUrl=\ scm:svn:file://localhost/c:/mvnbook/svn/proficio/tags/proficio-1. you can go for the real thing with the following command: C:\mvnbook\proficio> mvn release:prepare You'll notice that this time the operations on the SCM are actually performed. If this is not what you want to run. you'll see that a clean checkout was obtained from the created tag.plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <arguments>-DenableCiProfile=true</arguments> </configuration> </plugin> [.1-SNAPSHOT. while locally. This is run as follows: C:\mvnbook\proficio> mvn release:perform No special arguments are required. the release plugin will resume a previous attempt by reading the release. you can change the goals used with the goals parameter: C:\mvnbook\proficio> mvn release:perform -Dgoals="deploy" Better Builds With Maven 225 . the release still hasn't been generated yet – for that. and to deploy a copy of the site.
before you run the release:prepare goal. this requires that you remember to add the parameter every time..plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <useReleaseProfile>false</useReleaseProfile> </configuration> </plugin> [.xml file and the release-pom. add the following goals to the POM: [.apache. To do this. Since the goal is for consistency.org/plugins/maven-release-plugin/ for more information. as follows: [.. both the original pom. You can disable this profile by setting the useReleaseProfile parameter to false.xml file. it is necessary to know what version ranges are allowed for a dependency. The reason for this is that the POM files in the repository are used as dependencies and the original information is more important than the release-time information – for example.apache. the release plugin will confirm that the checked out project has the same release plugin configuration as those being used (with the exception of goals). or to set certain properties.. It is important in these cases that you consider the settings you want.maven. rather than the specific version used for the release.. When the release is performed. and the built artifacts are deployed. These are configured by default in the Maven POM as part of a profile that is activated when the release is performed..apache. and not the release-pom.] Better Builds With Maven 226 . For the same reason. To ensure reproducibility..0 You'll notice that the contents of the POM match the pom.plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <goals>deploy</goals> </configuration> </plugin> [.] <plugin> <groupId>org..] You may also want to configure the release plugin to activate particular profiles. check out the tag: C:\mvnbook> svn co \ file://localhost/mvnbook/svn/proficio/tags/proficio-1.] <plugin> <groupId>org.. you want to avoid such problems. though.maven.Team Collaboration with Maven However. you can examine the files that are placed in the SCM repository. during the process you will have noticed that Javadoc and source JAR files were produced and deployed into the repository for all the Java projects. Also. Refer to the plugin reference at http://maven.xml files are included in the generated JAR file. To do so.xml file.
All of the features described in this chapter can be used by any development team. Better Builds With Maven 227 . The site and reports you've created can help a team communicate the status of a project and their work more effectively. by making information about your projects visible and organized.] After the release process is complete..Extra plugin configuration would be inserted here --> </build> </profile> </profiles> [.9. the adoption of reusable plugins can capture and extend build knowledge throughout your entire organization. Maven was designed to address issues that directly affect teams of developers. the only step left is to clean up after the plugin. removing release. whether your team is large or small. Simply run the following command to clean up: C:\mvnbook\proficio> mvn release:clean 7. To do this. So. real-time engineering style. as follows: [.] <profiles> <profile> <id>release-profile</id> <build> <!-.. This in turn can lead to and facilitate best practices for developing in a community-oriented. and indeed this entire book. without having to declare and enable an additional profile. and while Maven focuses on delivering consistency in your build infrastructure through patterns. And all of these features build on the essentials demonstrated in chapters 1 and 2 that facilitate consistent builds.properties and any POM files generated as a result of the dry run. Lack of consistency is the source of many problems when working in a team. rather than creating silos of information around individual projects. define a profile with the identifier release-profile.. Maven provides value by standardizing and automating the build process.. There are also strong team-related benefits in the preceding chapters – for example. Summary As you've seen throughout this chapter. it can aid you in effectively using tools to achieve consistency in other areas of your development. you may want to include additional actions in the profile.Team Collaboration with Maven Instead.
Morpheus. testing and building jars with Maven. there is no turning back. The Matrix Better Builds With Maven 228 . You take the red pill .you stay in Wonderland and I show you how deep the rabbit-hole goes.4 and Java 5 Using Ant tasks from within Maven Using Maven with your current directory structure This is your last chance. Migrating to Maven Migrating to Maven This chapter explains how to migrate (convert) an existing build in Ant. You take the blue pill . After this. using both Java 1. .8. you wake up in your bed and believe whatever you want to believe. to a build in Maven: • • • • • Splitting existing sources and resources into modular Maven projects Taking advantage of Maven's inheritance and multi-project capabilities Compiling.the story ends.
You will learn how to use an existing directory structure (though you will not be following the standard. This example will take you through the step-by-step process of migrating Spring to a modularized. we will focus only on building version 2.Migrating to Maven 8. recommended Maven directory structure). listed in build order: • • • • • • • • • • • • • • • • • • spring-core spring-beans spring-aop spring-context spring-dao spring-jdbc spring-support spring-web spring-webmvc spring-remoting spring-portlet spring-jdo spring-hibernate2 spring-hibernate3 spring-toplink spring-ojb spring-mock spring-aspects Better Builds With Maven 229 . 8. how to run Ant tasks from within Maven. Introduction The purpose of this chapter is to show a migration path from an existing build in Ant to Maven. Maven build.1.0-m1 of Spring. and among other things. while enabling you to continue with your required work. This will allow you to evaluate Maven's technology. how to split your sources into modules or components. you will be introduced to the concept of dependencies. For the purpose of this example. The Maven migration example is based on the Spring Framework build.1. which uses an Ant script. which is the latest version at the time of writing. You will learn how to start building with Maven. The Spring release is composed of several modules. Introducing the Spring Framework The Spring Framework is one of today's most popular Java frameworks. Ant-based build system. component-based.1. while still running your existing.
with the Java package structure. resulting in JARs that contain both 1. Optional dependencies are indicated by dotted lines.4 and 1.5 compatible source code and JUnit Better Builds With Maven 230 . the Ant script compiles each of these different source directories and then creates a JAR for each module. you can see graphically the dependencies between the modules.5 classes. src and test: contain JDK 1. and each produces a JAR. Each of these modules corresponds.). properties files.4 compatible source code and JUnit tests respectively tiger/src and tiger/test: contain additional JDK 1. These modules are built with an Ant script from the following source directories: • • tests • mock: contains the source code for the spring-mock module • aspectj/src and aspectj/test: contain the source code for the spring-aspects module Each of the source directories also include classpath resources (XML files. TLD files. more or less. The src and tiger/src directories are compiled to the same destination as the test and tiger/test directories. using inclusions and exclusions that are based on the Java packages of each class. For Spring. etc.Migrating to Maven Figure 8-1: Dependency relationship between Spring modules In figure 8-1.
the rule of thumb to use is to produce one artifact (JAR.2. that means you will need to have a Maven project (a POM) for each of the modules listed above. To start. Figure 8-2: A sample spring module directory Better Builds With Maven 231 . you will need to create a directory for each of Spring's modules. WAR. In the Spring example.Migrating to Maven 8. Where to Begin? With Maven. Inside the 'm2' directory.) per Maven project file. etc. you will create a subdirectory called 'm2' to keep all the necessary Maven changes clearly separated from the current build system.
thereby eliminating the requirement to specify the dependency repeatedly across multiple modules. respectively. war. the main source and test directories are src and test..springframework. and ear values should be obvious to you (a pom value means that this project is used for metadata only) The other values are not strictly required. Maven will convert to the definitive. <groupId>com.1</version> <scope>test</scope> </dependency> </dependencies> As explained previously.mergere. department. the version you are developing in order to release. the Spring team would use org.mergere. company. <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. which will be used for testing in every module.SNAPSHOT – that is. you will use com. Let's begin with these directories. spring-parent) • version: this setting should always represent the next release version number appended with .8. Recall from previous chapters that during the release process.m2book. project. you will need to create a parent POM. • it should mimic standard package naming conventions to avoid duplicate values.migrating. For this example. however.m2book.org</url> <organization> <name>The Spring Framework Project</name> </organization> groupId: this setting indicates your area of influence. Better Builds With Maven 232 . each module will inherit the following values (settings) from the parent POM.Migrating to Maven In the m2 directory.0-m1-SNAPSHOT</version> <name>Spring parent</name> <packaging>pom</packaging> <description>Spring Framework</description> <inceptionYear>2002</inceptionYear> <url>http://www. • packaging: the jar. You will use the parent POM to store the common configuration settings that apply to all of the modules. in order to tag the release in your SCM. non-snapshot version for a short period of time. primary used for documentation purposes. as it is our 'unofficial' example version of Spring. and In this parent POM we can also add dependencies such as JUnit.springframework • artifactId: the setting specifies the name of this module (for example. For example.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2. in Spring. etc.
and failonerror (true) values.dir}" source="1. deprecation and optimize (false).compiler..3</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 233 . Spring's Ant script uses a debug parameter. so there is no need for you to add the configuration parameters./.3</source> <target>1.Migrating to Maven Using the following code snippet from Spring's Ant build script.maven. These last three properties use Maven's default values..3" target="1. you will need to append -Dmaven. so to specify the required debug function in Maven. as you will learn about that later in this chapter.3). that Maven automatically manages the classpath from its list of dependencies.attributes./test</testSourceDirectory> <plugins> <plugin> <groupId>org. At this point./.. <javac destdir="${target. For the debug attribute. in the buildmain target.src}"/> <classpath refid="all-libs"/> </javac> As you can see these include the source and target compatibility (1.apache.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1..tempdir. Recall from Chapter 2. your build section will look like this: <build> <sourceDirectory>.classes./src</sourceDirectory> <testSourceDirectory>. you can retrieve some of the configuration parameters for the compiler.dir}"/> <!-. you don't have to worry about the commons-attributes generated sources mentioned in the snippet.3" debug="${debug}" deprecation="false" optimize="false" failonerror="true"> <src path="${src. For now.debug=false to the mvn command (by default this is set to true).Include Commons Attributes generated Java sources --> <src path="${commons.
includes and test. by default. as Maven prints the test summary and stops for any test error or failure. haltonfailure and haltonerror settings.dir}"/> <!-. since the concept of a batch for testing does not exist.properties files etc take precedence --> <classpath location="${target.mockclasses. this value is read from the project. classpath is automatically managed by Maven from the list of dependencies. Maven sets the reports destination directory (todir) to target/surefire-reports.testclasses. formatter elements are not required as Maven generates both plain text and xml reports.classes.testclasses. by default.excludes}"/> </batchtest> </junit> You can extract some configuration information from the previous code: • • • • • • • forkMode="perBatch" matches with Maven's forkMode parameter with a value of once.dir}"/> <classpath location="${target.Need files loaded as resources --> <classpath location="${test.dir}"/> <classpath refid="all-libs"/> <formatter type="plain" usefile="false"/> <formatter type="xml"/> <batchtest fork="yes" todir="${reports.properties file loaded from the Ant script (refer to the code snippet below for details). You will need to specify the value of the properties test. • Better Builds With Maven 234 .awt.headless=true -XX:MaxPermSize=128m -Xmx128m"/> <!-. and this doesn't need to be changed.excludes from the nested fileset.dir}" includes="${test. Maven uses the default value from the compiler plugin. You will not need any printsummary.dir}"> <fileset dir="${target.Migrating to Maven The other configuration that will be shared is related to the JUnit tests.Must go first to ensure any jndi.dir}"/> <classpath location="${target. From the tests target in the Ant script: <junit forkmode="perBatch" printsummary="yes" haltonfailure="yes" haltonerror="yes"> <jvmarg line="-Djava.includes}" excludes="${test. so you will not need to locate the test classes directory (dir). The nested element jvmarg is mapped to the configuration parameter argLine As previously noted.
Since Maven requires JDK 1.excludes=**/Abstract* org/springframework/orm/hibernate3/** The includes and excludes referenced above.1 # being compiled with target JDK 1. which are processed prior to the compilation. mandatory when building in JDK 1.maven.3. translate directly into the include/exclude elements of the POM's plugin configuration. It makes tests run using the standard classloader delegation instead of the default Maven isolated classloader.excludes=**/Abstract* #test. test.awt. Better Builds With Maven 235 .class # # Wildcards to exclude among JUnit tests. # Second exclude needs to be used for JDK 1.4 to run you do not need to exclude hibernate3 tests.class</include> </includes> <excludes> <exclude>**/Abstract*</exclude> </excludes> </configuration> </plugin> The childDelegation option is required to prevent conflicts when running under Java 5 between the XML parser provided by the JDK and the one included in the dependencies in some modules.headless=true -XX:MaxPermSize=128m -Xmx128m </argLine> <includes> <include>**/*Tests.apache.includes=**/*Tests.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <forkMode>once</forkMode> <childDelegation>false</childDelegation> <argLine> -Djava. # Convention is that our JUnit test classes have XXXTests-style names. due to Hibernate 3. Spring's Ant build script also makes use of the commons-attributes compiler in its compileattr and compiletestattr targets. <plugin> <groupId>org.and generates sources from them that have to be compiled with the normal Java compiler. Note that it is possible to use another lower JVM to run tests if you wish – refer to the Surefire plugin reference documentation for more information. When building only on Java 5 you could remove that option and the XML parser (Xerces) and APIs (xml-apis) dependencies.4. test.Migrating to Maven # Wildcards to be matched by JUnit tests. The commons-attributes compiler processes javadoc style annotations – it was created before Java supported annotations in the core language on JDK 1.4.5 .
Better Builds With Maven 236 .java</include> </includes> <testIncludes> <include>org/springframework/aop/**/*.java</include> <include>org/springframework/jmx/**/*. --> <attribute-compiler destdir="${commons.attributes.mojo</groupId> <artifactId>commons-attributes-maven-plugin</artifactId> <executions> <execution> <configuration> <includes> <include>**/metadata/*.java"/> <fileset dir="${test. --> <fileset dir="${src.dir}" includes="**/metadata/*.src}"> <!-Only the PathMap attribute in the org.Compile to a temp directory: Commons Attributes will place Java Source here. to support indexing.springframework.dir}" includes="org/springframework/jmx/**/*. this same function can be accomplished by adding the commons-attributes plugin to the build section in the POM.tempdir.web. --> <attribute-compiler destdir="${commons.codehaus. so you will only need to add the inclusions for the main source and test source compilation.attributes.dir}" includes="org/springframework/aop/**/*. Maven handles the source and destination directories automatically.java"/> </attribute-compiler> From compiletestattr: <!-.java</include> </testIncludes> </configuration> <goals> <goal>compile</goal> <goal>test-compile</goal> </goals> </execution> </executions> </plugin> Later in this chapter you will need to modify these test configurations.metadata package currently needs to be shipped with an attribute. <plugin> <groupId>org.Migrating to Maven From compileattr: <!-.java"/> </attribute-compiler> In Maven.handler.Compile to a temp directory: Commons Attributes will place Java Source here.servlet.tempdir.test}"> <fileset dir="${test.
which centralizes and maintains information common to the project. etc.dir}/modules/spring-core.Migrating to Maven 8. This module is the best to begin with because all of the other modules depend on it. and organization name to the values in the POM.jar"> <fileset dir="${target. as those values are inherited from parent POM. you will need to tell Maven to pick the correct classes and resources from the core and util packages. To begin. JUnit test configuration. Compiling In this section.3. description. where spring-core JAR is created: <jar jarfile="${dist. In each subdirectory.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2. you will need to create a POM that extends the parent POM. compiler configuration. you need to create the POM files for each of Spring's modules. The following is the POM for the spring-core module. or they will get included in the JAR. For the resources. you won't need to specify the version or groupId elements of the current module. review the following code snippet from Spring's Ant script. tests will be dealt with later in the chapter. since the sources and resources are in the same directory in the current Spring build.mergere. version. you will need to exclude the *.classes. you will need to add a resources element in the build section. Creating POM files Now that you have the basic configuration shared by all modules (project information. While manifest entries can also be customized with additional configuration to the JAR plugin. <parent> <groupId>com.4. 8. setting the files you want to include (by default Maven will pick everything from the resource directory). in this case the defaults are sufficient. Maven will automatically set manifest attributes such as name.java files from the resources.).m2book.0-m1-SNAPSHOT</version> </parent> <artifactId>spring-core</artifactId> <name>Spring core</name> Again. Better Builds With Maven 237 . you will start to compile the main Spring source. you can determine which classes are included in the JAR and what attributes are written into the JAR's manifest. However.dir}"> <include name="org/springframework/core/**"/> <include name="org/springframework/util/**"/> </fileset> <manifest> <attribute name="Implementation-Title" value="${spring-title}"/> <attribute name="Implementation-Version" value="${spring-version}"/> <attribute name="Spring-Version" value="${spring-version}"/> </manifest> </jar> From the previous code snippet. As you saw before.
<build> <resources> <resource> <directory>./src</directory> <includes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <includes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> </configuration> </plugin> </plugins> </build> Better Builds With Maven 238 .java</exclude> </excludes> </resource> </resources> <plugins> <plugin> <groupId>org. which is inherited from the parent POM.Migrating to Maven For the classes.. Maven will by default compile everything from the source directory.apache.maven. because as with resources../. you will need to configure the compiler plugin to include only those in the core and util packages.
commons.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver.\.34] package org. you need to check the central repository at ibiblio.io. caused by the required classes not being on the classpath. the convention is to use a groupId that mirrors the package name.. you will find all the available versions of commons-logging under http://www.apache. In the case of commons-logging. Typically.ibiblio. what groupid. commons-logging groupId would become org.java:[31.24] cannot find symbol symbol : class Log location: class org.\.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver. Regarding the artifactId. you can now run mvn compile.org/maven2/commons-logging/commons-logging/..logging does not exist These are typical compiler messages.commons. However..Migrating to Maven To compile your Spring build.commons.core.logging. the option that is closest to what is required by your project. located in the org/apache/commons/logging directory in the repository.java:[30.org/maven2 commons logging.java:[107. you now know that you need the Apache Commons Logging library (commons-logging) to be added to the dependencies section in the POM.logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\. artifactId and version should we use? For the groupId and artifactId.apache..PathMatchingResourcePatternResolver C:\dev\m2book\code\migrating\spring\m2\springcore\. Better Builds With Maven 239 . and then choose from the search results.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver..commons.\src\org\springframework\util\xml\SimpleSaxErrorHandler. for historical reasons some groupId values don't follow this convention and use only the name of the project. You will see a long list of compilation failures. beginning with the following: [INFO] -----------------------------------------------------------------------[ERROR] BUILD FAILURE [INFO] -----------------------------------------------------------------------[INFO] Compilation failure C:\dev\m2book\code\migrating\spring\m2\springcore\.34] package org..java:[19.apache.34] package org.apache.springframework. Specify site:www. you can search the repository using Google. changing dots to slashes. From the previous output.\. the actual groupId is commons-logging.support. As an alternative.\..logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\. If you check the repository. But.. it's usually the JAR name without a version (in this case commonslogging). For example.ibiblio.
component-oriented. is under development (refer to the Maven Repository Manager project for details). to make explicit the dependencies and interrelationships of your projects. search the ibiblio repository through Google by calculating the MD5 checksum of the JAR file with a program such as md5sum. so you will have first hand knowledge about the dependencies and versions used. you will find that there is documentation for all of Spring's dependencies in readme. we strongly encourage and recommend that you invest the time at the outset of your migration.ibiblio. modular projects that are easier to maintain in the long term. you could search with: site:www. and then search in Google prepending site:www. for the hibernate3.0.txt in the lib directory of the Spring source. However. While adding dependencies can be the most painful part of migrating to Maven.1/hibernate-3.MF • For advanced users. we discovered that the commons-beanutils version stated in the documentation is wrong and that some required dependencies are missing from the documentation. Better Builds With Maven 240 .1). during the process of migrating Spring to Maven. <dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. You can use this as a reference to determine the versions of each of the dependencies.ibiblio. with the slashes changed to dots (org. you have to be careful as the documentation may contain mistakes and/or inaccuracies.org/maven2 to the query.md5 You can see that the last directory is the version (3.jar provided with Spring under lib/hibernate.1. For example.4</version> </dependency> </dependencies> Usually you will convert your own project. When needed. through inheritance. all sub-modules would use the same dependencies). although you could simply follow the same behavior used in Ant (by adding all the dependencies in the parent POM so that.hibernate) An easier way to search for dependencies. For instance. So.org/maven2 78d5c38f1415efc64f7498f828d8069a • The search will return: www. the previous directory is the artifactId (hibernate) and the other directories compose the groupId. using a web interface. there are some other options to try to determine the appropriate versions for the dependencies included in your build: Check if the JAR has the version in the file name • Open the JAR file and look in the manifest file META-INF/MANIFEST. explicit dependency management is one of the biggest benefits of Maven once you have invested the effort upfront.jar. Doing so will result in cleaner.Migrating to Maven With regard the version.org/maven2/org/hibernate/hibernate/3.ibiblio.
and it is just for the convenience of the users.1.Migrating to Maven Running again mvn compile and repeating the process previously outlined for commons-logging./test</directory> <includes> <include>log4j. setting which test resources to use. Using the optional tag does not affect the current project. you will need to add the log4j. and setting the JUnit test sources to compile. Now.properties file required for logging configuration. run mvn compile again .5. For the first step.1</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1. you will repeat the previous procedure for the main classes. This is because in other projects. Compiling Tests Setting the test resources is identical to setting the main resources. so log4j will not be included in other projects that depend on this. you will notice that you also need Apache Commons Collections (aka commons-collections) and log4j. Optional dependencies are not included transitively.properties</include> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*. with the exception of changing the location from which the element name and directory are pulled. 8. 8. Testing Now you're ready to compile and run the tests.. In addition.this time all of the sources for spring-core will compile.java</exclude> </excludes> </testResource> </testResources> Better Builds With Maven 241 ..2. we will cover how to run the tests. After compiling the tests. <testResources> <testResource> <directory>.9</version> <optional>true</optional> </dependency> Notice that log4j is marked as optional. <dependency> <groupId>commons-collections</groupId> <artifactId>commons-collections</artifactId> <version>3./. you may decide to use another log implementation.5.
but rather require other modules to be present. the key here is to understand that some of the test classes are not actually unit tests for springcore. spring-web and spring-beans modules. depend on classes from springcore.mock. <testIncludes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </testIncludes> You may also want to check the Log4JConfigurerTests.springframework. In other words. in order to compile the tests: <dependency> <groupId>javax. as before.java</exclude> <exclude>org/springframework/core/io/ResourceTests.beans packages are missing. you will get compilation errors.java</exclude> <exclude>org/springframework/util/ObjectUtilsTests. you will see the following error: package javax. Therefore.java</exclude> <exclude>org/springframework/util/SerializationTestUtils. not tests. If you run mvn test-compile again you will have a successful build. which one do we build first? Impossible to know. as this is not needed for the main sources.springframework.java class for any hard codes links to properties files and change them accordingly.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.Migrating to Maven Setting the test sources for compilation follows the same procedure. you will need to add the testIncludes element. if you try to compile the test classes by running mvn test-compile. but if you try to compile those other modules. org. Now.servlet does not exist This means that the following dependency must be added to the POM.springframework. add the testExcludes element to the compiler configuration as follows. if spring-core depends on spring-beans and spring-beans depends on spring-core. but this time there is a special case where the compiler complains because some of the classes from the org.4</version> <scope>test</scope> </dependency> The scope is set to test. when you run mvn test-compile. It may appear initially that spring-core depends on spring-mock. we cannot add a dependency from spring-core without creating a circular dependency. as all the test classes compile correctly now. <testExcludes> <exclude>org/springframework/util/comparator/ComparatorTests. as well. Better Builds With Maven 242 . As a result. you will see that their main classes. it makes sense to exclude all the test classes that reference other modules from this one and include them elsewhere.java</exclude> <exclude>org/springframework/util/ClassUtilsTests.java</exclude> </testExcludes> Now.web and org. To exclude test classes in Maven. So.java</exclude> <exclude>org/springframework/util/ReflectionUtilsTests. Inside the mavencompiler-plugin configuration.
you will need to check the test logs under target/surefire-reports.) Better Builds With Maven 243 .springframework.PathMatchingResourcePatternResolverTe sts. Failures: 1. Time elapsed: 0.io. You will get the following wonderful report: [INFO] -----------------------------------------------------------------------[INFO] BUILD SUCCESSFUL [INFO] ------------------------------------------------------------------------ The last step in migrating this module (spring-core) from Ant to Maven. Errors: 1 [INFO] -----------------------------------------------------------------------[ERROR] BUILD ERROR [INFO] -----------------------------------------------------------------------[INFO] There are test failures.2. [INFO] ------------------------------------------------------------------------ Upon closer examination of the report output. etc. Within this file.FileNotFoundException: class path resource [org/aopalliance/] cannot be resolved to URL because it does not exist.core.springframework. as it will process all of the previous phases of the build life cycle (generate sources. run tests. there is a section for each failed test called stacktrace. This command can be used instead most of the time.aopalliance package is inside the aopallience JAR. To debug the problem.5. However. The org. is to run mvn install to make the resulting JAR available to other projects in your local Maven repository.Migrating to Maven 8.PathMatchingResourcePatternResolverTests [surefire] Tests run: 5. compile. This indicates that there is something missing in the classpath that is required to run the tests. Errors: 1.io.txt. you will find the following: [surefire] Running org. for the test class that is failing org. Failures: 1.core.io. when you run this command.015 sec <<<<<<<< FAILURE !! This output means that this test has logged a JUnit failure and error.0</version> <scope>test</scope> </dependency> Now run mvn test again.support.support. The first section starts with java. Running Tests Running the tests in Maven. compile tests. so to resolve the problem add the following to your POM <dependency> <groupId>aopalliance</groupId> <artifactId>aopalliance</artifactId> <version>1. simply requires running mvn test. you will get the following error report: Results : [surefire] Tests run: 113.
Other Modules Now that you have one module working it is time to move on to the other modules. you will be adding the Surefire plugin configuration settings repeatedly for each module that you convert.groupId}</groupId> <artifactId>spring-core</artifactId> <version>${project. In the same way.6.version}</version> </dependency> Better Builds With Maven 244 . instead of repeatedly adding the same dependency version information to each module. 8.4</version> </dependency> </dependencyManagement> The following are some variables that may also be helpful to reduce duplication: • • ${project. each of the modules will be able to inherit the required Surefire configuration. To avoid duplication. See figure 8-1 to get the overall picture of the interdependencies between the Spring modules. use the parent POM's dependencyManagement section to specify this information once. since they have the same groupId and version: <dependency> <groupId>${project. Avoiding Duplication As soon as you begin migrating the second module. otherwise you will find that the main classes from some of the modules reference classes from modules that have not yet been built. That way.Migrating to Maven 8. If you follow the order of the modules described at the beginning of the chapter you will be fine. and remove the versions from the individual modules (see Chapter 3 for more information).0.1. Using the parent POM to centralize this information makes it possible to upgrade a dependency version across all sub-projects from a single location. <dependencyManagement> <dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. move these configuration settings to the parent POM instead. For instance. you will find that you are repeating yourself.6.version}: version of the current POM being built ${project. you can refer to spring-core from spring-beans with the following.groupId}: groupId of the current POM being built For example.
To eliminate this problem. make sure that when you run mvn install.3. they will need to run them under Java 5. Although it is typically not recommended. how can the Java 1. be sure to put that JAR in the test scope as follows: <dependency> <groupId>${project. attempting to use one of the Java 5 classes under Java 1.6.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <executions> <execution> <goals> <goal>test-jar</goal> </goals> </execution> </executions> </plugin> Once that JAR is installed.5 sources be added? To do this with Maven. and spring-web-mock.4. it's easier to deal with small modules. particularly in light of transitive dependencies.3 compatibility. However. Consider that if you include some classes compiled for Java 1.apache. By splitting them into different modules.3 or 1. Building Java 5 Classes Some of Spring's modules include Java 5 classes from the tiger folder.6. 8. you will need to create a new spring-beans-tiger module. First. this can cause previously-described cyclic dependencies problem. in this case it is necessary to avoid refactoring the test source code. with only those classes related to spring-web. Referring to Test Classes from Other Modules If you have tests from one component that refer to tests from other modules. As the compiler plugin was earlier configured to compile with Java 1. you need to create a new module with only Java 5 classes instead of adding them to the same module and mixing classes with different requirements.maven.Migrating to Maven 8.groupId}</groupId> <artifactId>spring-beans</artifactId> <version>${project. that a JAR that contains the test classes is also installed in the repository: <plugin> <groupId>org.version}</version> <type>test-jar</type> <scope>test</scope> </dependency> A final note on referring to test classes from other modules: if you have all of Spring's mock classes inside the same module. you can use it as a dependency for other components. by specifying the test-jar type. Better Builds With Maven 245 . you can split Spring's mock classes into spring-context-mock. users will know that if they depend on the module composed of Java 5 classes.2.3 and some compiled for Java 5 in the same JAR. with only those classes related to spring-context module. any users. there is a procedure you can use. So. Generally with Maven. would experience runtime errors.
the Java 5 modules will share a common configuration for the compiler. and then a directory for each one of the individual tiger modules. The best way to split them is to create a tiger folder with the Java 5 parent POM.Migrating to Maven As with the other modules that have been covered. as follows: Figure 8-3: A tiger module directory The final directory structure should appear as follows: Figure 8-4: The final directory structure Better Builds With Maven 246 .
you will need to add a module entry for each of the directories./.Migrating to Maven Figure 8-5: Dependency relationship.5</source> <target>1./../. with all modules In the tiger POM. as well as build sections with source folders and compiler options: <modules> <module>spring-beans-tiger</module> <module>spring-aop-tiger</module> <module>spring-dao-tiger</module> <module>spring-jdbc-tiger</module> <module>spring-support-tiger</module> <module>spring-hibernate3-tiger</module> <module>spring-aspects</module> </modules> <build> <sourceDirectory>.apache./tiger/src</sourceDirectory> <testSourceDirectory>.../.5</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 247 ./tiger/test</testSourceDirectory> <plugins> <plugin> <groupId>org.maven....plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.
you may find that Maven does not have a plugin for a particular task or an Ant target is so small that it may not be worth creating a new plugin.4 you will add that module in a profile that will be triggered only when using 1.Migrating to Maven In the parent POM.classes.5</jdk> </activation> <modules> <module>tiger</module> </modules> </profile> </profiles> 8.RmiInvocationWrapper"/> <rmic base="${target. <profiles> <profile> <id>jdk1.5 JDK. For example.rmi. you just need a new module entry for the tiger folder.classes. you need to use the Ant task in the spring-remoting module to use the RMI compiler. Using Ant Tasks From Inside Maven In certain migration cases.springframework.remoting. In this case.6.dir}" classname="org.RmiInvocationWrapper" iiop="true"> <classpath refid="all-libs"/> </rmic> Better Builds With Maven 248 . but to still be able to build the other modules when using Java 1.springframework.5</id> <activation> <jdk>1. Maven can call Ant tasks directly from a POM using the maven-antrun-plugin.4.rmi. with the Spring migration. this is: <rmic base="${target.remoting. From Ant.dir}" classname="org.
To complete the configuration..build. such as ${project.remoting.rmi. So. which is a classpath reference constructed from all of the dependencies in the compile scope or lower.compile. There are also references for anything that was added to the plugin's dependencies section./lib/tools. Better Builds With Maven 249 .directory}/classes" classname="org. add: <plugin> <groupId>org.sun</groupId> <artifactId>tools</artifactId> <scope>system</scope> <version>1. will take the compiled classes and generate the rmi skeleton. there are some references available already.apache.4</version> <systemPath>${java. such as the reference to the tools.plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <executions> <execution> <phase>process-classes</phase> <configuration> <tasks> <echo>Running rmic</echo> <rmic base="${project.classpath.compile.home}/.springframework.remoting. which is bundled with the JDK.classpath"/> </rmic> </tasks> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> <dependencies> <dependency> <groupId>com. stub and tie classes from them. which applies to that plugin only. and required by the RMI task. In this case.build.Migrating to Maven To include this in Maven build.rmi.jar above.maven.jar</systemPath> </dependency> </dependencies> </plugin> As shown in the code snippet above.RmiInvocationWrapper"/> <rmic base="${project. the rmic task.springframework.RmiInvocationWrapper" iiop="true"> <classpath refid="maven.build. the most appropriate phase in which to run this Ant task is in the processclasses phase.directory} and maven. you will need to determine when Maven should run the Ant task.directory}/classes" classname="org.
2 -Dpackaging=jar You will only need to do this process once for all of your projects or you may use a corporate repository to share them across your organization. Better Builds With Maven 250 . Non-redistributable Jars You will find that some of the modules in the Spring build depend on JARs that are not available in the Maven central repository. to install JavaMail: mvn install:install-file -Dfile=mail. You may need to download them yourself from the Sun site or get them from the lib directory in the example code for this chapter.3.html. as these test cases will not work in both Maven and Ant. NamespaceHandlerUtilsTests. mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging> For instance. which used relative paths in Log4JConfigurerTests class. Sun's Activation Framework and JavaMail are not redistributable from the repository due to constraints in their licenses. such as spring-aspects. These issues were shared with the Spring developer community and are listed below: • • Moving one test class. from test directory to tiger/test directory – as it depends on a tiger class Fixing toplink tests that don't compile against the oracle toplink jar (Spring developers use a different version than the official one from Oracle) In this example it is necessary to comment out two unit tests.6.apache.6. You can then install them in your local repository with the following command.org/guides/mini/guide-coping-with-sun-jars.mail -DartifactId=mail -Dversion=1. There is some additional configuration required for some modules. Some Special Cases In addition to the procedures outlined previously for migrating Spring to Maven. there are two additional. Using classpath resources is recommended over using file system resources. special cases that must be handled. which uses AspectJ for weaving the classes. see http://maven.5. For example.6. 8. For more information on dealing with this issue. These can be viewed in the example code.Migrating to Maven 8.jar -DgroupId=javax.
ObjectUtilsTests. ReflectionUtilsTests. for the spring-core module. Summary By following and completing this chapter. and install those JARs in your local repository using Maven. Better Builds With Maven 251 . in addition to the improvements to your build life cycle.7. Once you decide to switch completely to Maven. you will be able to take an existing Ant-based build. as Maven downloads everything it needs and shares it across all your Maven projects automatically . you will be able to keep your current build working. reports. create JARs. Restructuring the Code If you do decide to use Maven for your project. you can apply similar concepts to your own Ant based build.8. you would move all Java files under org/springframework/core and org/springframework/util from the original src folder to the module's folder src/main/java. compile and test the code. Now that you have seen how to do this for Spring. By doing this.Migrating to Maven 8. SerializationTestUtils and ResourceTests). In the case of the Spring example. reducing its size by two-thirds! 8. and quality metrics. By adopting Maven's standard directory structure. For example. ClassUtilsTests. you would eliminate the need to include and exclude sources and resources "by hand" in the POM files as shown in this chapter. Maven can eliminate the requirement of storing jars in a source code management system. you can realize Maven' other benefits . split it into modular components (if needed). At the same time.you can delete that 80 MB lib folder. these would move from the original test folder to src/test/java and src/test/resources respectively for Java sources and other files . Finally. you will be able to take advantage of the benefits of adopting Maven's standard directory structure. All of the other files under those two packages would go to src/main/resources.advantages such as built-in project documentation generation. you can simplify the POM significantly. Once you have spent this initial setup time Maven.just remember not to move the excluded tests (ComparatorTests. The same for tests. it it highly recommended that you go through the restructuring process to take advantage of the many timesaving and simplifying conventions within Maven.
Appendix A: Resources for Plugin Developers Appendix A: Resources for Plugin Developers In this appendix you will find: Maven's Life Cycles • Mojo Parameter Expressions • Plugin Metadata • Scotty: She's all yours. . I'll try not to take that personally. Scott. sir. A chimpanzee and two trainees could run her! Kirk: Thank you. All systems automated and ready.Star Trek Better Builds With Maven 252 . Mr.
2. mojo-binding defaults are specified in a packaging-specific manner. This section contains a listing of the phases in the default life cycle. For example. and distributing it into the Maven repository system. generate-sources – generate compilable code from other source formats. as when using Aspect-Oriented Programming techniques. It contains the following phases: 1. compile – compile source code into binary form. validate – verify that the configuration of Maven. along with a short description for the mojos which should be bound to each. along with a summary of bindings for the jar and maven-plugin packagings. 7. This is necessary to accommodate the inevitable variability of requirements for building different types of projects. process-sources – perform any source modification processes necessary to prepare the code for compilation. Better Builds With Maven 253 . cleaning a project of the files generated by a build. performing any associated tests. a mojo may apply source code patches here. process-classes – perform any post-processing of the binaries produced in the preceding step. in the target output location. The default Life Cycle Maven provides three life cycles. It begins by listing the phases in each life cycle. Maven's Life Cycles Below is a discussion of Maven's three life cycles and their default mappings. archiving it into a jar. corresponding to the three major activities performed by Maven: building a project from source. 6. It continues by describing the mojos bound to the default life cycle for both the jar and maven-plugin packagings. 9. it takes care of compiling the project's code. this section will describe the mojos bound by default to the clean and site life cycles.1.) from other source formats. Finally. such as instrumentation or offline code-weaving. 5. In other words. and generating a project web site. 3. Life-cycle phases The default life cycle is executed in order to perform a traditional build. For the default life cycle. 4. generate-resources – generate non-code resources (such as configuration files. generate-test-sources – generate compilable unit test code from other source formats.1. 8. and the content of the current set of POMs to be built is valid. etc. This may include copying these resources into the target classpath directory in a Java build.Appendix A: Resources for Plugin Developers A. process-resources – perform any modification of non-code resources necessary.1. A. initialize – perform any initialization steps required before the main part of the build can start.
18. post-integration-test – return the environment to its baseline form after executing the integration tests in the preceding step. 13. etc. test – execute unit tests on the application compiled and assembled up to step 8 above. 11.) from other source formats. using the environment configured in the preceding step. Better Builds With Maven 254 . process-test-sources – perform any source modification processes necessary to prepare the unit test code for compilation.Appendix A: Resources for Plugin Developers 10. preintegration-test – setup the integration testing environment for this project. generate-test-resources – generate non-code testing resources (such as configuration files. before it is available for installation or deployment. install – install the distributable archive into the local Maven repository. deploy – deploy the distributable archive into the remote Maven repository configured in the distributionManagement section of the POM. This could involve removing the archive produced in step 15 from the application server used to test it. 19. in the testing target output location. For example. 14. This may involve installing the archive from the preceding step into some sort of application server. process-test-resources – perform any modification of non-code testing resources necessary. integration-test – execute any integration tests defined for this project. 17. package – assemble the tested application code and resources into a distributable archive. a mojo may apply source code patches here. test-compile – compile unit test source code into binary form. 15. 12. 21. verify – verify the contents of the distributable archive. 16. 20. This may include copying these resources into the testing target classpath location in a Java build.
specified in the POM distribution Management section. Execute project unit tests. Filter variables if necessary. Compile project source code to the staging directory for jar creation. Create a jar archive from the staging directory. process-test. Install the jar archive into the local Maven repository. Compile unit-test source code to the test output directory.testRes maven-resourcesresources ources plugin test-compile test package install deploy testCom maven-compilerpile plugin test jar maven-surefireplugin maven-jar-plugin install maven-installplugin deploy maven-deployplugin Better Builds With Maven 255 . Table A-1: The default life-cycle bindings for the jar packaging Phase Mojo Plugin Description processresources compile resourc maven-resourceses plugin compile maven-compilerplugin Copy non-source-code resources to the staging directory for jar creation. Copy non-source-code test resources to the test output directory for unit-test compilation. Alongside each.Appendix A: Resources for Plugin Developers Bindings for the jar packaging Below are the default life-cycle bindings for the jar packaging. Deploy the jar archive to a remote Maven repository. you will find a short description of what that mojo does.
packaging. Below is a summary of the additional mojo bindings provided by the maven-plugin packaging: Table A-2: A summary of the additional mojo bindings Phase Mojo Plugin Description generateresources package descriptor maven-plugin-plugin Extract mojo metadata (from javadoc annotations. if one exists. for example). they undergo the same basic processes of marshaling non-source-code resources. the maven-plugin packaging also introduces a few new mojo bindings. maven-plugin-plugin Update the plugin registry. and the rest. addPluginArtifact Metadata updateRegistry maven-plugin-plugin Integrate current plugin information with plugin search metadata. testing. However. maven-plugin artifacts are in fact jar files. As such. to install reflect the new plugin installed in the local repository. and metadata references to latest plugin version. Better Builds With Maven 256 . Indeed. to extract and format the metadata for the mojos within.Appendix A: Resources for Plugin Developers Bindings for the maven-plugin packaging The maven-plugin project packaging behaves in almost the same way as the more common jar packaging. compiling source code. and generate a plugin descriptor.
Default life-cycle bindings Below are the clean life-cycle bindings for the jar packaging. along with a summary of the default bindings.Appendix A: Resources for Plugin Developers A. Table A-3: The clean life-cycle bindings for the jar packaging Phase Mojo Plugin Description clean clean maven-clean-plugin Remove the project build directory. The clean Life Cycle This life cycle is executed in order to restore a project back to some baseline state – usually. pre-clean – execute any setup or initialization procedures to prepare the project for cleaning 2. Life-cycle phases The clean life-cycle phase contains the following phases: 1. post-clean – finalize the cleaning process. you will find a short description of what that mojo does. the state of the project before it was built. Alongside each. Maven provides a set of default mojo bindings for this life cycle.1.2. effective for all POM packagings. along with any additional directories configured in the POM. which perform the most common tasks involved in cleaning a project. clean – remove all files that were generated during another build process 3. Better Builds With Maven 257 . Below is a listing of the phases in the clean life cycle.
and render documentation into HTML 3. and render documentation source files into HTML. you will find a short description of what that mojo does. It will run any reports that are associated with your project.Appendix A: Resources for Plugin Developers A. effective for all POM packagings. site – run all associated project reports. Default Life Cycle Bindings Below are the site life-cycle bindings for the jar packaging. site-deploy deploy Better Builds With Maven 258 . Maven provides a set of default mojo bindings for this life cycle. post-site – execute any actions required to finalize the site generation process. Alongside each. The site Life Cycle This life cycle is executed in order to generate a web site for your project. which perform the most common tasks involved in generating the web site for a project. Life-cycle phases The site life cycle contains the following phases: 1. and prepare the generated web site for potential deployment 4. and even deploy the resulting web site to your server.3. along with a summary of the default bindings. pre-site – execute any setup or initialization steps to prepare the project for site generation 2. render your documentation source files into HTML. Table A-4: The site life-cycle bindings for the jar packaging Phase Mojo Plugin Description site site maven-site-plugin maven-site-plugin Generate all configured project reports. Deploy the generated web site to the web server path specified in the POM distribution Management section. Below is a listing of the phases in the site life cycle. site-deploy – use the distributionManagement configuration in the project's POM to deploy the generated web site files to the web server.1.
Better Builds With Maven 259 . ${reactorProjects} ${reports} ${executedProject} java.MavenReport> life cycle executes.maven.execution.ma List of project instances which will be ven. in addition to providing a mechanism for looking up Maven components on-demand.maven. A.project.project.ArtifactRepository used to cache artifacts during a Maven build.1.List<org.Mav This is a cloned instance of the project enProject instance currently being built. and often eliminates dependencies on Maven itself beyond the plugin API. Simple Expressions Maven's plugin parameter injector supports several primitive expressions. java.apache. it will describe the algorithm used to resolve complex parameter expressions. org.apache.List<org.apache.M The current build session.maven.reporting. This contains avenSession methods for accessing information about how Maven was called.2.2.Appendix A: Resources for Plugin Developers A. which act as a shorthand for referencing commonly used build state objects. This section discusses the expression language used by Maven to inject build state and plugin configuration into mojos.artifact. This reduces the complexity of the code contained in the mojo. It is used for bridging results from forked life cycles back to the main line of execution.util. org. These expressions allow a mojo to traverse complex build state. and extract only the information it requires.apache.ma List of reports to be generated when the site ven.MavenProject> processed as part of the current build. Finally. Using the discussion below. They are summarized below: Table A-5: Primitive expressions supported by Maven's plugin parameter Expression Type Description ${localRepository} ${session} org. mojo developers should have everything they need to extract the build state they require. along with the published Maven API documentation.re This is a reference to the local repository pository.util. It will summarize the root objects of the build state which are available for mojo expressions. Mojo Parameter Expressions Mojo parameter values are resolved by way of parameter expressions when a mojo is initialized.apache.
maven. ${plugin} org.2. Better Builds With Maven 260 . Project org.settings.project.io.maven.m2/settings. Complex Expression Roots In addition to the simple expressions above.apache.Appendix A: Resources for Plugin Developers A. org.xml in the user's home directory.xml in the maven application directory and from .File The current project's root directory.Sett The Maven settings. Maven supports more complex expressions that traverse the object graph starting at some root object that contains build state. ptor.apache.Maven Project instance which is currently being built. unless specified otherwise.2. The valid root objects for plugin parameter expressions are summarized below: Table A-6: A summary of the valid root objects for plugin parameter expressions Expression Root Type Description ${basedir} ${project} ${settings} java.plugin. merged from ings conf/settings.PluginDescriptor including its dependency artifacts.descri The descriptor instance for the current plugin.maven.apache.
array index references.Appendix A: Resources for Plugin Developers A. The system properties. it will attempt to find a value in one of two remaining places. the value that was resolved last will be returned as the expression's value.The description element of the plugin's POM. It includes summaries of the essential plugin descriptor. or method invocations that don't conform to standard JavaBean naming conventions. The resulting value then becomes the new 'root' object for the next round of traversal. <plugin> <!-. If the parameter is still empty after these two lookups. If at some point the referenced object doesn't contain a property that matches the next expression part. and must correspond to one of the roots mentioned above. much like a primitive expression would. Its syntax has been annotated to provide descriptions of the elements.These are the identity elements (groupId/artifactId/version) | from the plugin POM. Repeating this.2. Currently. When there are no more expression parts. The POM properties. Otherwise. or an active profile. the expression is split at each '. following standard JavaBeans naming conventions. This includes properties specified on the command line using the -D commandline option. as well as the metadata formats which are translated into plugin descriptors from Java. Maven plugin parameter expressions do not support collection lookups.' character. if there is one. an ancestor POM. 2. Maven will consult the current system properties. resolved in this order: 1. |-> <groupId>org.maven. this reflective lookup process is aborted. First. then the string literal of the expression itself is used as the resolved value.apache. --> <description>Sample Maven Plugin</description> <!-.and Ant-specific mojo source files.3. During this process. The first is the root object. If a user has specified a property mapping this expression to a specific value in the current POM. No advanced navigation can take place using is such expressions. rendering an array of navigational directions. If the value is still empty. If at this point Maven still has not been able to resolve a value for the parameter expression. the next expression part is used as a basis for reflectively traversing that object' state. The Expression Resolution Algorithm Plugin parameter expressions are resolved using a straightforward algorithm. successive expression parts will extract values from deeper and deeper inside the build state.plugins</groupId> Better Builds With Maven 261 . From there. if the expression matches one of the primitive expressions (mentioned above) exactly. it will be resolved as the parameter value at this point. Plugin descriptor syntax The following is a sample plugin descriptor. Plugin metadata Below is a review of the mechanisms used to specify metadata for plugins. then the value mapped to that expression is returned. an expression part named 'child' translates into a call to the getChild() method on that object. This root object is retrieved from the running application using a hard-wired mapping.
This is optionally used in conjunction with the executePhase element. It's restricted to this plugin to avoid creating inter-plugin | dependencies. Combined with the 'goalPrefix' element above. |-> <goalPrefix>myplugin</goalPrefix> <!-.Which phase of the life cycle this mojo will bind to by default. This is | useful to inject specialized behavior in cases where the main life | cycle should remain unchanged.Ensure that this other mojo within the same plugin executes before | this one.This element provides the shorthand reference for this plugin. |-> <executePhase>process-resources</executePhase> <!-. |-> <inheritedByDefault>true</inheritedByDefault> <!-.</description> <!-. It is a good idea to provide this.0-SNAPSHOT</version> <!-. |-> <executeGoal>do-something-first</executeGoal> <!-. | This is useful when the user will be invoking this mojo directly from | the command line.This is a list of the mojos contained within this plugin. | and specifies a custom life-cycle overlay that should be added to the | cloned life cycle before the specified phase is executed.The name of the mojo. to give users a hint | at where this task should run. this plugin could be referred to from the command line using | the 'myplugin:' prefix. without | also having to specify which phase is appropriate for the mojo's | execution.This tells Maven to create a clone of the current project and | life cycle. | This allows the user to specify that this mojo be executed (via the | <execution> section of the plugin configuration in the POM). | this name allows the user to invoke this mojo from the command line | using 'myplugin:do-something'. |-> <goal>do-something</goal> <!-. but the mojo itself has certain life-cycle | prerequisites.Description of what this mojo does. then execute that life cycle up to the specified phase.Appendix A: Resources for Plugin Developers <artifactId>maven-myplugin-plugin</artifactId> <version>2. For | instance. --> <description>Do something cool. |-> Better Builds With Maven 262 . --> <mojos> <mojo> <!-.Whether the configuration for this mojo should be inherted from | parent to child POMs by default. |-> <executeLifecycle>myLifecycle</executeLifecycle> <!-.
Tells Maven that a valid list of reports for the current project are | required before this plugin can execute. unless the user specifies | <inherit>false</inherit>.maven. such mojos will | cause the build to fail. | It will be used as a backup for retrieving the parameter value. --> <language>java</language> <!-.The Java type for this parameter. |-> <requiresReports>false</requiresReports> <!-. Mojos that are marked as aggregators should use the | ${reactorProjects} expression to retrieve a list of the project | instances in the current build.Tells Maven that a valid project instance must be present for this | mojo to execute.Tells Maven that this mojo can ONLY be invoked directly.The class or script path (within the plugin's jar) for this mojo's | implementation. |-> <inheritedByDefault>true</inheritedByDefault> <!-.site. via the | command line.Appendix A: Resources for Plugin Developers <phase>compile</phase> <!-. this will often reflect the | parameter field name in the mojo class.plugins. |-> <requiresProject>true</requiresProject> <!-. |-> <aggregator>false</aggregator> <!-. it will be executed once for each project instance in the | current build. |-> <requiresDirectInvocation>false</requiresDirectInvocation> <!-. --> Better Builds With Maven 263 .The parameter's name. |-> <name>inputDirectory</name> <!-. |-> <alias>outputDirectory</alias> <!-.Determines how Maven will execute this mojo in the context of a | multimodule build. |-> <implementation>org.This is a list of the parameters used by this mojo. This flag controls whether the mojo requires | Maven to be online. If a mojo is marked as an aggregator. In Java mojos. |-> <requiresOnline>false</requiresOnline> <!-. it will only | execute once.The implementation language for this mojo. regardless of the number of project instances in the | current build. --> <parameters> <parameter> <!-. If the mojo is not marked as an | aggregator.SiteDeployMojo</implementation> <!-.This is an optional alternate parameter name for this parameter. If Maven is operating in offline mode.Some mojos cannot execute if they don't have access to a network | connection.apache.Tells Maven that the this plugin's configuration should be inherted | from a parent POM by default.
io. |-> <editable>true</editable> <!-. as in the case of the list of project dependencies.File. as | compared to the descriptive specification above. If set to | false. The expression used to extract the | parameter value is ${project.This is the list of non-parameter component references used by this | mojo. |-> <required>true</required> <!-.maven.For example.outputDirectory}</inputDirectory> </configuration> <!-.Whether this parameter's value can be directly specified by the | user. | and the primary expression used to extract the parameter's value. |-> <requirements> <requirement> <!-.WagonManager</role> <!-. Components are specified by their interface class name (role).apache. |-> <description>This parameter does something important.File">${project.File</type> <!-. | along with an optional classifier for the specific component instance | to be used (role-hint).maven.artifact.io. and it | expects a type of java.artifact.Appendix A: Resources for Plugin Developers <type>java. this parameter is named "inputDirectory". this parameter must be configured via some other section of | the POM. the requirement specification tells | Maven which mojo-field should receive the component instance. | | The general form is: | <param-name implementation="param-type">param-expr</param-name> | |-> <configuration> <!-. Each parameter must | have an entry here that describes the parameter name.Inject the component instance into the "wagonManager" field of | this mojo.WagonManager |-> <role>org. Finally.This is the operational specification of this mojo's parameters.outputDirectory}.Use a component of type: org. |-> <inputDirectory implementation="java.Description for this parameter. either via command-line or POM configuration. parameter type.reporting.Whether this parameter is required to have a value. the | mojo (and the build) will fail when this parameter doesn't have a | value.reporting.io. specified in the javadoc comment | for the parameter field in Java mojo implementations.manager.apache. |-> <field-name>wagonManager</field-name> </requirement> </requirements> </mojo> </mojos> </plugin> Better Builds With Maven 264 .manager.</description> </parameter> </parameters> <!-. If true.
executeGoal goal phase requiresDirectInvoc ation requiresProject requiresReports requiresOnline @aggregator true or false (default is false) No No (recommended) No N/A (class comment) @execute goal="mojo" phase="phase" lifecycle="lifecycle" @goal @phase @requiresDirectInvocation @requiresProject @requiresReports @requiresOnline Anything Any valid mojo.Appendix A: Resources for Plugin Developers A. Class-level annotations The table below summarizes the class-level javadoc annotations which translate into specific elements of the mojo section in the plugin descriptor. Java Mojo Metadata: Supported Javadoc Annotations The Javadoc annotations used to supply metadata about a particular mojo come in two types. Classlevel annotations correspond to mojo-level metadata elements. Table A-7: A summary of class-level javadoc annotations Descriptor Element Javadoc Annotation Values Required? aggregator description executePhase. and field-level annotations correspond to parameter-level metadata elements. executeLifecycle. life cycle name.2.4. phase. Alphanumeric. with dash ('-') Any valid phase name true or false (default is false) true or false (default is true) true or false (default is false) true or false (default is false) Yes No No No No No Better Builds With Maven 265 .
Appendix A: Resources for Plugin Developers Field-level annotations The table below summarizes the field-level annotations which supply metadata about mojo parameters.2. |-> <requiresDependencyResolution>compile</requiresDependencyResolution> <!-. |-> <mojos> <mojo> <!-. and Yes Requirements section required editable description deprecated usually left blank None None Anything Alternative parameter No No No No (recommended) No A.The default life-cycle phase binding for this mojo --> <phase>compile</phase> <!-.The dependency scope required for this mojo. Its syntax has been annotated to provide descriptions of the elements.Whether this mojo requires access to project reports --> <requiresReports>true</requiresReports> Better Builds With Maven 266 .Contains the list of mojos described by this metadata file. These metadata translate into elements within the parameter. Ant Metadata Syntax The following is a sample Ant-based mojo metadata file.Whether this mojo requires a current project instance --> <requiresProject>true</requiresProject> <!-. configuration. parameterconfiguration section @parameter expression="${expr}" alias="alias" default-value="val" @component roleHint="someHint" @required @readonly N/A (field comment) @deprecated Anything roleHint is optional.5. and requirements sections of a mojo's specification in the plugin descriptor. <pluginMetadata> <!-. Maven will resolve | the dependencies in this scope before this mojo executes. corresponding to the ability to map | multiple mojos into a single build script.The name for this mojo --> <goal>myGoal</goal> <!-. Table A-8: Field-level annotations Descriptor Element Javadoc Annotation Values Required? alias. NOTE: | multiple mojos are allowed here.
Whether this mojo requires Maven to execute in online mode --> <requiresOnline>true</requiresOnline> <!-. |-> <execute> <!-.Whether the configuration for this mojo should be inherited | from parent to child POMs by default.apache.The parameter name. |-> <property>prop</property> <!-.Whether this mojo operates as an aggregator --> <aggregator>true</aggregator> <!-.This is the type for the component to be injected.The phase of the forked life cycle to execute --> <phase>initialize</phase> <!-.maven.resolver.ArtifactResolver</role> <!-.The list of parameters this mojo uses --> <parameters> <parameter> <!-. |-> <inheritByDefault>true</inheritByDefault> <!-.The property name used by Ant tasks to reference this parameter | value. |-> <hint>custom</hint> </component> </components> <!-.A named overlay to augment the cloned life cycle for this fork | only |-> <lifecycle>mine</lifecycle> <!-. --> <role>org.This is an optional classifier for which instance of a particular | component type should be used.List of non-parameter application components used in this mojo --> <components> <component> <!-.Appendix A: Resources for Plugin Developers <!-.Whether this mojo must be invoked directly from the command | line.artifact. |-> <requiresDirectInvocation>true</requiresDirectInvocation> <!-.This describes the mechanism for forking a new life cycle to be | executed prior to this mojo executing. |-> <goal>goal</goal> </execute> <!-. --> <name>nom</name> <!-.Whether this parameter is required for mojo execution --> <required>true</required> Better Builds With Maven 267 .Another mojo within this plugin to execute before this mojo | executes.
The description of what the mojo is meant to accomplish --> <description> This is a test.artifactId}</defaultValue> <!-. |-> <deprecated>Use something else</deprecated> </parameter> </parameters> <!-.property}</expression> <!-.The Java type of this mojo parameter --> <type>org.Whether the user can edit this parameter directly in the POM | configuration or the command line |-> <readonly>true</readonly> <!-.The default value provided when the expression won't resolve --> <defaultValue>${project.If this is specified.apache. </description> <!-. it provides advice on which alternative mojo | to use.When this is specified.The expression used to extract this parameter's value --> <expression>${my.MavenProject</type> <!-.maven. |-> <deprecated>Use another mojo</deprecated> </mojo> </mojos> </pluginMetadata> Better Builds With Maven 268 .An alternative configuration name for this parameter --> <alias>otherProp</alias> <!-.project.Appendix A: Resources for Plugin Developers <!-.The description of this parameter --> <description>Test parameter</description> <!-. this element will provide advice for an | alternative parameter to use instead.
Star Trek Better Builds With Maven 269 .Appendix B: Standard Conventions Appendix B: Standard Conventions In this appendix you will find: Standard Directory Structure for Maven Project Content • Maven's Super POM • Maven's Default Build Life Cycle • Kirk: Do you want to know something? Everybody's human. Spock: I find that remark insulting. .
the generated site or anything else that might be generated as part of your build. you src/main/java/ src/main/resources/ src/main/filters/ src/main/assembly/ src/main/config/ src/test/java/ src/test/resources/ src/test/filters/ Standard location for application sources. Standard location for application configuration filters. A license file is encouraged for easy identification by users and is optional. Standard location for test resource filters. which is always at the top-level of a project. generated sources that may be compiled. Standard location for test resources.Appendix B: Standard Conventions B. may generate some sources from a JavaCC grammar. Better Builds With Maven 270 . Standard location for application resources.txt target/ Maven's POM. This would include compiled classes. Directory for all generated output.txt README. target/generated-sources/<plugin-id> Standard location for generated sources.xml LICENSE. Standard location for resource filters. Standard Directory Structure Table B-1: Standard directory layout for maven project content Standard Location Description pom.1. A simple note which might help first time users and is optional. Standard location for test sources. Standard location for assembly filters. For example.
Appendix B: Standard Conventions B.Plugin Repository Conventions --> <pluginRepositories> <pluginRepository> <id>central</id> <name>Maven Plugin Repository</name> <url>http://repo1. </project> Better Builds With Maven 271 .0</modelVersion> <name>Maven Default Project</name> <!-.Reporting Conventions --> <reporting> <outputDirectory>target/site</outputDirectory> </reporting> .org/maven2</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <!-..2.maven.0.maven.Build Conventions --> <build> <directory>target</directory> <outputDirectory>target/classes</outputDirectory> <finalName>${artifactId}-${version}</finalName> <testOutputDirectory>target/test-classes</testOutputDirectory> <sourceDirectory>src/main/java</sourceDirectory> <scriptSourceDirectory>src/main/scripts</scriptSourceDirectory> <testSourceDirectory>src/test/java</testSourceDirectory> <resources> <resource> <directory>src/main/resources</directory> </resource> </resources> <testResources> <testResource> <directory>src/test/resources</directory> </testResource> </testResources> </build> <!-.. Maven's Super POM <project> <modelVersion>4.Repository Conventions --> <repositories> <repository> <id>central</id> <name>Maven Repository Switchboard</name> <layout>default</layout> <url>http://repo1.org/maven2</url> <layout>default</layout> <snapshots> <enabled>false</enabled> </snapshots> <releases> <updatePolicy>never</updatePolicy> </releases> </pluginRepository> </pluginRepositories> <!-.
Generate any test source code for inclusion in compilation.Appendix B: Standard Conventions B. Create resources for testing. for example to do byte code enhancement on Java classes. These tests should not require the code be packaged or deployed. Install the package into the local repository. Generate any source code for inclusion in compilation. Better Builds With Maven 272 . Process and deploy the package if necessary into an environment where integration tests can be run. Copy and process the resources into the test destination directory. Perform actions required before integration tests are executed. Process the test source code. such as a JAR. for use as a dependency in other projects locally. This may including cleaning up the environment. Maven's Default Build Life Cycle Table B-2: Phases in Maven's life cycle Phase validate initialize generate-sources process-sources generate-resources process-resources compile process-classes generate-test-sources process-test-sources generate-test-resources process-test-resources test-compile test package pre-integration-test integration-test post-integration-test verify install deploy Initialize the build process. Copy and process the resources into the destination directory. This may involve things such as setting up the required environment. Done in an integration or release environment. Process the source code. Perform actions required after integration tests have been executed. ready for packaging. Description Validate the project is correct and all necessary information is available. for example to filter any values. Post-process the generated files from compilation. Run any checks to verify the package is valid and meets quality criteria. Compile the source code of the project. Take the compiled code and package it in its distributable format. Generate resources for inclusion in the package. for example to filter any values. copies the final package to the remote repository for sharing with other developers and projects. Compile the test source code into the test destination directory Run tests using a suitable unit testing framework.3.
Jim. Effective Java.codehaus.org/Merging+WAR+files Cargo Reference Documentation .http://cargo. Sun Developer Network .org/eclipse/development/java-api-evolution. June 8.http://checkstyle.http://java.codehaus. Joshua.codehaus.eclipse.net/config.codehaus.html Bloch. Evolving Java-based APIs.http://mojo. 2001 http://www.org/Maven2+plugin Cargo Merging War Files Plugin .org/ Checkstyle .codehaus.sf.html Better Builds With Maven 273 .org/Deploying+to+a+running+container Cargo Plugin Configuration Options .org/Containers Cargo Container Deployments .com/docs/books/effective/ Web Sites Axis Building Java Classes from WSDLhttp://ws.Bibliography Bibliography Online Books des Rivieres.http://cargo.http://ws.org/axis/java/ AxisTools Reference Documentation .apache.org/axis/java/userguide.http://cargo.org/axistools-maven-plugin/ Cargo Containers Reference .apache.http://cargo.html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL Axis Tool Plugin .sun.codehaus.http://cargo.
http://maven.org/download.sf.codehaus.http://tomcat.apache.0-doc/manager-howto.http://mojo.www.http://jetty.http://jester.html Xdoclet2 .net J2EE Specification .net/ XDoclet EjbDocletTask .html Cobertura .html Ruby on Rails .sf.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.html Introduction to the Build Life Cycle – Maven .au/products/simian/ Tomcat Manager Web Application .http://dbunit.com.net/howtomakearuleset.org/jdiff-maven-plugin Jetty 6 Plugin Documentation .html PMD Rulesets .org/guides/introduction/introduction-to-thelifecycle.sf.codehaus.redhillconsulting.sourceforge.apache.http://clirr.org/tomcat-5.org/plugins/maven-ejb-plugin/ ibiblio.sourceforge.maven.sf.html XDoclet Maven Plugin .http://checkstyle.http://maven.html Jdiff .codehaus.http://maven.apache.org/plugins/ Mojo .http://java.http://xdoclet.sf.http://mojo.org/maven-model/maven.sun.mortbay.apache.apache.Bibliography Checkstyle Available Checks .html Maven Plugins .sourceforge.codehaus.http://xdoclet.com/j2ee/reference/api/ Maven 2 Wiki .net/availablechecks.apache.com Introduction to Archetypes .http://xdoclet.http://maven.org/ PMD Best Practices .http://maven.net/ Clirr .net/bestpractices.http://mojo.http://xdoclet.html POM Reference .www.html Xdoclet .net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.net/ EJB Plugin Documentation .apache.sf.sourceforge.apache.apache.html Jester .http://www.rubyonrails.http://maven.org Maven Downloads .org/guides/introduction/introduction-to-archetypes.ibiblio.http://maven.org/xdoclet-maven-plugin/ XDoclet Reference Documentation http://xdoclet.org/plugins/maven-clover-plugin/ DBUnit Java API .http://cobertura.org/jetty6/maven-plugin/index.net/ Clover Plugin .org XDoclet2 Maven Plugin .http://pmd.codehaus.http://pmd.org/Maven2+Plugin Better Builds With Maven 274 .org/ Simian .http://www.
........... 205 Tomcat. 221 definition of............................... Christopher...................................20 Ant metadata syntax..............................................49-58.................................................................................... 70 container 56. 255.........25.......... 113115...................................................... 46 testing...................... 127........................................... 190-193 restructuring...........................32 artifactId................................. 126....... 21 standard directory structure.......................................................................................................16................ 156 Software Foundation................... 55................24..........197-200 Community-oriented Real-time Engineering (CoRE).....................Index A Alexander................................195 classpath adding resources for unit tests...272 Maven's super POM....................................................................... 43-45 handling resources.................. 81 deploying... 179 CPD report.... 98...................................170.......................273........200 application building J2EE... 121.......... 206-220 creating standard project.................126..... 50 preparing a release............ 34... 201.......................................................................................................... 68.. 40-46 preventing filtering of resources........................................ 37 tests..................................................... 77.............................................20.............................. 77-79......................... 21 default.. 30 Berard...................76-79......................................................... 36.22 copy/paste detection report.. 53-56...... 143.. 197 setting up shared development environments......................................... 62.......... 239 ASF..................... 239 Geronimo project........... 17........ 237-241 test sources....50 single primary output per project................... 75........ 90.................. 156 collaborating with teams introduction to....................... 105-107....................................... 122 Changes report........................181 Commons Collections .................................................................................................... 121..................................................... 17 aspectj/src directory............................. Edward V............ 179-181 Clancy.................................... 70 archetypes creating standard project............... 45... 211 Continuum continuous integration with...251 Codehaus Mojo project............ 103................................. 74 creating a Web site for......................................... 123.........157 Better Builds With Maven . 272 Butler.. 271 naming............................ 241 Commons Logging library........ 223-227 project inheritance................. 196 compiling application sources............................. 77........................................... 105-124 creating......... 88 HTTPd...............241................................................................. 153....... 242 Confluence format.............. 175..... 49 bibliography...................................... Jon.............................270 standard naming conventions............................... 22 standard directory layout for projects............ 274 binding..... 75 modules................... 86.......196.... 222 conventions about...... 61. 103................................. Samuel. 126...............41............................ 228-251 Apache Avalon project......................................................... 78...................................................................................49.............. 230 aspectj/test directory...................................... 171 Checkstyle report......................... 182-186 code improving quality of........................................................ 221............... 75 Separation of Concerns (SoC). 56................ 203...50 setting up the directory structure......... 256....... Tom.. 232............ 34 main Spring source................69-75 DayTrader.... 230 C Cargo................................................................................ 94-96................................. 42 filtering resources.................. 150................ 49............................................................................................................... 81-101................................................................................................................ 135..... 257 Clirr report........... 126-128................... 69...... 195 issues facing teams...............................................................24 default build life cycle................. 171........... 251 code restructuring to migrate to Maven. 33. 103................................................ 258 build life cycle............... 50-53 APT format............................................................................200 Maven project........................................................................................................... 49.......................... 174.. 94-96........................ 171........266-268 migrating from.. 75 managing dependencies........................................................................................... 156........................171......................... 190-193 Cobertura.............. 66...................... 102.......... 179 275 B Bentley...................................... 220................. 29 clean life cycle.......................................
.............................................................................................................................................................78 default build life cycle....... 232 mock...................Object..........................34............................ 57 using version ranges to resolve conflicts.......................................................................................................................................................................37 naming conventions.............................. 200 J J2EE building applications.......................28 maintaining............................. 25.... 85 flat........................................................................................................... 103...................................... 193 internal repository...................... 50 pom..............79 nested.........................................................................................................................................................................................................................................................................69 G groupId....... 94-96 plugin documentation...................................... 44 structures...................................67 with SSH2....................................................... 68 F Feynman...................................................................................... 68.........................................................265-268 Spring Framework... 67 development environment.... 26 relationship between Spring modules........ 98 testing applications...................... 18 dependencies determining versions for....................68 with FTP.........76-79.............Index D DayTrader architecture...24... 272 conventions....... 173 Better Builds With Maven 276 ........ 24 Java EE..... 172........................ 24 location of local repository........................ 235 Jester...................................................69 with SFTP.......................125 filtering classpath resources....................................................... 21 hibernate3 test.......43-45 preventing on classpath resources...............................................................................170.................................90 Xdoclet.................................................. 230 m2.............................................................. 20................................................... 117-119........................171 Deployer tool..............................................................................................................................45...................58-61 Dependency Convergence report.... 90...................... 77 Javadoc class-level annotations.......................... 96 JXR report......................................................... 86 deploying........................................170........231............................................................80 DocBook format............................. 230 resolving conflicts.................................................................................................................... 246.............. 192.... Richard............................... 78 building a Web module... 33...................................24 mojo metadata.230 tiger/test.................................................. 232 standard layout for projects............................................................................................................................................................................................................................... 70 DocBook Simple format............77................................... 114... 24 java........... 115 deploying applications methods of....................................... 86-90 canonical directory structure for..................... 15 EJB building a project.lang.......... Albert............ 245............ 66 with an external SSH...................................................................................................................... 41.....................................66...230 directory structures building a Web services client project................ 114............................................................................................................................................................................... 115................ 121-124 Java description.............. 187-189 organization of........................... 237 url..................... 229-233... 235 I IBM............ 46 FindBugs report.........xml............ 61.. 230............. 232 tiger................................266 report............ 186 JSP................................................................... 230............................... 239 H Hansson.............. 81 Quote Streamer................................................................................ 77 improving quality of code.................................................................................................70 FTP........................... 230 my-app....................................58-61 specifying snapshot versions for............ 172-174 JDK...............21 standard structure............................................ 82-101......... 91 external SSH. 240 locating dependency artifacts.................................... 32........................................................32 src.............................................................................................190.............................. 70 E Einstein................. 28.................................... 265 field-level annotations.................................................. 248 tiger/src..................................................... 43. 117 Geronimo specifications JAR.................. 232.......................................................................... 182 FML format........96-99 organizing the directory structure. 69 to the file system....................... 79.............................................................................. 197-200 directories aspectj/src.......................... David Heinemeier................ 78.......... 270 test..................... 105-124 deploying applications...................................................................................230 aspectj/test.......
................................................................................................. 43-45. 161-163 creating your first project................32 N name (element)................................61............. 39 requirement for Maven..... 126 developer resources..............76 L life cycle default. 79 installing non-redistributable JARs.................130 preparing to use................................. 30 migrating to Maven.....................................................230 EAR............................................................ 50 nested directory structure................. 47.......................................................... 228-241 mock directory.................................................... 93 maven-plugin packaging.....................................126-128 plugin descriptor.........................................133-143 capturing information with Java.......................................... 24............................................................................................ 133-138 definition of................................. 156 artifact guideline.............................................. 195-227 compiling application sources............................. 126.......................................................245-248 dedpendency relationship between Spring........................................................... 126............................................................................................. 127................................................................... 128 developing custom plugins.......................................248.......................................................................................... 80 referring to test classes from...................................244 building EJB with Xdoclet............ 132 parameter expressions.......................................................... 78 flat directory structure.............. 129..................................................246 WAR..............144-153 basic development.. 92 XDoclet2............ 232 Maven Apache Maven project........................................................................................................... 128 local repository default location of...........................29 M m2 directory......................... 70..... 79 mojos accessing build information....182...... 48 groupId.......................... 253....................... 51 naming..........................78 EJB......................................................................................24 naming conventions................................................................. 30-41.................................228-241 naming conventions.................................................................................................................79 naming conventions......... 232 parameter injection.................... 126-128 requiring dependency resolution........................................................................................................................................24 modules avoiding duplication........ 28 integrating with Cobertura................. 62.............................................................................................29 local repository....................... 128 Plugin Matrix....................................... 127.......................250 JAR...................23.................................. 249 using plugins.....29 locating dependency artifacts...................... 50 origins of................................................... 130-132 framework for......................32....................................... 146 writing Ant mojos to send e-mail..................... 269-272 super POM..............................................256 McIlroy...................................................................................................................................................................125.........................................................................90-93 building Java 5 classes.................................. 34 collaborating with............. 158 XDoclet plugin........................ 125-156 documentation formats for Web sites......................... 127 phase binding.................................................................... 245 tiger....................... 17 plugin descriptor...................................................201 standard conventions...........................................Index K Keller................. 50 O overview benefits of Maven........ 37 installing to.......... 20 P packaging........253................... 20-29 Ruby on Rails (ROR)............................129 plugin descriptor ................................ Helen..260 advanced development....... 271 using Ant tasks from inside................................................... 130 plugins definition of........................ Doug.................................. 31 Repository Manager (MRM)........................ 272 developing custom.. 230 modelVersion............................................................................145....................... 254 for jar packaging........................................................................ 33 default build life cycle............................................................. 129-156 development tools........................78 multi-module build............231............26 storing artifacts in....78 build life cycle...............25.................................................................... 26-28 principles of Maven. 47 using to assess project health..259-268 phase binding..........................126 implementation language......... 184-186 JDK requirement.50.................................... 140-143 my-app directory................................................33................... 254 migrating to...............................................................................37..................................................................................................... 34 configuration of reports........................................................................................ 129 addition........................................................................................................................................... 252-268 developing custom............................................................. 71 getting started with............................................................................................................................................................................ 235 life-cycle phases................................ 126 277 Better Builds With Maven ..................................
.................................................................. 179 creating source code reference................................ 162...36......... 104-108........ 58-61 W Web development building a Web services client project.......................... 61.............................. 168....... 171..................... 230.................. 87...................................................................... 191..................................... 117......................... 270 preparing to use Maven............................ 16 repository creating a shared......................................93 Better Builds With Maven 278 ......172-174 Dependency Convergence... 216.... 98.................................................. 251 Ruby on Rails (ROR). 114........................... 194.... 232............171...... 92....... 214..................................................... 221. 230..................... 242 hibernate3............ 182...... 230 Twiki format................223-227 reports adding to project Web site..........171......... 91 XDoclet2... 105 X XDOC format.... 224............................................... 192........ 67 Surefire report.......................................................200 local.............................. 29.....90........... 171............................................................16........................................... 146............ 199.........29..... 175.xml........................................................................ 26................ 226................................247 pom.................... 53-56..................... 223-226 SFTP...... 215 Spring Framework... 29 manager... 182.......... 28......235 JUnit............................. 70 Xdoclet...... 33.................................................. 160......................................................... 171.. 190-193 configuration of............. 186 Tag List... 75 monitoring overall health of.................... 213..............171....194 project management framework............. 182 V version.................................. 258 snapshot.................................................... 172-174 JavaNCSS......................... 49........ 58........ 57. 163...................... 182 Javadoc... 105-107 improving productivity....................................164-169 standard project information reports. 170............... 202.243 S SCM...................... 175................................. 237 key elements................................. 243 tiger/src directory............................. 31 profiles..................... 23...........................................................171 FindBugs....................... 83............... 179 CPD............................................................ 24....................... 185.Index terminology..... 237 src directory................................49........................ 126........... 37 tests compiling...................... 271 tiger.......................241.......... 217.......................... 94......................................................................... 62-66 project assessing health of......... 119............................................................ 163............... 162........................... 173...... 159-161 Changes.........................203-205 creating files.... 26 restructuring code............................................... 48 PMD report...................................................................................................................159..................49................................................................ 203.................. 47.......................... 182................... 200. 16 Project Object Model....... 174...................... 171..... 32.......... 161............ 171 separating from user documentation........... 181......... 175-179 selecting............ 60................... 159. 163........ 161-163 copy/paste detection........ 209.. 157-194 inheritance.......... 232 testing sources...................... 70 R releasing projects..... 159......... 127 using................................................................................... 203 creating an organization........................................ 72 Surefire.. 175......... 182 test directory..................................................................72 site life cycle................... 184. 171 Checkstyle.............................. 185.......................... 97......... 200-202 internal..........................24 super. 230 monitoring.... 208.................................................................................................. 24......................................................... 121..............182-186 running.. 164............ 100......... 171......... 88..... 160......................................................................................... 239 version ranges.......... 232 SSH2..................... 67 site descriptor........................................................... 181............... 217........................................... 186 Q Quote Streamer........ 173 PMD......................................................... 82-84...........................49.......................... 79-81............................... 179-181 Clirr......................... 229-233........... 185.. 176-178........................... 100-103.........................170....................24... 115......... 175-179 POM............................................. 171............. 167.................182 JXR...........................230 tiger/test directory................. 78 T Tag List report....................................170.............274 running tests.......................................................................................... 181........................... 201 types of...................170............ 172................................................... 108-113 deploying Web applications.............
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