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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: March 2006 in the USA
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 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
To Lisa Malgeri and Elena Renard.support. and submit fixes. I'm grateful to have had the opportunity to finally write a book about Maven. contribute ideas. doing additional copy editing and organizing its release. for trusting my judgment to use Maven on our projects. friends.I'd like to start by thanking everyone who has been involved in the Maven community over the years. for her dedication to see this through. for loving me as I am despite all my flaws. My most heartfelt thanks and all of my love go to my wife Laura. whose work made this book as professional and polished as it is. 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. Brett Porter ii . and for leaving her native Michigan to live in a bizarre foreign land. and without whom I would never have been able to get involved in the project in the first place. answer questions. Vincent. despite having all of the least enjoyable tasks of keeping the development on track. I'd like to say how much I appreciate all of my family. Personally. for sticking with it through some of the early development and for holding the development team to a higher standard. To the authors Jason. and those of St Paul's Anglican church for all of their care. 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. Both I and the Maven project owe you all a debt of gratitude. 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. To Natalie Burdick. John and Carlos congratulations on a job well done. for her great patience and sacrifice in allowing me to work at all hours from home. doing what you enjoy and being able to see your our own personal vision realized. for their copy editing. and to do so with such a number of my talented friends and colleagues. formatting and development of the book's template. Maven is the cumulative work of nearly 40 committers and an even larger number of contributors who've taken the time to give feedback. help and encouragement in everything that I do. test features. but for the opportunity to work in such a tremendous environment. I'd also like to thank Paul Russell and the development team during my time at Fairfax Digital. I continue to hope that it was for me and not just because of the warmer climate.
we would like to thank all the reviewers who greatly enhanced the content and quality of this book: Natalie Burdick. John. Ruel Loehr. Carlos Sanchez Many thanks to Jesse McConnell for his contributions to the book. Abel Rodriguez. David Blevins. Chris Berry. Ramirez. Lester Ecarma. Allan Ramirez. Jerome Lacoste. Thanks also to all the people in Galicia for that delicious food I miss so much when traveling around the world. Felipe Leme. and the teammates during my time at Softgal. for accepting my crazy ideas about open source. Also. Jason. Jerome Lacoste. Mark Hobson. Elena Renard and Joakim Erdfelt for their many contributions to the book. Fabrice Bellingard. Emmanuel Venisse and John Tolentino. Brett and Carlos iii . Stephane Nicoll. Tim O'Brien.I would like to thank professor Fernando Bellas for encouraging my curiosity about the open source world. It is much appreciated. Napoleon Esmundo C. Finally. Bill Dudney. especially my parents and my brother for helping me whenever I needed. Vincent. All of us would like to thank Lisa Malgeri. I'd like to thank my family for their continuous support.
Carlos Sanchez received his Computer Engineering degree in the University of Coruña. In addition to his work on Maven. and working on his house. This is Vincent's third book. financial. telecommunications and. 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. Brett is a co-founder and the Director of Engineering at Mergere. and is a Member of the Apache Software Foundation. discovering Maven while searching for a simpler way to define a common build process across projects. which has led to the founding of the Apache Maven project. John was elected to the Maven Project Management Committee (PMC).0 major releases. John Casey became involved in the Maven community in early 2002.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. Additionally. Jason van Zyl focuses on improving the Software Development Infrastructure associated with medium to large scale projects. where he hopes to be able to make the lives of other developers easier. Spain. he is a co-author of JUnit in Action. He is grateful to work and live in the suburbs of Sydney. Brett has become involved in a variety of other open source projects. Vincent lives and works in Paris. He was invited to become a Maven committer in 2004. a company which specializes in collaborative offshore software development using Agile methodologies. Build management and open source involvement have been common threads throughout his professional career.. software development. when he began looking for something to make his job as Ant "buildmeister" simpler. of course. Jason Van Zyl: As chief architect and co-founder of Mergere. and started early in the open source technology world. he founded the Jakarta Cactus project-a simple testing framework for server-side Java code and the Cargo project-a J2EE container manipulation framework. John lives in Gainesville. iv . Inc. Vincent has directly contributed to Maven's core. as well as to various Maven plugins. joining the Maven Project Management Committee (PMC) and directing traffic for both the 1. published by O'Reilly in 2005 (ISBN 0-596-00750-7).0 and 2. Australia. Emily. Brett Porter has been involved in the Apache Maven project since early 2003. roasting coffee. Florida with his wife. When he's not working on Maven.. specializing in open source consulting. supporting both European and American companies to deliver pragmatic solutions for a variety of business problems in areas like e-commerce. Immediately hooked. and in 2005. CSSC. Inc. He enjoys cycling and raced competitively when he was younger. where he is the technical director of Pivolis. published by Manning in 2003 (ISBN 1-930-11099-5) and Maven: A Developer's Notebook. John enjoys amateur astrophotography. his focus in the Maven project has been the development of Maven 2. He continues to work directly on Maven and serves as the Chair of the Apache Maven Project Management Committee. He created his own company. Since 2004.
................ 20 Standard directory layout for projects.................................................... Using Snapshots........................Table of Contents Preface................56 v ......................................2..................................... Maven Overview..........2......................3............... Preventing Filtering of Binary Resources................................6...... 42 2...22 Standard naming conventions........38 2....................6.....................31 2.........................28 1.......................................... 22 1.............................. Handling Test Classpath Resources.......................................................52 3..............................................3............................................................................ 20 1............................................................................................... 40 2........................................................................2.....................................................................................................2............................ 49 3................. 23 Maven's project object model (POM).................. 29 2..........2...........................................2................................................................ 49 3...................................................... Convention Over Configuration............................... What Does Maven Provide?.................................................1........... Declarative Execution...................................................................................... 12 1................................................... 34 2...............................................1..........................................................1............................ Filtering Classpath Resources..................1...........4......................................... 23 1........................... 25 1............3.............. Preparing to Use Maven................................................................................................ Maven's Benefits................... Compiling Application Sources.. Using Project Inheritance.....8.................................................................................................................................................. Introducing Maven............................6............................... Compiling Test Sources and Running Unit Tests.................................................... 21 One primary output per project.......... Introduction.............................................................2................... Setting Up an Application Directory Structure.........................2.3...................................1........................................... 32 2... Summary..............5........................4....................................................................................6........... 30 2.......................................................2............................................................................................................................46 2............................................7............. 48 3.................. Using Maven Plugins........................... Packaging and Installation to Your Local Repository...................................................................................... 47 3............................................................................................................................23 Maven's build life cycle... Reuse of Build Logic...1.............................................1.... 41 2.............................................54 3................................... 17 1....... Maven's Principles...................................................................................... Coherent Organization of Dependencies................. Creating Applications with Maven........................................................... 16 1..........1..................................................... 18 1..............................................4............................................... Creating Your First Maven Project........................................3........................... 16 1.....................................................................................................................2............................................ 45 2............................................... Maven's Origins............................................. 36 2...............................................................26 Locating dependency artifacts............................15 1................................5....................... What is Maven?................................................................................... Handling Classpath Resources........................ Getting Started with Maven..... 25 Local Maven repository...............................................3................1............................. Managing Dependencies.......................................................
.........................2...................................................................................................... 66 3..1.................................................1.................. 85 4..............3..................................... 66 3........................................................................................................................................11...............2................................. 74 4...............................................................11..................................................................................................... Building an EJB Module With Xdoclet............ Resolving Dependency Conflicts and Using Version Ranges......3....................4..................................7........................................................................... 78 4..................... Deploying with FTP...................... Deploying your Application...................................................... 76 4..9................ A Review of Plugin Terminology................13......................................................... Building an EJB Project.............................................................................. Developing Your First Mojo................................. A Note on the Examples in this Chapter...........................11.............................................. Introduction....................3..........................................................................................................14........ Introducing the DayTrader Application.................1..2............ 132 Using the archetype plugin to generate a stub plugin project............126 5... 75 4...............................................60 3................ Utilizing the Build Life Cycle.................... Deploying to the File System.....100 4............................................................ Building a Web Application Project.......................................................................................................................1. Bootstrapping into Plugin Development................7.............................. 81 4.................... Creating a Web Site for your Application.............66 3............57 3...........12.......... 136 The output........................................................................................................................ Building a Web Services Client Project............ 135 Binding to the life cycle................89 4........................6....... 125 5.................. Building an EAR Project..................................................................................................................................................................................................... 76 4........6...................... 125 5...............................................................................................4.............. 131 5................................................................................. 67 3.................. 128 The plugin descriptor...........................................................................................4...........................103 4....................................................128 5.................................. Developing Custom Maven Plugins.........................1....... 127 Accessing build information..................................................... 95 4.......................................... Deploying with SFTP......................................10............................................................................ Deploying with an External SSH............ Summary.................................... Plugin Development Tools..........................................................................................................................................................3.............................. 91 4......12. Testing J2EE Applications...........................................2...9....................................... Building J2EE Applications....................................................... Improving Web Development Productivity..5........................10.............................113 4..... Deploying EJBs..............................................................................................11....................... 126 Participation in the build life cycle.....107 4........................................116 4......13................................................................ 131 5....124 5.... Deploying with SSH2........................... The Plugin Framework................................................................ 61 3...........................................................................................................8............................. 68 3.................... 129 Choose your mojo implementation language............................................................................................................................1............................................................ 132 The mojo...............................................................3..................... 133 The plugin POM........67 3...... 132 5............................................................................................................................................................ BuildInfo Example: Capturing Information with a Java Mojo ....9..... Deploying a J2EE Application...................................................................... Deploying Web Applications............ 123 5... Organizing the DayTrader Directory Structure......................................................3....................3........................................................................ Using Profiles.............................8.................................................... Introduction......................................... 137 vi ........... Summary.............68 3...
....................................219 7.........................................................................5........................................................................................ Summary................................................................... Advanced Mojo Development........................................................................................................145 5... Monitoring and Improving the Health of Your Source Code..................1........................................................................................... Separating Developer Reports From User Documentation.......................... Assessing Project Health with Maven....................149 Accessing the resource list............................................................1............ Migrating to Maven....................... 143 5................. Creating a Shared Repository............................12...................3................................................................ 143 Injecting the project dependency set.................4................................................5..................................................181 6................................ Cutting a Release.............5......................................................... 147 Adding a resource to the build......................6.............................. Adding Reports to the Project Web site................................... 228 vii ............8....................... 156 6...............10....................................................5.......................................................... Summary.......................................................... 148 Accessing the source-root list............................................7............................. 171 6....... 158 6....................199 7.................................................. 153 5.......1........................... 221 7.......................................................1....... 205 7................... 138 The mojo metadata file........... Monitoring and Improving the Health of Your Dependencies.........................................................................................................2.......................................................................................................................3................................................................................................. 228 8...................................4........... What Does Maven Have to do With Project Health?........... Viewing Overall Project Health............... 174 6...11.... Summary................................................................................................................................186 6.........9.............. 169 6............................................................. 157 6............ Monitoring and Improving the Health of Your Tests................ 150 Note on testing source-roots and resources............................................ Creating an Organization POM..................................................................................................................... 138 The Ant target.....................................................2............... 189 6...... 146 Adding a source directory to the build...................................................... Accessing Project Dependencies............ 138 Modifying the plugin POM for Ant mojos...... Monitoring and Improving the Health of Your Releases..... Choosing Which Reports to Include........................... Continuous Integration with Continuum........................ Accessing Project Sources and Resources............................196 7........ The Issues Facing Teams..3........................................................................................................................................... Attaching Artifacts for Installation and Deployment...................................................................................... 193 7.........................9.......... 142 5................................................................................................. 144 BuildInfo example: logging dependency versions................ 195 7.......................................................................................................... BuildInfo Example: Notifying Other Developers with an Ant Mojo...............................................5..... 140 Binding the notify mojo to the life cycle...............................5.1...................................................................2................................................................................................................................................... 160 6.......6....... 152 5........... Introduction.... 214 7............................................................ Team Collaboration with Maven........................ Introducing the Spring Framework..................... 226 8.................................................163 6.. How to Setup a Consistent Developer Environment................2.......................................193 6.... Creating Reference Material............... 194 7..........................1............7........................ 155 6.... Creating a Standard Project Archetype. 143 Requiring dependency resolution............................ 202 7.............. 227 8.......................................................................................5...................................................8............. Configuration of Reports..6..........4................................................................................................................... Team Dependency Management Using Snapshots.......................................
.............................256 Default life-cycle bindings..........................260 Plugin descriptor syntax........... 251 A.................................... Some Special Cases.........................................................................2............................................................. 258 A......................... Testing........6..2...........2................................................................ Referring to Test Classes from Other Modules. Maven's Super POM................................1................................................................................................................................................................1..........................3......................................................5........................................................................ Complex Expression Roots........................... Standard Directory Structure...................230 8....................................................................5.. 243 8................................................................................................240 8..............................................................2..........257 A............... Summary.......6................. 272 viii ............5............................................6...8................... 250 8.............................. 260 Plugin metadata.................................................1.................................. 252 Life-cycle phases.........................................................................................................6............................................. Ant Metadata Syntax..........1............................. Maven's Life Cycles...............................6...................................................................................................................................................................................2............2..........................................................252 Bindings for the jar packaging..........................1.................................................. 254 Bindings for the maven-plugin packaging......... 240 8........................................................................................................ 258 A........................................... Java Mojo Metadata: Supported Javadoc Annotations............................................................................... Compiling Tests..........2...................255 A..............................................................................8...7....................................... 264 Class-level annotations...............................................1..........................1........................................................... 249 8.......... The default Life Cycle................................. 264 Field-level annotations.......256 A........... Simple Expressions.............. Compiling...........................................260 A................................................................................... 244 8....... 256 Life-cycle phases..............................236 8..........................................................................2..................................................................... Using Ant Tasks From Inside Maven...................................... Other Modules....5............................................4..... Where to Begin?................................ Maven's Default Build Life Cycle...............3................................................2.............................................................6......... The site Life Cycle.......................3.......... 265 A. 243 8...........................................................................................................................3................................................................................................. 249 8............ Mojo Parameter Expressions........... 244 8.................. 269 B..........................................................1.................................................................................................................................................... Running Tests........................................................... Building Java 5 Classes. 265 Appendix B: Standard Conventions....... Avoiding Duplication..................................................................... 270 B..................................................252 A..... 271 Bibliography.........................................................2..................................................... The Expression Resolution Algorithm.....6. 268 B............................... 242 8......................................................................................... Creating POM files.......................................................5.................................................................................................................................................. 259 A.............................4..................257 Default Life Cycle Bindings................................................................. 250 Appendix A: Resources for Plugin Developers............ 236 8...........................................................................6........ 257 Life-cycle phases........................................................... The clean Life Cycle................................ 247 8..............................1..........4............. Non-redistributable Jars......2.................................................2............................2............................................................................................ Restructuring the Code......................................................
....................... 256 Table A-4: The site life-cycle bindings for the jar packaging................................................................................................................................................................ 180 Table A-1: The default life-cycle bindings for the jar packaging.... 257 Table A-5: Primitive expressions supported by Maven's plugin parameter........................................................................................................269 Table B-2: Phases in Maven's life cycle................................... 169 Table 6-3: Built-in Checkstyle configurations.......259 Table A-7: A summary of class-level javadoc annotations.....................................71 Table 4-1: WAR plugin configuration properties....271 ix ...................................List of Tables Table 3-1: Module packaging types...............................59 Table 3-3: Site descriptor............. 265 Table B-1: Standard directory layout for maven project content..............................................................................................................................164 Table 6-2: Report highlights...............................................................................................258 Table A-6: A summary of the valid root objects for plugin parameter expressions..................................................................................................................................................................................................................................................................................................................................................................................................................... 94 Table 4-2: Axis generated classes.............................................................................................................................................................................................. 103 Table 5-1: Life-cycle bindings for jar packaging....................................................................................................................................................................................... 51 Table 3-2: Examples of version ranges...........................................................264 Table A-8: Field-level annotations..........................................................................254 Table A-2: A summary of the additional mojo bindings.................................................................................................................................................. 255 Table A-3: The clean life-cycle bindings for the jar packaging........................................................ 127 Table 5-2: Key differences between compile-time and test-time mojo activities.........................................................152 Table 6-1: Project Web site content types................
...................................182 Figure 6-11: An example dependency report....................................... 73 Figure 3-6: The sample generated site........59 Figure 3-4: The site directory structure................................................................... EJB and Web modules................................... 50 Figure 3-2: Proficio-stores directory....................................................................................................................................86 Figure 4-7: Directory structure for the DayTrader web module showing some Web application resources........................................ 158 Figure 6-2: The Surefire report...................... 40 Figure 2-3: Directory structure of the JAR file created by Maven...... 74 Figure 4-1: Architecture of the DayTrader application................................................................................................... 116 Figure 4-14: Directory structure for the functional-tests module....................................................................................List of Figures Figure 1-1: Artifact movement from remote to local repository............................ 28 Figure 2-1: Directory structure after archetype generation.................. 42 Figure 3-1: Proficio directory structure...........................................................................................................................................................................................................................................178 Figure 6-9: An example Checkstyle report......... 80 Figure 4-5: Directory structure for the DayTrader ejb module....................................................79 Figure 4-4: Nested directory structure for the EAR.................. 96 Figure 4-9: Modified registration page automatically reflecting our source change................................186 Figure 6-12: The dependency convergence report......................... 118 Figure 6-1: The reports generated by Maven...................................................................................................................... 27 Figure 1-2: General pattern for the repository layout............................... 188 x ........................................................................41 Figure 2-4: Directory structure after adding test resources........................................................................................................................................................................................................................ 174 Figure 6-8: An example CPD report............................................................................................................................................................................................................................................................................79 Figure 4-3: Modules split according to a server-side vs client-side directory organization..........................51 Figure 3-3: Version parsing...........................................................................................................................................................................................................................................113 Figure 4-13: The new functional-tests module amongst the other DayTrader modules .................................97 Figure 4-10: Directory structure of the wsappclient module............................................................................................. 103 Figure 4-11: Directory structure of the ear module..................................................................................................................... 28 Figure 1-3: Sample directory structure.................................................................................................. 165 Figure 6-4: The directory layout with a user guide................................................................................................................................................................................. 81 Figure 4-6: Directory structure for the DayTrader ejb module when using Xdoclet...................................... 159 Figure 6-3: The initial setup............................................... 33 Figure 2-2: Directory structure after adding the resources directory..................... 179 Figure 6-10: An example Cobertura report................................................................................ 76 Figure 4-2: Module names and a simple flat directory structure....................................................................................................................................69 Figure 3-5: The target directory........................................................................................................................................................................................166 Figure 6-5: The new Web site..................................................................................... 107 Figure 4-12: Directory structure of the ear module showing the Geronimo deployment plan...........................................91 Figure 4-8: DayTrader JSP registration page served by the Jetty6 plugin........ 167 Figure 6-6: An example source code cross reference..................................................................................................................................................171 Figure 6-7: An example PMD report..........................................................................................................................
................................................................................................................................................................................................230 Figure 8-3: A tiger module directory............................................................................... 209 Figure 7-4: Schedule configuration....................245 Figure 8-4: The final directory structure.................................................................................................................................................................................................217 Figure 7-7: Archetype directory layout............................................................................................. with all modules.............................................................................................................................................................. 212 Figure 7-6: Continuum configuration........................................................................246 xi .................... 229 Figure 8-2: A sample spring module directory................................................................ 219 Figure 8-1: Dependency relationship between Spring modules..................... 208 Figure 7-3: Summary page after projects have built....................................................................................................206 Figure 7-2: Add project screen shot....................................................................................189 Figure 7-1: The Continuum setup screen................................................... 211 Figure 7-5: Adding a build definition for site deployment..............................................................................................................245 Figure 8-5: Dependency relationship................................Figure 6-13: An example Clirr report...................................................
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.0. reading this book will take you longer. an indispensable guide to understand and use Maven 2. Maven works equally well for small and large projects. Perhaps. Maven 2 is a product that offers immediate value to many users and organizations. This guide is intended for Java developers who wish to implement the project management and comprehension capabilities of Maven 2 and use it to to make their day-to-day work easier and generally help with the comprehension of any Java-based project.Preface Preface Welcome to Better Builds with Maven. We hope that this book will be useful for Java project managers as well. it does not take long to realize those benefits. Better Builds With Maven 12 . it is recommended that you step through the material in a sequential fashion. For first time users. For users more familiar with Maven (including Maven 1. which provides a wide range of topics from understanding Maven's build platform to programming nuances. this guide endeavors to provide a quick solution for the need at hand.x). As you will soon find.
At this stage you'll pretty much become an expert Maven user.Preface Organization Here is how the book is organized. Assessing Project Health with Maven. split it into modular components if needed. and install those JARs in your local repository using Maven. Finally. the chapter covers the tools available to simplify the life of the plugin developer. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. In this chapter. and compiling and packaging it. Chapter 4. EJB. Building J2EE Applications. and document for reuse the artifacts that result from a software project. visualize. gives detailed instructions on creating your first project. After reading this chapter. WAR. In this chapter you will learn to setup a directory structure for a typical application and the basics of managing the application's development with Maven. you will be revisiting the Proficio application that was developed in Chapter 3. shows how to use Maven to build J2EE archives (JAR. The first two chapters are geared toward a new user of Maven 2. Better Builds With Maven 13 . Chapter 1. and how to use Maven to deploy J2EE archives to a container. compile and test the code. Chapter 6. discusses Maven's monitoring tools. You will learn how to use Maven to ensure successful team development. and learning more about the health of the project. Chapter 5. reporting tools. Chapter 2. goes through the background and philosophy behind Maven and defines what Maven is. EAR. Introducing Maven. they discuss what Maven is and get you started with your first Maven project. These tools aid the team to organize. Chapter 3 builds on that and shows you how to build a real-world project. you will be able to take an existing Ant-based build. create JARs. Chapter 7. shows how to create the build for a full-fledged J2EE application. Chapter 7 discusses using Maven in a team development environment and Chapter 8 shows you how to migrate Ant builds to Maven. Developing Custom Maven Plugins. Chapter 3. At the same time. Chapter 8. It starts by describing fundamentals. it discusses the various ways that a plugin can interact with the Maven build environment and explore some examples. From there. focuses on the task of writing custom plugins. After reading this chapter. explains a migration path from an existing build in Ant to Maven. Getting Started with Maven. Team Collaboration with Maven. you should be up and running with Maven. you will be able to keep your current build working. Migrating to Maven. Chapter 5 focuses on developing plugins for Maven. and how to use Maven to generate a Web site for your project. Web Services). looks at Maven as a set of practices and tools that enable effective team communication and collaboration. illustrates Maven's best practices and advanced uses by working on a real-world example application. Chapter 4 shows you how to build a J2EE application and deploy it. Creating Applications with Maven. Chapter 6 discusses project monitoring issues and reporting.
mergere.com. So if you have Maven 2.0 installed.com. We'll check the information and. Better Builds With Maven 14 .Preface Errata We have made every effort to ensure that there are no errors in the text or in the code. errata. on the book details page. 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.mergere. How To Download the Source Code All of the source code used in this book is available for download at http://library. However. How To Contact Us We want to hear about any errors you find in this book. and technical support from the Mergere Web site at http://library. we are human. so occasionally something will come up that none of us caught prior to publication. then you're ready to go. We offer source code for download. Then. Simply email the information to community@mergere. simply locate the appropriate Download link on the page and you can obtain all the source code for the book. go to http://library. On this page you will be able to view all errata that have been submitted for this book and posted by Maven editors. post an update to the book's errata page and fix the problem in subsequent editions of the book. if appropriate. Once at the site.com and locate the title in the title lists.com. click the Book Errata link.
Reuse of build logic .Albert Einstein Better Builds With Maven 15 . Introducing Maven Introducing Maven This chapter covers: An overview of Maven • Maven's objectives • Maven's principles: .Coherent organization of dependencies .Maven's benefits • Things should be made as simple as possible.Declarative execution . .1. but not any simpler.Convention over configuration .
what is it? Here's one attempt at a description: Maven is a set of standards. standards. From compilation. Maven provides the necessary abstractions that encourage reuse and take much of the work out of project builds. to documentation. richer definition of Maven read this introduction. to team collaboration. Too often technologists rely on abstract phrases to capture complex topics in three or four words. distribution. Revolutionary ideas are often difficult to convey with words. and many developers who have approached Maven as another build tool have come away with a finely tuned build system. but the term project management framework is a meaningless abstraction that doesn't do justice to the richness and complexity of Maven. It provides a framework that enables easy reuse of common build logic for all projects following Maven's standards. testing. 1. a framework that greatly simplifies the process of managing a software project. sound-bite answer.1. While you are free to use Maven as "just another build tool". Maven Overview Maven provides a comprehensive approach to managing software projects. to view it in such limited terms is akin to saying that a web browser is nothing more than a tool that reads hypertext. If you are reading this introduction just to find something to tell your manager1. documentation. This book focuses on the core tool produced by the Maven project. Perhaps you picked up this book because someone told you that Maven is a build tool. it will prime you for the concepts that are to follow. and they expect a short. Don't worry. and with repetition phrases such as project management and enterprise software start to lose concrete meaning. they will usually ask "What exactly is Maven?".Introducing Maven 1. a repository format. "Well it is a build tool or a scripting framework" Maven is more than three boring. you can stop reading now and skip to Chapter 2.1. 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. Maven can be the build tool you are looking for. What is Maven? Maven is a project management framework. and a piece of software used to manage and describe projects. You may have been expecting a more straightforward answer. uninspiring words. to distribution. It defines a standard life cycle for building.1. and software. first-order problems such as simplifying builds." Better Builds With Maven 16 . In addition to solving straightforward. If you are interested in a fuller. It simultaneously reduces your headcount and leads to remarkable operational efficiencies. and deploying project artifacts. If Maven isn't a "project management framework". and it is impossible to distill the definition of Maven to simply digested sound-bites. It is a combination of ideas. Maven 2. When someone wants to know what Maven is. Maven also brings with it some compelling second-order benefits. but this doesn't tell you much about Maven. Maven and the technologies related to the Maven project are beginning to have a transformative effect on the Java community. It's the most obvious three-word definition of Maven the authors could come up with. 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). and the deployment process.
If you followed the Maven Way. 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. they would not have to go through this process again when they moved on to the next project. Ultimately. Many people come to Maven familiar with Ant so it's a natural association. The same effect extended to testing. In addition. Using Maven has made it easier to add external dependencies and publish your own components. you will wonder how you ever developed without it. such as Jakarta Commons. and Web site generation. every project at the ASF had a different approach to compilation. Maven is not just a build tool. it becomes easier to build relationships between projects and to build systems that navigate and report on these relationships. Soon after the creation of Maven other projects. The ASF was effectively a series of isolated islands of innovation. but Maven is an entirely different creature from Ant. the barrier to entry for a project with a difficult build system was extremely high. developers were building yet another build system. Prior to Maven. generating metrics and reports. So to answer the original question: Maven is many things to many people. It is the next step in the evolution of how individuals and organizations collaborate to create software systems.1. Maven entered the scene by way of the Turbine project. If developers spent time understanding how one project was built. Maven's standard formats enable a sort of "Semantic Web" for programming projects. and deploying. 1. Instead of focusing on creating good component libraries or MVC frameworks. but different communities were creating different build systems of varied complexity and there was no reuse of build logic between projects.Introducing Maven As more and more projects and products adopt Maven as a foundation for project management. It is a set of standards and an approach as much as it is a piece of software. distribution. predictable way. The build process for Tomcat was different from the build process used by Struts. test. 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. Etc. It is a way of approaching a set of software as a collection of interdependent components which can be described in a common format. and not just a replacement for Ant. People stopped figuring out creative ways to compile. Maven's Origins Maven was borne of the practical desire to make several projects at the Apache Software Foundation (ASF) work in the same. and started focusing on component development. Developers within the Turbine project could freely move between subcomponents. knowing clearly how they all worked just by understanding how one of them worked. generating documentation. the Codehaus community started to adopt Maven 1 as a foundation for project management. There were some common themes to each separate build. Once you get up to speed on the fundamentals of Maven. and package. This lack of a common approach to building software meant that every new project tended to copy and paste another project's build system.2. and it immediately sparked interest as a sort of Rosetta Stone for software project management. Maven's standards and central repository have defined a new naming system for projects. Better Builds With Maven 17 . your project gained a build by default. the Turbine developers used a different approach to site generation than the developers of Jakarta Commons.
install) is effectively delegated to the POM and the appropriate plugins. more reusable. The key value to developers from Maven is that it takes a declarative approach rather than developers creating the build process themselves. if you've learned how to drive a Jeep. and output. Maven provides you with: A comprehensive model for software projects • Tools that interact with this Declarative Model • Better Builds With Maven 18 . However. you can apply it to all projects. Plugins allow developers to call existing Ant scripts and Make files and incorporate those existing functions into the Maven build life cycle. and to retrieve project dependencies from a shared storage area makes the building process much less time consuming. and easier to comprehend. documentation. referred to as "building the build". Make files and Ant are alternatives to Maven. and if you can apply a testing plugin to one project. Much of the project management and build orchestration (compile. Maven's ability to standardize locations for source files. Maven is about the application of patterns in order to facilitate project management through the reuse of common build strategies.1. and you gain access to expertise and best-practices of an entire industry. existing Ant scripts and Make files can be complementary to Maven and used through Maven's plugin architecture. to provide a common layout for project documentation. 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. What Does Maven Provide? It provides a comprehensive model that can be applied to all software projects. Given the highly inter-dependent nature of projects in open source. the car provides a known interface. and much more transparent. and the software tool named Maven is just a secondary side-effect of this model. An individual Maven project's structure and contents are declared in a Project Object Model (POM). 1.Introducing Maven Whereas Ant provides a toolbox for scripting builds. Maven takes a similar approach to software projects: if you can build one Maven project you can build them all. assemble. 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. test. if your project currently relies on an existing Ant build script that must be maintained. more maintainable. You describe your project using Maven's model. Projects and systems that use this standard declarative approach tend to be more transparent. Developers can build any given project without having to understand how the individual plugins work (scripts in the Ant world). Maven provides a common project "language".3. you can easily drive a Camry.
it is improbable that multiple individuals will work productively together on a project.Maven lowers the barrier to reuse not only of build logic but of components. Maintainability . and aesthetically consistent relation of parts." Reusability . When using Maven it is easier to create a component and integrate it into a multi-project build.Maven is built upon a foundation of reuse. Maven projects are more maintainable because they have fewer surprises and follow a common model. home-grown build system.Introducing Maven Organizations and projects that adopt Maven benefit from: • Coherence . When everyone is constantly searching to find all the different bits and pieces that make up a project. • • • Without these characteristics. The definition of this term from the American Heritage dictionary captures the meaning perfectly: "Marked by an orderly. Better Builds With Maven 19 . This is a natural effect when processes don't work the same way for everyone. logical. there is little chance anyone is going to comprehend the project as a whole.Organizations that adopt Maven can stop building the build. and start focusing on the application. When code is not reused it is very hard to create a maintainable system. As a result you end up with a lack of shared knowledge along with the commensurate degree of frustration among team members. It is easier for developers to jump between different projects without a steep learning curve that accompanies a custom. When you adopt Maven you are effectively reusing the best practices of an entire industry. Without visibility it is unlikely one individual will know what another has accomplished and it is likely that useful code will not be reused. Because Maven projects adhere to a standard model they are less opaque.Maven allows organizations to standardize on a set of best practices. Agility .
and I believe that's why it works. Maven's Principles According to Christopher Alexander "patterns help create a shared language for communicating insight and experience about problems and their solutions". but the use of these sensible default strategies is encouraged and should be strayed from only when absolutely necessary. Rails does. 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. sooner. you trade flexibility at the infrastructure level to gain flexibility at the application level. One of those ideals is flexibility. 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. you're rewarded by not having to configure that link. Well. 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. If you follow basic conventions. 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. and better at the application level. The class automatically knows which table to use for persistence. If you are happy to work along the golden path that I've embedded in Rails.2. We have a ton of examples like that. This is not to say that you can't override them. such as classes are singular and tables are plural (a person class relates to a people table). the notion that we should try to accommodate as many approaches as possible. One characteristic of opinionated software is the notion of "convention over configuration". that we shouldn't pass judgment on one form of development over another. you gain an immense reward in terms of productivity that allows you to do more.1. As mentioned earlier Maven creates a sense of structure so that problems can be approached in terms of this structure.2."2 2 O'Reilly interview with DHH Better Builds With Maven 20 . It eschews placing the old ideals of software in a primary position. With Rails. 1. which all add up to make a huge difference in daily use. 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.Introducing Maven 1.
Maven encourages a common arrangement of project content so that once you are familiar with the standard locations. configuration files. If this saves you 30 minutes for each new project you look at. or deploying. It is a very simple idea but it can save you a lot of time. generating documentation. you need to ask yourself if the extra configuration that comes with customization is really worth it. In this case. 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. 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. Standard directory layout for projects The first convention used by Maven is a standard directory layout for project sources. and this is what Maven provides for you. All of these things should simply work. and allows you to create value in your applications faster with less effort. 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. Better Builds With Maven 21 . makes it easier to communicate to others. You can override any of Maven's defaults to create a directory layout of your choosing. project resources. generated output. when you do this. 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. but. even if you only look at a few new projects a year that's time better spent on your application. you will be able to navigate within any Maven project you encounter in the future. you will be able to adapt your project to your customized layout at a cost. increased complexity of your project's POM 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. 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. You don't want to spend time fiddling with building.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. These components are generally referred to as project content. Using standard conventions saves time. You shouldn't need to spend a lot of time getting your development infrastructure functioning. Follow the standard directory layout. and you will make it easier to communicate about your project. he probably doesn't even know what Maven is and wouldn't like if he did because it's not written in Ruby yet!). and documentation.
jar. in a separate JAR file. In this scenario the code contained in each separate project has a different role to play. The intent behind the naming conventions employed by Maven is that you can tell exactly what you are looking at by. extendibility and reusability. a project for the server portion of the application. well. The conventions provide clarity and immediate comprehension. Systems that cannot cope with information rich artifacts like commons-logging-1. If the JAR were named commonslogging.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. It doesn't make much sense to exclude pertinent information when you have it at hand to use.2. Maven pushes you to think clearly about the separation of concerns when setting up your projects because modularity leads to reuse.2 of Commons Logging. the server code. looking at it. Having the utility code in a separate project. This is illustrated in the Coherent Organization of Dependencies section. easy to see manner. is much easier to reuse. Better Builds With Maven 22 . Standard naming conventions The third convention. This is important if there are multiple projects involved. later in this chapter. because the naming convention keeps them separate in a logical. is a standard naming convention for directories and a standard naming convention for the primary output of a project. and they should be separated. but Maven would encourage you to have three separate projects: a project for the client portion of the application. and some shared utility code. a set of conventions really. and a project for the shared utility code. The separation of concerns (SoC) principle states that a given problem involves different kinds of concerns.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. It is immediately obvious that this is version 1. To illustrate this point consider a set of sources for a client/server-based application that contained the client code.2. A simple example of the naming convention might be commons-logging-1. 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.Introducing Maven One primary output per project The second convention used by Maven is the concept of a Maven project producing one primary output. maintainability. which should be identified and separated to cope with complexity and to achieve the required engineering quality factors such as adaptability. You could produce a single JAR file which contained all the compiled classes. It's happened to all of us and it doesn't have to. or concern. If you have placed all the sources together in a single project.
mycompany. test.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. being the observant reader. Better Builds With Maven 23 . 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. Plugins are the key building blocks for everything in Maven.2. will ask how this is possible using a 15 line file. 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. Without POM.2. In Maven there is a plugin for compiling source code. Maven encourages a separation of concerns because it promotes reuse. and the POM is Maven's description of a single project.0. Maven puts this principle into practice by encapsulating build logic into coherent modules called plugins.Introducing Maven 1.the POM is Maven's currency. Maven's project object model (POM) Maven is project-centric by design. 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. You. and the answer lies in Maven's implicit use of its Super POM. One important concept to keep in mind is that everything accomplished in Maven is the result of a plugin executing.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. Reuse of Build Logic As you have already learned.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM will allow you to compile. Maven can be thought of as a framework which coordinates the execution of plugins in a well defined way. It's a very good and essential question in fact. a plugin for running tests.0</modelVersion> <groupId>com. and generate basic documentation. The POM below is an example of what you could use to build and test a project. specifically from the plugin configurations contained in the POM. 1. Maven is useless . and many others. 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).3. a plugin for creating JARs. a plugin for creating Javadocs.8.2.
description .plugins is the designated groupId for all Maven plugins. but still displays the key elements every POM contains. WAR. For a complete reference of the elements available for use in the POM please refer to the POM reference at http://maven. For now. which indicates that a project is in a state of development.).This element indicates the unique base name of the primary artifact being generated by this project.lang. • • url . The POM contains every important piece of information about your project. • version .apache. The version of the model itself changes very infrequently.maven. This not only means that the artifact produced is a JAR.This element indicates the unique identifier of the organization or group that created the project. • groupId . The groupId is one of the key identifiers of a project and is typically based on the fully qualified domain name of your organization. • name . In Java.0. The POM shown above is a very simple POM.org/maven-model/maven. Additional artifacts such as source bundles also use the artifactId as part of their file name.<extension> (for example. and during the build process for your project. myapp-1.Object.This element indicates the display name used for the project. The default value for the packaging element is jar so you do not have to specify this in most cases. but also indicates a specific life cycle to use as part of the build process. The life cycle is a topic dealt with later in the chapter. This is often used in Maven's generated documentation. all objects have the implicit parent of java.apache.This element provides a basic description of your project. and is the analog of the Java language's java. A typical artifact produced by Maven would have the form <artifactId>-<version>. Likewise.This required element indicates the version of the object model this POM is using. in Maven all POMs have an implicit parent which is Maven's Super POM.jar). artifactId .Introducing Maven Maven's Super POM carries with it all the default conventions that Maven encourages. • • project . or other projects that use it as a dependency. Better Builds With Maven 24 . For example org. 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. but it is mandatory in order to ensure stability when Maven introduces new features or other model changes. • • packaging .This element indicates the package type to be used by this artifact (JAR.html. 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. or EAR.xml files. Maven goes a long way to help you with version management and you will often see the SNAPSHOT designator in a version.Object class. just keep in mind that the selected packaging of a project plays a part in customizing the build life cycle. EAR. WAR. modelVersion .This element indicates where the project's site can be found.This element indicates the version of the artifact generated by the project. etc.lang.This is the top-level element in all Maven pom.
Coherent Organization of Dependencies We are now going to delve into how Maven resolves dependencies and discuss the intimately connected concepts of dependencies. The standard build life cycle consists of many phases and these can be thought of as extension points.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. or goals. our example POM has a single dependency listed. For example.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM states that your project has a dependency on JUnit. 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. compilation. or test. related to that phase.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. packaging. which is for Junit: <project> <modelVersion>4. The actions you need to have performed are stated at a high level and Maven deals with the details behind the scenes. In Maven. process-sources. artifacts. which is straightforward. For example. you tell Maven that you want to compile. artifacts. generate-resources. Chapter 2 includes a demonstrates the customization of a Maven build with a Maven plugin. the validate. or install. 1. 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. In "Maven-speak" an artifact is a specific piece of software. If you recall. and compile phases will execute. 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. testing. When you need to add some functionality to the build life cycle you do so with a plugin.4.0. the compile phase invokes a certain set of goals to compile a set of classes. and repositories work.Introducing Maven Maven's build life cycle Software projects generally follow a similar. well-trodden paths: preparation.mycompany. or package. Better Builds With Maven 25 . the build life cycle consists of a series of phases where each phase can perform one or more actions.0</modelVersion> <groupId>com. The path that Maven moves along to accommodate an infinite variety of projects is called the build life cycle. Maven plugins provide reusable build logic that can be slotted into the standard build life cycle. In Maven you do day-to-day work by invoking particular phases in this standard build life cycle.8. installation. generate-sources.2. initialize. and repositories.
With Maven.jar: Better Builds With Maven 26 . or EAR file. artifactId and version. but a Java artifact could also be a WAR. and it supplies these coordinates to its own internal dependency mechanisms.8. you are simply telling Maven what a specific project expects. A dependency is uniquely identified by the following identifiers: groupId.1. If a matching artifact is located.jar. You must have a local repository in order for Maven to work.8.Introducing Maven In Java. By default. for artifacts that match the dependency request. Maven transports it from that remote repository to your local repository for general use.8. When a dependency is declared. grabbing a dependency. the most common artifact is a JAR file. Maven creates your local repository in ~/. Maven tries to satisfy that dependency by looking in all of the remote repositories that are available. 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. Dependency Management is one of the most easily understood and powerful features in Maven. 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. but the key concept is that Maven dependencies are declarative. Maven takes the dependency coordinates you provide in a POM. Maven usually interacts with your local repository. The following folder structure shows the layout of a local Maven repository that has a few locally installed dependency artifacts such as junit-3. we can describe the process of dependency management as Maven reaching out into the world.1 of the junit artifact produced by the junit group. instead you deal with logical dependencies. There is more going on behind the scenes. within the context of your project.m2/repository. SAR. At a basic level. and providing this dependency to your software project. A dependency is a reference to an specific artifact that resides in a repository. Maven needs to know what repository to look in as well as the dependency's coordinates. Your project doesn't require junit-3. you stop focusing on a collection of JAR files.1. Read the following sections for specific details about where Maven searches for these dependencies. it depends on version 3. In order for Maven to attempt to satisfy a dependency. In the POM you are not specifically telling Maven where the dependencies are physically. Maven has two types of repositories: local and remote.
but in practice the repository is a directory structure in your file system. 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.jar artifact that landed in your local repository. We'll stick with our JUnit example and examine the junit-3.1. so you understand how the layout works. Above you can see the directory structure that is created when the JUnit dependency is resolved.8. In theory a repository is just an abstract storage mechanism.
1.ibiblio.8. Maven will attempt to download an artifact from each remote repository in the order defined in your POM.jar. for example. Maven will attempt to find the artifact with a groupId of "junit".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 x. By default. the artifact is downloaded and installed in your local repository. artifactId of "junit". If this file is not present.maven.apache.8. First. Locating dependency artifacts When satisfying dependencies.org/maven2.y. Once the dependency is satisfied. Maven will generate a path to the artifact in your local repository.1/junit-3.1" in ~/. it will be fetched from a remote repository. Maven attempts to locate a dependency's artifact using the following process. If your project's POM contains more than one remote repository.8. Maven will attempt to fetch an artifact from the central Maven repository at http://www. Better Builds With Maven 28 .z 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. and a version of "3.m2/repository/junit/unit/3.
Introducing Maven From this point forward. the common pattern in most project was to store JAR files in a project's subdirectory. Better Builds With Maven 29 . you would check in the 10-20 JAR files your project relies upon into a lib directory. it should rarely. shielding you from complexity and allowing you to focus on your specific task. Each project relies upon a specific artifact via the dependencies listed in a POM.8.2. and they don't deserve to be versioned in an SCM. Using Maven is more than just downloading another JAR file and a set of scripts. in doing so. be a part of your thought process. Maven is a framework. Dependencies are not you projects code. Maven is also a vibrant. a useful technology just works. To summarize. if ever. and you build would add these dependencies to your classpath. and Maven is software. you simply changed some configuration. You don't have to worry about whether or not it's going to work. rather than imposing one. and it is a trivial process to upgrade all of your ten web applications to Spring 2.6 of the Spring Framework. active open-source community that produces software focused on project management. Before Maven. In other words. it is the adoption of processes that allow you to take your software development to the next level. Maven provides such a technology for project management.0 JARs to every project. Instead of having to add the Spring 2. it simplifies the process of development. every project with a POM that references the same dependency will use this single copy installed in your local repository. it doesn't scale easily to support an application with a great number of small components.3.1. in the background.jar for each project that needs it. 1. Maven is a repository. you don't store a copy of junit3. Maven's Benefits A successful technology takes away a burden. Like the engine in your car or the processor in your laptop. you don't have to jump through hoops trying to get it to work. there is no need to store the various spring JAR files in your project. Storing artifacts in your SCM along with your project may seem appealing but it is incompatible with the concept of small. With Maven. If you were coding a web application. all project referencing this dependency share a single copy of this JAR. if your project has ten web applications which all depend on version 1. and. While this approach works for a few project. Declare you dependencies and let Maven take care of details like compilation and testing classpaths. modular project arrangements. Maven is a set of standards. Your local repository is one-stop-shopping for all artifacts that you need regardless of how many projects you are working on.0 by change your dependency declarations.
2. 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. The terrible temptation to tweak should be resisted unless the payoff is really noticeable. . not battalions of special cases.Jon Bentley and Doug McIlroy Better Builds With Maven 30 .
Better Builds With Maven 31 .m2/settings.mycompany. so for now simply assume that the above settings will work.mycompany. If you have not set up Maven yet.mycompany. Depending on where your machine is located.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.xml file with the following content: <settings> <proxies> <proxy> <active>true</active> <protocol>http</protocol> <host>proxy. The settings. it is assumed that you are a first time Maven user and have already set up Maven on your local system. Maven requires network access.Getting Started with Maven 2. <mirrors> <mirror> <id>maven. Now you can perform the following basic check to ensure Maven is working correctly: mvn -version If Maven's version is displayed. then please refer to Maven's Download and Installation Instructions before continuing.1. If you are behind a firewall. Create a <your-home-directory>/. If there is an active Maven proxy running. then note the URL and let Maven know you will be using a 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.xml file.com/maven2</url> <mirrorOf>central</mirrorOf> </mirror> </mirrors> </settings> In its optimal mode. Preparing to Use Maven In this chapter. ask your administrator if there if there is an internal Maven proxy. then you will have to set up Maven to understand that.m2/settings. it may be necessary to make a few more preparations for Maven to function correctly.com</id> <name>My Company's Maven Proxy</name> <url>http://maven.xml file with the following content. create a <your-homedirectory>/. then you should be all set to create your first Maven project. To do this.
Getting Started with Maven 2. 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. which looks like the following: <project> <modelVersion>4. and it in fact adheres to Maven's standard directory layout discussed in Chapter 1. Creating Your First Maven Project To create your first project. An archetype is defined as an original pattern or model from which all other things of the same kind are made.mycompany.0</modelVersion> <groupId>com. but if you would like more information about archetypes. you will use Maven's Archetype mechanism.1</version> <scope>test</scope> </dependency> </dependencies> </project> At the top level of every project is your pom. To create the Quick Start Maven project. First.2.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. In Maven.8.xml file you know you are dealing with a Maven project.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven. execute the following: C:\mvnbook> mvn archetype:create -DgroupId=com.xml.xml file.app \ -DartifactId=my-app You will notice a few things happened when you executed this command. which is combined with some user input to produce a fullyfunctional Maven project. This chapter will show you how the archetype mechanism works. an archetype is a template of a project.mycompany.0. Better Builds With Maven 32 . please refer to the Introduction to Archetypes. Whenever you see a directory structure which contains a pom.apache.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. and this directory contains your pom.
In this first stage you have Java source files only. and so on). testing.Getting Started with Maven Figure 2-1: Directory structure after archetype generation The src directory contains all of the inputs required for building. the site. documenting. Better Builds With Maven 33 . various descriptors such as assembly descriptors. and some test sources. some application sources. and deploying the project (source files. you are ready to build your project. 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.
in one fell swoop. ${basedir}.apache.apache.3. [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. Better Builds With Maven 34 .plugins:maven-resources-plugin: checking for updates from central . 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. 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. [INFO] artifact org. Compiling Application Sources As mentioned in the introduction. Then.plugins:maven-compiler-plugin: checking for updates from central .. Change into the <my-app> directory.maven.. [INFO] [resources:resources] . for the my-app project.Getting Started with Maven 2.. in order to accomplish the desired task. in a declarative way. at a very high level.. you will compile your application sources using the following command: C:\mvnbook\my-app> mvn compile 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. you tell Maven what you need.. The <my-app> directory is the base directory. Before you issue the command to compile the application sources.maven..
override this default location. now you know how Maven finds application sources. As you can see from the output. what Maven uses to compile the application sources. This default value (though not visible in the POM above) was. The standard compiler plugin.Getting Started with 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. by default. of course. 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 . along with its default configuration. The next question is. and how Maven invokes the compiler plugin. Therefore. in fact. The first time you execute this (or any other) command. The next time you execute the same command again. in the first place? You might be guessing that there is some background process that maps a simple command to a particular plugin. In fact. Maven will execute the command much more quickly. If you're a keen observer you'll notice that using the standard conventions makes the POM above very small. So. What actually compiled the application sources? This is where Maven's second principle of "reusable build logic" comes into play. Even the simplest of POMs knows the default location for application sources. The same build logic encapsulated in the compiler plugin will be executed consistently across any number of projects. how was Maven able to decide to use the compiler plugin. it took almost 4 minutes with a broadband connection). is target/classes. The same holds true for the location of the compiled classes which. how was Maven able to retrieve the compiler plugin? After all. if you poke around the standard Maven installation. Maven downloads plugins when they are needed. application sources are placed in src/main/java. You can. you won't find the compiler plugin since it is not shipped with the Maven distribution. if you use the default location for application sources. it won't download anything new. is the tool used to compile your application sources. the compiled classes were placed in target/classes. From a clean installation of Maven this can take quite a while (in the output above. there is a form of mapping and it is called Maven's default build life cycle. Although you now know that the compiler plugin was used to compile the application sources. but there is very little reason to do so. which is specified by the standard directory layout. because Maven already has what it needs. Maven will download all the plugins and related dependencies it needs to fulfill the command. or where your output should go. This means you don't have to state this location at all in any of your POMs. inherited from the Super POM. Instead. By default.
apache.maven.. wink wink*).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 . Failures: 0.. simply tell Maven you want to test your sources.app.. This implies that all prerequisite phases in the life cycle will be performed to ensure that testing will be successful. [INFO] [resources:resources] [INFO] [compiler:compile] [INFO] Nothing to compile . programmers always write and execute their own unit tests *nudge nudge. 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. Errors: 0. Again.AppTest [surefire] Tests run: 1.plugins:maven-surefire-plugin: checking for updates from central . 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 . [INFO] [surefire:test] [INFO] Setting reports dir: C:\Test\Maven2\test\my-app\target/surefire-reports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running com.4. Compiling Test Sources and Running Unit Tests Now that you're successfully compiling your application's sources. Failures: 0.mycompany..Getting Started with Maven 2. you probably have unit tests that you want to compile and execute as well (after all. Time elapsed: 0 sec Results : [surefire] Tests run: 1.
how to package your application. compile the tests. • If you simply want to compile your test sources (but not execute the tests). as well as all the others defined before it. Maven compiles the main code (all these classes are up-to-date.Getting Started with Maven Some things to notice about the output: Maven downloads more dependencies this time. 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 can execute the following command: C:\mvnbook\my-app> mvn test-compile However. and execute the tests. you'll want to move on to the next logical step. Now that you can compile the application sources. mvn test will always run the compile and test-compile phases first. Better Builds With Maven 37 . remember that it isn't necessary to run this every time. • Before compiling and executing the tests. since we haven't changed anything since we compiled last).
Getting Started with Maven 2.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]------------------------------------------------------------------- Better Builds With Maven 38 . Failures: 0.m2/repository is the default location of the repository.0-SNAPSHOT\my-app-1. Failures: 0. Errors: 0 [INFO] [jar:jar] [INFO] Building jar: <dir>/my-app/target/my-app-1.jar [INFO] [install:install] [INFO] Installing c:\mvnbook\my-app\target\my-app-1. This is how Maven knows to produce a JAR file from the above command (you'll read more about this later). It can then be used by other projects as a dependency. Time elapsed: 0. execute the following command: C:\mvnbook\my-app> mvn install 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. To install.0-SNAPSHOT.jar to <localrepository>\com\mycompany\app\my-app\1. The directory <your-homedirectory>/.5.0-SNAPSHOT.001 sec Results : [surefire] Tests run: 1.you will notice the packaging element is set to jar.0-SNAPSHOT. Now.app. you'll want to install the artifact (the JAR file) you've generated into your local repository.AppTest [surefire] Tests run: 1. Take a look in the the target directory and you will see the generated JAR file. Errors: 0. 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.mycompany.
By default. given Maven's re-usable build logic? With even the simplest POM. for example: C:\mvnbook\my-app> mvn clean This will remove the target directory with the old build data before starting. and installing a typical Maven project. this covers the majority of tasks users perform. so it is fresh. alternatively you might like to generate an Eclipse descriptor: C:\mvnbook\my-app> mvn eclipse:eclipse Better Builds With Maven 39 . For projects that are built with Maven. Of course. if you're pressed for time and just need to create a basic Web site for your project. you must keep making error-prone additions. So. packaging.java • **/Test*. This chapter will cover one in particular.java **/Abstract*TestCase.Getting Started with Maven Note that the Surefire plugin (which executes the test) looks for tests contained in files with a particular naming convention. it will update the settings rather than starting fresh.java • Conversely. In this case. testing. the following tests are excluded: • • **/Abstract*Test.java • **/*TestCase. Without any work on your part. as it is one of the highly-prized features in Maven. In contrast. and if you've noticed. as it currently stands. Or. 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. building. this POM has enough information to generate a Web site for your project! Though you will typically want to customize your Maven site. there is far more functionality available to you from Maven without requiring any additions to the POM. there are a great number of Maven plugins that work out of the box. what other functionality can you leverage.java You have now completed the process for setting up. 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. everything done up to this point has been driven by an 18-line POM. the following tests are included: **/*Test. to get any more functionality out of an Ant build script.
is the packaging of resources into a JAR file. you need to add the directory src/main/resources.Getting Started with Maven 2. starting at the base of the JAR. 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. Maven again uses the standard directory layout. This means that by adopting Maven's standard conventions. simply by placing those resources in a standard directory structure. you can package resources within JARs. Handling Classpath Resources Another common use case which requires no changes to the POM shown previously.6. In the example following. 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. If you unpacked the JAR that Maven created you would see the following: Better Builds With Maven 40 . For this common task. That is where you place any resources you wish to package in the JAR.properties file within that directory.
properties file is there in the META-INF directory.6. At this point you have a project directory structure that should look like the following: Better Builds With Maven 41 .properties file. Handling Test Classpath Resources To add resources to the classpath for your unit tests.xml and pom. Operating on the POM file would require you to use Maven utilities. as well as a pom. but the properties can be utilized using the standard Java APIs. should the need arise.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. You will also notice some other files there like META-INF/MANIFEST.xml and pom. but Maven will generate one by default if you don't.MF. These come standard with the creation of a JAR in Maven. except place resources in the src/test/resources directory. You can create your own manifest if you choose. One simple use might be to retrieve the version of your application. The pom.1. 2.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. follow the same pattern as you do for adding resources to the JAR.
] // Retrieve resource InputStream is = getClass(). Filtering Classpath Resources Sometimes a resource file will need to contain a value that can be supplied at build time.xml. simply set filtering to true for the resource directory in your pom. only. you could use a simple snippet of code like the following for access to the resource required for testing: [. To have Maven filter resources when copying.Getting Started with Maven Figure 2-4: Directory structure after adding test resources In a unit test.xml. a value defined in the user's settings..properties" ). // Do something with the resource [... To accomplish this in Maven.xml: <project> Better Builds With Maven 42 . or a system property.6. put a reference to the property that will contain the value into your resource file using the syntax ${<property name>}.getResourceAsStream( "/test. The property can be either one of the values defined in your pom.] 2.. a property defined in an external properties file.2.
properties file.name=${project.apache. and ${project.1</version> <scope>test</scope> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> </project> You'll notice that the build.version=${project.version} With that in place.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. resources. ${project. this information had to be added to the pom. To continue the example.finalName} refers to the final name of the file created. To override the default value for filtering and set it to true. To reference a property defined in your pom. whose values will be supplied when the resource is filtered as follows: # application.build.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven. So ${project.0</modelVersion> <groupId>com.properties application. In addition. you can execute the following command (process-resources is the build life cycle phase where the resources are copied and filtered): mvn process-resources Better Builds With Maven 43 .name} refers to the name of the project. In fact. create an src/main/resources/application.8.mycompany. which weren't there before. the property name uses the names of the XML elements that define the value.name} application.version} refers to the version of the project. any element in your POM is available when filtering resources.xml.xml.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. the POM has to explicitly state that the resources are located in the src/main/resources directory. and resource elements have been added. when the built project is packaged.Getting Started with Maven <modelVersion>4.0. All of this information was previously provided as default values.
properties</filter> </filters> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> [.properties file under target/classes.xml and you'd get the same effect (notice you don't need the references to src/main/filters/filter..version=1.properties file as follows: # application..properties application.value} The next execution of the mvn process-resources command will put the new property value into application. As an alternative to defining the my.] <build> <filters> <filter>src/main/filters/filter. create an external properties file and call it src/main/filters/filter.Getting Started with Maven The application.filter. First.value property in an external file.name=Maven Quick Start Archetype application.. you could have defined it in the properties section of your pom.xml.] Then.version} message=${my. which will eventually go into the JAR looks like this: # application. add a reference to this property in the application.name} application.properties either): Better Builds With Maven 44 .properties.properties application.filter..filter.0-SNAPSHOT To reference a property defined in an external file. all you need to do is add a reference to this external file in your pom. add a reference to this new file in the pom.version=${project.properties: # filter.xml file: [.properties my.name=${project.value=hello! Next.
value> </properties> </project> Filtering resources can also retrieve values from system properties.line.apache.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. with filtering disabled.version} command.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven. when you execute the following command (note the definition of the command.filter. The build element would look like the following: Better Builds With Maven 45 .0.version=${java. If you had a src/main/resources/images that you didn't want to be filtered.home).filter. the application. but you do not want them filtered.line. This is most often the case with binary resources.version or user. then you would create one resource entry that handled the filtering of resources with an exclusion on the resources you wanted unfiltered.prop=hello again" 2.prop=${command.properties file will contain the values from the system properties.prop property on the command line).properties file to look like the following: # application.6.1</version> <scope>test</scope> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> <properties> <my.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. In addition you would add another resource entry. Preventing Filtering of Binary Resources Sometimes there are classpath resources that you want included in your JAR.properties java. or properties defined on the command line using the standard Java -D parameter.line.value>hello</my. and an inclusion of your images directory.line.8. for example image files. To continue the example.0</modelVersion> <groupId>com. change the application.Getting Started with Maven <project> <modelVersion>4. either the system properties built into Java (like java.mycompany.prop} Now.3. mvn process-resources "-Dcommand.
For example..5</source> <target>1.7.Getting Started with Maven <project> . </project> 2. Using Maven Plugins As noted earlier in the chapter..0</version> <configuration> <source>1. you may want to configure the Java compiler to allow JDK 5. or configure parameters for the plugins already included in the build... Better Builds With Maven 46 . you must include additional Maven plugins.. To illustrate the similarity between plugins and dependencies.0 sources.5</target> </configuration> </plugin> </plugins> </build> .maven. but in most cases these elements are not required.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2. This is as simple as adding this following to your POM: <project> . to customize the build for a Maven project. the groupId and version elements have been shown. in much the same way that a dependency would be handled. This plugin will be downloaded and installed automatically.and in some ways they are. if it is not present on your local system... <build> <plugins> <plugin> <groupId>org. <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> </include> </resource> </resources> </build> .apache.. </project> You'll notice that all plugins in Maven 2 look very similar to a dependency.
you can lock down a specific version. you have gained access to every single project uses Maven.apache. the compiler plugin is already used as part of the build process and this just changes the configuration. You might need to refer to the next chapter for more information about customizing your build to fit your project's unique needs.apache. If you want to see the options for the maven-compiler-plugin shown previously.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. test.maven. or settings. In seventeen pages. read on. You can specify an additional groupId to search within your POM. but if you find something has changed . you've seen how you can use Maven to build your project. The next few chapters provide you with the tools to customize Maven's behavior and use Maven to manage interdependent software projects. The chapter focused on Maven as a concrete build tool. you would know enough to compile. then Maven will default to looking for the plugin with the org.8.codehaus. If someone throws a Maven project at you. 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.xml. Better Builds With Maven 47 . This is often the most convenient way to use a plugin. If you want to find out what the plugin's configuration options are.Getting Started with Maven If you do not specify a groupId. The configuration element applies the given parameters to every goal from the compiler plugin.maven. You've learned a new language and you've taken Maven for a test drive. use the mvn help:describe command.mojo groupId label. If you do not specify a version then Maven will attempt to use the latest released version of the specified plugin. In the above case. you'll know how to exercise the basic features of Maven: creating a project. compiling a project.apache. If someone gave you a project using Maven tomorrow. For the most part. By learning how to build a Maven project. and build it.plugins or the org. it laid a good foundation for the rest of this book.org/plugins/ and navigating to the plugin and goal you are using. and packaging a project. plugin developers take care to ensure that new versions of plugins are backward compatible so you are usually OK with the latest release. you should be up and running with Maven. testing a project. you could safely stop reading this book now. If you are interested in learning how Maven builds upon the concepts introduced in the Introduction and the practical tools introduced in Chapter 2. and if you were just looking for a build tool. 2. but you may want to specify the version of a plugin to ensure reproducibility. Summary After reading this chapter.
Edward V. . Berard Better Builds With Maven 48 .3. 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.
• Proficio API: The application programming interface for Proficio. which is Latin for "help". Proficio has a very simple memory-based store and a simple XStream-based store. are discrete and coherent components. Setting Up an Application Directory Structure In setting up the directory structure for Proficio. These are default naming conventions that Maven uses. using a real-world example. encapsulate. 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 49 . The only real criterion to which to adhere is that your team has a single convention. which consists of a set of interfaces. goal. The natural outcome of this practice. which consists of all the classes that will be used by Proficio as a whole. The guiding principle in determining how best to decompose your application is called the Separation of Concerns (SoC). which enables code reusability. Introduction In the second chapter you stepped though the basics of setting up a simple project. and modular builds. but you are free to name your modules in any fashion your team decides. • Proficio Stores: The module which itself houses all the store modules. or purpose. 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). lets start by discussing the ideal directory structure for Proficio. As such. task. The interfaces for the APIs of major components. The application that you are going to create is called Proficio. In examining the top-level POM for Proficio. Now you will delve in a little deeper. Concerns are the primary motivation for organizing and decomposing software into smaller. it is important to keep in mind that Maven emphasizes the practice of discrete. you can see in the modules element all the modules that make up the Proficio application. and can easily identify what a particular module does simply by looking at its name.1. and operate on the pieces of software that are relevant to a particular concept. coherent. So. • • Proficio CLI: The code which provides a command line interface to Proficio. and they it clearly understands that convention. A module is a reference to another Maven project. 3.Creating Applications with Maven 3. you will see that the Proficio sample application is made up of several modules: Proficio Model: The data model for the Proficio application. each of which addresses one or more concerns. • Proficio Core: The implementation of the API. which really means a reference to another POM. more manageable and comprehensible parts. In doing so you will be guided through the specifics of setting up an application and managing that structure.2. like the store. a necessary goal for every software development project. are also kept here. In this chapter. SoC refers to the ability to identify.
0</modelVersion> <groupId>org. In Maven 1.. 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 50 .x documentation. </project> An important feature to note in the POM above is the value of the version element.0-SNAPSHOT.0. You should take note of the packaging element.. which has a value of pom.Creating Applications with Maven <project> <modelVersion>4. 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..org</url> . 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.maven.0-SNAPSHOT</version> <name>Maven Proficio</name> <url>http://maven.apache.proficio</groupId> <artifactId>proficio</artifactId> <packaging>pom</packaging> <version>1.apache. which you can see is 1. For POMs that contain modules..x these were commonly referred to as multi-project builds and some of this vestigial terminology carried over to the Maven 2. 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. <modules> <module>proficio-model</module> <module>proficio-api</module> <module>proficio-core</module> <module>proficio-stores</module> </modules> . but the Maven team is now trying to consistently refer to these setups as multimodule builds. Currently there is some variance on the Maven web site when referring to directory structures that contain more then one Maven project.
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 51 .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. but the interesting thing here is that we have a another project with a packaging type of pom. Looking at the module names is how Maven steps into the right directory to process the POM located there.0-SNAPSHOT</version> </parent> <modelVersion>4. 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.proficio</groupId> <artifactId>proficio</artifactId> <version>1.apache. which is the proficio-stores module.0. 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.maven.
This is the snippet in each of the POMs that lets you draw on the resources stated in the specified top-level POM and from which you can inherit down to any level you wish . 3...enabling you to add resources where it makes sense in the hierarchy of your projects.. Let's examine a case where it makes sense to put a resource in the top-level POM. just as has been done with Proficio's multiple storage mechanisms. Using Project Inheritance One of the most powerful features in Maven is project inheritance. note specifically there is no visible dependency declaration for JUnit: Better Builds With Maven 52 . in any of your child POMs. you will see that in the dependencies section there is a declaration for JUnit version 3.1.. The dependency is stated as following: <project> .. So. If you look at the top-level POM for Proficio. if you take a look at the POM for the proficio-core module you will see the following. state your deployment information. In this case the assumption being made is that JUnit will be used for testing in all our child projects. which are all placed in one directory. You can nest sets of projects like this to any level.apache. you never have to declare this dependency again. So. <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. 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: .0-SNAPSHOT</version> </parent> .3. by stating the dependency in the top-level POM once. or state your common dependencies . using our the top-level POM for the sample Proficio application. </project> What specifically happens for each child POM..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... organizing your projects in groups according to concern.maven. <parent> <groupId>org.proficio</groupId> <artifactId>proficio</artifactId> <version>1.8.all in a single place. Being the observant user. is that each one inherits the dependencies section of the top-level POM.1</version> <scope>test</scope> </dependency> </dependencies> .8. Using project inheritance allows you to do things like state your organizational information.
maven. So in this case..apache.Creating Applications with Maven <project> <parent> <groupId>org.8.codehaus.1 dependency: <project> . </project> You will have noticed that the POM that you see when using the mvn help:effective-pom is bigger then you expected. But remember from Chapter 2 that the Super POM sits at the top of the inheritance hierarchy. the proficio-core project inherits from the toplevel Proficio project. <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. <dependencies> .8...0</modelVersion> <artifactId>proficio-core</artifactId> <packaging>jar</packaging> <name>Maven Proficio Core</name> <dependencies> <dependency> <groupId>org..apache.proficio</groupId> <artifactId>proficio</artifactId> <version>1. </dependencies> . After you move into the proficio-core module and run the command.. Better Builds With Maven 53 ... which in turn inherits from the Super POM. take a look at the resulting POM you will see the JUnit version 3. 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..0.0-SNAPSHOT</version> </parent> <modelVersion>4.maven.1</version> <scope>test</scope> </dependency> . This command will show you the final result for a target POM.proficio</groupId> <artifactId>proficio-api</artifactId> </dependency> <dependency> <groupId>org.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.
plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1. Managing Dependencies When you are building applications you have many dependencies to manage and the number of dependencies only increases over time. Better Builds With Maven 54 . you use the dependency management section in the top-level POM of an application. versions of dependencies across several projects. for example. To illustrate how this mechanism works. as the results can be far from desirable.. to end up with multiple versions of a dependency on the classpath when your application executes. making dependency management difficult to say the least.4. You want to make sure that all the versions. which is the application version.version} specification is the version specified by the top-level POM's version element. or align.maven..0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> . individual projects.version}</version> </dependency> <dependency> <groupId>org. In order to manage. You don't want. <dependencyManagement> <dependencies> <dependency> <groupId>org. let's look at the dependency management section of the Proficio top-level POM: <project> . Maven's strategy for dealing with this problem is to combine the power of project inheritance with specific dependency management elements in the POM.proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project.maven.version}</version> </dependency> <dependency> <groupId>org..Creating Applications with Maven 3. it is likely that some of those projects will share common dependencies. When you write applications which consist of multiple. so that the final application works correctly.codehaus.version}</version> </dependency> <dependency> <groupId>org.. across all of your projects are in alignment so that your testing accurately reflects what you will deploy as your final result.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project.proficio</groupId> <artifactId>proficio-core</artifactId> <version>${project.apache. </project> Note that the ${project.apache.apache.maven. When this happens it is critical that the same version of a given dependency is used for all your projects. of all your dependencies.
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.. to make it complete. Better Builds With Maven 55 .apache. you will see a single dependency declaration and that it does not specify a version: <project> . whereas the top-level dependencies element does affect the dependency graph. <dependencies> <dependency> <groupId>org..version}) for proficio-model so that version is injected into the dependency above. 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.maven. The dependencies stated in the dependencyManagement only come into play when a dependency is declared without a version. If you take a look at the POM for the proficio-api module. 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. The dependencyManagement declares a stated preference for the 1.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.0-SNAPSHOT (stated as ${project.
.. By default Maven will look for snapshots on a daily basis.0-SNAPSHOT</version> <dependencyManagement> <dependencies> <dependency> <groupId>org.proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project.0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> .maven. If you look at the top-level POM for Proficio you will see a snapshot version specified: <project> .plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1.apache.. Using Snapshots While you are developing an application with multiple modules. Your build system needs to be able to easily deal with this real-time flux. but you can use the -U command line option to force the search for updates.. Snapshot dependencies are assumed to be changing. </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. or you may be doing some refactoring.codehaus.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project.maven. When you specify a non-snapshot version of a dependency Maven will download that dependency once and never attempt to retrieve it again. A snapshot in Maven is an artifact which has been prepared using the most recent sources available.version}</version> </dependency> <dependency> <groupId>org. Your APIs might be undergoing some change or your implementations are undergoing change and are being fleshed out.5.version}</version> </dependency> <dependency> <groupId>org.apache. <version>1. so Maven will attempt to update them. and this is where Maven's concept of a snapshot comes into play. it is usually the case that each of the modules are in flux.Creating Applications with Maven 3. Controlling how snapshots work will be explained in detail in Chapter 7. Better Builds With Maven 56 .
it is inevitable that two or more artifacts will require different versions of a particular dependency. However. the version selected is the one declared "nearest" to the top of the tree .8.0-alpha-9 (selected for compile) plexus-utils:1. Maven must choose which version to provide. to compile. you can remove the incorrect version from the tree.1 (selected for test) plexus-container-default:1.Creating Applications with Maven 3. this has limitations: The version chosen may not have all the features required by the other dependency. you can exclude the dependency from the graph by adding an exclusion to the dependency that introduced it.. the output will contain something similar to: proficio-core:1.1-alpha-2 (selected for compile) junit:3. modify the plexus-container-default dependency in the proficio-core/pom.8. • If multiple versions are selected at the same depth. and more importantly ways to avoid it as the author of a reusable library.1 (selected for compile) Once the path to the version has been identified. However.0-SNAPSHOT (selected for compile) plexus-utils:1. or you can override both with the correct version. the least number of dependencies that were traversed to get this version. To ensure this.that is. as the graph grows. A dependency in the POM being built will be used over anything else. To manually resolve conflicts. then the result is undefined.xml file as follows: Better Builds With Maven 57 . In this case. and Proficio requires version 1. 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. plexus-utils occurs twice.. Resolving Dependency Conflicts and Using Version Ranges With the introduction of transitive dependencies in Maven 2.0-SNAPSHOT junit:3. In Maven 2.4 (selected for compile) classworlds:1. if you run mvn -X test on the proficio-core module. and to allow Maven to calculate the full dependency graph.0. see section 6.0.1 (not setting.6. it became possible to simplify your own POM by only including the dependencies you need directly. For example.1 be used. local scope test wins) proficio-api:1. In this example. • While further dependency management features are scheduled for the next release of Maven at the time of writing.0-SNAPSHOT (selected for compile) proficio-model:1. there are ways to manually resolve these conflicts as the end user of a dependency.9 in Chapter 6).
Creating Applications with Maven . the dependency should be specified as follows: Better Builds With Maven 58 . not for compilation. a WAR file). so that the 1. that will be used widely by others. When a version is declared as 1.4 version of plexus-utils in the dependency graph.. the dependency is used only for packaging. The reason for this is that it distorts the true dependency graph..codehaus.. Maven has no knowledge about what versions will definitely work. You'll notice here that the runtime scope is used. for stability it would always be declared in the current POM as a dependency .1. you may require a feature that was introduced in plexus-utils version 1...1. so in the case of a conflict with another dependency.codehaus.1 version is used instead. Maven assumes that all versions are valid and uses the "nearest dependency" technique described previously to determine which version to use.0.1. In this case. Neither of these solutions are ideal. which will accumulate if this project is reused as a dependency itself. This is because in this situation.regardless of whether another dependency introduces it..plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1. However. is to include it directly in the POM. as follows: . However. This is achieved using version ranges instead. 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.codehaus.. as shown above for plexus-utils.plexus</groupId> <artifactId>plexus-utils</artifactId> </exclusion> </exclusions> </dependency> .0-alpha-9</version> <exclusions> <exclusion> <groupId>org. In fact.plexus</groupId> <artifactId>plexus-utils</artifactId> <version>1.1</version> <scope>runtime</scope> </dependency> </dependencies> . This ensures that Maven ignores the 1.. The alternate way to ensure that a particular version of a dependency is used. <dependencies> <dependency> <groupId>org. but that other versions may be acceptable. <dependency> <groupId>org. this indicates that the preferred version of the dependency is 1. This is extremely important if you are publishing a build. 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. for a library or framework. if it were required for compilation.
If the nearest version does not match.0] [22.214.171.124.Creating Applications with Maven <dependency> <groupId>org. To understand how ranges work. 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. Finally. and table 3-2 shows some of the values that can be used.2 and 1. It is intended that the qualifier indicates a version prior to release (for example.plexus</groupId> <artifactId>plexus-utils</artifactId> <version>[1.).codehaus. but less than 2. Figure 3-3: Version parsing As you can see. while the nearest dependency technique will still be used in the case of a conflict.0 Greater than or equal to 1. the version you are left with is [1. You can see how a version is partitioned by Maven in figure 3-1.0 Between 1.1. In the current version scheme.1. and so on. then the next nearest will be tested.1. Better Builds With Maven 59 .5. that is greater than or equal to 1.1 By being more specific through the use of version ranges.) (. Table 3-2: Examples of version ranges Range Meaning (. The notation used above is set notation.0. if none of them match. or only the build number. This means that the latest version. you also need to avoid being too specific.0.)</version> </dependency> What this means is that.2. minor and bug fix releases. you can provide only the qualifier.1. beta-1.3] [1.) Less than or equal to 1. the version that is used must fit the range given. the build will fail. However.5 Any version. If two ranges in a dependency graph do not intersect at all. In a regular version. the snapshot (as shown above) is a special case where the qualifier and build number are both allowed. a version is broken down into five parts: the major.1. or there were no conflicts originally.1). alpha-1. except 1. then the qualifier and finally a build number.0) [1. will be retrieved from the repository. rc1). it is necessary to understand how versions are compared.(1. while the build number is an increment after release to indicate patched builds.3 (inclusive) Greater than or equal to 1.
and finally. However. it means that the version is older than if the qualifier didn't. second .Creating Applications with Maven With regard to ordering. the ranges do not differentiate.7. the updatePolicy value is changed for releases.2-beta-1 will be selected. and the versions 1. or forced from the command line using the -U option for a particular Maven execution.2-beta-1 exist. by build number. 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 60 .by minor version. which is actually Maven's default build life cycle. the repository is checked once a day for updates to the versions of artifacts in use. all projects have different requirements and it is sometimes necessary to augment the life cycle to satisfy these requirements. or release betas as milestones along the way. you should deploy them to a snapshot repository as is discussed in Chapter 7 of this book. which binds itself to a standard phase in Maven's default life cycle. then 1.first by major version..). Maven accommodates this requirement by allowing the declaration of a plugin. <releases> <updatePolicy>interval:60</updatePolicy> </releases> </repository> 3. This will ensure that the beta versions are used in a range only if the project has declared the snapshot (or development) repository explicitly. the elements are considered in sequence to determine which is greater . By default. For example. If it will be configured for a particular repository. through the use of a separate repository. the two versions are compared entirely as strings. the Modello plugin is used to generate the Java sources for Proficio's data model. In some cases. Conversely.. so to avoid such a situation. Often this is not desired. if the build number exists. this can be configured perrepository to be on a more regular interval. <repository> . which means the plugin is bound to a specific phase in the default life cycle. If a qualifier exists. you must structure your releases accordingly.1.if the major versions were equal . fourth by qualifier (using string comparison). 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. This mechanism is identical to that of the snapshots that you learned in section 3. Maven's default build life cycle will suffice for a great number of projects without any augmentation but. Whether you use snapshots until the final release. Proficio has a requirement to generate Java sources from a model. the versions will not match this syntax. A final note relates to how version updates are determined when a range is in use. typically. if you use the range [1. For example: . Plugins in Maven are created with a specific task in mind.1 and 1. the generate-sources phase. third by bug fix version..6. that is considered newer than if it doesn't.. of course. In Proficio. In those case. So. Because all of these elements are considered part of the version.
0-SNAPSHOT</version> </parent> <modelVersion>4.0</modelVersion> <artifactId>proficio-model</artifactId> <packaging>jar</packaging> <name>Proficio Model</name> <build> <plugins> <plugin> <groupId>org. testing. or referencing the local file system. A plugin in Maven may have several goals. building with different JVMs. but here you see an additional executions element. Profiles modify the POM at build time. testing with different databases.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.maven. and can be activated in several ways. 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.Creating Applications with Maven <project> <parent> <groupId>org. Better Builds With Maven 61 . Profiles are specified using a subset of the elements available in the POM itself (plus one extra section). and production environments).apache. the path of the application server root in the development.modello</groupId> <artifactId>modello-maven-plugin</artifactId> <version>1.8. but sometimes you simply have to take into consideration variation across systems and this is why profiles were introduced in Maven.0-alpha-5</version> <executions> <execution> <goals> <goal>java</goal> </goals> </execution> </executions> <configuration> <version>1.codehaus.0. so you need to specify which goal in the plugin you wish to run.0. for example.proficio</groupId> <artifactId>proficio</artifactId> <version>1. 3.0</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. by specifying the goal in the executions element. Typically you try to encapsulate as much as possible in the POM to ensure that builds are portable.
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. • <profiles> <profile> <id>profile1</id> .xml file as well. For example: <settings> . When this option is specified.xml • The POM itself • In any of the above three profile sites.m2/settings. but used behind the scenes) modules reporting dependencyManagement distributionManagement A subset of the build element. </settings> Better Builds With Maven 62 ..Creating Applications with Maven As such. used properly. </profile> </profiles> <activeProfiles> <activeProfile>profile1</activeProfile> </activeProfiles> . no profiles other than those specified in the option argument will be activated..xml) • A file in the the same directory as the POM. 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. profiles can easily lead to differing build results from different members of your team. each containing a profile-id.profile2 install Profiles can be activated in the Maven settings. called profiles.. Note that you must have defined the profiles in your settings. you can define the following elements: • • • • • • • • • repositories pluginRepositories dependencies plugins properties (not actually available in the main POM. However. via the activeProfiles section. This section takes a list of activeProfile elements. For example: mvn -Pprofile1. This option takes an argument that contains a comma-delimited list of profile-ids..
4")... <profile> <id>profile1</id> .Creating Applications with Maven • Profiles can be triggered automatically based on the detected state of the build environment. Now that you are familiar with profiles. <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". Currently. These activators are specified via an activation section in the profile itself.2_07".4.4</jdk> </activation> </profile> This activator will trigger the profile when the JDK's version starts with "1. this detection is limited to prefix-matching of the JDK version.. or the value of a system property. Here are some examples: <profile> <id>profile1</id> . 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. the presence of a system property.... 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.4" (eg. Better Builds With Maven 63 .0_08". "1.4. <activation> <jdk>1. <activation> <property> <name>debug</name> </property> </activation> </profile> This will activate the profile when the system property "debug" is specified with any value. "1. "1. <profile> <id>profile1</id> .
<!-.xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>memory</name> </property> </activation> </profile> <!-.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..xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>xstream</name> </property> </activation> </profile> </profiles> </project> Better Builds With Maven 64 .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.Creating Applications with Maven If you take a look at the POM for the proficio-cli module you will see the profile definitions: <project> .Profiles for the two assemblies to create for deployment --> <profiles> <!-..
Better Builds With Maven 65 . 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.jar file.0-SNAPSHOT. 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. You will also notice that the profiles are activated using a system property.jar file and the XStream-based store only contains the proficio-store-xstream-1.0-SNAPSHOT.Creating Applications with Maven You can see there are two profiles: one with an id of memory and another with an id of xstream. In each of these profiles you are configuring the assembly plugin to point at the assembly descriptor that will create a tailored assembly.
and external SSH deployment.. which would typically be your top-level POM so that all child POMs can inherit this information.yourcompany.. FTP deployment. you'll want to share it with as many people as possible! So. </project> Better Builds With Maven 66 . <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scp://sshserver.. Deploying with SSH2 To deploy to an SSH2 server you would use something like the following: <project> . SFTP deployment. Deploying to the File System To deploy to the file system you would use something like the following: <project> . it is now time to deploy your application assembly.10. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>file://${basedir}/target/deploy</url> </repository> </distributionManagement> ... Currently Maven supports several methods of deployment include simple file-based deployment. In order to deploy you need to correctly configure your distributionManagement element in your POM. </project> 3.9.9. Here are some examples of how to configure your POM via the various deployment mechanisms...com/deploy</url> </repository> </distributionManagement> . Deploying your Application Now that you have an application assembly. SSH2 deployment. 3.1..Creating Applications with Maven 3.
.Creating Applications with Maven 3.apache.wagon</groupId> <artifactId>wagon-ssh-external</artifactId> <version>1..yourcompany. <project> .11. but also a build extension. the first three methods illustrated are included with Maven.com/deploy</url> </repository> </distributionManagement> <build> <extensions> <extension> <groupId>org.. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scpexe://sshserver.0-alpha-6</version> </extension> </extensions> </build> . </project> The build extension specifies the use of the Wagon external SSH provider. Deploying with SFTP To deploy to an SFTP server you would use something like the following: <project> .maven.11.yourcompany. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>sftp://ftpserver. but to use an external SSH command to deploy you must configure not only the distributionManagment element. </project> 3.1....com/deploy</url> </repository> </distributionManagement> ... which does the work of moving your files to the remote server. so only the distributionManagement element is required. Wagon is the general purpose transport mechanism used throughout Maven. Better Builds With Maven 67 . Deploying with an External SSH Now.
Creating Applications with Maven
3.11.2. Deploying with FTP
To deploy with FTP you must also specify a build extension. To deploy to an FTP server you would use something like the following:
<project> ... <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>ftp://ftpserver.yourcompany.com/deploy</url> </repository> </distributionManagement> <build> <extensions> <extension> <groupId>org.apache.maven.wagon</groupId> <artifactId>wagon-ftp</artifactId> <version>1.0-alpha-6</version> </extension> </extensions> </build> ... </project>
Once you have configured your POM accordingly, and you are ready to initiate deployment, simply execute the following command:
mvn deploy
3.12. Creating a Web Site for your Application
Now that you have walked though the process of building, testing and deploying Proficio, it is time for you to see how a standard web site is created for an application. 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 go generate the web site. If you take a look you will see that we have something similarly the following:
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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. 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. Maven supports a number of different documentation formats to accommodate various needs and preferences. Currently the most well supported formats available are: The XDOC format, which is a simple XML format used widely at Apache. • The APT format (Almost Plain Text), which is a wiki-like format that allows you to write simple, structured documents (like this) very quickly. A full reference of the APT Format is available. • The FML format, which is the FAQ format. A simple XML format for managing FAQs. • The DocBook Simple format, which is a less complex version of the full DocBook format.
Maven also has limited support for: The Twiki format, which is a popular Wiki markup format. • The Confluence format, which is another popular Wiki markup format. • The DocBook format.
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We will look at a few of the more well supported formats further on in the chapter, 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 the generate 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.apache.org/</href> </bannerLeft> <bannerRight> <name>Proficio</name> <src>http://maven.apache.org/images/apache-maven project.png</src> </bannerRight> <skin> <groupId>org.apache.maven.skins</groupId> <artifactId>maven-default-skin</artifactId> <version>1.0-SNAPSHOT</version> </skin> <publishDate format="dd MMM yyyy" /> <body> <links> <item name="Apache" href="http://www.apache.org/"/> <item name="Maven" href="http://maven.apache.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.html"/> </menu> <menu name="About Proficio"> <item name="What is Proficio?" href="/what-is-maven.html"/> </menu> ${reports} </body> </project>
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Creating Applications with Maven
This is a fairly standard site descriptor, 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, href and optional src element, which can be used for images. 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 format of the publish date is that of the SimpleDateFormat class in Java. The link elements control the references that are displayed below the banner and take a simple name and href. The head element allows you to insert anything in the head element of generated pages. You may wish to add metadata, 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. You can have any number of menu items each containing any number of links. The inclusion of the ${reports} reference controls whether the project reports are displayed in the web site. You might exclude ${reports} reference for a site that consists purely of user documentation for example.
One of the most popular features of Maven are the standard reports that can be produced with little effort. If you simply include the ${reports} reference in your site descriptor you will, by default, have the standard project information reports generated and displayed automatically for you. The standard project information reports consist of the following:
• • • • • • •
Dependencies Report Mailing Lists Report Continous Integration Report Source Repository Report Issue Tracking Report Project Team Report License
Even though the standard reports are very useful, often you will want to customize the projects reports that are created and displayed in your web site. The reports created and displayed are controlled in the build/reports element in the POM. 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. You do so by configuring the plugin as follows:
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<project> ... <reporting> ... <plugins> <plugin> <groupId>org.apache.maven.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> ... <reporting> ... </project>
Now that you have a good grasp on what formats are supported, how the site descriptor works, and how to configure reports it's time for you to generate the site. You can do so by executing the following command: mvn site
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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 73 .
13. how to make small modifications to Maven's build life cycle. and how to create a simple Web site for your application. 3. 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. augmenting your site to view quality metrics. how to manage your application's dependencies. You should now have a grasp of how project inheritance works. Better Builds With Maven 74 .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. and using Maven in a collaborative environment. 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. Keeping in mind this simple rule you can add any resources you wish to your site. 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.
EAR.4. WAR. . 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.Helen Keller Better Builds With Maven 75 . Building J2EE Applications Building J2EE Applications This chapter covers: • • • • • Organizing the directory structure Building J2EE archives (EJB.
and it's architecture is shown in Figure . Introduction J2EE (or Java EE as it is now called) applications are everywhere. Its goal is to serve as both a functional example of a full-stack J2EE 1.1. As importantly. you'll learn how to build EARs.4 application and as a test bed for running performance tests. Through this example. This chapter demonstrates how to use Maven on a real application to show how to address the complex issues related to automated builds.Building J2EE Applications 4. 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. Web services. Whether you are using the full J2EE stack with EJBs or only using Web applications with frameworks such as Spring or Hibernate. As a consequence the Maven community has developed plugins to cover every aspect of building J2EE applications. This chapter will take you through the journey of creating the build for a full-fledged J2EE application called DayTrader. EJBs. 4. you'll learn how to automate configuration and deployment of J2EE application servers. it's likely that you are using J2EE in some of your projects. and Web applications. Introducing the DayTrader Application DayTrader is a real world application developed by IBM and then donated to the Apache Geronimo project.2. The functional goal of the DayTrader application is to buy and sell stock. Figure 4-1: Architecture of the DayTrader application Better Builds With Maven 76 .
logout. The creation of the "open" order is confirmed for the user. The Trade Broker calls the Trade Session bean which in turn calls the CMP entity beans to mark the order as "completed". This request is handled by the Trade Session bean. Once this happens the Trade Broker MDB is notified 6.Quote and AccountProfile). 5.Building J2EE Applications There are 4 layers in the architecture: • The Client layer offers 3 ways to access the application: using a browser. and so on. and using the Quote Streamer. • • • A typical "buy stock" use case consists of the following steps that were shown in Figure : 1. get a stock quote. The user gives a buy order (by using the Web client or the Web services client). Asynchronously the order that was placed on the queue is processed and the purchase completed. Better Builds With Maven 77 . It uses container-managed persistence (CMP) entity beans for storing the business objects (Order. The Web layer offers a view of the application for both the Web client and the Web services client. The Trade Session is a stateless session bean that offers the business services such as login. The user is notified of the completed order on a subsequent request. using Web services. buy or sell a stock. cancel an order. 2. 3. The Data layer consists of a database used for storing the business objects and the status of each purchase. and a JMS Server for interacting with the outside world. The Quote Streamer is a Swing GUI application that monitors quote information about stocks in real-time as the price changes. 4. A new "open" order is saved in the database using the CMP Entity Beans. and Message-Driven Beans (MDB) to send purchase orders and get quote changes. It uses servlets and JSPs. The EJB layer is where the business logic is. The order is then queued for processing in the JMS Message Server. Account. Holding.
Let's discuss the pros and cons of each layout.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. Better Builds With Maven 78 . a WAR which will contain the Web application. Thus you simply need to figure out what artifacts you need. The next step is to give these modules names and map them to a directory structure. a JAR that will contain the Quote Streamer client application. it is usually easier to choose names that represent a technology instead. As a general rule.Building J2EE Applications 4. 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.the module containing the EJBs web .the module containing the client side streamer application wsappclient . In addition you may need another module producing an EAR which will contain the EJB and WAR produced from the other modules. Organizing the DayTrader Directory Structure The first step to organizing the directory structure is deciding what build modules are required. This EAR will be used to easily deploy the server code into a J2EE container. If there isn't a strong need you may find that managing several modules can be more cumbersome than useful. another JAR that will contain the Web services client application. it is important to split the modules when it is appropriate for flexibility.3. For example. For example. For the DayTrader application the following names were chosen: • • • • • ejb .the module containing the Web application streamer . However. Looking again at Figure you can see that the following modules will be needed: A module producing • A module producing • A module producing • A module producing • an EJB which will contain all of the server-side EJBs.the module containing the Web services client application ear . if you needed to physically locate the WARs in separate servlet containers to distribute the load. The easy answer is to follow Maven's artifact guideline: one module = one main artifact. Best practices suggest to do this only when the need arises. It is flat because you're locating all the modules in the same directory. On the other hand. Figure 4-2 shows these modules in a flat directory structure. It is possible to come up with more. Note that this is the minimal number of modules required.
. and is the structure used in this chapter. for more details): [.Building J2EE Applications Figure 4-2: Module names and a simple flat directory structure The top-level daytrader/pom.xml file contains the POM elements that are shared between all of the modules. Figure 4-3: Modules split according to a server-side vs client-side directory organization As before. if you have many modules in the same directory you may consider finding commonalities between them and create subdirectories to partition them. each directory level containing several modules contains a pom. Note that in this case the modules are still separate. For example. not nested within each other. you might separate the client side modules from the server side modules in the way shown in Figure 4-3.] This is the easiest and most flexible structure to use...] <modules> <module>ejb</module> <module>web</module> <module>streamer</module> <module>wsappclient</module> <module>ear</module> </modules> [. Better Builds With Maven 79 .. However. Creating Applications with Maven. This file also contains the list of modules that Maven will build when executed from this directory (see the Chapter 3.xml file containing the shared POM elements and the list of modules underneath.
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. Having this nested structure clearly shows how nested modules are linked to their parent. the ejb and web modules are nested in the ear module. as shown in Figure 4-4. This makes sense as the EAR artifact is composed of the EJB and WAR artifacts produced by the ejb and web modules. In those cases using a nested directory structure should be avoided. but then you'll be restricted in several ways. but by some client-side application. A flat layout is more neutral with regard to assembly and should thus be preferred. the ejb or web modules might depend on a utility JAR and this JAR may be also required for some other EAR. In this case. The Assembler has a pool of modules and its role is to package those modules for deployment. Figure 4-4: Nested directory structure for the EAR. Or the ejb module might be producing a client EJB JAR which is not used by the EAR. 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. In addition. Now that you have decided on the directory structure for the DayTrader application. 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. EAR project).Building J2EE Applications The other alternative is to use a nested directory structure. You'd need to consider the three modules as one project. • It doesn't allow flexible packaging. etc. EJB and Web modules However. EJB project. For example. even though the nested directory structure seems to work quite well here. • These examples show that there are times when there is not a clear parent for a module. For example. starting with the EJB module.
xml. the standard ejb-jar.xml deployment descriptor is in src/main/resources/META-INF/ejb-jar. Tests that require the container to run are called integration tests and are covered at the end of this chapter. Figure 4-5: Directory structure for the DayTrader ejb module Figure 4-5 shows a canonical directory structure for EJB projects: Runtime Java source code in src/main/java. Better Builds With Maven 81 . • Runtime classpath resources in c.4.Building J2EE Applications 4. Any container-specific deployment descriptor should also be placed in this directory. More specifically. • • 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. Building an EJB Project Let's create a build for the ejb module.
geronimo.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.geronimo.xml file. you're extending a parent POM using the parent element.0</modelVersion> <parent> <groupId>org.xml file: <project> <modelVersion>4.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1.apache.class</clientExclude> </clientExcludes> </configuration> </plugin> </plugins> </build> </project> As you can see.0.maven.specs</groupId> <artifactId>geronimo-j2ee_1. Now run maven -N install in daytrader/ in order to install the parent POM in your local repository and make it available to all modules when you build them: Better Builds With Maven 82 .3</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.0.apache.Building J2EE Applications Now.samples. take a look at the content of this project's pom.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean. This is because the DayTrader build is a multi-module build and you are gathering common POM elements in a parent daytrader/pom.4_spec</artifactId> <version>1.apache.
**/*Session. By default the EJB plugin does not generate the client JAR. the pom..apache.Building J2EE Applications C:\dev\m2book\code\j2ee\daytrader>mvn -N install [INFO] Scanning for projects. You should note that you're using a provided scope instead of the default compile scope.. Better Builds With Maven 83 . Even though this dependency is provided at runtime. it still needs to be listed in the POM so that the code can be compiled.xml contains a configuration to tell the Maven EJB plugin to generate a Client EJB JAR file when mvn install is called. However. [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. You make this clear to Maven by using the provided scope.]\. The reason is that this dependency will already be present in the environment (being the J2EE application server) where your EJB will execute. • Lastly.0. 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.pom The ejb/pom.maven.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean. so you must explicitly tell it to do so: <plugin> <groupId>org. You could instead specify a dependency on Sun's J2EE JAR. 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.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.class. this prevents the EAR module from including the J2EE JAR when it is packaged.0\daytrad er-1. **/*CMP. This is achieved by specifying a dependency element on the J2EE JAR.xml to C:\[.m2\repository\org\apache\geronimo\samples\daytrader\daytrader\1.html. Fortunately.class. the Geronimo project has made the J2EE JAR available under an Apache license and this JAR can be found on ibiblio. The Client will be used in a later examples when building the web module.class and **/package..
0-client [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.apache.jar to C:\[.0.class). Relax and type mvn install: C:\dev\m2book\code\j2ee\daytrader\ejb>mvn install [INFO] Scanning for projects. Failures: 0.FinancialUtilsTest [surefire] Tests run: 1. 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..samples. Failures: 0.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ejb\1. Time elapsed: 0.geronimo.0\daytrader-ejb-1.jar [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1. [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..jar [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1. You're now ready to execute the build.0-client.0.]\.0.0 [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.jar [INFO] Building ejb client daytrader-ejb-1. [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.Building J2EE Applications In this example.jar to C:\[.daytrader. 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. Errors: 0 [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1.0-client. Note that it's also possible to specify a list of files to include using clientInclude elements.0-client. Errors: 0.class pattern and which need to be present in the generated client EJB JAR.. [INFO] ----------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [install] [INFO] ----------------------------------------------------------[INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources.]\.02 sec Results : [surefire] Tests run: 1.jar Better Builds With Maven 84 .m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ejb\1....0\daytrader-ejb-1.
org/plugins/maven-ejb-plugin/. When writing EJBs it means you simply have to write your EJB implementation class and XDoclet will generate the Home interface. you can run the XDoclet processor to generate those files for you. the container-specific deployment descriptors. Using XDoclet is easy: by adding Javadoc annotations to your classes.Building J2EE Applications Maven has created both the EJB JAR and the client EJB JAR and installed them in your local Maven repository. Note that if you're an EJB3 user. you can safely skip this section – you won't need it! Better Builds With Maven 85 . Early adopters of EJB3 may be interested to know how Maven supports EJB3.apache. The EJB plugin has several other configuration elements that you can use to suit your exact needs. and the ejb-jar. There is a working prototype of an EJB3 Maven plugin. Please refer to the EJB plugin documentation on http://maven. 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. the Remote and Local interfaces.xml descriptor.5. the EJB3 specification is still not final. however in the future it will be added to the main EJB plugin after the specification is finalized. Stay tuned! 4. At the time of writing.
the project's directory structure is the same as in Figure 4-5.ejb.geronimo.JMSException.daytrader.home * generate="remote" * remote-class= * "org.jms.Building J2EE Applications Here's an extract of the TradeBean session EJB using Xdoclet: /** * Trade Session EJB manages all Trading services * * @ejb. create a copy of the DayTrader ejb module called ejb-xdoclet.interface-method * view-type="remote" * @ejb.apache.ejb.samples.ejb.xml file anymore as it's going to be generated by Xdoclet. but you don't need the ejb-jar.daytrader.geronimo.geronimo.apache. Exception […] To demonstrate XDoclet.samples. As you can see in Figure 4-6.apache.Trade" * […] */ public class TradeBean implements SessionBean { […] /** * Queue the Order identified by orderID to be processed in a * One Phase commit […] * * @ejb.daytrader.TradeHome" * @ejb. Figure 4-6: Directory structure for the DayTrader ejb module when using Xdoclet Better Builds With Maven 86 .transaction * type="RequiresNew" *[…] */ public void queueOrderOnePhase(Integer orderID) throws javax.bean * display-name="TradeEJB" * name="TradeEJB" * view-type="remote" * impl-class-name= * "org.samples.TradeBean" * @ejb.interface * generate="remote" * remote-class= * "org.
This is achieved by using the Maven XDoclet plugin and binding it to the generate-sources life cycle phase. Better Builds With Maven 87 .directory}/generated-sources/xdoclet (you can configure this using the generatedSourcesDirectory configuration element). in the tasks element you use the ejbdoclet Ant task provided by the XDoclet project (for reference documentation see http://xdoclet. but here the need is to use the ejbdoclet task to instrument the EJB class files.build.java classes and remove all of the Home. Local and Remote interfaces as they'll also get generated. This is required by Maven to bind the xdoclet goal to a phase.directory}/generated-sources/xdoclet"> <fileset dir="${project.sourceDirectory}"> <include name="**/*Bean. Here's the portion of the pom.sourceforge.html).java"></include> <include name="**/*MDB.java"></include> </fileset> <homeinterface/> <remoteinterface/> <localhomeinterface/> <localinterface/> <deploymentdescriptor destDir="${project.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.outputDirectory}/META-INF"/> </ejbdoclet> </tasks> </configuration> </execution> </executions> </plugin> The XDoclet plugin is configured within an execution element. The plugin generates sources by default in ${project. In practice you can use any XDoclet task (or more generally any Ant task) within the tasks element.build.1" destDir= "${project.build.build. 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. this has to be run before the compilation phase occurs.Building J2EE Applications The other difference is that you only need to keep the *Bean.xml that configures the plugin: <plugin> <groupId>org.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. Since XDoclet generates source files. Finally. It also tells Maven that this directory contains sources that will need to be compiled when the compile phase executes. Now you need to tell Maven to run XDoclet on your project.codehaus.
daytrader.apache.codehaus.apache.samples.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.XDocletMain start INFO: Running <deploymentdescriptor/> Generating EJB deployment descriptor (ejb-jar. It's based on a new architecture but the tag syntax is backwardcompatible in most cases.samples. There's also a Maven 2 plugin for XDoclet2 at http://xdoclet. 2006 16:53:50 xdoclet.0 […] You might also want to try XDoclet2.apache.daytrader.geronimo. […] 10 janv.AccountBean'.xml). […] 10 janv.samples.ejb. However.daytrader.ejb.daytrader. 2006 16:53:51 xdoclet.samples.XDocletMain start INFO: Running <localinterface/> Generating Local interface for 'org.TradeBean'.ejb.TradeBean'.geronimo. 2006 16:53:51 xdoclet.XDocletMain start INFO: Running <homeinterface/> Generating Home interface for 'org.ejb.apache. […] INFO: Running <remoteinterface/> Generating Remote interface for 'org. 2006 16:53:50 xdoclet.geronimo.geronimo.org/Maven2+Plugin. Better Builds With Maven 88 . 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. […] 10 janv. […] [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1.AccountBean'.XDocletMain start INFO: Running <localhomeinterface/> Generating Local Home interface for 'org.
In order to build this project you need to create a Profile where you define the ${installDir} property's value.directory}/cargo. you will also learn how to test it automatically. Netbeans.org/Debugging for full details.build..sourceforge. stopping. Later.. configuring them and deploying modules to them.log</log> [. you can use the log element to specify a file where Cargo logs will go and you can also use the output element to specify a file where the container's output will be dumped. In the container element you tell the Cargo plugin that you want to use JBoss 4. you will need to have Maven start the container automatically.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <zipUrlInstaller> <url>http://internap. First. It offers generic APIs (Java. Maven 2.log</output> <log>${project. the JBoss container will be used.0. Cargo is a framework for manipulating containers.6.] <plugin> <groupId>org. IntelliJ IDEA.. To do so you're going to use the Maven plugin for Cargo. Deploying EJBs Now that you know how to build an EJB project. Ant.x (containerId element) and that you want Cargo to download the JBoss 4. Let's discover how you can automatically start a container and deploy your EJBs into it.2.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> </plugin> </plugins> </build> If you want to debug Cargo's execution. Maven 1.) for performing various actions on containers such as starting.net/ sourceforge/jboss/jboss-4. For example: <container> <containerId>jboss4x</containerId> <output>${project.codehaus.xml file and add the following Cargo plugin configuration: <build> <plugins> [.] See http://cargo.2 distribution from the specified URL and install it in ${installDir}. in the Testing J2EE Applications section of this chapter. you will learn how to deploy it. etc.. In this example.directory}/jboss4x.dl. Better Builds With Maven 89 .codehaus. Edit the ejb/pom.Building J2EE Applications 4.0. The location where Cargo should install JBoss is a user-dependent choice and this is why the ${installDir} property was introduced.build.
Thus the best place is to create a profiles. so run mvn package to generate it.2 starting.xml file defines a profile named vmassol.0.0.xml file.2</home> That's all you need to have a working build and to deploy the EJB JAR into JBoss..2] [INFO] [talledLocalContainer] JBoss 4. activated by default and in which the ${installDir} property points to c:/apps/cargo-installs.Building J2EE Applications As explained in Chapter 3. In this case. [INFO] ----------------------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [cargo:start] [INFO] ----------------------------------------------------------------------[INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4.0. you can define a profile in the POM. in a settings. The Cargo plugin does all the work: it provides a default JBoss configuration (using port 8080 for example).xml file. Better Builds With Maven 90 .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. as the content of the Profile is user-dependent you wouldn't want to define it in the POM.0.2 started on port [8080] [INFO] Press Ctrl-C to stop the container. In that case replace the zipURLInstaller element with a home element. in a profiles.... the EJB JAR should first be created. It's also possible to tell Cargo that you already have JBoss installed locally. and the EJB JAR has been deployed. 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.xml file... Of course. [INFO] Searching repository for plugin with prefix: 'cargo'. That's it! JBoss is running. [INFO] [talledLocalContainer] JBoss 4. Nor should the content be shared with other Maven projects at large. For example: <home>c:/apps/jboss-4. or in a settings. it detects that the Maven project is producing an EJB from the packaging element and it automatically deploys it when the container is started.
Building a Web Application Project Now. except that there is an additional src/main/webapp directory for locating Web application resources such as HTML pages.org/Maven2+plugin. Subsequent calls will be fast as Cargo will not download JBoss again. the first time you execute cargo:start it will take some time. Figure 4-7: Directory structure for the DayTrader web module showing some Web application resources Better Builds With Maven 91 . etc. to stop the container call mvn cargo:stop. especially if you are on a slow connection. Finally.Building J2EE Applications As you have told Cargo to download and install JBoss. modifying various container parameters. Cargo has many other configuration options such as the possibility of using an existing container installation. JSPs. The layout is the same as for a JAR module (see the first two chapters of this book). deploying on a remote machine. WEB-INF configuration files. you would run the cargo:deploy goal. let's focus on building the DayTrader web module. and more. (see Figure 4-7). Check the documentation at http://cargo.7. If the container was already started and you wanted to just deploy the EJB. 4.codehaus.
apache.0</version> </parent> <artifactId>daytrader-web</artifactId> <name>DayTrader :: Web Application</name> <packaging>war</packaging> <description>DayTrader Web</description> <dependencies> <dependency> <groupId>org. This is why you told the EJB plugin to generate a client JAR earlier on in ejb/pom.xml.0</modelVersion> <parent> <groupId>org.0.0</version> <type>ejb-client</type> </dependency> Note that you're specifying a type of ejb-client and not ejb.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1.geronimo.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1. then the WAR you generate will be overlaid with the Better Builds With Maven 92 . It's always cleaner to depend on the minimum set of required classes. Depending on the main EJB JAR would also work.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1. The reason you are building this web module after the ejb module is because the web module's servlets call the EJBs.Building J2EE Applications As usual everything is specified in the pom. Therefore.samples. If you add a dependency on a WAR.geronimo.geronimo. the servlets only need the EJB client JAR in their classpath to be able to call the EJBs.xml: <dependency> <groupId>org.apache. Therefore. This is because the servlets are a client of the EJBs.xml file: <project> <modelVersion>4. but it's not necessary and would increase the size of the WAR file. for example to prevent coupling.samples.apache. you specify the required dependencies.apache.4_spec</artifactId> <version>1.0</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.specs</groupId> <artifactId>geronimo-j2ee_1.geronimo. you need to add a dependency on the ejb module in web/pom.samples.0</version> <type>ejb-client</type> </dependency> <dependency> <groupId>org.
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. As seen in the introduction.war Better Builds With Maven 93 .war [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.0..0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. allowing the aggregation of multiple WAR files. it recursively adds your module's dependencies.codehaus.org/Merging+WAR+files). Maven 2 supports transitive dependencies.xml file and reduces maintenance.]\. and files such as web.m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-web\1. When it generates your WAR.0. Otherwise it would have surfaced in the WEB-INF/lib directory of the generated WAR.war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.xml won't be merged..0. An alternative is to use the uberwar goal from the Cargo Maven Plugin (see http://cargo.. Running mvn install generates the WAR and installs it in your local repository: C:\dev\m2book\code\j2ee\daytrader\web>mvn install [.0. Again. it's a good practice to use the default conventions as much as possible. As you know.war to C:\[. the Geronimo J2EE specifications JAR is used with a provided scope (as seen previously when building the EJB). [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. only files not in the existing Web application will be added.Building J2EE Applications content of that dependent WAR. The configuration is very simple because the defaults from the WAR plugin are being used. as it reduces the size of the pom.. However.] [INFO] [war:war] [INFO] Exploding webapp..0\daytrader-web-1.xml. This is why we defined the J2EE JAR using a provided scope in the web module's pom. The final dependency listed is the J2EE JAR as your web module uses servlets and calls EJBs.
xml Location of Web application resources to include in the WAR. Better Builds With Maven 94 . Specify the files to include/exclude from the generated WAR.apache.finalName} For the full list.org/plugins/maven-war-plugin/.xml file. see the reference documentation for the WAR plugin at http://maven.build.Building J2EE Applications Table 4-1 lists some other parameters of the WAR plugin that you may wish to configure.xml file found in ${warSourceDirectory}/WEBINF/web. Name of the generated WAR. Table 4-1: WAR plugin configuration properties Configuration property Default value Description warSourceDirectory webXml ${basedir}/src/main/webapp The web. warSourceIncludes/war All files are included SourceExcludes warName ${project. Specify where to find the web.
the project dependencies and the compiled classes and classpath resources in target/classes. Thus any recompilation in your IDE will trigger a redeploy of your Web application in Jetty.0</version> <scope>provided</scope> </dependency> </dependencies> </plugin> […] The scanIntervalSeconds configuration property tells the plugin to monitor for changes every 10 seconds.4_spec</artifactId> <version>1.jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> <scanIntervalSeconds>10</scanIntervalSeconds> </configuration> <dependencies> <dependency> <groupId>org. the web. Add the following to the web/pom.geronimo. JSP or servlet code.xml file.Building J2EE Applications 4. The plugin is configured by default to look for resource files in src/main/webapp.xml file: […] <build> <plugins> <plugin> <groupId>org. Since the Web application earlier declared that the specification must be provided through the provided scope. The Jetty6 plugin creates a custom Jetty 6 configuration that is wired to your source tree.apache. Let's try the Jetty6 plugin on the DayTrader web module. the src/main/webapp tree. 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. There are two plugins that can alleviate this problem: the Cargo plugin and the Jetty6 plugin. Fortunately. the plugin reloads the Web application in Jetty.xml file. If any change is detected. Maven can help. 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). and it adds the compiled classes in target/classes to its execution classpath. adding this dependency to the plugin adds it to the classpath for Jetty.mortbay.specs</groupId> <artifactId>geronimo-j2ee_1. The plugin monitors the source tree for changes.8. You execute the Jetty6 plugin by typing mvn jetty6:run: Better Builds With Maven 95 . providing an extremely fast turnaround time for development. 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. including the pom. 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.
SimpleLogger@1242b11 via org.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.Started SelectChannelConnector @ 0.. [INFO] No connectors configured. As you can see.0:8080 [INFO] Starting scanner at interval of 10 seconds. [INFO] Finished setting up classpath [INFO] Started configuring web.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 .0.mortbay.0. using defaults: org. Open a browser with the http://localhost:8080/daytrader-web/register. Maven pauses as Jetty is now started. Figure 4-8: DayTrader JSP registration page served by the Jetty6 plugin Better Builds With Maven 96 . resource base= C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Finished configuring web.xml 681 [main] INFO org.log.mortbay. Your Web application has been deployed and the plugin is waiting.log .slf4j.impl.. listening for changes.jsp URL as shown in Figure 4-8 to see the Web application running..SelectChannelConnector listening on 8080 with maxIdleTime 30000 0 [main] INFO org.mortbay.Slf4jLog [INFO] Context path = /daytrader-web [INFO] Webapp directory = C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Setting up classpath .xml file located at: C:\dev\m2book\code\j2ee\daytrader\ web\src\main\webapp\WEB-INF\web.xml.mortbay.log .Logging to org.nio.jetty..
The reason is that we have only deployed the Web application here.properties. but the EJBs and all the back end code has not been deployed. In order to make it work you'd need to have your EJB container started with the DayTrader code deployed in it.jsp. For example if you wanted to run Jetty on port 9090 with a user realm defined in etc/realm. isn't it? What happened is that the Jetty6 plugin realized the page was changed and it redeployed the Web application automatically. The Jetty container automatically recompiled the JSP when the page was refreshed. Edit web/src/main/webapp/register. 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 4-9: Figure 4-9: Modified registration page automatically reflecting our source change That's nifty.Building J2EE Applications Note that the application will fail if you open a page that calls EJBs. Now let's try to modify the content of this JSP by changing the opening account balance. In practice it's easier to deploy a full EAR as you'll see below. you would use: Better Builds With Maven 97 . There are various configuration parameters available for the Jetty6 plugin such as the ability to define Connectors and Security realms.
mortbay.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. Calling this goal ensures that the generated Web application is the correct one.xml and pom.nio.jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> […] <connectors> <connector implementation= "org.jetty.mortbay. Then it deploys the unpacked Web application located in target/ (whereas the jetty6:run-war goal deploys the WAR file). It's also possible to pass in a jetty.xml.html.jetty. The plugin then watches the following files: WEB-INF/lib. possibly generating some files. In that case anything in the jetty. and so on.Building J2EE Applications <plugin> <groupId>org. Better Builds With Maven 98 .mortbay. any change to those files results in a hot redeployment.xml configuration file using the jettyConfig configuration element. Fortunately there's a solution. 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.HashUserRealm"> <name>Test Realm</name> <config>etc/realm.security. By default the plugin uses the module's artifactId from the POM. WEB-INF/web. WEB-INF/classes.mortbay. for example) or when the pom.SelectChannelConnector"> <port>9090</port> <maxIdleTime>60000</maxIdleTime> </connector> </connectors> <userRealms> <userRealm implementation= "org. The Jetty6 plugin also contains two goals that can be used in this situation: • etty6:run-war: The plugin first runs the package phase which generates the WAR file.xml file is modified. For a reference of all configuration options see the Jetty6 plugin documentation at http://jetty. • jetty6:run-exploded: The plugin runs the package phase as with the jetty6:run-war goal. that you have custom plugins that do all sorts of transformations to Web application resource files.org/jetty6/mavenplugin/index.xml file will be applied first. 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. Now imagine that you have an awfully complex Web application generation process. The WAR plugin has an exploded goal which produces an expanded Web application in the target directory.
. No more excuses! Better Builds With Maven 99 .0.slf4j.. Listeners completed.0 [INFO] Assembling webapp daytrader-web in C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.... 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 . Restart completed..mortbay. Restarting webapp ...Logging to org..0... Stopping webapp . 0 [main] INFO org.Slf4jLog [INFO] Context path = /daytrader-web 2214 [main] INFO org..0.Started SelectChannelConnector @ 0.impl.mortbay...war [INFO] [jetty6:run-exploded] [INFO] Configuring Jetty for project: DayTrader :: Web Application [INFO] Starting Jetty Server . [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.] [INFO] [war:war] [INFO] Exploding webapp.Building J2EE Applications To demonstrate.log.. Reconfiguring webapp ..0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1. Scanning .SimpleLogger@78bc3b via org. You're now ready for productive web development.0:8080 [INFO] Scanning .0. execute mvn jetty6:run-exploded goal on the web module: C:\dev\m2book\code\j2ee\daytrader\web>mvn jetty6:run-exploded [.log . [INFO] Scan complete at Wed Feb 15 11:59:00 CET 2006 [INFO] Starting scanner at interval of 10 seconds.war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1...log .mortbay. As you can see the WAR is first assembled in the target directory and the Jetty plugin is now waiting for changes to happen.
Thus.codehaus. As seen in the Deploying EJBs section the installDir property is user-dependent and should be defined in a profiles. This is very useful when you're developing an application and you want to verify it works on several containers. A cargo.port element has been introduced to show how to configure the containers to start on port 8280 instead of the default 8080 port.xml file. This is very useful if you have containers already running your machine and you don't want to interfere with them. However. Deploying Web Applications You have already seen how to deploy a Web application for in-place Web development in the previous section. so now the focus will be on deploying a packaged WAR to your target container.servlet. edit the web module's pom.xml file: Better Builds With Maven 100 . Those properties will be defined in a Profile.codehaus. the containerId and url properties should be shared for all users of the build.port>8280</cargo.servlet.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.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>${containerId}</containerId> <zipUrlInstaller> <url>${url}</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <configuration> <properties> <cargo.xml file and add the Cargo configuration: <plugin> <groupId>org.servlet. First. add the following profiles to the web/pom. There are two differences though: • • Two new properties have been introduced (containerId and url) in order to make this build snippet generic.Building J2EE Applications 4. This example uses the Cargo Maven plugin to deploy to any container supported by Cargo (see http://cargo.org/Containers).9.
..0. starts the JBoss container and deploys the WAR into it: C:\dev\m2book\code\j2ee\daytrader\web>mvn install cargo:start [.0.30/bin/ jakarta-tomcat-5.0..Building J2EE Applications [. [INFO] [CopyingLocalDeployer] Deploying [C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.org/dist/jakarta/tomcat-5/v5..2] [INFO] [talledLocalContainer] JBoss 4.war] to [C:\[.30 started on port [8280] [INFO] Press Ctrl-C to stop the container..0.]\Temp\cargo\50866\webapps]. Executing mvn install cargo:start generates the WAR.] </build> <profiles> <profile> <id>jboss4x</id> <activation> <activeByDefault>true</activeByDefault> </activation> <properties> <containerId>jboss4x</containerId> <url>http://ovh.zip</url> </properties> </profile> <profile> <id>tomcat5x</id> <properties> <containerId>tomcat5x</containerId> <url>http://www... You could add as many profiles as there are containers you want to execute your Web application on. [INFO] [talledLocalContainer] JBoss 4.0..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).. [INFO] [talledLocalContainer] Tomcat 5..2.30 starting.net/sourceforge/jboss/jboss4.0.2 started on port [8280] [INFO] Press Ctrl-C to stop the container. Better Builds With Maven 101 ....sourceforge.0...2 starting.30..apache.0...0.] [INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4.] [INFO] [cargo:start] [INFO] [talledLocalContainer] Tomcat 5. 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 [.dl.
remote.Building J2EE Applications This is useful for development and to test that your code deploys and works.hostname>${remoteServer}</cargo. the changes are: A remote container and configuration type to tell Cargo that the container is remote and not under Cargo's management. Better Builds With Maven 102 .remote.remote.username> <cargo. • Check the Cargo reference documentation for all details on deployments at http://cargo.username>${remoteUsername}</cargo. Let's now discover how to build Web services modules.hostname> <cargo.servlet. One solution is to have your container running on that integration platform and to perform a remote deployment of your WAR to it.xml: <plugin> <groupId>org. • 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>${remotePort}</cargo. All the properties introduced need to be declared inside the POM for those shared with other users and in the profiles.password> </properties> </configuration> </configuration> </plugin> When compared to the configuration for a local deployment above.servlet.xml file (or the settings.xml file) for those user-dependent.codehaus.org/Deploying+to+a+running+container.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <type>remote</type> </container> <configuration> <type>runtime</type> <properties> <cargo. once this is verified you'll want a solution to deploy your WAR into an integration platform.codehaus.port> <cargo. At this stage you have learned how to build and deploy EJBs and WARs. Note that there was no need to specify a deployment URL as it is computed automatically by Cargo. To deploy the DayTrader's WAR to a running JBoss server on machine remoteserver and executing on port 80. However.remote. you would need the following Cargo plugin configuration in web/pom.password>${remotePassword}</cargo.
see http://ws.10. the WSDL files are in src/main/wsdl. Axis generates the following: Table 4-2: 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 plugin uses the Axis framework (http://ws. As the name suggests.org/axis/java/).html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL.org/axis/java/userguide. and this will be used from DayTrader's wsappclient module. which is the default used by the Axis Tools plugin: Figure 4-10: Directory structure of the wsappclient module Better Builds With Maven 103 . As you may notice. and Maven's ability to integrate toolkits can make them easier to add to the build process. Figure 4-10 shows the directory structure of the wsappclient module. For example.Building J2EE Applications 4. the Maven plugin called Axis Tools plugin takes WSDL files and generates the Java files needed to interact with the Web services it defines. Building a Web Services Client Project Web services are a part of many J2EE applications.apache.apache.
codehaus..Building J2EE Applications The location of WSDL source can be customized using the sourceDirectory property. the wsappclient/pom.mojo</groupId> <artifactId>axistools-maven-plugin</artifactId> <configuration> <sourceDirectory> src/main/resources/META-INF/wsdl </sourceDirectory> </configuration> [.] <plugin> <groupId>org.xml file must declare and configure the Axis Tools plugin: <project> [.. it allows users of your project to automatically get the dependency transitively.wsdl file. This is because after the sources are generated.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.] In order to generate the Java source files from the TradeServices. At this point f you were to execute the build.] <build> <plugins> [. it would fail.... Similarly. you will require a dependency on Axis and Axis JAXRPC in your pom..xml.codehaus. Better Builds With Maven 104 .. and more importantly. While you might expect the Axis Tools plugin to define this for you.] <plugin> <groupId>org. 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. For example: [.. any tools that report on the POM will be able to recognize the dependency.
Better Builds With Maven 105 . they are not present on ibiblio and you'll need to install them manually.4_spec</artifactId> <version>1.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>axis</groupId> <artifactId>axis-jaxrpc</artifactId> <version>1.apache. you need to add the J2EE specifications JAR to compile the project's Java sources. Thus add the following two dependencies to your POM: <dependencies> <dependency> <groupId>axis</groupId> <artifactId>axis</artifactId> <version>1.Building J2EE Applications As before.geronimo. Run mvn install and Maven will fail and print the installation instructions.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.0</version> <scope>provided</scope> </dependency> </dependencies> The Axis JAR depends on the Mail and Activation Sun JARs which cannot be redistributed by Maven.specs</groupId> <artifactId>geronimo-j2ee_1. Thus.
.] Note that the daytrader-wsappclient JAR now includes the class files compiled from the generated source files..0.0.jar [... The Axis Tools plugin boasts several other goals including java2wsdl that is useful for generating the server-side WSDL file from handcrafted Java classes.wsdl [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources. But that's another story. [INFO] [compiler:testCompile] [INFO] No sources to compile [INFO] [surefire:test] [INFO] No tests to run.] [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. [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. Better Builds With Maven 106 ...0\daytrader-wsappclient-1.jar [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1.]\.. [INFO] [jar:jar] [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1.jar to C:\[..0. in addition to the sources from the standard source directory.codehaus. The generated WSDL file could then be injected into the Web Services client module to generate client-side Java files.org/axistoolsmaven-plugin/.Building J2EE Applications Running the build with mvn install leads to: C:\dev\m2book\code\j2ee\daytrader\wsappclient>mvn install [. The Axis Tools reference documentation can be found at http://mojo.m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-wsappclient\1.
11.Building J2EE Applications 4.xml file.. It's time to package the server module artifacts (EJB and WAR) into an EAR for convenient deployment. define all of the dependencies that need to be included in the generated EAR: Better Builds With Maven 107 . it solely consists of a pom.apache. Start by defining that this is an EAR project by using the packaging element: <project> <modelVersion>4.xml file (see Figure 4-11).daytrader</groupId> <artifactId>daytrader</artifactId> <version>1. The ear module's directory structure can't be any simpler. Figure 4-11: Directory structure of the ear module As usual the magic happens in the pom. Building an EAR Project You have now built all the individual modules..0.0</version> </parent> <artifactId>daytrader-ear</artifactId> <name>DayTrader :: Enterprise Application</name> <packaging>ear</packaging> <description>DayTrader EAR</description> Next.geronimo.0</modelVersion> <parent> <groupId>org.samples.
daytrader</groupId> <artifactId>daytrader-web</artifactId> <version>1.0</version> <type>ejb</type> </dependency> <dependency> <groupId>org.0</version> </dependency> </dependencies> Finally. the description to use. and the J2EE version to use.geronimo.geronimo. Web modules. you need to configure the Maven EAR plugin by giving it the information it needs to automatically generate the application. At the time of writing. jar. ejb3. par.0</version> </dependency> <dependency> <groupId>org.apache.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1. This includes the display name to use.geronimo. Better Builds With Maven 108 .samples. war.apache. and EJB modules.apache.samples.samples. ejb-client.Building J2EE Applications <dependencies> <dependency> <groupId>org.0</version> <type>war</type> </dependency> <dependency> <groupId>org. It is also necessary to tell the EAR plugin which of the dependencies are Java modules.geronimo. rar.xml deployment descriptor file.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <version>1. the EAR plugin supports the following module types: ejb. sar and wsr.apache.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <version>1.samples.
geronimo.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <webModule> <groupId>org. or those with a scope of test or provided. However.apache.samples. You should also notice that you have to specify the includeInApplicationXml element in order to include the streamer and wsappclient libraries into the EAR.samples.apache.xml file.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <javaModule> <groupId>org.Building J2EE Applications By default.apache.daytrader</groupId> <artifactId>daytrader-web</artifactId> <contextRoot>/daytrader</contextRoot> </webModule> </modules> </configuration> </plugin> </plugins> </build> </project> Here.samples. 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.apache.geronimo.maven. with the exception of those that are optional. Better Builds With Maven 109 .4</version> <modules> <javaModule> <groupId>org. it is often necessary to customize the inclusion of some dependencies such as shown in this example: <build> <plugins> <plugin> <groupId>org. By default. all dependencies are included.plugins</groupId> <artifactId>maven-ear-plugin</artifactId> <configuration> <displayName>Trade</displayName> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <version>1. only EJB client JARs are included when specified in the Java modules list.geronimo.
if you wanted to put the libraries inside a lib subdirectory of the EAR you would use the bundleDir element: <javaModule> <groupId>org. 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.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <includeInApplicationXml>true</includeInApplicationXml> <bundleDir>lib</bundleDir> </javaModule> <javaModule> <groupId>org. The streamer module's build is not described in this chapter because it's a standard build generating a JAR.] 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-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: [.apache.] <defaultBundleDir>lib</defaultBundleDir> <modules> <javaModule> [. Run mvn install in daytrader/streamer. Better Builds With Maven 110 .apache...Building J2EE Applications It is also possible to configure where the JARs' Java modules will be located inside the generated EAR.. For example..geronimo.samples.geronimo.org/plugins/maven-ear-plugin..apache..] </javaModule> [.samples.
daytrader: daytrader-ejb:1.jar] [INFO] Copying artifact [jar:org.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ear\1.geronimo.ear [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1.0] to [daytrader-wsappclient-1..0.daytrader: daytrader-streamer:1.jar] [INFO] Copying artifact [war:org.MF .apache.samples.0] to [daytrader-web-1.daytrader: daytrader-ejb:1.apache.geronimo.0.0\daytrader-ear-1.apache. run mvn install: C:\dev\m2book\code\j2ee\daytrader\ear>mvn install […] [INFO] [ear:generate-application-xml] [INFO] Generating application.0-client.jar] [INFO] Copying artifact [ejb-client:org.0] to [daytrader-ejb-1.apache.]\.war] [INFO] Copying artifact [ejb:org.daytrader: daytrader-wsappclient:1.geronimo.jar] [INFO] Could not find manifest file: C:\dev\m2book\code\j2ee\daytrader\ear\src\main\application\ META-INF\MANIFEST. [INFO] [ear:ear] [INFO] Copying artifact [jar:org.Building J2EE Applications To generate the EAR.0] to [daytrader-streamer-1.0.0.ear to C:\[.ear Better Builds With Maven 111 .geronimo.0.0..samples.0] to[daytrader-ejb-1.0.xml [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources.daytrader: daytrader-web:1.samples.samples.Generating one [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1.samples.apache.geronimo.
jar</ejb> </module> </application> This looks good.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.jar</java> </module> <module> <web> <web-uri>daytrader-web-1.jar</java> </module> <module> <java>daytrader-wsappclient-1. Better Builds With Maven 112 .sun.com/xml/ns/j2ee/application_1_4. The next section will demonstrate how to deploy this EAR into a container.sun.sun.war</web-uri> <context-root>/daytrader</context-root> </web> </module> <module> <ejb>daytrader-ejb-1.0" encoding="UTF-8"?> <application xmlns="http://java.0.w3.0.Building J2EE Applications You should review the generated application.4"> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <display-name>Trade</display-name> <module> <java>daytrader-streamer-1.xsd" version="1.xml to prove that it has everything you need: <?xml version="1.com/xml/ns/j2ee" xmlns:xsi="http://www.0.com/xml/ns/j2ee http://java.0.
xml. enabling the Geronimo plan to be modified to suit the deployment environment. how to map J2EE resources in the container. Deploying EARs follows the same principle. Geronimo is somewhat special among J2EE containers in that deploying requires calling the Deployer tool with a deployment plan. You'll need to use the JDK 1. it is recommended that you use an external plan file so that the deployment configuration is independent from the archives getting deployed.xml configuration snippet: Better Builds With Maven 113 . etc. However. Deploying a J2EE Application You have already learned how to deploy EJBs and WARs into a container individually. A plan is an XML file containing configuration information such as how to map CMP entity beans to a specific database. The DayTrader application does not deploy correctly when using the JDK 5 or newer.12. To get started. as shown on Figure 4-2. You would need the following pom. In this example. Geronimo also supports having this deployment descriptor located within the J2EE archives you are deploying.Building J2EE Applications 4. Like any other container. store the deployment plan in ear/src/main/deployment/geronimo/plan. you'll deploy the DayTrader EAR into Geronimo. 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.
cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www.directory}/${project. in this section you'll learn how to use the Maven Exec plugin.xm</plan> </properties> </deployable> </deployables> </deployer> </configuration> </plugin> However. or when Cargo doesn't support the container you want to deploy into.build.jar</argument> <argument>--user</argument> <argument>system</argument> <argument>--password</argument> <argument>manager</argument> <argument>deploy</argument> <argument> ${project. You'll use it to run the Geronimo Deployer tool to deploy your EAR into a running Geronimo container.0.home}/bin/deployer.Building J2EE Applications <plugin> <groupId>org.xml </argument> </arguments> </configuration> </plugin> Better Builds With Maven 114 .codehaus. Even though it's recommended to use a specific plugin like the Cargo plugin.build. This plugin can execute any process.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <deployer> <deployables> <deployable> <properties> <plan>${basedir}/src/main/deployment/dayTrader-plan.codehaus. learning how to use the Exec plugin is useful in situations where you want to do something slightly different.ear </argument> <argument> ${basedir}/src/main/deployment/geronimo/plan.mojo</groupId> <artifactId>exec-maven-plugin</artifactId> <configuration> <executable>java</executable> <arguments> <argument>-jar</argument> <argument>${geronimo.xml to configure the Exec plugin: <plugin> <groupId>org.finalName}. Modify the ear/pom.apache.org/dist/geronimo/1.0/ geronimo-tomcat-j2ee-1.
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.0-tomcat/bin/deployer. As the location where Geronimo is installed varies depending on the user.Building J2EE Applications You may have noticed that you're using a geronimo.jar –user system –password manager deploy C:\dev\m2book\code\j2ee\daytrader\ear\target/daytrader-ear-1.xml file: <profiles> <profile> <id>vmassol</id> <properties> <geronimo.jar [INFO] [INFO] `-> daytrader-wsappclient-1. Better Builds With Maven 115 . the Exec plugin will transform the executable and arguments elements above in the following command line: java -jar c:/apps/geronimo-1.0-SNAPSHOT.jar [INFO] [INFO] `-> TradeDataSource [INFO] [INFO] `-> TradeJMS You can now access the DayTrader application by opening your browser to http://localhost:8080/daytrader/.jar [INFO] [INFO] `-> daytrader-streamer-1.ear C:\dev\m2book\code\j2ee\daytrader\ear/src/main/deployment/geronimo/plan.0-tomcat</geronimo.home> </properties> </profile> </profiles> At execution time.home property that has not been defined anywhere.0-SNAPSHOT.] [INFO] [exec:exec] [INFO] Deployed Trade [INFO] [INFO] `-> daytrader-web-1. start your preinstalled version of Geronimo and run mvn exec:exec: C:\dev\m2book\code\j2ee\daytrader\ear>mvn exec:exec [.0-SNAPSHOT.xml First..war [INFO] [INFO] `-> daytrader-ejb-1. put the following profile in a profiles..0.home>c:/apps/geronimo-1.0-SNAPSHOT.xml or settings.
create a functional-tests module as shown in Figure 4-12. Since Geronimo 1.xml so that it's built along with the others. Functional tests can take a long time to execute.xml file as follows: Better Builds With Maven 116 .0-tomcat\bin>deploy stop geronimo/daytrader-derby-tomcat/1. you should first stop it.13. To achieve this. At the time of writing. For example. Testing J2EE Applications In this last section you'll learn how to automate functional testing of the EAR built previously. Maven only supports integration and functional testing by creating a separate module.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. by creating a new execution of the Exec plugin or run the following: C:\apps\geronimo-1.0 comes with the DayTrader application bundled. modify the daytrader/pom.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. 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. so you can define a profile to build the functional-tests module only on demand.
but running mvn install-Pfunctional-test will. This means that running mvn install will not build the functional-tests module. Figure 4-1 shows how it is organized: Functional tests are put in src/it/java.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. see Chapter 7. Now. • Better Builds With Maven 117 . • The Geronimo deployment Plan file is located in src/deployment/geronimo/plan.xml. take a look in the functional-tests module itself. • Classpath resources required for the tests are put in src/it/resources (this particular example doesn't have any resources).
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. the compiler and Surefire plugins are not triggered during the build life cycle of projects with a pom packaging. However. so these need to be configured in the functional-tests/pom.xml file: Better Builds With Maven 118 .
.samples.apache.0-SNAPSHOT</version> <type>ear</type> <scope>provided</scope> </dependency> [.samples..plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <executions> <execution> <goals> <goal>testCompile</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.geronimo.] </dependencies> <build> <testSourceDirectory>src/it</testSourceDirectory> <plugins> <plugin> <groupId>org..0.0</modelVersion> <parent> <groupId>org.geronimo.daytrader</groupId> <artifactId>daytrader-ear</artifactId> <version>1.maven.] </plugins> </build> </project> Better Builds With Maven 119 .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.maven..plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <executions> <execution> <phase>integration-test</phase> <goals> <goal>test</goal> </goals> </execution> </executions> </plugin> [.Building J2EE Applications <project> <modelVersion>4.apache.
As the Surefire plugin's test goal has been bound to the integration-test phase above.8</version> <scope>test</scope> </dependency> <dependency> <groupId>org. This is because the EAR artifact is needed to execute the functional tests. Start by adding the Cargo dependencies to the functional-tests/pom.cargo</groupId> <artifactId>cargo-core-uberjar</artifactId> <version>0.8</version> <scope>test</scope> </dependency> </dependencies> Better Builds With Maven 120 . you will usually utilize a real database in a known state. in the case of the DayTrader application..sourceforge.] <dependencies> [. However.. You're going to use the Cargo plugin to start Geronimo and deploy the EAR into it. thus ensuring the proper order of execution. 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. In addition. 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 top-level in daytrader/. To set up your database you can use the DBUnit Java API (see http://dbunit. and it is started automatically by Geronimo. You may be asking how to start the container and deploy the DayTrader EAR into it. there's a DayTrader Web page that loads test data into the database.. For integration and functional tests.codehaus.] <dependency> <groupId>org.codehaus. so DBUnit is not needed to perform any database operations.xml file: <project> [.net/).. Derby is the default database configured in the deployment plan.cargo</groupId> <artifactId>cargo-ant</artifactId> <version>0.Building J2EE Applications As you can see there is also a dependency on the daytrader-ear module.
zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> <executions> <execution> <id>start-container</id> <phase>pre-integration-test</phase> <goals> <goal>start</goal> <goal>deploy</goal> </goals> <configuration> <deployer> <deployables> <deployable> <groupId>org. Better Builds With Maven 121 ..geronimo.0/ geronimo-tomcat-j2ee-1.] <plugin> <groupId>org.samples..daytrader</groupId> <artifactId>daytrader-ear</artifactId> <type>ear</type> <properties> <plan>${basedir}/src/deployment/geronimo/plan.] The deployer element is used to configure the Cargo plugin's deploy goal.org/dist/geronimo/1.codehaus. thus ensuring that the EAR is ready for servicing when the tests execute. a pingURL element is specified so that Cargo will ping the specified URL till it responds..apache.apache.Building J2EE Applications Then create an execution element to bind the Cargo plugin's start and deploy goals: <build> <plugins> [.0.xml</plan> </properties> <pingURL>http://localhost:8080/daytrader</pingURL> </deployable> </deployables> </deployer> </configuration> </execution> [.. It is configured to deploy the EAR using the Geronimo Plan file.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <wait>false</wait> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www. In addition.
1</version> <scope>test</scope> </dependency> Better Builds With Maven 122 . by wrapping it in a JUnit TestSetup class to start the container in setUp() and stop it in tearDown(). as you're only using them for testing: <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. with both defined using a test scope.net/) to call a Web page from the DayTrader application and check that it's working. You're going to use the HttpUnit testing framework (http://httpunit. An alternative to using Cargo's Maven plugin is to use the Cargo Java API directly from your tests.1</version> <scope>test</scope> </dependency> <dependency> <groupId>httpunit</groupId> <artifactId>httpunit</artifactId> <version>1. add an execution element to bind the Cargo plugin's stop goal to the post-integration-test phase: [.6. The only thing left to do is to add the tests in src/it/java. Add the JUnit and HttpUnit dependencies...Building J2EE Applications Last.8.sourceforge.] <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.
samples.getResponse(request).samples.geronimo.Building J2EE Applications Next. Failures: 0. import com. import junit.meterware.531 sec [INFO] [cargo:stop {execution: stop-container}] 4.*.daytrader.. WebRequest request = new GetMethodWebRequest( "http://localhost:8080/daytrader"). Better Builds With Maven 123 .getTitle()).FunctionalTest [surefire] Tests run: 1. type mvn install and relax: C:\dev\m2book\code\j2ee\daytrader\functional-tests>mvn install [. 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.java. In addition you've discovered how to automate starting and stopping containers. 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. Errors: 0.apache.14. } } It's time to reap the benefits from your build. In the class.] [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..daytrader.framework. assertEquals("DayTrader".apache.*. response. WebResponse response = wc.geronimo. and more. deploying J2EE archives and implementing functional tests. how to effectively set up Maven in a team. how to gather project health information from your builds. Change directory into functional-tests. the http://localhost:8080/daytrader URL is called to verify that the returned page has a title of "DayTrader": package org. public class FunctionalTest extends TestCase { public void testDisplayMainPage() throws Exception { WebConversation wc = new WebConversation(). Time elapsed: 0.httpunit. add a JUnit test class called src/it/java/org/apache/geronimo/samples/daytrader/FunctionalTest.
.Richard Feynman Better Builds With Maven 124 . 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. reality must take precedence over public relations. for Nature cannot be fooled. and resources from a plugin Attaching an artifact to the project For a successful technology.5. source directories.
called phases. plugins provide a grouping mechanism for multiple mojos that serve similar functions within the build life cycle. such as integration with external tools and systems. When a number of mojos perform related tasks. executing all the associated mojos at each phase of the build. For example. 5. it is still likely that a plugin already exists to perform this task. or work. allowing shared configuration to be added to a single section of the POM. A Review of Plugin Terminology Before delving into the details of how Maven plugins function and how they are written. of the build process are executed by the set of plugins associated with the phases of a project's build life-cycle. the maven-compiler-plugin incorporates two mojos: compile and testCompile. and organizing and running plugins. It starts by describing fundamentals. Such supplemental plugins can be found at the Apache Maven project the loosely affiliated CodeHaus Mojo project. the build process for a project is comprised of set of mojos executing in a particular. The actual functional tasks. 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). Even if a project requires a special task to be performed. Just like Java packages. This ordering is called the build life cycle. it may be necessary to write a custom plugin to integrate these tasks into the build life cycle. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. it traverses the phases of the life cycle in order. When Maven executes a build.1.2. A mojo is the basic unit of work in the Maven application. resolving project dependencies. let's begin by reviewing the terminology used to describe a plugin and its role in the build. refer to the Plugin Matrix. Additionally. if your project requires tasks that have no corresponding plugin. it will discuss the various ways that a plugin can interact with the Maven build environment and explore some examples. it enables these mojos to share common code more easily. From there. This chapter will focus on the task of writing custom plugins. Maven's core APIs handle the "heavy lifting" associated with loading project definitions (POMs). Maven is actually a platform that executes plugins within a build life cycle. Correspondingly. With most projects. Recall that a mojo represents a single task in the build process. and more. but also extending a project's build to incorporate new functionality. the common theme for these tasks is the function of compiling code. well-defined order. Better Builds With Maven 125 . the chapter will cover the tools available to simplify the life of the plugin developer. 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. It executes an atomic build task that represents a single step in the build process.Developing Custom Maven Plugins 5. resolving dependencies. This makes Maven's plugin framework extremely important as a means of not only building a project. This association of mojos to phases is called binding and is described in detail below. they are packaged together into a plugin. However. Each mojo can leverage the rich infrastructure provided by Maven for loading projects. Finally. Packaging these mojos inside a single plugin provides a consistent access mechanism for users. in order to perform the tasks necessary to build a project. and is defined as a set of task categories. In this case. injecting runtime parameter information. Introduction As described in Chapter 2.
and as such. and parameter resolution and injection.3. will not have a life-cycle phase binding at all since they don't fall into any natural category within a typical build process.1. Maven also provides a well-defined procedure for building a project's sources into a distributable archive. including a well-defined build life cycle. which correspond to the phases of the build life cycle.3. they can be bound to any phase in the life cycle. or aid integration with external development tools. Bootstrapping into Plugin Development In addition to understanding Maven's plugin terminology. As a result. 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).Developing Custom Maven Plugins Together with phase binding. using the plugin executions section of the project's POM. plus much more. a mojo may be designed to work outside the context of the build life cycle. so be sure to check the documentation for a mojo before you re-bind it. you will also need a good understanding of how plugins are structured and how they interact with their environment. While mojos usually specify a default phase binding. successive phases can make assumptions about what work has taken place in the previous phases. a mojo can pick and choose what elements of the build state it requires in order to execute its task. The Plugin Framework Maven provides a rich framework for its plugins. it is important to provide the appropriate phase binding for your mojos. the ordered execution of Maven's life cycle gives coherence to the build process. 5. Since phase bindings provide a grouping mechanism for mojos within the life cycle. in addition to determining its appropriate phase binding. Using Maven's parameter injection infrastructure. before a mojo can execute. mojos have a natural phase binding which determines when a task should execute within the life cycle. since they often perform tasks for the POM maintainer. However. a given mojo can even be bound to the life cycle multiple times during a single build. As a plugin developer. it may still require that certain activities have already been completed. While Maven does in fact define three different lifecycles. Think of these mojos as tangential to the the Maven build process. Understanding this framework will enable you to extract the Maven build-state information that each mojo requires. Most mojos fall into a few general categories. you must understand the mechanics of life-cycle phase binding and parameter injection. Indeed. Each execution can specify a separate phase binding for its declared set of mojos. the discussion in this chapter is restricted to the default life cycle. to ensure compatibility with other plugins. These mojos are meant to be used by way of direct invocation. Such mojos may be meant to check out a project from version control. In some cases. sequencing the various build operations. A discussion of all three build life cycles can be found in Appendix A. or even create the directory structure for a new project. 5. dependency management. Binding to a phase of the Maven life cycle allows a mojo to make assumptions based upon what has happened in the preceding phases. Better Builds With Maven 126 . Using the life cycle. parameter injection and life-cycle binding form the cornerstone for all mojo development. Together. Therefore.
is often as important as the modifications made during execution itself. The testCompile mojo from the maven-compiler-plugin will compile the test sources. These mojos were always present in the life-cycle definition. Then. the jar mojo from the maven-jarplugin will harvest these class files and archive them into a jar file. This level of extensibility is part of what makes Maven so powerful. at least two of the above mojos will be invoked. If this basic Maven project also includes source code for unit tests. then the test mojo from the maven-surefire-plugin will execute those compiled tests. Maven will execute a default life cycle for the 'jar' packaging. Since our hypothetical project has no "non-code" resources. Instead. Only those mojos with tasks to perform are executed during this build. but until now they had nothing to do and therefore. but a requirement of a well-designed mojo. During this build process. did not execute. many more plugins can be used to augment the default life-cycle definition. As a specific example of how plugins work together through the life cycle. none of the mojos from the maven-resources-plugin will be executed. Better Builds With Maven 127 . Maven's plugin framework ensures that almost anything can be integrated into the build life cycle. validation of project content.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. First. providing functions as varied as deployment into the repository system. In good mojo design. 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. 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. determining when not to execute. generation of the project's website. the compile mojo from the maven-compiler-plugin will compile the source code into binary class files in the output directory. Indeed. consider a very basic Maven build: a project with source code that should be compiled and archived into a jar file for redistribution. This is not a feature of the framework. then two additional mojos will be triggered to handle unit testing. and much more.
and once resolved. This mojo would retrieve the list of source directories from the current build information using the following expression: ${project.and machine-level Maven settings. see Appendix A.compileSourceRoots} Then. along with any system properties that were provided when Maven was launched. the expression associated with a parameter is resolved against the current build state. each declared mojo parameter includes information about the various expressions used to resolve its value. the expression to retrieve that information might look as follows: ${patchDirectory} For more information about which mojo expressions are built into Maven. assuming the patch directory is specified as mojo configuration inside the POM. This information comes in two categories: • • Project information – which is derived from the project POM. whether it is editable. For the complete plugin descriptor syntax. how do you instruct Maven to inject those values into the mojo instance? Further. in addition to any programmatic modifications made by previous mojo executions. It contains information about the mojo's implementation class (or its path within the plugin jar). Maven allows mojos to specify parameters whose values are extracted from the build state using expressions. a mojo can keep its dependency list to a bare minimum. That is to say. and what methods Maven uses to extract mojo parameters from the build state. Within this descriptor. see Appendix A. The descriptor is an XML file that informs Maven about the set of mojos that are contained within the plugin. a mojo that applies patches to the project source code will need to know where to find the project source and patch files. how do you associate mojo parameters with their expression counterparts.xml. the life-cycle phase to which the mojo should be bound. and the mechanism for injecting the parameter value into the mojo instance. Better Builds With Maven 128 . they require information about the state of the current build. The plugin descriptor Though you have learned about binding mojos to life-cycle phases and resolving parameter values using associated expressions. For example. and the resulting value is injected into the mojo. under the path /META-INF/maven/plugin. Using the correct parameter expressions. until now you have not seen exactly how a life-cycle binding occurs. whether it is required for the mojo's execution. how do you instruct Maven to instantiate a given mojo in the first place? The answers to these questions lie in the plugin descriptor. using a language-appropriate mechanism. To gain access to the current build state. Environment information – which is more static. the set of parameters the mojo declares. thereby avoiding traversal of the entire build-state object graph. and more. and consists of the user.Developing Custom Maven Plugins Accessing build information In order for mojos to execute effectively. At runtime. The Maven plugin descriptor is a file that is embedded in the plugin jar archive.
• Of course. The clean mojo also defines the following: Better Builds With Maven 129 . this flexibility comes at a price. one per supported mojo language). it's a simple case of providing special javadoc annotations to identify the properties and parameters of the mojo. This is where Maven's plugin development tools come into play. it consists of a framework library which is complemented by a set of provider libraries (generally. For example. to generate the plugin descriptor). the format used to write a mojo's metadata is dependent upon the language in which the mojo is implemented. Maven's development tools expose only relevant specifications in a format convenient for a given plugin's implementation language. 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. it uses a complex syntax. so it can be referenced from lifecycle mappings. POM configurations. 5. Maven's plugindevelopment tools remove the burden of maintaining mojo metadata by hand. Plugin Development Tools To simplify the creation of plugin descriptors. By abstracting many of these details away from the plugin developer. the maven-plugin-plugin simply augments the standard jar life cycle mentioned previously as a resource-generating step (this means the standard process of turning project sources into a distributable jar archive is modified only slightly. and direct invocations (as from the command line). Using Java. except when configuring the descriptor. Maven provides plugin tools to parse mojo metadata from a variety of formats. This metadata is embedded directly in the mojo's source code where possible.2. 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. 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.Developing Custom Maven Plugins The plugin descriptor is very powerful in its ability to capture the wiring information for a wide variety of mojos. However. The maven-plugin-plugin – which uses the plugin extractor framework. adding any other plugin-level metadata through its own configuration (which can be modified in the plugin's POM). and its format is specific to the mojo's implementation language. and orchestrates the process of extracting metadata from mojo implementations. In short. This framework generates both plugin documentation and the coveted plugin descriptor.3. To accommodate the extensive variability required from the plugin descriptor.
However. * * @parameter default-value="${project.verbose}" default=value="false" */ private boolean verbose. For instance. like Ant. it's implicit when using the @parameter annotation. Moreover. consider the following field annotation from the resources mojo in the maven-resources-plugin: /** * Directory containing the classes. it specifies that this parameter can be configured from the POM using: <configuration> <verbose>true</verbose> </configuration> You may notice that this configuration name isn't explicitly specified in the annotation.Developing Custom Maven Plugins /** * Be verbose in the debug log-level? * * @parameter expression="${clean. the annotation identifies this field as a mojo parameter. rather than in the Java field initialization code. In this case. especially when you could just declare the field as follows: private boolean verbose = true. Better Builds With Maven 130 . default-value and expression.outputDirectory}" */ private File classesDirectory. Remember. namely the java.build. which references the output directory for the current project. the underlying principles remain the same. this parameter annotation also specifies two attributes. The first specifies that this parameter's default value should be set to true. it's impossible to initialize the Java field with the value you need. then the mechanism for specifying mojo metadata such as parameter definitions will be different. However. But consider what would happen if the default value you wanted to inject contained a parameter expression. these annotations are specific to mojos written in Java. it might seem counter-intuitive to initialize the default value of a Java field using a javadoc annotation. For a complete list of javadoc annotations available for specifying mojo metadata.io. Since the plugin tools can also generate documentation about plugins based on these annotations. it's a good idea to consistently specify the parameter's default value in the metadata. When the mojo is instantiated. The second specifies that this parameter can also be configured from the command line as follows: -Dclean. this value is resolved based on the POM and injected into this field. If you choose to write mojos in another language. see Appendix A.File instance.verbose=true At first. Here.
you risk confusing the issue at hand – namely. mojo mappings and parameters definitions are declared via an associated metadata file. 5. or any combination thereof. During the early phases of such a migration. A Note on the Examples in this Chapter When learning how to interact with the different aspects of Maven from within a mojo. This pairing of the build script and accompanying metadata file follows a naming convention that allows the maven-plugin-plugin to correlate the two files and create an appropriate plugin descriptor. you will need to work with an external project. it's important to keep the examples clean and relatively simple. You can install it using the following simple command: mvn install Better Builds With Maven 131 .Developing Custom Maven Plugins Choose your mojo implementation language Through its flexible plugin descriptor format and invocation framework. in certain cases you may find it easier to use Ant scripts to perform build tasks. In addition. Such information might include details about the system environment. Java is the language of choice. Plugin parameters can be injected via either field reflection or setter methods. due to the mitigation value of Ant-based mojos when converting a build to Maven. 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. Simple javadoc annotations give the plugin processing plugin (the maven-plugin-plugin) the instructions required to generate a descriptor for your mojo. when translating a project build from Ant to Maven (refer to Chapter 8 for more discussion about migrating from Ant to Maven). the particular feature of the mojo framework currently under discussion. this technique also works well for Beanshell-based mojos. In these cases. This relieves you of the burden associated with traversing a large object graph in your code. the specific snapshot versions of dependencies used in the build. and minimizes the number of dependencies you will have on Maven's core APIs.3. Maven can accommodate mojos written in virtually any language. Maven currently supports mojos written in Java. which is used to read and write build information metadata files. this chapter will also provide an example of basic plugin development using Ant. individual mojos each mapped to separate scripts. Maven can wrap an Ant build target and use it as if it were a mojo. it also provides good alignment of skill sets when developing mojos from scratch. Otherwise. To facilitate these examples. called mavenbuildinfo. and so on. it is often simpler to wrap existing Ant build targets with Maven mojos and bind them to various phases in the life cycle. Ant. Whatever language you use. For example. Since Java is currently the easiest language for plugin development. Maven lets you select pieces of the build state to inject as mojo parameters.3. This project can be found in the source code that accompanies this book. Since Beanshell behaves in a similar way to standard Java. To make Ant scripts reusable. Therefore. However. and because many Maven-built projects are written in Java. this chapter will focus primarily on plugin development in this language. For many mojo developers. This is especially important during migration. Since it provides easy reuse of third-party APIs from within your mojo. and Beanshell.
since it can have a critical effect on the build process and the composition of the resulting Guinea Pig artifacts.0-alpha-4 This will create a project with the standard layout under a new subdirectory called mavenbuildinfo-plugin within the current working directory. This information should capture relevant details about the environment used to build the Guinea Pig artifacts. and this dependency is injected by one of the aforementioned profiles. For the purposes of this plugin. which will be triggered by the value of a given system property – say. you will need to modify the POM as follows: Change the name element to Maven BuildInfo Plugin. refer to Chapter 3). When triggered.name is set to the value Linux (for more information on profiles. if the system property os. 5. and has no impact on transitive dependencies for users of this project. simply execute the following: mvn archetype:create -DgroupId=com. 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). Here. Using the archetype plugin to generate a stub plugin project To jump-start the process of writing a new plugin. you will look at the development effort surrounding a sample project.plugins \ -DartifactId=maven-buildinfo-plugin \ -DarchetypeGroupId=org. • Remove the url element.mergere.1. for the purposes of debugging. this dependency is used only during testing. In addition to simply capturing build-time information.apache. If you have a test dependency which contains a defect. consider a case where the POM contains a profile. the values of system properties used in the build are clearly very important. since this plugin doesn't currently have an associated web site. To generate a stub plugin project for the buildinfo plugin.4. For simplicity.Developing Custom Maven Plugins 5.mvnbook. writing your custom mojo is simple. called Guinea Pig. Once you have the plugin's project structure in place. Inside. which allows the build to succeed in that environment. you'll find a basic POM and a sample mojo. it's helpful to use the archetype plugin to create a simple stub project.archetypes \ -DarchetypeArtifactId=maven-archetype-mojo \ -DarchetypeVersion=1. Developing Your First Mojo For the purposes of this chapter. then the value of the triggering system property – and the profile it triggers – could reasonably determine whether the build succeeds or fails. which will be deployed to the Maven repository system.4. this profile adds a new dependency on a Linux-specific library. a default profile injects a dependency on a windows-specific library. BuildInfo Example: Capturing Information with a Java Mojo To begin. Therefore. When this profile is not triggered.maven. This development effort will have the task of maintaining information about builds that are deployed to the development repository. • Better Builds With Maven 132 . you will need to disseminate the build to the rest of the development team. Capturing this information is key. 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.
length.Developing Custom Maven Plugins You will modify the POM again later.MISSING_INFO_PLACEHOLDER ). * @goal extract * @phase package */ public class WriteBuildInfoMojo extends AbstractMojo { /** * Determines which system properties are added to the file. for ( int i = 0...trim(). Properties sysprops = System.build. However. you should remove the sample mojo.outputFile}" defaultvalue="${project. i++ ) { String key = keys[i]. It can be found in the plugin's project directory. String value = sysprops. } try Better Builds With Maven 133 .addSystemProperty( key. under the following path: src/main/java/org/codehaus/mojo/MyMojo. this simple version will suffice for now.outputDirectory}/${project. public void execute() throws MojoExecutionException { BuildInfo buildInfo = new BuildInfo(). fairly simple Java-based mojo: [. } buildInfo.xml" * @required */ private File outputFile. value ).artifactId}-${project. * This is a comma-delimited list.] /** * Write environment information for the current build to file. if ( systemProperties != null ) { String[] keys = systemProperties. BuildInfoConstants.version}buildinfo. The mojo You can handle this scenario using the following. Finally.java." ).getProperties().split( ". as you know more about your mojos' dependencies.getProperty( key. * @parameter expression="${buildinfo. since you will be creating your own mojo from scratch. i < keys. /** * The location to write the buildinfo file. * @parameter expression="${systemProperties}" */ private String systemProperties.
it makes sense to execute this mojo in the package phase.systemProperties=java. Aside from the class-level comment. will allow this mojo field to be configured using the plugin configuration specified in the POM.writeXml( buildInfo.getMessage(). so it will be ready to attach to the project artifact. } While the code for this mojo is fairly straightforward. the complexity is justified. since you have more specific requirements for this parameter. you have several field-level javadoc comments.dir Finally. outputFile ). When you invoke this mojo. This is where the expression attribute comes into play. } catch ( IOException e ) { throw new MojoExecutionException( "Error writing buildinfo XML file. However.systemProperties}" */ This is one of the simplest possible parameter specifications. so they will be considered separately. the outputFile parameter presents a slightly more complex example of parameter annotation. Using the expression attribute. it's worthwhile to take a closer look at the javadoc annotations. with no attributes. tells the plugin tools to treat this class as a mojo named extract. you will use this name. In general. Using the @parameter annotation by itself. First. Take another look: Better Builds With Maven 134 . In this case. @goal. The second annotation tells Maven where in the build life cycle this mojo should be executed. 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.version. the expression attribute allows you to specify a list of system properties on-the-fly. Each offers a slightly different insight into parameter specification.user. consider the systemProperties parameter: /** * @parameter expression="${buildinfo. e ). you're collecting information from the environment with the intent of distributing it alongside the main project artifact in the repository. there are two special annotations: /** * @goal extract * @phase package */ The first annotation. In this case. However. Therefore. In the class-level javadoc comment. Reason: " + e.Developing Custom Maven Plugins { } } BuildInfoUtils. as follows: localhost $ mvn buildinfo:java-write \ -Dbuildinfo. you may want to allow a user to specify which system properties to include in the build information file. you can specify the name of this parameter when it's referenced from the command line. which are used to specify the mojo's parameters.
To ensure that this parameter has a value. the build will fail with an error. which simply adds plugin descriptor extraction and generation to the build process. Also.mergere.outputFile}" defaultvalue="${project. Note the dependency on the buildinfo project.artifactId}-${project.0-SNAPSHOT</version> <packaging>maven-plugin</packaging> <dependencies> <dependency> <groupId>org.maven</groupId> <artifactId>maven-plugin-api</artifactId> <version>2. If this parameter has no value when the mojo is configured. you want the mojo to use a certain value – calculated from the project's information – as a default value for this parameter. This mapping is a slightly modified version of the one used for the jar packaging.plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <version>1. as follows: <project> <modelVersion>4.0-SNAPSHOT</version> </dependency> </dependencies> </project> This POM declares the project's identity and its two dependencies. you can see why the normal Java field initialization is not used. In addition. In this example. note the packaging – specified as maven-plugin – which means that this plugin build will follow the maven-plugin life-cycle mapping.0.xml" * * @required */ In this case. using several expressions to extract project information on-demand.build.mvnbook.mergere.0</modelVersion> <groupId>com.outputDirectory}/${project. the mojo cannot function unless it knows where to write the build information file. as execution without an output file would be pointless. * * @parameter expression="${buildinfo.mvnbook.0</version> </dependency> <dependency> <groupId>com.apache. you can construct an equally simple POM which will allow you to build the plugin. the mojo uses the @required annotation.Developing Custom Maven Plugins /** * The location to write the buildinfo file.version}buildinfo.shared</groupId> <artifactId>buildinfo</artifactId> <version>1. The default output path is constructed directly inside the annotation. which provides the parsing and formatting utilities for the build information file. Better Builds With Maven 135 . The plugin POM Once the mojo has been written.
mvnbook.plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> <configuration> <systemProperties> <systemProperty>os..name system property. Better Builds With Maven 136 ... </plugins> ..name</systemProperty> </systemProperties> </configuration> <goals> <goal>extract</goal> </goals> </execution> </executions> </plugin> . as follows: <build> . and capture the os. so that every build triggers it. you need to ensure that every build captures this information. This involves modification of the standard jar lifecycle. <plugins> <plugin> <groupId>com..Developing Custom Maven Plugins Binding to the life cycle Now that you have a method of capturing build-time environmental information..mergere. </build> The above binding will execute the extract mojo from your new maven-buildinfo-plugin during the package phase of the life cycle. The easiest way to guarantee this is to bind the extract mojo to the life cycle. which you can do by adding the configuration of the new plugin to the Guinea Pig POM.
Better Builds With Maven 137 . 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.. the output of of the generated build information is clear enough.. you can build the plugin and try it out! First.] [buildinfo:extract {execution:extract}] ------------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------------- Under the target directory.0" encoding="UTF-8"?><buildinfo> <systemProperties> <os...name> </systemProperties> </buildinfo> Formatting aside. there should be a file named: guinea-pig-1.name>Linux</os.0-SNAPSHOT-buildinfo.Developing Custom Maven Plugins The output Now that you have a mojo and a POM. a property that can have profound effects on binary compatibility. you should see output similar to the following: [. Your mojo has captured the version of Java being used to execute the build. you will find information similar to the following: <?xml version="1.xml In the file.] [INFO] [INFO] [INFO] [INFO] [. build the buildinfo plugin with the following commands: > C:\book-projects\maven-buildinfo-plugin > mvn clean install Next.
For now. After writing the Ant target to send the notification e-mail. you need to share it with others in your team when the resulting project artifact is deployed. It's important to remember that in the Maven world. However. To ensure these project properties are in place within the Ant Project instance. and how. Information like the to: address will have to be dynamic. The mojo metadata file Unlike the prior Java examples.4.build. it might be enough to send a notification e-mail to the project development mailing list. metadata for an Ant mojo is stored in a separate file. mature tasks available for build script use (including one specifically for sending e-mails). From here. BuildInfo Example: Notifying Other Developers with an Ant Mojo Now that some important information has been captured.xml and should appear as follows: Better Builds With Maven 138 .outputFile}"> <to>${listAddr}</to> </mail> </target> </project> If you're familiar with Ant. so that other team members have access to it. The corresponding metadata file will be called notify. such a task could be handled using a Java-based mojo and the JavaMail API from Sun. In this example. therefore. The Ant target To leverage the output of the mojo from the previous example – the build information file – you can use that content as the body of the e-mail. and the dozens of well-tested. Of course.xml. simply declare mojo parameters for them.2. given the amount of setup and code required. Your new mojo will be in a file called notify.xml. you'll notice that this mojo expects several project properties.mojos.name}" mailhost="${mailHost}" mailport="${mailPort}" messagefile="${buildinfo. which is associated to the build script using a naming convention. it should be extracted directly from the POM for the project we're building. "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. and should look similar to the following: <project> <target name="notify-target"> <mail from="maven@localhost" replyto="${listAddr}" subject="Build Info for Deployment of ${project. the build script was called notify.build. it's simpler to use Ant.Developing Custom Maven Plugins 5. it's a simple matter of specifying where the email should be sent.
name</name> <defaultValue>${project.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.build.version}-buildinfo. Better Builds With Maven 139 .outputFile</name> <defaultValue> ${project.Developing Custom Maven Plugins <pluginMetadata> <mojos> <mojo> <call>notify-target</call> <goal>notify</goal> <phase>deploy</phase> <description><![CDATA[ Email environment information from the current build to the development mailing list when the artifact is deployed.xml </defaultValue> <required>true</required> <readonly>false</readonly> </parameter> <parameter> <name>listAddr</name> <required>true</required> </parameter> <parameter> <name>project.artifactId}${project.directory}/${project. you will see many similarities. the contents of this file may appear different than the metadata used in the Java mojo. however. upon closer examination. ]]></description> <parameters> <parameter> <name>buildinfo.
2). parameters are injected as properties and references into the Ant Project instance. Finally. default value. Fortunately. If one of the parameters were some other object type. you will have to add support for Ant mojo extraction to the maven-plugin-plugin. its value is injected as a project reference.lang. then its value is injected as a property.0 shipped without support for Ant-based mojos (support for Ant was added later in version 2. to develop an Ant-based mojo. so it's pointless to spam the mailing list with notification e-mails every time a jar is created for the project. metadata specify a list of parameters for the mojo. As with the Java example. Better Builds With Maven 140 . Any build that runs must be deployed for it to affect other development team members. the notification e-mails will be sent only when a new artifact becomes available in the remote repository. some special configuration is required to allow the maven-plugin-plugin to recognize Ant mojos.String. This is an important point in the case of this mojo. Maven allows POM-specific injection of plugin-level dependencies in order to accommodate plugins that take a framework approach to providing their functionality. in order to capture the parameter's type in the specification. Modifying the plugin POM for Ant mojos Since Maven 2. notice that this mojo is bound to the deploy phase of the life cycle.lang. the difference here is the mechanism used for this injection. the overall structure of this file should be familiar. In an Ant-based mojo however. with its use of the MojoDescriptorExtractor interface from the maven-plugin-tools-api library. or through JavaBeans-style setXXX() methods. since you now have a good concept of the types of metadata used to describe a mojo. but expressed in XML. and parameter flags such as required are still present. As with the Java example. When this mojo is executed. expression. The rule for parameter injection in Ant is as follows: if the parameter's type is java. This allows developers to generate descriptors for Java. In Java. In this example.or Beanshell-based mojos with no additional configuration. all of the mojo's parameter types are java. parameter injection takes place either through direct field assignment. Instead. by binding the mojo to the deploy phase of life cycle. otherwise. Maven still must resolve and inject each of these parameters into the mojo. and more.0. However. mojo-level metadata describes details such as phase binding and mojo name. each with its own information like name. The expression syntax used to extract information from the build state is exactly the same. 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. because you're going to be sending e-mails to the development mailing list. The maven-plugin-plugin is a perfect example. Also. you'd have to add a <type> element alongside the <name> element. a more in-depth discussion of the metadata file for Ant mojos is available in Appendix A. The maven-plugin-plugin ships with the Java and Beanshell provider libraries which implement the above interface.String (the default).Developing Custom Maven Plugins First of all.
. The second new dependency is. it will be quite difficult to execute an Ant-based plugin. the specifications of which should appear as follows: <dependencies> [. and it is always necessary for embedding Ant scripts as mojos in the Maven build process..0.5</version> </dependency> [.apache.maven</groupId> <artifactId>maven-plugin-tools-ant</artifactId> <version>2.] <dependency> <groupId>org... 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> [.] </project> Additionally. quite simply..0..maven</groupId> <artifactId>maven-script-ant</artifactId> <version>2.] </dependencies> The first of these new dependencies is the mojo API wrapper for Ant build scripts.] <build> <plugins> <plugin> <artifactId>maven-plugin-plugin</artifactId> <dependencies> <dependency> <groupId>org.. since the plugin now contains an Ant-based mojo. a dependency on the core Ant library (whose necessity should be obvious). If you don't have Ant in the plugin classpath.2</version> </dependency> <dependency> <groupId>ant</groupId> <artifactId>ant</artifactId> <version>1.apache.6..Developing Custom Maven Plugins To accomplish this. it requires a couple of new dependencies. Better Builds With Maven 141 .2</version> </dependency> </dependencies> </plugin> </plugins> </build> [.
because non-deployed builds will have no effect on other team members. notification happens in the deploy phase only. Instead. Now. Better Builds With Maven 142 . which supplies the listAddr parameter value. This is because an execution section can address only one phase of the build life cycle. execute the following command: > mvn deploy The build process executes the steps required to build and deploy a jar ..] </execution> <execution> <id>notify</id> <goals> <goal>notify</goal> </goals> <configuration> <listAddr>dev@guineapig.] <plugins> <plugin> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> [. In order to tell the notify mojo where to send this e-mail.. Adding a life-cycle binding for the new Ant mojo in the Guinea Pig POM should appear as follows: <build> [. Again.] </plugins> </build> The existing <execution> section – the one that binds the extract mojo to the build – is not modified. it behaves like any other type of mojo to Maven..except in this case.codehaus. and these two mojos should not execute in the same phase (as mentioned previously).org</listAddr> </configuration> </execution> </executions> </plugin> [. it will also extract the relevant environmental details during the package phase. and send them to the Guinea Pig development mailing list in the deploy phase.. a new section for the notify mojo is created... you should add a configuration section to the new execution section.Developing Custom Maven Plugins Binding the notify mojo to the life cycle Once the plugin descriptor is generated for the Ant mojo. Even its configuration is the same.
since the dependency resolution process is what populates the set of artifacts that make up the project's dependencies).. only the following two changes are required: First. • Second.. and are not required for developing basic mojos. namely it disables configuration via the POM under the following section: <configuration> <dependencies>. To enable a mojo to work with the set of artifacts that comprise the project's dependencies. This declaration should be familiar to you. since it defines a parameter with a default value that is required to be present before the mojo can execute.artifacts}" * @required * @readonly */ private java. The following sections do not build on one another. Accessing Project Dependencies Many mojos perform tasks that require access to a project's dependencies.1. However.5. In addition. • Injecting the project dependency set As described above.</dependencies> </configuration> Better Builds With Maven 143 . the mojo must tell Maven that it requires the project's dependencies be resolved (this second requirement is critical. Fortunately. this declaration has another annotation. This annotation tells Maven not to allow the user to configure this parameter directly. As with all declarations.5.util. then read on! 5. the mojo must tell Maven that it requires the project dependency set. The next examples cover more advanced topics relating to mojo development. Maven makes it easy to inject a project's dependencies. 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. For example. the compile mojo in the maven-compiler-plugin must have a set of dependency paths in order to build the compilation classpath.Set dependencies. if you want to know how to develop plugins that manage dependencies. and artifact attachments. if the mojo works with a project's dependencies. project source code and resources. and how to annotate the mojo with a name and a preferred phase binding.Developing Custom Maven Plugins 5. 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. which might not be as familiar: @readonly. it must tell Maven that it requires access to that set of artifacts. However. Advanced Mojo Development The preceding examples showed how to declare basic mojo parameters.
such as: -Ddependencies=[.x. Rather. direct configuration could result in a dependency being present for compilation. this is a direct result of the rigid dependency resolution design in Maven 1. if your mojo needs to work with the project's dependencies. the clean process will fail – though not because the clean goal requires the project dependencies. any dependencies specific to the test scope will remain unresolved. Maven 2. it will force all of the dependencies to be resolved (test is the widest possible scope. In other words. the build process doesn't incur the added overhead of resolving them. and if so.. if a mojo declares that it requires dependencies for the compile scope. If a mojo doesn't need access to the dependency list. Requiring dependency resolution Having declared a parameter that injects the projects dependencies into the mojo. if later in the build process. If you've used Maven 1. "How exactly can I configure this parameter?" The answer is that the mojos parameter value is derived from the dependencies section of the POM. rather than configuring a specific plugin only. To gain access to the project's dependencies. you may be wondering. In this case. Returning to the example. Maven 2 addresses this problem by deferring dependency resolution until the project's dependencies are actually required. It's important to note that your mojo can require any valid dependency scope to be resolved prior to its execution. Better Builds With Maven 144 . Even then. 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. the @readonly annotation functions to force users to configure the POM. Therefore.. If the project's dependencies aren't available. encapsulating all others). Consider the case where a developer wants to clean the project directory using Maven 1. users could easily break their builds – particularly if the mojo in question compiled project source code. Failure to do so will cause an empty set to be injected into the mojo's dependencies parameter. it will have to tell Maven to resolve them. Maven encounters another mojo that declares a requirement for test-scoped dependencies. Maven will resolve only the dependencies that satisfy the requested scope. Maven provides a mechanism that allows a mojo to specify whether it requires the project dependencies to be resolved. Maven 2 will not resolve project dependencies until a mojo requires it.x.0 uses the term 'mojo' as roughly equivalent to the Maven 1. but being unavailable for testing. However. your mojo must declare that it needs them.x term 'goal'). so you configure this parameter by modifying that section directly.Developing Custom Maven Plugins It also disables configuration via system properties. If this parameter could be specified separately from the main dependencies section.] So. at which scope. the mojo is missing one last important step.
adding the information for each individual dependency to your buildinfo object. 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.setType( artifact.addResolvedDependency( rd ). along with their versions – including those dependencies that are resolved transitively.getClassifier() != null ) { rd. Once you have access to the project dependency set. } Better Builds With Maven 145 . ResolvedDependency rd = new ResolvedDependency(). rd.iterator().Developing Custom Maven Plugins You can declare the requirement for the test-scoped project dependency set using the following classlevel annotation: /** * @requiresDependencyResolution test [.getGroupId() ). rd. } } buildInfo. This will result in the addition of a new section in the buildinfo file.isEmpty() ) { for ( Iterator it = dependencies.setGroupId( artifact.getScope() ). BuildInfo example: logging dependency versions Turning once again to the maven-buildinfo-plugin. ) { Artifact artifact = (Artifact) it. the mojo should be ready to work with the dependency set. it. For example.setResolvedVersion( artifact.setClassifier( artifact.getVersion() ).getArtifactId() ).setOptional( artifact. This is critical when the project depends on snapshot versions of other libraries. rd.getType() ). if ( artifact.isOptional() ).hasNext(). In this case. rd.setScope( artifact. you will need to iterate through the set. you will want to log the versions of the dependencies used during the build. To that end.getClassifier() )..next().] */ Now. rd. one of the dependency libraries may have a newer snapshot version available. rd. knowing the specific set of snapshots used to compile a project can lend insights into why other builds are breaking.setArtifactId( artifact. The code required is as follows: if ( dependencies != null && !dependencies. which enumerates all the dependencies used in the build.
but consider the next dependency: guinea-pigapi. Better Builds With Maven 146 . the resolvedVersion in the output above would be 1..] </resolvedDependencies> The first dependency listed here.0-alpha-SNAPSHOT. it's possible that a plugin may be introduced into the build process when a profile is activated.] <resolvedDependency> <groupId>com.5.0-alpha-SNAPSHOT in the POM. This won't add much insight for debuggers looking for changes from build to build. The actual snapshot version used for this artifact in a previous build could yield tremendous insight into the reasons for a current build failure.mvnbook.. Accessing Project Sources and Resources In certain cases.2.0-20060210. or new source code directories to the build. and other mojos may need to produce reports based on those same source directories. junit. This dependency is part of the example development effort. when a project is built in a JDK 1. it may be necessary to augment a project's code base with an additional source directory.4 environment.1. has a static version of 3. If this plugin adds resources like images. it can have dramatic effects on the resulting project artifact.8. Therefore. Once this new source directory is in place.. and is still listed with the version 1.094434-1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>compile</scope> </resolvedDependency> [.guineapig</groupId> <artifactId>guinea-pig-api</artifactId> <resolvedVersion>1. 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.. the extract mojo should produce the same buildinfo file.1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>test</scope> </resolvedDependency> [. This is because snapshot time-stamping happens on deployment only.Developing Custom Maven Plugins When you re-build the plugin and re-run the Guinea Pig build. particularly if the newest snapshot version is different. If you were using a snapshot version from the local repository which has not been deployed. 5. the compile mojo will require access to it. For instance.mergere. with an additional section called resolvedDependencies that looks similar to the following: <resolvedDependencies> <resolvedDependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <resolvedVersion>3.8.
Maven will fail the build if it doesn't have a current project instance and it encounters a mojo that requires one. used to add new source directory to the build. or simply need to augment the basic project code base. instead.directory}/generated-sources/<plugin-prefix> While conforming with location standards like this is not required. which tells Maven that it's OK to execute this mojo in the absence of a POM. This declaration identifies the project field as a required mojo parameter that will inject the current MavenProject instance into the mojo for use. when generating source code. The current project instance is a great example of this. the accepted default location for the generated source is in: ${project.Developing Custom Maven Plugins Adding a source directory to the build Although the POM supports only a single sourceDirectory entry. if you expect your mojo to be used in a context where there is no POM – as in the case of the archetype plugin – then simply add the class-level annotation: @requiresProject with a value of false. Further. which can be injected into a mojo using the following code: /** * Project instance. So. allowing plugins to add new source directories as they execute. Once the current project instance is available to the mojo. Chapter 3 of this book). Maven's project API bridges this gap. unless declared otherwise. it refers to a part of the build state that should always be present (a more in-depth discussion of this annotation is available in section 3.build. This can be very useful when plugins generate source code. mojos require a current project instance to be available. any normal build will have a current project.6. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project. as in the following example: project. It is possible that some builds won't have a current project. and no other project contains current state information for this build. Maven's concept of a project can accommodate a whole list of directories. This annotation tells Maven that users cannot modify this parameter. it's a simple matter of adding a new source root to it. The generally-accepted binding for this type of activity is in the generate-sources life-cycle phase. It requires access to the current MavenProject instance only. as in the case where the mavenarchetype-plugin is used to create a stub of a new project. As in the prior project dependencies discussion. it does improve the chances that your mojo will be compatible with other plugins bound to the same life cycle.addCompileSourceRoot( sourceDirectoryPath ). this parameter also adds the @readonly annotation. Better Builds With Maven 147 . However. Mojos that augment the source-root list need to ensure that they execute ahead of the compile phase.
Normally. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project. so your mojo simply needs to ask for it. Namely. which means it's always present. the process of adding a new resource directory to the current build is straightforward. To be clear.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. as discussed previously. used to make addition of resources * simpler. However. as in the case of Maven itself. to make it simpler to add resources to a project. the Maven application itself is well-hidden from the mojo developer. in most cases. or it could be added to help identify some key attribute about the artifact to other developers. you should notice something very different about this parameter. which will be packaged up in the same jar as the project classes. * @component */ private MavenProjectHelper helper. Just as the current project instance is required in order to add a new source root. the project helper is not a build state. the project is also required to achieve this. This declaration will inject the current project instance into the mojo. and abstract the associated complexities away from the mojo developer. it is a utility. This component is part of the Maven application. However. Maven components can make it much simpler to interact with the build process. However. Right away. this is what Maven calls a component requirement (it's a dependency on an internal component of the running Maven application). the mojo also needs access to the MavenProjectHelper component. it does require a new type of parameter declaration: a requirement based on another component within the Maven application. that it's not a parameter at all! In fact. Component requirements are not available for configuration by users. the unadorned @component annotation – like the above code snippet – is adequate. Better Builds With Maven 148 . the MavenProjectHelper is provided to standardize the process of augmenting the project instance. The project parameter is declared as follows: /** * Project instance. Whatever the purpose of the mojo. The project helper component can be injected as follows: /** * project-helper instance. used to add new source directory to the build. Component requirements are simple to declare. This could be some sort of descriptor for binding the project artifact into an application framework. in some special cases. For example. It provides methods for attaching artifacts and adding new resource definitions to the current project.
The prior example instantiates the resource's directory. includes. With these two objects at your disposal. The parameter is also required for this mojo to execute. Better Builds With Maven 149 . or else bind a mojo to the life-cycle phase that will add an additional source directory to the build. 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. Again. In a typical case. Other examples include javadoc mojo in the maven-javadoc-plugin. along with inclusion and exclusion patterns for resources within that directory. instead. and exclusion patterns as local variables. * @parameter default-value="${project. excludes). which may or may not be directly configurable. Accessing the source-root list Just as some mojos add new source directories to the build. however. Resources are copied to the classes directory of the build during the process-resources phase. these values would come from other mojo parameters. it will need to execute ahead of this phase. they have to modify the sourceDirectory element in the POM. as it is particularly useful to mojo developers. if it's missing. and the jar mojo in the maven-source-plugin. and then call a utility method on the project helper. helper.singletonList("**/*"). adding a new resource couldn't be easier. directory. List includes = Collections. If your mojo is meant to add resources to the eventual project artifact. as in the following example: /** * List of source roots containing non-test code. The most common place for such activities is in the generate-resources life-cycle phase.Developing Custom Maven Plugins A complete discussion of Maven's architecture – and the components available – is beyond the scope of this chapter. the MavenProjectHelper component is worth mentioning here. which actually compiles the source code contained in these root directories into classes in the project output directory. this parameter declaration states that Maven does not allow users to configure this parameter directly. Simply define the resources directory to add. List excludes = null. The classic example is the compile mojo in the maven-compiler-plugin. inclusion patterns. Similar to the parameter declarations from previous sections. in order to perform some operation on the source code.addResource(project.compileSourceRoots}" * @required * @readonly */ private List sourceRoots. The code should look similar to the following: String directory = "relative/path/to/some/directory". it's important to understand where resources should be added during the build life cycle. Again. others must read the list of active source directories. conforming with these standards improves the compatibility of your plugin with other plugins in the build. for the sake of brevity. the entire build will fail.
which copies all non-code resources to the output directory for inclusion in the project artifact. source roots are expressed as absolute file-system paths. any reference to the path of the project directory in the local file system should be removed. it. Remember. In this case however. One thing to note about this code snippet is the makeRelative() method. applying whatever processing is necessary. You've already learned that mojos can modify the list of resources included in the project artifact. it could be critically important to track the list of source directories used in a particular build. 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. In order to make this information more generally applicable. Returning to the buildinfo example. in order to incorporate list of source directories to the buildinfo object. it can be bound to any phase in the life cycle. you need to add the following code: for ( Iterator it = sourceRoots. To be clear. This involves subtracting ${basedir} from the source-root paths.iterator(). If a certain profile injects a supplemental source directory into the build (most likely by way of a special mojo binding). When you add this code to the extract mojo in the maven-buildinfo-plugin. now. By the time the mojo gains access to them. 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. ) { String sourceRoot = (String) it.Developing Custom Maven Plugins Now that the mojo has access to the list of project source roots. then this profile would dramatically alter the resulting project artifact when activated. However. This is the mechanism used by the resources mojo in the maven-resources-plugin. it can iterate through them. the ${basedir} expression refers to the location of the project directory in the local file system. since compile is the phase where source files are converted into classes.addSourceRoot( makeRelative( sourceRoot ) ). } buildInfo. Accessing the resource list Non-code resources complete the picture of the raw materials processed by a Maven build. for eventual debugging purposes. it will add a corresponding section to the buildinfo file that looks like the following: <sourceRoots> <sourceRoot>src/main/java</sourceRoot> <sourceRoot>some/custom/srcDir</sourceRoot> </sourceRoots> Since a mojo using this code to access project source-roots does not actually modify the build state in any way. as in the case of the extract mojo. Better Builds With Maven 150 .next().hasNext(). Therefore. binding to any phase later than compile should be acceptable.
Developing Custom Maven Plugins
Much like the source-root list, the resources list is easy to inject as a mojo parameter. The parameter appears as follows:
/** * List of Resource objects for the current build, containing * directory, includes, and excludes. * @parameter default-value="${project.resources}" * @required * @readonly */ private List resources;
Just like the source-root injection parameter, this parameter is declared as required for mojo execution and cannot be edited by the user. In this case, the user has the option of modifying the value of the list by configuring the resources section of the POM. As noted before with the dependencies parameter, allowing direct configuration of this parameter could easily produce results that are inconsistent with other resource-consuming mojos. It's also important to note that this list consists of Resource objects, which in fact contain information about a resource root, along with some matching rules for the resource files it contains. Since the resources list is an instance of java.util.List, and Maven mojos must be able to execute in a JDK 1.4 environment that doesn't support Java generics, mojos must be smart enough to cast list elements as org.apache.maven.model.Resource instances. Since mojos can add new resources to the build programmatically, capturing the list of resources used to produce a project artifact can yield information that is vital for debugging purposes. For instance, 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. Therefore, it is important that the buildinfo file capture the resource root directories used in the build for future reference. It's a simple task to add this capability, and can be accomplished through the following code snippet:
if ( resources != null && !resources.isEmpty() ) { for ( Iterator it = resources.iterator(); it.hasNext(); ) { Resource resource = (Resource) it.next(); String resourceRoot = resource.getDirectory(); } buildInfo.addResourceRoot( makeRelative( resourceRoot ) );
As with the prior source-root example, you'll notice the makeRelative() method. This method converts the absolute path of the resource directory into a relative path, by trimming the ${basedir} prefix. All POM paths injected into mojos are converted to their absolute form first, to avoid any ambiguity. It's necessary to revert resource directories to relative locations for the purposes of the buildinfo plugin, since the ${basedir} path won't have meaning outside the context of the local file system.
Better Builds With Maven
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. That section should appear as follows:
<resourceRoots> <resourceRoot>src/main/resources</resourceRoot> <resourceRoot>target/generated-resources/xdoclet</resourceRoot> </resourceRoots>
Once more, it's worthwhile to discuss the proper place for this type of activity within the build life cycle. Since all project resources are collected and copied to the project output directory in the processresources phase, any mojo seeking to catalog the resources used in the build should execute at least as late as the process-resources phase. This ensures that any resource modifications introduced by mojos in the build process have been completed. Like the vast majority of activities, which may be executed during the build process, collecting the list of project resources has an appropriate place in the life cycle.
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, which must be processed and included in the final project artifact. It's important to note however, that for every activity examined that relates to source-root directories or resource definitions, a corresponding activity can be written to work with their test-time counterparts. This chapter does not discuss test-time and compile-time source roots and resources as separate topics; instead, due to the similarities, the key differences are summarized in the table below. The concepts are the same; only the parameter expressions and method names are different. 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.addCompileSourceRoot() ${project.compileSourceRoots} helper.addResource() ${project.resources}
project.addTestSourceRoot() ${project.testSourceRoots} helper.addTestResource() ${project.testResources}
Better Builds With Maven
Developing Custom Maven Plugins
5.5.3. Attaching Artifacts for Installation and Deployment
Occasionally, mojos produce new artifacts that should be distributed alongside the main project artifact in the Maven repository system. These artifacts are typically a derivative action or side effect of the main build process. Maven treats these derivative artifacts as attachments to the main project artifact, in that they are never distributed without the project artifact being distributed. Classic examples of attached artifacts are source archives, javadoc bundles, and even the buildinfo file produced in the examples throughout this chapter. Once an artifact attachment is deposited in the Maven repository, it can be referenced like any other artifact. Usually, an artifact attachment will have a classifier, like sources or javadoc, which sets it apart from the main project artifact in the repository. Therefore, this classifier must also be specified when declaring the dependency for such an artifact, by using the classifier element for that dependency section within the POM. When a mojo, or set of mojos, produces a derivative artifact, an extra piece of code must be executed in order to attach that artifact to the project artifact. Doing so guarantees that attachment will be distributed when the install or deploy phases are run. This extra step, which is still missing from the maven-buildinfo-plugin example, can provide valuable information to the development team, since it provides information about how each snapshot of the project came into existence. While an e-mail describing the build environment is transient, and only serves to describe the latest build, 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, for historical reference. Including an artifact attachment involves adding two parameters and one line of code to your mojo. First, you'll need a parameter that references the current project instance as follows:
/** * Project instance, to which we want to add an attached artifact. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project;
This is the target of the attachment activities, in that it contains the project artifact that the build is in the process of creating. However, for convenience you should also inject the following reference to MavenProjectHelper, which will make the process of attaching the buildinfo artifact a little easier:
/** * This helper class makes adding an artifact attachment simpler. * @component */ private MavenProjectHelper helper;
See Section 5.6.2 for a discussion about MavenProjectHelper and component requirements.
Better Builds With Maven
Developing Custom Maven Plugins
Once you include these two fields in the extract mojo within the maven-buildinfo-plugin, the process of attaching the generated buildinfo file to the main project artifact can be accomplished by adding the following code snippet:
helper.attachArtifact( project, "xml", "buildinfo", outputFile );
From the prior examples, the meaning and requirement of project and outputFile references should be clear. However, there are also two somewhat cryptic string values being passed in: "xml" and "buildinfo". These values represent the artifact extension and classifier, respectively. By specifying an extension of "xml", you're telling Maven that the file in the repository should be named using a.xml extension. By specifying the "buildinfo" classifier, 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. It identifies the file as being produced by the the mavenbuildinfo-plugin, as opposed to another plugin in the build process which might produce another XML file with different meaning. This serves to attach meaning beyond simply saying, "This is an XML file". Now that you've added code to distribute the buildinfo file, you can test it by re-building the plugin, then running Maven to the install life-cycle phase on our test project. If you build the Guinea Pig project using this modified version of the maven-buildinfo-plugin, you should see the buildinfo file appear in the local repository alongside the project jar, as follows:
> > > > mvn install cd C:\Documents and Settings\jdcasey\.m2\repository cd org\codehaus\guineapig\guinea-pig-core\1.0-SNAPSHOT dir
guinea-pig-core-1.0-SNAPSHOT-buildinfo.xml guinea-pig-core-1.0-SNAPSHOT.jar guinea-pig-core-1.0-SNAPSHOT.pom
Now, the maven-buildinfo-plugin is ready for action. It can extract relevant details from a running build and generate a buildinfo file based on these details. From there, it can attach the buildinfo file to the main project artifact so that it's distributed whenever Maven installs or deploys the project. Finally, when the project is deployed, the maven-buildinfo-plugin can also generate an e-mail that contains the buildinfo file contents, and route that message to other development team members on the project development mailing list.
Better Builds With Maven
Developing Custom Maven Plugins
5.6. Summary
In its unadorned state, Maven represents an implementation of the 80/20 rule. Using the default lifecycle mapping, Maven can build a basic project with little or no modification – thus covering the 80% case. However, in certain circumstances, a project requires special tasks in order to build successfully. Whether they be code-generation, reporting, or verification steps, Maven can integrate these custom tasks into the build process through its extensible plugin framework. Since the build process for a project is defined by the plugins – or more accurately, the mojos – that are bound to the build life cycle, there is a standardized way to inject new behavior into the build by binding new mojos at different life-cycle phases. In this chapter, you've learned that it's a relatively simple to create a mojo, 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. Working with project dependencies and resources is equally as simple. Finally, you've also learned how a plugin generated file can be distributed alongside the project artifact in Maven's repository system, enabling you to attach custom artifacts for installation or deployment. Many plugins already exist for Maven use, only a tiny fraction of which are a part of the default lifecycle mapping. If your project requires special handling, chances are good that you can find a plugin to address this need at the Apache Maven project, the Codehaus Mojo project, or the project web site of the tools with which your project's build must to integrate. If not, developing a custom Maven plugin is an easy next step. 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. Using the plugin mechanisms described in this chapter, you can integrate almost any tool into the build process. However, remember that whatever problem your custom-developed plugin solves, it's unlikely to be a requirement unique to your project. So, if you have the means, please consider contributing back to the Maven community by providing access to your new plugin. It is in great part due to the re-usable nature of its plugins that Maven can offer such a powerful build platform.
Better Builds With Maven
6. 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.Samuel Butler Better Builds With Maven 156 . it is an art. .
finding out whether there is any activity on the project. But. and learning more about the health of the project. Maven takes all of the information you need to know about your project and brings it together under the project Web site. The next three sections demonstrate how to set up an effective project Web site. 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!). it was pointed out that Maven's application of patterns provides visibility and comprehensibility. The code that concluded Chapter 3 is also included in Code_Ch03. if the build fails its checks? The Web site also provides a permanent record of a project's health. you will be revisiting the Proficio application that was developed in Chapter 3.zip for convenience as a starting point.1. there will be too many failed builds.zip file into C:\mvnbook or your selected working directory. It provides additional information to help determine the reasons for a failed build. Maven can analyze. Better Builds With Maven 157 . relate. and how well it adapts to change. Conversely. why have a site. In this chapter. to get a build to pass. and what the nature of that activity is. It is these characteristics that assist you in assessing the health of your project.Assessing Project Health with Maven 6. and using a variety of tools. and whether the conditions for the checks are set correctly. which everyone can see at any time. and then run mvn install from the proficio subdirectory to ensure everything is in place. What Does Maven Have to do With Project Health? In the introduction. new tools that can assess its health are easily integrated. there are two aspects to consider: • • Code quality . you'll learn how to use a number of these tools effectively. This is important. To begin. Through the POM. When referring to health. Maven has access to the information that makes up a project. Because the POM is a declarative model of the project. Project vitality . unzip the Code_Ch03. This is unproductive as minor changes are prioritized over more important tasks. the project will meet only the lowest standard and go no further. if the bar is set too low. because if the bar is set too high. 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. For this reason. In this chapter. how well it is tested.determining how well the code works. and display that information in a single place.
However. Project Reports. On a new project. unless you choose to disable them. These reports provide a variety of insights into the quality and vitality of the project. and so on. Adding Reports to the Project Web site This section builds on the information on project Web sites in Chapter 2 and Chapter 3. Figure 6-1: The reports generated by Maven You can see that the navigation on the left contains a number of reports. and to reference as links in your mailing lists.2. issue tracker. review the project Web site shown in figure 6-1. These reports are useful for sharing information with others. by including the following section in proficio/pom.Assessing Project Health with Maven 6. you can add the Surefire report to the sample application. To start. adding a new report is easy. The Project Info menu lists the standard reports Maven includes with your site by default. this menu doesn't appear as there are no reports included. having these standard reports means that those familiar with Maven Web sites will always know where to find the information they need. SCM. For newcomers to the project.xml: Better Builds With Maven 158 . For example. is the focus of the rest of this chapter. The second menu (shown opened in figure 6-1). and now shows how to integrate project health information.
and as a result.Assessing Project Health with Maven ..maven. You can now run the following site task in the proficio-core directory to regenerate the site... <reporting> <plugins> < plugin> <groupId>org.html. Figure 6-2: The Surefire report Better Builds With Maven 159 . </project> This adds the report to the top level project. and is shown in figure 62.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> </plugin> </plugins> </reporting> . it will be inherited by all of the child modules.apache. C:\mvnbook\proficio\proficio-core> mvn site This can now be found in the file target/site/surefire-report..
maven.xml: . as seen in the previous section... Configuration for a reporting plugin is very similar. however it is added to the reporting section of the POM..apache. 6. <reporting> <plugins> <plugin> <groupId>org. it is important to understand how the report configuration is handled in Maven. You might recall from Chapter 2 that a plugin is configured using the configuration element inside the plugin declaration in pom.5</target> </configuration> </plugin> </plugins> </build> .maven...Assessing Project Health with Maven As you may have noticed in the summary..5</source> <target>1. Configuration of Reports Before stepping any further into using the project Web site. the defaults are sufficient to get started with a useful report.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <showSuccess>false</showSuccess> </configuration> </plugin> </plugins> </reporting> . Better Builds With Maven 160 . 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. and due to using convention over configuration.apache.3. Maven knows where the tests and test results are. <build> <plugins> <plugin> <groupId>org. For example.. for example: . the report shows the test results of the project.xml. For a quicker turn around. the report can be modified to only show test failures by adding the following configuration in pom. The addition of the plugin element triggers the inclusion of the report in the Web site..plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1. while the configuration can be used to modify its appearance or behavior.
even though it is not specific to the execution.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <outputDirectory> ${project. "Executions" such as this were introduced in Chapter 3.maven. To continue with the Surefire report. some reports apply to both the site.directory}/surefire-reports </outputDirectory> </configuration> <executions> <execution> <phase>test</phase> <goals> <goal>report</goal> </goals> </execution> </executions> </plugin> </plugins> </build> .build. However. To do this. you might think that you'd need to configure the parameter in both sections. the plugin would need to be configured in the build section instead of. this isn't the case – adding the configuration to the reporting section is sufficient.. always place the configuration in the reporting section – unless one of the following is true: 1. and not site generation. Plugins and their associated configuration that are declared in the build section are not used during site generation. consider if you wanted to create a copy of the HTML report in the directory target/surefirereports every time the build ran. or in addition to. is used only during the build. and the build.. they will all be included. Any plugin configuration declared in the reporting section is also applied to those declared in the build section. The configuration value is specific to the build stage Better Builds With Maven 161 . The reports will not be included in the site 2. Fortunately. the reporting section: ..apache. However. When you configure a reporting plugin.. The plugin is included in the build section to ensure that the configuration.Assessing Project Health with Maven If a plugin contains multiple reports. <build> <plugins> <plugin> <groupId>org. 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.
For example.build. To generate two HTML reports for these results. and cases where a particular report will be run more than once.html. by default all reports available in the plugin are executed once. Each report set can contain configuration. and that you had had generated its XML results to target/surefire-reports/unit and target/surefire-reports/perf respectively.xml: . Both of these cases can be achieved with the reportSets element. <reporting> <plugins> <plugin> <groupId>org. Better Builds With Maven 162 . However. consider if you had run Surefire twice in your build.maven..build. there are cases where only some of the reports that the plugin produces will be required. once for unit tests and once for a set of performance tests. and a list of reports to include.Assessing Project Health with Maven When you are configuring the plugins to be used in the reporting section.directory}/surefire-reports/perf </reportsDirectory> <outputName>surefire-report-perf</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> </reportSets> </plugin> </plugins> </reporting> . Running mvn site with this addition will generate two Surefire reports: target/site/surefire-reportunit. each time with a different configuration.html and target/site/surefire-report-perf... you would include the following section in your pom.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <reportSets> <reportSet> <id>unit</id> <configuration> <reportsDirectory> ${project..directory}/surefire-reports/unit </reportsDirectory> <outputName>surefire-report-unit</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> <reportSet> <id>perf</id> <configuration> <reportsDirectory> ${project. which is the reporting equivalent of the executions element in the build section.apache.
where the end user documentation is on a completely different server than the developer information. but quite separate to the end user documentation.. Consider the following: The commercial product. While the defaults are usually sufficient. • Better Builds With Maven 163 . depending on the project. 6.plugins</groupId> <artifactId>maven-project-info-reports-plugin</artifactId> <reportSets> <reportSet> <reports> <report>mailing-list</report> <report>license</report> </reports> </reportSet> </reportSets> </plugin> . • The open source graphical application. they must be enumerated in this list. Maven will use only the configuration that is specified in the plugin element itself. The reports in this list are identified by the goal names that would be used if they were run from the command line. If you want all of the reports in a plugin to be generated.. This approach to balancing these competing requirements will be vary. 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. On the entrance page there are usage instructions for Proficio. who isn't interested in the state of the source code. It is also possible to include only a subset of the reports in a plugin. running mvn surefire-report:report will not use either of these configurations.4. <plugin> <groupId>org. as with executions. add the following to the reporting section of the pom.Assessing Project Health with Maven However. and most likely doesn't use Maven to generate it. The reports element in the report set is a required element. where much of the source code and Javadoc reference is of interest to the end user. When a report is executed individually. • The open source reusable library.apache. to generate only the mailing list and license pages of the standard reports. For example. This may be confusing for the first time visitor.. there's something subtly wrong with the project Web site. which are targeted at an end user.xml file: . which are targeted at the developers.. Separating Developer Reports From User Documentation After adding a report.maven. but in the navigation there are reports about the health of the project. outside of any report sets. where the developer information is available. this customization will allow you to configure reports in a way that is just as flexible as your build.
You can maintain a stable branch. Some standard reports. This is typically true for the end user documentation. However. as it is confusing for those reading the site who expect it to reflect the latest release. The best compromise between not updating between releases. is to branch the end user documentation in the same way as source code. and not introducing incorrect documentation. the Javadoc and other reference material are usually distributed for reference as well. and the content's characteristics. This is true of the news and FAQs. that can be updated between releases without risk of including new features. 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. The Separated column indicates whether the documentation can be a separate module or project.Assessing Project Health with Maven To determine the correct balance. including the end user documentation in the normal build is reasonable as it is closely tied to the source code reference. This is documentation for the end user including usage instructions and guides. each section of the site needs to be considered. the Updated column indicates whether the content is regularly updated. source code references should be given a version and remain unchanged after being released. Better Builds With Maven 164 . and a development branch where new features can be documented for when that version is released. It refers to a particular version of the software. in some cases down to individual reports. but usually not distributed or displayed in an application. It is good to update the documentation on the Web site between releases. The situation is different for end user documentation. and to maintain only one set of documentation. Table 6-1: Project Web site content types Content Description Updated Distributed Separated News. which are based on time and the current state of the project. and sometimes they are available for download separately. Javadoc) that in a library or framework is useful to the end user. like mailing list information and the location of the issue tracker and SCM are updated also. which are continuously published and not generally of interest for a particular release. The Distributed column in the table indicates whether that form of documentation is typically distributed with the project. It is also true of the project quality and vitality reports. regardless of releases. Yes Yes No Yes Yes No No Yes No Yes No No In the table. Sometimes these are included in the main bundle. This is reference material (for example. Features that are available only in more recent releases should be marked to say when they were introduced. While there are some exceptions. These are the reports discussed in this chapter that display the current state of the project to the developers. It is important not to include documentation for features that don't exist in the last release. For libraries and frameworks. the source code reference material and reports are usually generated from the modules that hold the source code and perform the build. For a single module library. Table 6-1 lists the content that a project Web site may contain.
The current structure of the project is shown in figure 6-3. In the following example. The resulting structure is shown in figure 6-4. This avoids including inappropriate report information and navigation elements. a module is created since it is not related to the source code reference material.mvnbook. or maybe totally independent. which you can later add content to. This separated documentation may be a module of the main project. Better Builds With Maven 165 . While these recommendations can help properly link or separate content according to how it will be used. you will learn how to separate the content and add an independent project for the news and information Web site.Assessing Project Health with Maven However.mergere. in most cases. This is done using the site archetype : C:\mvnbook\proficio> mvn archetype:create -DartifactId=user-guide \ -DgroupId=com.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple This archetype creates a very basic site in the user-guide subdirectory. Figure 6-3: The initial setup The first step is to create a module called user-guide for the end user documentation. the site currently contains end user documentation and a simple report. It is important to note that none of these are restrictions placed on a project by Maven. In Proficio. you are free to place content wherever it best suits your project. but make it an independent project when it forms the overall site with news and FAQs. In this case. and is not distributed with the project. You would make it a module when you wanted to distribute it with the rest of the project. the documentation and Web site should be kept in a separate module dedicated to generating a site.
com/mvnbook/proficio. In this example..mergere. <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. edit the top level pom. First.com/www/library/mvnbook/proficio/reference/${project.com/mvnbook/proficio/user-guide. is useful if you are maintaining multiple public versions. Adding the version to the development documentation. <distributionManagement> <site> . Under the current structure. whether to maintain history or to maintain a release and a development preview.version} </url> </site> </distributionManagement> . the development documentation would go to that location. the URL and deployment location were set to the root of the Web site: http://library. 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. while optional..xml file to change the site deployment url: .. Better Builds With Maven 166 .mergere.. Previously.
C:\mvnbook> mvn archetype:create -DartifactId=proficio-site \ -DgroupId=com. edit the user-guide/pom. This will include news and FAQs about the project that change regularly. Now that the content has moved.com/www/library/mvnbook/proficio/user-guide </url> </site> </distributionManagement> . This time. you can create a new site using the archetype.. run it one directory above the proficio directory.mvnbook.xml as follows: Better Builds With Maven 167 .site</id> <url> scp://mergere.mergere..mergere.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple The resulting structure is shown in figure 6-5.xml file to set the site deployment url for the module: .com/mvnbook/proficio/reference/1.com/mvnbook/proficio/user-guide/ • http://library. As before.0-SNAPSHOT/ • You will not be able to deploy the Web site to the location scp://mergere. 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.. a top level site for the project is required. in the ch06-1 directory.Assessing Project Health with Maven Next. <distributionManagement> <site> <id>mvnbook.mergere. There are now two sub-sites ready to be deployed: http://library..com/www/library/mvnbook/proficio/user-guide and it is included here only for illustrative purposes.
] <url>http://library...Proficio project started Finally. replace the src/site/apt/index.. Better Builds With Maven 168 . like the following: ----Proficio ----Joe Blogs ----2 February 2006 ----Proficio Proficio is super. so that link won't work even if the site is deployed.] <distributionManagement> <site> <id>mvnbook.. 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..com/www/library/mvnbook/proficio</url> </site> </distributionManagement> [.. add some menus to src/site/site. You can now run mvn site in proficio-site to see how the separate site will look..] Next.xml that point to the other documentation as follows: . * News * <16 Jan 2006> .0-SNAPSHOT/" /> </menu> . Note that you haven't produced the apidocs directory yet. Generating reference documentation is covered in section 6.Assessing Project Health with Maven [.apt file with a more interesting news page.website</id> <url>scp://mergere.com/mvnbook/proficio</url> [... <menu name="Documentation"> <item name="User's Guide" href="/user-guide/" /> </menu> <menu name="Reference"> <item name="API" href="/reference/1.mergere. If you deploy both sites to a server using mvn site-deploy as you learned in Chapter 3.. you will then be able to navigate through the links and see how they relate.6 of this chapter.0-SNAPSHOT/apidocs/" /> <item name="Developer Info" href="/reference/1.
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.0 features Use to enforce a standard code style. 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. and look at the output to determine which reports to use. it is recommended that these checks be constrained to the continuous integration and release environments if they cause lengthy builds. While these aren't all the reports available for Maven. Table 6-2: Report highlights Report Description Visual Check Notes ✔ ✔ ✔ ✔ ✗ Javadoc Produces an API reference from Javadoc.5. the performance of your build will be affected by this choice. the guidelines should help you to determine whether you need to use other reports. While future versions of Maven will aim to streamline this. Team Collaboration with Maven.Assessing Project Health with Maven 6. it is possible in the future that reports for other languages will be available. or you can walk through all of the examples one by one. Not useful if there are a lot of errors to be fixed – it will be slow and the result unhelpful. in addition to the generic reports such as those for dependencies and change tracking. JXR Yes N/A Checkstyle Checks your source code against a standard descriptor for formatting issues. Yes Yes ✔ ✔ ✗ Better Builds With Maven 169 . While this is certainly the case at present. such as Checkstyle Doesn't handle JDK 5. Report results and checks performed should be accurate and conclusive – every developer should know what they mean and how to address them. See Chapter 7. Produces a source cross reference for any Java code. the reports that utilize unit tests often have to re-run the tests with new parameters. and an applicable build check (for testing a certain condition and failing the build if it doesn't pass). and which checks to perform during the build. You may notice that many of these tools are Java-centric. there is also a note about whether it has an associated visual report (for project site inclusion). In particular. Table 6-2 covers the reports discussed in this chapter and reasons to use them. Recommended to enhance readability of the code. is an important decision that will determine the effectiveness of your build reports. Choosing Which Reports to Include Choosing which reports to include. In some instances. for more information. For each report.
Show the results of unit tests visually. Simple report on outstanding tasks or other markers in source code Analyze code statement coverage during unit tests or other code execution. checks for duplicate source code blocks that indicates it was copy/pasted. Recommended for multiple module builds where consistent versions are important.Assessing Project Health with Maven Report Description Visual Check Notes ✔ ✔ PMD Checks your source code against known rules for code smells. Can help find snapshots prior to release. Avoids issues when one piece of code is fixed/updated and the other forgotten Useful for tracking TODO items Very simple. Part of PMD. Check already performed by surefire:test. Should be used for keeping teams up to date on internal projects also. so additional tools may be required. Doesn't identify all missing or inadequate tests. Recommended for all publicly released projects. Can also show any tests that are long running and slowing the build. convenient set up Can be implemented using Checkstyle rules instead. 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 170 . 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. Some overlap with Checkstyle rules Can be used to identify lazy copy/pasted code that might be refactored into a shared method. Recommended for easier browsing of results. Recommended for teams with a focus on tests Can help identify untested or even unused code.
and. however the content pane is now replaced with a syntax-highlighted. This page links to the two sets of cross references: one for the main source tree. Figure 6-6: An example source code cross reference Figure 6-6 shows an example of the cross reference.Assessing Project Health with Maven 6. and one for the unit tests. 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. 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. by running the following command: C:\mvnbook\proficio\proficio-core> mvn jxr:jxr You should now see a target/site/jxr. Better Builds With Maven 171 . Javadoc – the Java documentation tool You can get started with JXR on the example project very quickly. The hyper links in the content pane can be used to navigate to other classes and interfaces within the cross reference. The two reports this section illustrates are: • • JXR – the Java source cross reference. crossreferenced Java source file for the selected class.6.html created.
. The end result is the familiar Javadoc output. A Javadoc report is only as good as your Javadoc! Make sure you document the methods you intend to display in the report. In most cases.apache. the links can be used to quickly find the source belonging to a particular exception.. However... Unlike JXR. however if you'd like a list of available configuration options.. with most of the command line options of the Javadoc tool available. in target/site/apidocs.xml: .plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> </plugin> .. so an equally important piece of reference material is the Javadoc report. Better Builds With Maven 172 .xml as a site report to ensure it is run every time the site is regenerated: .. Including JXR as a permanent fixture of the site for the project is simple. many of the other reports demonstrated in this chapter will be able to link to the actual code to highlight an issue. and if possible use Checkstyle to ensure they are documented. browsing source code is too cumbersome for the developer if they only want to know about how the API works. Using Javadoc is very similar to the JXR report and most other reports in Maven. see the plugin reference at http://maven..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. <plugin> <groupId>org.. the Javadoc report is quite configurable. Now that you have a source cross reference.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. if you don't have the project open in your IDE. and can be done by adding the following to proficio/pom.plugins</groupId> <artifactId>maven-jxr-plugin</artifactId> </plugin> .maven. you should include it in proficio/pom. Or. Again. the default JXR configuration is sufficient.maven. 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.apache.. <reporting> <plugins> <plugin> <groupId>org. </plugins> </reporting> .org/plugins/maven-jxr-plugin/.
but this would still limit the available classes in the navigation as you hop from module to module. Setting up Javadoc has been very convenient. will link both the JDK 1. If you regenerate the site in proficio-core with mvn site again. ensuring that the deployed Javadoc corresponds directly to the artifact with which it is deployed for use in an IDE.String and java. <plugin> <groupId>org. when added to proficio/pom.plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> <configuration> <links> <link>http://java. One option would be to introduce links to the other modules (automatically generated by Maven based on dependencies. are linked to API documentation on the Sun website.apache..html. Try running mvn clean javadoc:javadoc in the proficio directory to produce the aggregated Javadoc in target/site/apidocs/index. Edit the configuration of the existing Javadoc plugin in proficio/pom..lang.4 API documentation and the Plexus container API documentation used by Proficio: . but conversely to have the Javadoc closely related. but it results in a separate set of API documentation for each library in a multi-module build.0-alpha-9/apidocs</link> </links> </configuration> </plugin> .com/j2se/1. this is not sufficient.Object. Better Builds With Maven 173 .Assessing Project Health with Maven One useful option to configure is links. For example.. the Javadoc plugin provides a way to produce a single set of API documentation for the entire project. of course!). When built from the top level project.org/ref/1. as well as any references to classes in Plexus. This setting must go into the reporting section so that it is used for both reports and if the command is executed separately.. <configuration> <aggregate>true</aggregate> . this simple change will produce an aggregated Javadoc and ignore the Javadoc report in the individual modules.sun. the following configuration..4.xml. the next section will allow you to start monitoring and improving its health.xml by adding the following line: . you'll see that all references to the standard JDK classes such as java.. Instead. this will link to an external Javadoc reference at a given URL.maven. Now that the sample application has a complete reference for the source code..codehaus.2/docs/api</link> <link>http://plexus. Since it is preferred to have discreet functional pieces separated into distinct modules. In the online mode.. this setting is always ignored by the javadoc:jar goal.. However.lang.. </configuration> .
net/) • Checkstyle (http://checkstyle. 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. some source files are identified as having problems that could be addressed. Also. 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.7. The result can help identify bugs. this is important for both the efficiency of other team members and also to increase the overall level of code comprehension. copy-and-pasted code. and this section will look at three: PMD (http://pmd.sf.net/) • Tag List • PMD takes a set of either predefined or user-defined rule sets and evaluates the rules across your Java source code. Figure 6-7: An example PMD report As you can see. since the JXR report was included earlier.Assessing Project Health with Maven 6. Figure 6-7 shows the output of a PMD report on proficio-core.sf. the line numbers in the report are linked to the actual source code so you can browse the issues. Better Builds With Maven 174 . and violations of a coding standard. such as unused methods and variables. which is obtained by running mvn pmd:pmd.
xml file: . In either case. <plugin> <groupId>org. with the following content: <?xml version="1. you can choose to create a custom rule set. However.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>/rulesets/basic. The "basic" rule set includes checks on empty blocks. Adding new rule sets is easy. you could create a rule set with all the default rules.. adding: Better Builds With Maven 175 .maven.xml..plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> </plugin> . to include the default rules.. methods. redundant or unused import declarations.0"?> <ruleset name="custom"> <description> Default rules.. if you configure these. <plugin> <groupId>org. add the following to the plugin configuration you declared earlier: .xml file.apache. You may find that you like some rules in a rule set. The default PMD report includes the basic.xml</ruleset> <ruleset>/rulesets/finalizers. no unused private field warning </description> <rule ref="/rulesets/basic. and the finalizer rule sets.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. unnecessary statements and possible bugs – such as incorrect loop variables. For example..xml" /> <rule ref="/rulesets/unusedcode..xml</ruleset> <ruleset>/rulesets/imports.xml" /> <rule ref="/rulesets/imports. For example. and imports rule sets. but exclude the "unused private field" rule.maven.xml</ruleset> <ruleset>/rulesets/unusedcode. change the configuration by overriding it in the proficio-core/pom. variables and parameters.xml</ruleset> </rulesets> </configuration> </plugin> . The "unused code" rule set will locate unused private fields. but not others. create a file in the proficio-core directory of the sample application called src/main/pmd/custom. To try this.apache. by passing the rulesets configuration to the plugin. unused code..xml"> <exclude name="UnusedPrivateField" /> </rule> </ruleset> To use this rule set.. you may use the same rule sets in a number of projects. Or. you must configure all of them – including the defaults explicitly. The "imports" rule set will detect duplicate.
One important question is how to select appropriate rules.Assessing Project Health with Maven ..maven.. and imports are useful in most scenarios and easily fixed. and add more as needed. you need to make sure it stays that way. Start small.net/bestpractices. 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.sf.sf. It is also possible to write your own rules if you find that existing ones do not cover recurring problems in your source code.html.xml</ruleset> </rulesets> </configuration> </plugin> </plugins> </reporting> . For PMD. From this starting. <reporting> <plugins> <plugin> <groupId>org. basic. [INFO] --------------------------------------------------------------------------- Better Builds With Maven 176 .html: • • Pick the rules that are right for you... unusedcode. select the rules that apply to your own project.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>${basedir}/src/main/pmd/custom. see the instructions on the PMD Web site at http://pmd. For more examples on customizing the rule sets.net/howtomakearuleset. If you've done all the work to select the right rules and are correcting all the issues being discovered. try the following guidelines from the Web site at http://pmd. Try this now by running mvn pmd:check on proficio-core. There is no point having hundreds of violations you won't fix.apache.
.xml file: <build> <plugins> <plugin> <groupId>org. To do so. it can be slow and obtrusive during general development. By default. To correct this. the build will succeed. You will see that the build fails.apache.. try running mvn verify in the proficio-core directory. fix the errors in the src/main/java/com/mergere/mvnbook/proficio/DefaultProficio.. This is done by binding the goal to the build life cycle. See Continuous Integration with Continuum section in the next chapter for information on using profiles and continuous integration. adding the check to a profile.. For that reason. While this check is very useful. add the following section to the proficio/pom.. but recall from Configuring Reports and Checks section of this chapter that the reporting configuration is applied to the build as well.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> ..java file by adding a //NOPMD comment to the unused variables and method: . you should include the check in the build. Better Builds With Maven 177 . 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. the pmd:check goal is run in the verify phase.. but mandatory in an integration environment. </plugins> </build> You may have noticed that there is no configuration here. If you need to run checks earlier. // NOPMD . // Trigger PMD and checkstyle int i..maven. which is executed only in an appropriate environment. can make the check optional for developers. which occurs after the packaging phase. int j.Assessing Project Health with Maven Before correcting these errors. so that it is regularly tested.. // NOPMD .. If you run mvn verify again. private void testMethod() // NOPMD { } .
Better Builds With Maven 178 . and it includes a list of duplicate code fragments discovered across your entire source base. An example report is shown in figure 6-8. or copy/paste detection report.Assessing Project Health with Maven While the PMD report allows you to run a number of different rules. there is one that is in a separate report. or to enforce a check will depend on the environment in which you are working. which defaults to 100. resulting in developers attempting to avoid detection by making only slight modifications. Whether to use the report only. rather than identifying a possible factoring of the source code. This is the CPD. and will appear as "CPD report" in the Project Reports menu. With this setting you can fine tune the size of the copies detected.au/products/simian/). Simian can also be used through Checkstyle and has a larger variety of configuration options for detecting duplicate source code. However. This may not give you enough control to effectively set a rule for the source code. pmd:cpd-check can be used to enforce a failure if duplicate source code is found. Figure 6-8: An example CPD report In a similar way to the main check. the CPD report contains only one variable to configure: minimumTokenCount.com.redhillconsulting. There are other alternatives for copy and paste detection. such as Checkstyle.This report is included by default when you enable the PMD plugin in your reporting section. and a commercial product called Simian (http://www.
refer to the list on the Web site at http://checkstyle. similar to PMD. the rules used are those of the Sun Java coding conventions.net/availablechecks. but Proficio is using the Maven team's code style. warnings or errors are listed in a summary.html. If you need to learn more about the available modules in Checkstyle. with a link to the corresponding source line – if the JXR report was enabled. and still rely on other tools for greater coverage. and then the errors are shown. • Use it to check code formatting and selected other problems.sf. • 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. Figure 6-9 shows the Checkstyle report obtained by running mvn checkstyle:checkstyle from the proficio-core directory. and rely on other tools for detecting other problems. Better Builds With Maven 179 . but has more recently added checks for other code issues. It was originally designed to address issues of format and style. in many ways. That's a lot of errors! By default. Depending on your environment.Assessing Project Health with Maven Checkstyle is a tool that is. you may choose to use it in one of the following ways: Use it to check code formatting only. Some of the extra summary information for overall number of errors and the list of checks used has been trimmed from this display.
Table 6-3: Built-in Checkstyle configurations Configuration config/sun_checks.0 and above.xml config/maven_checks. you will need to create a Checkstyle configuration. By default.0.html.net/config.com/docs/codeconv/ http://maven.org/turbine/common/codestandards. and typically. Better Builds With Maven 180 .html No longer online – the Avalon project has closed. While this chapter will not go into an example of how to do this. as explained at http://maven.sun. This report. Before completing this section it is worth mentioning the Tag List plugin. then it is likely to be more readable and easily learned by people joining your project. The configLocation parameter can be set to a file within your build.plugins</groupId> <artifactId>maven-checkstyle-plugin</artifactId> <configuration> <configLocation>config/maven_checks. <plugin> <groupId>org. filter the results.xml config/turbine_checks.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. a URL. this will identify the tags TODO and @todo in the comments of your source code. known as "Task List" in Maven 1.apache. one or the other will be suitable for most people. The Checkstyle plugin itself has a large number of configuration options that allow you to customize the appearance of the report. or would like to use the additional checks introduced in Checkstyle 3.apache. or a resource within a special dependency also. These checks are for backwards compatibility only.html#Maven%20Code%20Style http://jakarta. add the following to the reporting section of proficio/pom. It is a good idea to reuse an existing Checkstyle configuration for your project if possible – if the style you use is common. It is also possible to share a Checkstyle configuration among multiple projects. The built-in Sun and Maven standards are quite different. the Checkstyle documentation provides an excellent reference at http://checkstyle. However. and to parameterize the Checkstyle configuration for creating a baseline organizational standard that can be customized by individual projects.sf.html.Assessing Project Health with Maven This style is also bundled with the Checkstyle plugin.org/plugins/maven-checkstyle-plugin/tips.org/guides/development/guidem2-development.xml</configLocation> </configuration> </plugin> Table 6-3 shows the configurations that are built into the Checkstyle plugin. if you have developed a standard that differs from these.maven.apache.xml: . so to include the report in the site and configure it to use the Maven style.xml config/avalon_checks..apache.. will look through your source code for known tags and provide a report on those it finds.
using this report on a regular basis can be very helpful in spotting any holes in the test plan. add the following to the reporting section of proficio/pom. 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. run mvn cobertura:cobertura in the proficio-core directory of the sample application. While the default Surefire configuration fails the build if the tests fail. Failing the build is still recommended – but the report allows you to provide a better visual representation of the results. PMD. the report (run either on its own. It is actually possible to achieve this using Checkstyle or PMD rules. and more plugins are being added every day. will ignore these failures when generated to show the current test state. or as part of the site).mojo</groupId> <artifactId>taglist-maven-plugin</artifactId> <configuration> <tags> <tag>TODO</tag> <tag>@todo</tag> <tag>FIXME</tag> <tag>XXX</tag> </tags> </configuration> </plugin> . As you learned in section 6. such as FindBugs. There are additional testing stages that can occur after the packaging step to verify that the assembled package works under other circumstances. FIXME.Assessing Project Health with Maven To try this plugin. Knowing whether your tests pass is an obvious and important assessment of their health. This configuration will locate any instances of TODO.. 6.. 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. have beta versions of plugins available from the http://mojo.sf.. based on the theory that you shouldn't even try to use something before it has been tested.8. Checkstyle. In the build life cycle defined in Chapter 2. or XXX in your source code. and Tag List are just three of the many tools available for assessing the health of your project's source code.. <plugin> <groupId>org. In addition to that. JavaNCSS and JDepend. Some other similar tools. it is easy to add a report to the Web site that shows the results of the tests that have been run.html.2.codehaus. Setting Up the Project Web Site. Figure 6-10 shows the output that you can view in target/site/cobertura/index. Cobertura (http://cobertura. 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.org/ project at the time of this writing.codehaus. you saw that tests are run before the packaging of the library or application for distribution. Better Builds With Maven 181 . @todo. To see what Cobertura is able to report. for assessing coverage.net) is the open source tool best integrated with Maven.xml: . While you are writing your tests. At the time of writing. Another critical technique is to determine how much of your source code is covered by the test execution.
comments and white space. 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. or for which all possible branches were not executed.Assessing Project Health with Maven The report contains both an overall summary. you'll notice the following markings: • • • Unmarked lines are those that do not have any executable code associated with them. a branch is an if statement that can behave differently depending on whether the condition is true or false. Lines in red are statements that were not executed (if the count is 0). in the familiar Javadoc style framed layout. For example. Unmarked lines with a green number in the second column are those that have been completely covered by the test execution. For a source file. This includes method and class declarations. Figure 6-10: An example Cobertura report Better Builds With Maven 182 . and a line-by-line coverage analysis of each source file.
might indicate a method should be re-factored into simpler pieces. add the following to the build section of proficio/pom. Add the following to the reporting section of proficio/pom.. High numbers (for example. To ensure that this happens.. you might consider having PMD monitor it. you'll see that the cobertura. If you now run mvn site under proficio-core.Assessing Project Health with Maven The complexity indicated in the top right is the cyclomatic complexity of the methods in the class. over 10). the report will be generated in target/site/cobertura/index. While not required. as it can be hard to visualize and test the large number of alternate code paths. 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> . Better Builds With Maven 183 .codehaus. which measures the number of branches that occur in a particular method..ser. as well as the target directory. If you now run mvn clean in proficio-core. Due to a hard-coded path in Cobertura. If this is a metric of interest.codehaus. there is another useful setting to add to the build section. <plugin> <groupId>org.ser file is deleted.. and is not cleaned with the rest of the project. <build> <plugins> <plugin> <groupId>org.. the database used is stored in the project directory as cobertura.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> <executions> <execution> <id>clean</id> <goals> <goal>clean</goal> </goals> </execution> </executions> </plugin> </plugins> </build> .. The Cobertura report doesn't have any notable configuration.xml: ..html. so including it in the site is simple..xml: .
This ensures that if you run mvn cobertura:check from the command line.. You would have seen in the previous examples that there were some lines not covered. these are instrumented in a separate directory.... and decide to reduce the overall average required. the check will be performed. 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. so running the check fails. and 100% branch coverage rate. The rules that are being used in this configuration are 100% overall line coverage rate. This wouldn't be the case if it were associated with the life-cycle bound check execution. You can do this for Proficio to have the tests pass by changing the setting in proficio/pom. add a configuration and another execution to the build plugin definition you added above when cleaning the Cobertura database: . Better Builds With Maven 184 . You'll notice that your tests are run twice. and the tests are re-run using those class files instead of the normal ones (however. you would add unit tests for the functions that are missing tests. This is because Cobertura needs to instrument your class files. looking through the report..xml: . <configuration> <check> <totalLineRate>80</totalLineRate> . <configuration> <check> <totalLineRate>100</totalLineRate> <totalBranchRate>100</totalBranchRate> </check> </configuration> <executions> .Assessing Project Health with Maven To configure this goal for Proficio. If you now run mvn verify under proficio-core. Note that the configuration element is outside of the executions. However. the check passes.. so are not packaged in your application). the configuration will be applied.. If you run mvn verify again. you may decide that only some exceptional cases are untested. Normally. as in the Proficio example.... <execution> <id>check</id> <goals> <goal>check</goal> </goals> </execution> </executions> .
0 support is also available. For example. Set some known guidelines for what type of code can remain untested. involve the whole development team in the decision. Better Builds With Maven 185 .org/cobertura-maven-plugin. and get integration with these other tools for free. For more information. Of course. it is possible for you to write a provider to use the new tool. It also won't tell you whether the results of untested input values produce the correct results. using packageLineRate and packageBranchRate. The best known commercial offering is Clover. In both cases. These reports won't tell you if all the features have been implemented – this requires functional or acceptance testing. It is just as important to allow these exceptions. there is more to assessing the health of tests than success and coverage. the easiest way to increase coverage is to remove code that handles untested. 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. or as the average across each package. such as handling checked exceptions that are unexpected in a properly configured system and difficult to test. refer to the Cobertura plugin configuration reference at http://mojo. and you can evaluate it for 30 days when used in conjunction with Maven. It behaves very similarly to Cobertura. Some helpful hints for determining the right code coverage settings are: • • • • • • Like all metrics. 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. 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. although not yet integrated with Maven directly. Don't set it too high. You may want to enforce this for each file individually as well.Assessing Project Health with Maven These settings remain quite demanding though. may be of assistance there. Remember. This will allow for some constructs to remain untested. Tools like Jester (http://jester. and at the time of writing experimental JUnit 4. as it will become a minimum benchmark to attain and rarely more. as it will discourage writing code to handle exceptional cases that aren't being tested. only allowing a small number of lines to be untested.sf. To conclude this section on testing. Surefire supports tests written with TestNG.apache. 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. Don't set it too low.org/plugins/maven-clover-plugin/. It is also possible to set requirements on individual packages or classes using the regexes parameter. and setting the total rate higher than both.codehaus. Choosing appropriate settings is the most difficult part of configuring any of the reporting metrics in Maven. Cobertura is not the only solution available for assessing test coverage. using lineRate and branchRate. Consider setting any package rates higher than the per-class rate. which is very well integrated with Maven as well. For more information. so that they understand and agree with the choice. these reports work unmodified with those test types. Remain flexible – consider changes over time rather than hard and fast rules. Choose to reduce coverage requirements on particular classes or packages rather than lowering them globally.net).
the full graph of a project's dependencies can quickly balloon in size and start to introduce conflicts.0 introduced transitive dependencies. While this is only one of Maven's features. used well it is a significant time saver. and browse to the file generated in target/site/dependencies. and a number of other features such as scoping and version selection.Assessing Project Health with Maven 6. Maven 2. If you haven't done so already.html. but does introduce a drawback: poor dependency maintenance or poor scope and version selection affects not only your own project. but any projects that depend on your project. Figure 6-11: An example dependency report Better Builds With Maven 186 . This brought much more power to Maven's dependency mechanism. Left unchecked.9. 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. where the dependencies of dependencies are included in a build. run mvn site in the proficio-core directory. The result is shown in figure 6-11.
A dependency graphing plugin that will render a graphical representation of the information. as well as comments about what versions and scopes are selected. The file target/site/dependencyconvergence. This will output the dependency tree as it is calculated. and that plexus-container-default attempts to introduce junit as a compile dependency. but appears in a multi-module build only. 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. but more importantly in the second section it will list all of the transitive dependencies included through those dependencies. Another report that is available is the "Dependency Convergence Report".8. For example.Assessing Project Health with Maven This report shows detailed information about your direct dependencies. This report is also a standard report.0-SNAPSHOT (selected for compile) Here you can see that.4 (selected for compile) classworlds:1. To see the report for the Proficio project.0-SNAPSHOT junit:3. or an incorrect scope – and choose to investigate its inclusion. this requires running your build with debug turned on. which indicates dependencies that are in development.1 (selected for test) plexus-container-default:1. Whether there are outstanding SNAPSHOT dependencies in the build.0-SNAPSHOT (selected for compile) proficio-model:1. and is shown in figure 6-12.0.8. run mvn site from the base proficio directory. This can be quite difficult to read. Currently. and must be updated before the project can be released. It also includes some statistics and reports on two important factors: • Whether the versions of dependencies used for each module is in alignment. an incorrect version. and why. using indentation to indicate which dependencies introduce other dependencies. for example. This helps ensure your build is consistent and reduces the probability of introducing an accidental incompatibility. local scope test wins) proficio-api:1. The report shows all of the dependencies included in all of the modules within the project. such as mvn -X package.1 (not setting scope to: compile.0-alpha-9 (selected for compile) plexus-utils:1.1-alpha-2 (selected for compile) junit:3. It's here that you might see something that you didn't expect – an extra dependency. but that it is overridden by the test scoped dependency in proficio-core. • Better Builds With Maven 187 . proficio-model is introduced by proficio-api.html will be created. here is the resolution process of the dependencies of proficio-core (some fields have been omitted for brevity): proficio-core:1.
Better Builds With Maven 188 . 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. To improve your project's health and the ability to reuse it as a dependency itself.Assessing Project Health with Maven Figure 6-12: The dependency convergence report These reports are passive – there are no associated checks for them. rather than using the latest available. Use a range of supported dependency versions. or runtime if it is needed to bundle with or run the application but not for compiling your source code). declaring the absolute minimum supported as the lower boundary. You can control what version is actually used by declaring the dependency version in a project that packages or runs the application. they can provide basic help in identifying the state of your dependencies once you know what to find.
this section will focus on improving the quality of the code released. Better Builds With Maven 189 .Assessing Project Health with Maven • Add exclusions to dependencies to remove poorly defined dependencies from the tree. there is no verification that a library is binary-compatible – incompatibility will be discovered only when there's a failure. Given the importance of this task. Libraries will often be substituted by newer versions to obtain new features or bug fixes. An important tool in determining whether a project is ready to be released is Clirr (http://clirr. Clirr detects whether the current version of a library has introduced any binary incompatibilities with the previous release. While the next chapter will go into more detail about how Maven can help automate that task and make it more reliable. Two that are in progress were listed above. and the information released with it. 6. more tools are needed in Maven. Because existing libraries are not recompiled every time a version is changed.10. but then expected to continue working as they always have. but it is often tedious and error prone. specification dependencies that let you depend on an API and manage the implementation at runtime. 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.net/). 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. An example Clirr report is shown in figure 6-13.sf. and more. Catching these before a release can eliminate problems that are quite difficult to resolve once the code is "in the wild". This is particularly the case for dependencies that are optional and unused by your project. Monitoring and Improving the Health of Your Releases Releasing a project is one of the most important procedures you will perform.
[clirr:clirr] Comparing to version: 0. that is before the current development version. [INFO] [INFO] [INFO] [INFO] [INFO] . you'll notice that Maven reports that it is using version 0. For example. back to the first release. By default. the interactions between the project's own components will start behaving as if they were externally-linked. You can obtain the same result by running the report on its own using mvn clirr:clirr.. the Clirr report shows only errors and warnings. by setting the minSeverity parameter.. where the dependency mechanism is based on the assumption of binary compatibility between versions... This gives you an overview of all the changes since the last release.codehaus.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <minSeverity>info</minSeverity> </configuration> </plugin> </plugins> </reporting> . As a project grows. If you run either of these commands.9 of proficio-api against which to compare (and that it is downloaded if you don't have it already): . However. If you run mvn site in proficio-api..xml: .. To see this in action. the answer here is clearly – yes.9 ------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------- This version is determined by looking for the newest release in repository. Maven currently works best if any version of an artifact is backwards compatible. <reporting> <plugins> <plugin> <groupId>org.8 release. While methods of marking incompatibility are planned for future versions. even if they are binary compatible.. add the following to the reporting section of proficio-api/pom.8 Better Builds With Maven 190 . This is particularly true in a Maven-based environment.. to compare the current code to the 0. the report will be generated in target/site/clirrreport. run the following command: mvn clirr:clirr -DcomparisonVersion=0.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. You can change the version used with the comparisonVersion parameter. you can configure the plugin to show all informational messages.html. Different modules may use different versions. or a quick patch may need to be made and a new version deployed into an existing application.
The longer poor choices remain. Once a version has been released that is intended to remain binary-compatible going forward. it is almost always preferable to deprecate an old API and add a new one. add the following to the build section: . rather than removing or changing the original API and breaking binary compatibility.zip file. and it can assist in making your own project more stable. delegating the code. Like all of the quality metrics...0 would be more stable in the long run.. the harder they are to change as adoption increases. This is the most important one to check. there is nothing in Java preventing them from being used elsewhere. Better Builds With Maven 191 . since this early development version had a different API. </plugins> </build> . and to check them automatically. <build> <plugins> <plugin> <groupId>org.. you are monitoring the proficio-api component for binary compatibility changes only. as it will be used as the interface into the implementation by other applications. However. Even if they are designed only for use inside the project. it is a good idea to monitor as many components as possible. In this instance.xml file.Assessing Project Health with Maven These versions of proficio-api are retrieved from the repository. The Clirr plugin is also capable of automatically checking for introduced incompatibilities through the clirr:check goal.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> . to discuss and document the practices that will be used. if the team is prepared to do so. To add the check to the proficio-api/pom. 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. It is best to make changes earlier in the development cycle. however you can see the original sources by extracting the Codeh_Ch06-2. on the acceptable incompatibilities.. You'll notice there are a more errors in the report. so that fewer people are affected. and later was redesigned to make sure that version 1. it is important to agree up front. If it is the only one that the development team will worry about breaking.codehaus..
Hopefully a future version of Clirr will allow acceptable incompatibilities to be documented in the source code. it takes a very different approach. A limitation of this feature is that it will eliminate a class entirely. and so is most useful for browsing. and then act accordingly. it will not pinpoint potential problems for you. you will see that the build fails due to the binary incompatibility introduced between the 0. you can create a very useful mechanism for identifying potential release disasters much earlier in the development process.0 version.codehaus.9 release. and particularly so if you are designing a public API.. However. which is available at http://mojo..mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <excludes> <exclude>**/Proficio</exclude> </excludes> </configuration> . While the topic of designing a strong public API and maintaining binary compatibility is beyond the scope of this book. Better Builds With Maven 192 . it is listed only in the build configuration. so the report still lists the incompatibility. This can be useful in getting a greater level of detail than Clirr on specific class changes. Since this was an acceptable incompatibility due to the preview nature of the 0.. taking two source trees and comparing the differences in method signatures and Javadoc annotations. Note that in this instance.Assessing Project Health with Maven If you now run mvn verify. and ignored in the same way that PMD does. It has a functional Maven 2 plugin. you can choose to exclude that from the report by adding the following configuration to the plugin: . <plugin> <groupId>org. A similar tool to Clirr that can be used for analyzing changes between releases is JDiff. With this simple setup. </plugin> This will prevent failures in the Proficio class from breaking the build in the future. the following articles and books can be recommended: • • Evolving Java-based APIs contains a description of the problem of maintaining binary compatibility. Built as a Javadoc doclet.. not just the one acceptable failure.org/jdiff-maven-plugin. as well as strategies for evolving an API without breaking it.codehaus. This allows the results to be collected over time to form documentation about known incompatibilities for applications using the library. Effective Java describes a number of practical rules that are generally helpful to writing code in Java.9 preview release and the final 1.
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. a large amount of information was presented about a project.12. In the absence of these reports. individual checks that fail the build when they're not met. How well this works in your own projects will depend on the development culture of your team. it requires a shift from a focus on time and deadlines. Viewing Overall Project Health In the previous sections of this chapter. Once established.zip source archive. Best of all. but none related information from another report to itself.Assessing Project Health with Maven 6. none of the reports presented how the information changes over time other than the release announcements. to a focus on quality. it should be noted that the Maven reporting API was written with these requirements in mind specifically. the model remains flexible enough to make it easy to extend and customize the information published on your project web site. as there is a constant background monitor that ensures the health of the project is being maintained.0. along with techniques to ensure that the build checks are now automated. Most Maven plugins allow you to integrate rules into the build that check certain constraints on that piece information once it is well understood. regularly scheduled. then. they did not address all of these requirements. will reduce the need to gather information from various sources about the health of the project. and have not yet been implemented for Maven 2. each in discrete reports. These are all important features to have to get an overall view of the health of a project. it is important that your project information not remain passive. the Dashboard plugin). of the visual display is to aid in deriving the appropriate constraints to use. and run in the appropriate environment. Finally. enforcing good. Summary The power of Maven's declarative project model is that with a very simple setup (often only 4 lines in pom. and incorporates the concepts learned in this chapter. The additions and changes to Proficio made in this chapter can be found in the Code_Ch06-1. It is important that developers are involved in the decision making process regarding build constraints. and as the report set stabilizes – summary reports will start to appear. this focus and automated monitoring will have the natural effect of improving productivity and reducing time of delivery again.xml). However. Some of the reports linked to one another. Better Builds With Maven 193 . so that they feel that they are achievable. and will be used as the basis for the next chapter. The next chapter examines team development and collaboration. However.11.0 (for example. The purpose. In some cases. and few of the reports aggregated information across a multiple module build. 6. While some attempts were made to address this in Maven 1.
Tom Clancy Better Builds With Maven 194 . 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. .7.
component-based projects despite large. As each member retains project information that isn't shared or commonly accessible. repeating errors previously solved or duplicating efforts already made. iterative cycles. 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. real-time stakeholder participation. This problem gets exponentially larger as the size of the team increases. or forgotten. A Community-oriented Real-time Engineering (CoRE) process excels with this information challenge. This value is delivered to development teams by supporting project transparency. and asynchronous engineering. rapid development. faces a number of challenges to the success of the effort. widely-distributed teams. However. CoRE enables globally distributed development teams to cohesively contribute to high-quality software. although a distributed team has a higher communication overhead than a team working in a single location. CoRE is based on accumulated learnings from open source projects that have achieved successful. Many of these challenges are out of any given technology's control – for instance finding the right people for the team. An organizational and technology-based framework. further contributing to the problem. project information can still be misplaced. Using the model of a community. working on complex. However. Even though teams may be widely distributed.Team Collaboration with Maven 7. every other member (and particularly new members). web-based communication channels and web-based project management tools. will inevitably have to spend time obtaining this localized information. 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. The CoRE approach to development also means that new team members are able to become productive quickly. These tools aid the team to organize. While Maven is not tied directly to the CoRE framework. 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. misinterpreted. resulting in shortened development cycles. and that existing team members become more productive and effective. it does encompass a set of practices and tools that enable effective team communication and collaboration. While it's essential that team members receive all of the project information required to be productive. Even when it is not localized. in rapid. one of the biggest challenges relates to the sharing and management of development information. As teams continue to grow. This problem is particularly relevant to those working as part of a team that is distributed across different physical locations and timezones. visualize. The Issues Facing Teams Software development as part of a team. whether it is 2 people or 200 people.1. 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. Better Builds With Maven 195 . but also to incorporate feedback. which is enabled by the accessibility of consistently structured and organized information such as centralized code repositories. CoRE emphasizes the relationship between project information and project members. and dealing with differences in opinions. and document for reuse the artifacts that result from a software project.
such as proxy settings. multiple JDK versions.2. In Maven. In a shared development environment.xml file contains a number of settings that are user-specific. it's a good idea to leverage Maven's two different settings files to separately manage shared and user-specific settings. and to effectively define and declare them. Without it.xml: Better Builds With Maven 196 . this is taken a step further. demonstrating how Maven provides teams with real-time information on the builds and health of a project. The settings. How to Setup a Consistent Developer Environment Consistency is important when establishing a shared development environment. 7. Additionally. Common configuration settings are included in the installation directory. there are unavoidable variables that remain. <maven home>/conf/settings. In this chapter. and the use of archetypes to ensure consistency in the creation of new projects. error-prone and full of omissions. such as different installation locations for software. This file can be stored in the conf directory of your Maven installation. To maintain build consistency. While one of Maven's objectives is to provide suitable conventions to reduce the introduction of inconsistencies in the build environment. because the environment will tend to evolve inconsistently once started that way. the set up process for a new developer can be slow. and other discrete settings such as user names and passwords. varying operating systems. the key is to minimize the configuration required by each individual developer. these variables relate to the user and installation settings files. but also several that are typically common across users in a shared environment. In Chapter 2.xml file.m2 subdirectory of your home directory (settings in this location take precedence over those in the Maven installation directory).Team Collaboration with Maven As described in Chapter 6. This chapter also looks at the adoption and use of a consistent development environment. and to user-specific profiles. Maven can gather and share the knowledge about the health of a project. or in the . you learned how to create your own settings. through the practice of continuous integration. it will be the source of timeconsuming development problems in the future. while an individual developer's settings are stored in their home directory. while still allowing for this natural variability. The following is an example configuration file that you might use in the installation directory.
mycompany.username}</username> <filePermissions>664</filePermissions> <directoryPermissions>775</directoryPermissions> </server> </servers> <profiles> <profile> <repositories> <repository> <id>internal</id> <name>Internal Repository</name> <url>http://repo.mycompany.com/internal/</url> </pluginRepository> </pluginRepositories> </profile> </profiles> <activeProfiles> <activeProfile>property-overrides</activeProfile> <activeProfile>default-repositories</activeProfile> </activeProfiles> <pluginGroups> <pluginGroup>com.plugins</pluginGroup> </pluginGroups> </settings> Better Builds With Maven 197 .mycompany.com/internal/</url> </repository> </repositories> <pluginRepositories> <pluginRepository> <id>internal</id> <name>Internal Plugin Repository</name> <url>http://repo.Team Collaboration with Maven <settings> <proxies> <proxy> <active>true</active> <protocol>http</protocol> <host>proxy</host> <port>8080</port> </proxy> </proxies> <servers> <server> <id>website</id> <username>${website.
which is typically one that has been set up within your own organization or department. These repositories are independent of the central repository in this configuration. You'll notice that the local repository is omitted in the prior example. it would usually be set consistently across the organization or department. which are run from the command line and not defined in the POM. Using the basic template. ${user. internal repositories that contain a given organization's or department's released artifacts. the local repository is defined as the repository of single user. The server settings will typically be common among a set of developers. The user-specific configuration is also much simpler as shown below: <settings> <profiles> <profile> <id>property-overrides</id> <properties> <website. The active profiles listed enable the profile defined previously in every environment. This profile will be defined in the user's settings file to set the properties used in the shared file. In Maven. The profile defines those common. The mirror element can be used to specify a mirror of a repository that is closer to you. Another profile. By placing the common configuration in the shared settings.3 for more information on setting up an internal repository.username>myuser</website. See section 7. The previous example forms a basic template that is a good starting point for the settings file in the Maven installation. you can view the merged result by using the following help plugin command: C:\mvnbook> mvn help:effective-settings Better Builds With Maven 198 . See section 7. such as ${website.home}/maven-repo). The plugin groups are necessary only if an organization has plugins. property-overrides is also enabled by default. While you may define a standard location that differs from Maven's default (for example. issues with inconsistently-defined identifiers and permissions are avoided.Team Collaboration with Maven There are a number of reasons to include these settings in a shared configuration: • • • • • • If a proxy server is allowed. without having to worry about integrating local changes made by individual developers.username}.username> </properties> </profile> </profiles> </settings> To confirm that the settings are installed correctly.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. at a single physical location. across users. it is important that you do not configure this setting in a way that shares a local repository. with only specific properties such as the user name defined in the user's settings.
For an explanation of the different types of repositories.jar 8081 Better Builds With Maven 199 . and when possible. in this example C:\mvnbook\repository will be used. If this infrastructure is available. create a new directory in which to store the files. If necessary. or other custom solution. so that multiple developers and teams can collaborate effectively. However. just as any other external repository would be. see Chapter 3. an individual will need to customize the build of an individual project. To set up your organization's internal repository using Jetty. The following are a few methods to achieve this: • • • • Rebuild the Maven release distribution to include the shared configuration file and distribute it internally. or create a new server using Apache HTTPd. the next step is to establish a repository to and from which artifacts can be published and dependencies downloaded. but it is also important to ensure that that the shared settings are easily and reliably installed with Maven. Retrieving an update from an SCM will easily update the configuration and/or installation. each execution will immediately be up-to-date. by one of the following methods: Using the M2_HOME environment variable to force the use of a particular installation. 7.1. To do this. or if there are network problems. or any number of other servers. Apache Tomcat.xml file. To set up Jetty.10-bundle. it is possible to maintain multiple Maven installations. and run: C:\mvnbook\repository> java -jar jetty-5. download the Jetty 5. developers must use profiles in the profiles. To publish releases for use across different environments within their network. Use an existing desktop management solution. Now that each individual developer on the team has a consistent set up that can be customized as needed. however it applies to all projects that are built in the developer's environment. Each developer can check out the installation into their own machines and run it from there. While it can be stored anywhere you have permissions. While any of the available transport protocols can be used. Place the Maven installation on a read-only shared or network drive from which each developer runs the application. see Chapter 2. since not everyone can deploy to the central Maven repository. or other source control management (SCM) system. In some circumstances however. Check the Maven installation into CVS.Team Collaboration with Maven Separating the shared settings from the user-specific settings is helpful. You can use an existing HTTP server for this.xml file covers the majority of use cases for individual developer customization.10 server bundle from the book's Web site and copy it to the repository directory. Creating a Shared Repository Most organizations will need to set up one or more shared repositories. the most popular is HTTP. organization's will typically want to set up what is referred to as an internal repository. located in the project directory.3. • Configuring the settings. A new release will be required each time the configuration is changed.1. Setting up an internal repository is simple. This internal repository is still treated as a remote repository in Maven. if M2_HOME is not set. Jetty. doing so will prevent Maven from being available off-line. Subversion. but requires a manual procedure. For more information on profiles. • Adjusting the path or creating symbolic links (or shortcuts) to the desired Maven executable. easily updated. Change to that directory.
ftp. To populate the repository you just created. In addition.8G. • The Maven Repository Manager (MRM) is a new addition to the Maven build platform that is designed to administer your internal repository. configured securely and monitored to ensure it remains running at all times. and keep a copy in your internal repository for others on your team to reuse. For more information. The setting for using this was shown in the mirror element of the settings file in section 7.2.Team Collaboration with Maven You can now navigate to http://localhost:8081/ and find that there is a web server running displaying that directory. as well as friendly repository browsing. For the first repository. The repository manager can be downloaded from http://maven. using the following command: C:\mvnbook\repository> mkdir central This repository will be available at http://localhost:8081/central/. separate repositories. create a subdirectory called internal that will be available at http://localhost:8081/internal/. it is common in many organizations as it eliminates the requirement for Internet access or proxy configuration. by avoiding any reliance on Maven's relatively open central repository. However. Better Builds With Maven 200 . refer to Chapter 3. At the time of writing. Use rsync to take a copy of the central repository and regularly update it.apache. While this isn't required.org/repositorymanager/. and is all that is needed to get started. and gives full control over the set of artifacts with which your software is built. accessible location. Your repository is now set up. 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. but rather than set up multiple web servers. sftp and more. This will download anything that is not already present. you will want to set up or use an existing HTTP server that is in a shared. the size of the Maven repository was 5. You can create a separate repository under the same server. searching. and reporting. scp. This chapter will assume the repositories are running from http://localhost:8081/ and that artifacts are deployed to the repositories using the file system. it is possible to user a repository on another server with any combination of supported protocols including http. However. It is deployed to your Jetty server (or any other servlet container) and provides remote repository proxies. 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 creates an empty repository. Later in this chapter you will learn that there are good reasons to run multiple. it provides faster performance (as most downloads to individual developers come from within their own network). The server is set up on your own workstation for simplicity in this example. you can store the repositories on this single server.
that declares shared settings within an organization and its departments. or had it in their source code check out. Not only is this very inconvenient. as shown in section 7. Better Builds With Maven 201 . This makes it impossible to define the repository in the parent. you should override the central repository. or hierarchy. You would use it as a mirror if it is intended to be a copy of the central repository exclusively. To override the central repository with your internal repository. Usually. to configure the repository from the project level instead of in each user's settings (with one exception that will be discussed next). unless you have mirrored the central repository using one the techniques discussed previously. it is necessary to declare only those that contain an inherited POM. Repositories such as the one above are configured in the POM usually. for a situation where a developer might not have configured their settings and instead manually installed the POM. if you want to prevent access to the central repository for greater control. and as a result. 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. otherwise Maven will fail to download any dependencies that are not in your local repository. there is a problem – when a POM inherits from another POM that is not in the central repository. it must retrieve the parent from the repository. or the original central repository directly without consequence to the outcome of the build. this must be defined as both a regular repository and a plugin repository to ensure all access is consistent. However. or to include your own artifacts in the same repository. 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. It is still important to declare the repositories that will be used in the top-most POM itself.2.2. it would need to be declared in every POM. If you have multiple repositories. The next section discusses how to set up an "organization POM". there are two choices: use it as a mirror. and if it's acceptable to have developers configure this in their settings as demonstrated in section 7. or have it override the central repository. so that a project can add repositories itself for dependencies located out of those repositories configured initially. On the other hand. Developers may choose to use a different mirror.xml file.Team Collaboration with Maven When using this repository for your projects.
its departments. itself. <modules> <module>maven-scm-api</module> <module>maven-scm-providers</module> . As an example. consider the Maven project itself. there are three levels to consider when working with any individual module that makes up the Maven project.3.. which is shared across all Maven projects through inheritance.maven.. so it's possible to have one or more parents that define elements common to several projects. You may have noticed the unusual version declaration for the parent project. Maven Continuum. from section 7. you'd find that there is very little deployment or repositoryrelated information. consider the POM for Maven SCM: <project> <modelVersion>4. and then the teams within those departments. the current project – Maven 2 now retrieves parent projects from the repository.0</modelVersion> <parent> <groupId>org.. </modules> </project> If you were to review the entire POM. Maven SCM. Since the version of the POM usually bears no resemblance to the software. It is important to recall. project inheritance can be used to assist in ensuring project consistency.0 – that is.apache.scm</groupId> <artifactId>maven-scm</artifactId> <url>http://maven. has a number of sub-projects (Maven. These parents (levels) may be used to define departments. Any number of levels (parents) can be used. as this is consistent information. It is a part of the Apache Software Foundation. and is a project that. depending on the information that needs to be shared..Team Collaboration with Maven 7.4.apache. While project inheritance was limited by the extent of a developer's checkout in Maven 1. To continue the Maven example. wherein there's the organization. As a result. that if your inherited projects reside in an internal repository. Better Builds With Maven 202 . the easiest way to version a POM is through sequential numbering.xml file in the shared installation (or in each developer's home directory). etc.maven</groupId> <artifactId>maven-parent</artifactId> <version>1</version> </parent> <groupId>org. By declaring shared elements in a common parent POM. or the organization as a whole.0.org/maven-scm/</url> . Creating an Organization POM As previously mentioned in this chapter.apache. then that repository will need to be added to the settings.). consistency is important when setting up your build infrastructure. This project structure can be related to a company structure. Future versions of Maven plan to automate the numbering of these types of parent projects to make this easier.
</mailingList> </mailingLists> <developers> <developer> ..0</modelVersion> <parent> <groupId>org. you'd see it looks like the following: <project> <modelVersion>4. <mailingLists> <mailingList> <name>Maven Announcements List</name> <post>firstname.lastname@example.com</groupId> <artifactId>maven-parent</artifactId> <version>5</version> <url>http://maven..apache. </developer> </developers> </project> Better Builds With Maven 203 .org</post> ..apache</groupId> <artifactId>apache</artifactId> <version>1</version> </parent> <groupId>org.0.org/</url> ....Team Collaboration with Maven If you look at the Maven project's parent POM.
apache.org/</url> </organization> <url>http://www. and deployed with their new version as appropriate... is regarding the storage location of the source POM files. such as the announcements mailing list and the list of developers that work across the whole project.apache</groupId> <artifactId>apache</artifactId> <version>1</version> <organization> <name>Apache Software Foundation</name> <url>http://www. An issue that can arise. 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 the deployment locations. when working with this type of hierarchy.. the Maven Repository Manager will allow POM updates from a web interface)... modified. These parent POM files are likely to be updated on a different.apache.6).0. <distributionManagement> <repository> .org/maven-snapshot-repository</url> <releases> <enabled>false</enabled> </releases> </repository> </repositories> . </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.snapshots</id> <name>Apache Snapshot Repository</name> <url>http://svn.0</modelVersion> <groupId>org. it is best to store the parent POM files in a separate area of the source control tree.Team Collaboration with Maven The Maven parent POM includes shared elements.. you can retain the historical versions in the repository if it is backed up (in the future. and less frequent schedule than the projects themselves. most of the elements are inherited from the organization-wide parent project.. For this reason. Better Builds With Maven 204 .org/</url> . in this case the Apache Software Foundation: <project> <modelVersion>4. <repositories> <repository> <id>apache. </repository> <snapshotRepository> . In fact. Again. there is no best practice requirement to even store these files in your source control management system.apache.. where they can be checked out.
3. The examples discussed are based on Continuum 1. however. press Ctrl-C in the window that is running Continuum). and learn how to use Continuum to build this project on a regular basis. as well as the generic bin/plexus.org/. ensuring that conflicts are detected earlier in a project's release life cycle. In this chapter.tigris. continuous integration is a key element of effective collaboration. The examples also assumes you have Subversion installed.5. rather than close to a release. you will pick up the Proficio example from earlier in the book. You can verify the installation by viewing the web site at http://localhost:8080/continuum/. Better Builds With Maven 205 . if you are running Continuum on your desktop and want to try the examples in this section.0. however newer versions should be similar. Continuous Integration with Continuum If you are not already familiar with it. which you can obtain for your operating system from http://subversion. and the company information for altering the logo in the top left of the screen. and you must stop the server to make the changes (to stop the server. This is very simple – once you have downloaded it and unpacked it. 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.sh for use on other Unix-based platforms. iterative changes that can more easily support concurrent development processes. some additional steps are required. continuous integration can enable a better development culture where team members can make smaller. For most installations this is all the configuration that's required. these additional configuration requirements can be set only after the previous step has been completed. you can run it using the following command: C:\mvnbook\continuum-1. The first screen to appear will be the one-time setup page shown in figure 7-1.3> bin\win32\run There are scripts for most major platforms.3.0.0. As such. As of Continuum 1. Continuum is Maven's continuous integration and build server.Team Collaboration with Maven 7. you will need to install Continuum. First. continuous integration enables automated builds of your project on a regular interval. More than just nightly builds.
since paths can be entered from the web interface. this is disabled as a security measure..org/continuum/guides/mini/guide-configuration. The default is to use localhost:25. edit the file above to change the smtp-host setting.UrlValidator </implementation> <configuration> <allowedSchemes> .plexus.. refer to http://maven.html. To have Continuum send you e-mail notifications. you can start Continuum again. you will also need an SMTP server to which to send the messages. POM files will be read from the local hard disk where the server is running.. By default.apache.. Better Builds With Maven 206 .codehaus.validation... To enable this setting. <implementation> org. edit apps/continuum/conf/application. If you do not have this set up on your machine. <allowedScheme>file</allowedScheme> </allowedSchemes> </configuration> .formica.Team Collaboration with Maven Figure 7-1: The Continuum setup screen In the following examples. After these steps are completed. For instructions.xml and uncomment the following line: .
. by uncommenting and modifying the following lines: ..zip archive and unpacking it in your environment. <ciManagement> <system>continuum</system> <url>http://localhost:8080/continuum <notifiers> <notifier> <type>mail</type> <configuration> <address>youremail@yourdomain.. 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.xml to correct the e-mail address to which notifications will be sent. You can then check out Proficio from that location. The ciManagement section can be used to configure a project for easier integration with Continuum. Better Builds With Maven 207 . <scm> <connection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </connection> <developerConnection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </developerConnection> </scm> .. Edit proficio/pom.version} </url> </site> </distributionManagement> . <distributionManagement> <site> <id>website</id> <url> file://localhost/c:/mvnbook/repository/sites/proficio /reference/${project.Team Collaboration with Maven The next step is to set up the Subversion repository for the examples.. This requires obtaining the Code_Ch07. and edit the location of the Subversion repository.. since not all of the required details were known at the time of its creation.com</address> </configuration> </notifier> </notifiers> </ciManagement> ...
If you return to the http://localhost:8080/continuum/ location that was set up previously. you will see an empty project list. or with another account you have since created with appropriate permissions. Better Builds With Maven 208 . you can now select Maven 2. as in the Proficio example. Instead. Continuum will return to the project summary page. in Continuum 1. with the following command: C:\mvnbook\proficio> mvn install You are now ready to start using Continuum. Once you have logged in. If you haven't done so already. This will present the screen shown in figure 7-2.3 for information on how to set this up. or a Subversion HTTP server. The result is shown in figure 7-3. After submitting the URL. and each of the modules will be added to the list of projects.xml You should build all these modules to ensure everything is in order. commit the file with the following command: C:\mvnbook\proficio> svn ci -m 'my settings' pom. When you set up your own system later. the builds will be marked as New and their checkouts will be queued. under the Continuum logo. enter the file:// URL as shown. you must either log in with the administrator account you created during installation.3 this does not work when the POM contains modules.0. This assumes that you are still running the repository Web server on localhost:8081. Initially. or perform other tasks.0+ Project from the Add Project menu. The login link is at the top-left of the screen. You have two options: you can provide the URL for a POM. a ViewCVS installation. Before you can add a project to the list. Figure 7-2: Add project screen shot This is all that is required to add a Maven 2 project to Continuum. you will enter either a HTTP URL to a POM in the repository.Team Collaboration with Maven The distributionManagement setting will be used in a later example to deploy the site from your continuous integration environment. Once these settings have been edited to reflect your setup. refer to section 7. While uploading is a convenient way to configure from your existing check out. or upload from your local drive. from the directory C:\mvnbook\repository.
and send an e-mail notification if there are any problems. First. Jabber. To avoid receiving this error every hour. but you may wish to go ahead and try them. If you want to put this to the test. the build will show an "In progress" status.java. press Build Now on the Continuum web interface next to the Proficio API module. MSN and Google Talk are all supported.] Now. check the file in: C:\mvnbook\proficio\proficio-api> svn ci -m 'introduce error' \ src/main/java/com/mergere/mvnbook/proficio/Proficio...Team Collaboration with Maven Figure 7-3: Summary page after projects have built Continuum will now build the project hourly..java Finally. for example. Better Builds With Maven 209 .. you should receive an e-mail at the address you configured earlier. 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). you might want to set up a notification to your favorite instant messenger – IRC. The Build History link can be used to identify the failed build and to obtain a full output log. For example. and then fail. In addition. go to your earlier checkout and introduce an error into Proficio. restore the file above to its previous state and commit it again. The build in Continuum will return to the successful state. remove the interface keyword: [.] public Proficio [. This chapter will not discuss all of the features available in Continuum.
enhancements that are planned for future versions. it is also important that failures don't occur due to old build state. Run clean builds. but rather keeping changes small and well tested. separate from QA and production releases. Fix builds as soon as possible. there are a few tips for getting the most out of the system: • Commit early. Avoid customizing the JDK. Continuum has preliminary support for system profiles and distributed testing. test and production environments. When a failure occurs in the continuous integration environment. if it isn't something already in use in other development. operating system and other variables. Better Builds With Maven 210 . This doesn't mean committing incomplete code. This is another way continuous integration can help with project collaboration and communication. it is recommend that a separate. This can be helpful for non-developers who need visibility into the state of the application. While this seems obvious. While rapid. Consider a regular. Continuous integration is most effective when developers commit regularly. If multiple branches are in development. In Chapter 6.Team Collaboration with Maven Regardless of which continuous integration server you use. Run a copy of the application continuously. for example. they need to be kept up-todate. periodically. For these reports to be of value. This will make it much easier to detect the source of an error when the build does break. • • • • • • • In addition to the above best practices. and profile usage. commit often. Run comprehensive tests. iterative builds are helpful in some situations. if the source control repository supports post-commit hooks. but it is best to detect a failure as soon as possible. before the developer moves on or loses focus. This also means that builds should be fast – long integration and performance tests should be reserved for periodic builds. Establish a stable environment. Continuous integration will be pointless if developers repetitively ignore or delete broken build notifications. there are two additional topics that deserve special attention: automated updates to the developer web site. Continuous integration is most beneficial when tests are validating that the code is working as it always has. based on selected schedules. but regular schedule is established for site generation. This will be constrained by the length of the build and the available resources on the build machine. you learned how to create an effective site containing project information and reports about the project's health and vitality. Continuum currently defaults to doing a clean build. the continuous integration environment should be set up for all of the active branches. clean build. If the application is a web application. it is often ignored. and independent of the environment being used. Though it would be overkill to regenerate the site on ever commit. and your team will become desensitized to the notifications in the future. In addition. Continuum can be configured to trigger a build whenever a commit occurs. Build all of a project's active branches. not just that the project still compiles after one or more changes occur. or local settings. it is beneficial to test against all different versions of the JDK. and a future version will allow developers to request a fresh checkout. it is important that it can be isolated to the change that caused it. Run builds as often as possible. run a servlet container to which the application can be deployed from the continuous integration environment.
and select the top-most project. In addition to building the sites for each module. only the default schedule is available. Click the Add button to add a new schedule. 9:00:00. which will be configured to run every hour during business hours (8am – 4pm weekdays). use the non-recursive mode instead. The project information shows just one build on the default schedule that installs the parent POM. 16:00:00 from Monday to Friday. and add the same build definition to all of the modules.3. Once you add this schedule. Better Builds With Maven 211 .opensymphony. since commits are not atomic and a developer might be committing midway through a update.0. The downside to this approach is that Continuum will build any unchanged modules. The appropriate configuration is shown in figure 7-4... The "quiet period" is a setting that delays the build if there has been a commit in the defined number of seconds prior. there is no way to make bulk changes to build definitions. In Continuum 1. but does not recurse into the modules (the -N or --non-recursive argument). 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. select Schedules. Maven Proficio. so you will need to add the definition to each module individually. return to the project list.html.. This is useful when using CVS. You will see that currently. Next.com/quartz/api/org/quartz/CronTrigger. as well – if this is a concern. Figure 7-4: Schedule configuration The cron expression entered here is much like the one entered for a Unix crontab and is further described at http://www. from the Administration menu on the left-hand side. It is not typically needed if using Subversion.Team Collaboration with Maven Verify that you are still logged into your Continuum instance. The example above runs at 8:00:00.. it can aggregate changes into the top-level site as required.
It is rare that the site build will fail. which will be visible from http://localhost:8081/sites/proficio/. The arguments provided are --batch-mode. However. You can see also that the schedule is set to use the site generation schedule created earlier. The --non-recursive option is omitted. on the business hours schedule. The meaning of this system property will be explained shortly. and view the generated site from http://localhost:8081/sites/proficio/. so that if the build fails because of a failed check. verify or integrationtest goal to the list of goals. which is essential for all builds to ensure they don't block for user input. To add a new build definition. Any of these test goals should be listed after the site-deploy goal. since most reports continue under failure conditions. The Add Build Definition screen is shown in figure 7-5. Better Builds With Maven 212 . which means that Build Now from the project summary page will not trigger this build. to ensure these checks are run.Team Collaboration with Maven In this example you will add a new build definition to run the site deployment for the entirety of the multi-module build. if you want to fail the build based on these checks as well. and -DenableCiProfile=true. The site will be deployed to the file system location you specified in the POM. you can add the test. Click this for the site generation build definition. the generated site can be used as reference for what caused the failure. when you first set up the Subversion repository earlier in this chapter. Figure 7-5: Adding a build definition for site deployment The goals to run are clean and site-deploy. and that it is not the default build definition. which sets the given system property. However. click the Add button below the default build definition. 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.
at least in the version of Continuum current at the time of writing. <profiles> <profile> <id>ciProfile</id> <activation> <property> <name>enableCiProfile</name> <value>true</value> </property> </activation> <plugins> <plugin> <groupId>org. If you compare the example proficio/pom. Profiles are a means for selectively enabling portions of the build. and clicking Edit next to the default build definition. please refer to Chapter 3. The first is to adjust the default build definition for each module. you'll see that these checks have now been moved to a profile. . by going to the module information page. the profile is enabled only when the enableCiProfile system property is set to true.xml: . a system property called enableCiProfile was set to true. for all projects in Continuum. it reads the ${user..apache.m2/settings. However. it is necessary to do this for each module individually. The other alternative is to set this profile globally... as well as the settings in the Maven installation.xml file for the user under which it is running. if you run mvn -DenableCiProfile=true verify.. Better Builds With Maven 213 . these checks delayed the build for all developers. As Maven 2 is still executed as normal.. As you saw before.home}/.. There are two ways to ensure that all of the builds added in Continuum use this profile. <activeProfile>ciProfile</activeProfile> </activeProfiles> .Team Collaboration with Maven In the previous example. If you haven't previously encountered profiles. they will be. However. none of the checks added in the previous chapter are executed.. <activeProfiles> . In Chapter 6. a number of plugins were set up to fail the build if certain project health checks failed..plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> .xml file in <maven home>/conf/settings.. which can be a discouragement to using them.maven. such as the percentage of code covered in the unit tests dropping below a certain value.. You'll find that when you run the build from the command line (as was done in Continuum originally). In this particular case.xml file in your Subversion checkout to that used in Chapter 6. add the following configuration to the settings. To enable this profile by default from these settings.
you'll see that the repository was defined in proficio/pom. While building all of the modules from source can work well and is handled by Maven inherently.6. such as the internal repository set up in section 7. the team dynamic makes it critical. Snapshots were designed to be used in a team environment as a means for sharing development versions of artifacts that have already been built. building from source doesn't fit well with an environment that promotes continuous integration. using binary snapshots that have been built and tested already. but the timing and configuration can be changed depending upon your circumstances. which are not changed. you will learn about using snapshots more effectively in a team environment. or for the entire multi-module project to run the additional checks after the site has been generated. which is discussed in section 7. snapshots have been used to refer to the development version of an individual module. if the additional checks take too much time for frequent continuous integration builds. Instead. Team Dependency Management Using Snapshots Chapter 3 of this book discussed how to manage your dependencies in a multi-module build. Projects in Maven stay in the snapshot state until they are released. 7. In this section. where projects are closely related.Team Collaboration with Maven In this case the identifier of the profile itself. these artifacts will be updated frequently. and how to enable this within your continuous integration environment. the verify goal may need to be added to the site deployment build definition. the build involves checking out all of the dependent projects and building them yourself. and in contrast to regular dependencies. For example. as discussed previously. it may be necessary to schedule them separately for each module. 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. Usually. and while dependency management is fundamental to any Maven build. it can lead to a number of problems: • • • • It relies on manual updates from developers.xml: Better Builds With Maven 214 . in an environment where a number of modules are undergoing concurrent development. In Maven. which can be error-prone. The guidelines discussed in this chapter will help point your team in the right direction. you must build all of the modules simultaneously from a master build.3. in some cases. rather than the property used to enable it. Considering that example.8 of this chapter. indicates that the profile is always active when these settings are read. The generated artifacts of the snapshot are stored in the local repository. 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. is preferred. Additionally. So far in this book. this is achieved by regularly deploying snapshots to a shared repository.
0SNAPSHOT.. Currently. To add the internal repository to the list of repositories used by Proficio regardless of settings. In this case. or to lock down a stable version by declaring the dependency version to be the specific equivalent such as 1.0-SNAPSHOT: checking for updates from internal . though it may have been configured as part of your settings files... <distributionManagement> <repository> <id>internal</id> <url>file://localhost/c:/mvnbook/repository/internal</url> </repository> ..xml: . If you were to deploy again. the version used is the time that it was deployed (in the UTC timezone) and the build number..131114-1.. While this is not usually the case.131114-1. Better Builds With Maven 215 . 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. similar to the example below (note that this output has been abbreviated): .. to see the updated version downloaded. the Proficio project itself is not looking in the internal repository for dependencies. <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> </repository> </repositories> .jar.. proficio-api:1.. The filename that is used is similar to proficio-api-1.0-20060211. build proficio-core with the following command: C:\mvnbook\proficio\proficio-core> mvn -U install During the build. </distributionManagement> Now. This technique allows you to continue using the latest version by declaring a dependency on 1.. add the following to proficio/pom.. but rather relying on the other modules to be built first. Now. If you are developing plugins. you will see that some of the dependencies are checked for updates. locking the version in this way may be important if there are recent changes to the repository that need to be ignored temporarily.0-20060211. the time stamp would change and the build number would increment to 2.. you may also want to add this as a pluginRepository element as well.Team Collaboration with Maven .
This is because the default policy is to update snapshots daily – that is.. Continuum can be configured to deploy its builds to a Maven snapshot repository automatically. assuming that the other developers have remembered to follow the process. However. and interval:minutes.. and then deploy the snapshot to share with the other team members. you must ensure that the distributionManagement section of the POM is correctly configured. If it were omitted. It is possible to establish a policy where developers do an update from the source control management (SCM) system before committing. so let's go ahead and do it now. making it out-of-date. You can always force the update using the -U command..5 of this chapter. any snapshot dependencies will be checked once an hour to determine if there are updates in the remote repository. it updates both releases and snapshots. To see this. this introduces a risk that the snapshot will not be deployed at all. To deploy from your server... but you can also change the interval by changing the repository configuration. by default. Since the continuous integration server regularly rebuilds the code from a known state. In section 6. without having to manually intervene. In this example.xml: .. deployed with uncommitted code. daily (the default). as you saw earlier.Team Collaboration with Maven The -U argument in the prior command is required to force Maven to update all of the snapshots in the build. However. If there is a repository configured to which to deploy them. Several of the problems mentioned earlier still exist – so at this point. this feature is enabled by default in a build definition. Whenever you use the -U argument. always. it makes sense to have it build snapshots. This causes many plugins to be checked for updates. This technique can ensure that developers get regular updates. all that is being saved is some time. shown in figure 7-6. <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> . A much better way to use snapshots is to automate their creation. add the following configuration to the repository configuration you defined above in proficio/pom. you were not asked to apply this setting. The settings that can be used for the update policy are never. the updates will still occur only as frequently as new versions are deployed to the repository. <repository> . to check for an update the first time that particular dependency is used after midnight local time. and without slowing down the build by checking on every access (as would be the case if the policy were set to always). or deployed without all the updates from the SCM. as well. Better Builds With Maven 216 . no update would be performed. Log in as an administrator and go to the following Configuration screen. How you implement this will depend on the continuous integration server that you use. However. as well as updating any version ranges.
you can enter a full repository URL such as scp://repositoryhost/www/repository/internal. If this is not the case. 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. and click Build Now on the Proficio API project. or build from source. Better yet. but still keep a full archive of releases. enter the location of your internal repository: C:\mvnbook\repository\internal.Team Collaboration with Maven Figure 7-6: Continuum configuration In Deployment Repository field. when necessary. To try this feature. With this setup. while you get regular updates from published binary dependencies. follow the Show Projects link. 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. you can either lock a dependency to a particular build. This can be useful if you need to clean up snapshots on a regular interval. Better Builds With Maven 217 . with an updated time stamp and build number. you can avoid all of the problems discussed previously. Once the build completes. This relies on your internal repository and Continuum server being in the same location.
Better Builds With Maven 218 .snapshots</id> <url>http://localhost:8081/snapshots</url> <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> </repositories> .. when it doesn't... you would add the following: . if you had a snapshot-only repository in /www/repository/snapshots. <distributionManagement> . This will deploy to that repository whenever the version contains SNAPSHOT.. this separation is achieved by adding an additional repository to the distributionManagement section of your POM. <snapshotRepository> <id>internal.. <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> <repository> <id>internal..... For example. The replacement repository declarations in your POM would look like this: . you can make the snapshot update process more efficient by not checking the repository that has only releases for updates.. Given this configuration.snapshots</id> <url>file://localhost/www/repository/snapshots</url> </snapshotRepository> </distributionManagement> .Team Collaboration with Maven If you are using the regular deployment mechanism (instead of using Continuum). and deploy to the regular repository you listed earlier.
Writing an archetype is quite like writing your own project. and replacing the specific values with parameters.7. There are two ways to create an archetype: one based on an existing project using mvn archetype:create-from-project. While this is convenient. you have seen the archetypes that were introduced in Chapter 2 used to quickly lay down a project structure.mvnbook \ -DartifactId=proficio-archetype \ -DarchetypeArtifactId=maven-archetype-archetype The layout of the resulting archetype is shown in figure 7-7. using an archetype. in a way that is consistent with other projects in your environment. either in adding or removing content from that generated by the archetypes. by hand. Figure 7-7: Archetype directory layout Better Builds With Maven 219 . and the other. Beyond the convenience of laying out a project structure instantly. you can create one or more of your own archetypes. the requirement of achieving consistency is a key issue facing teams. Creating a Standard Project Archetype Throughout this book. As you saw in this chapter. run the following command: C:\mvnbook\proficio> mvn archetype:create \ -DgroupId=com. To avoid this. To get started with the archetype.Team Collaboration with Maven 7. there is always some additional configuration required. archetypes give you the opportunity to start a project in the right way – that is.mergere.
org/maven-v4_0_0.0.xml at the top level.xsd"> <modelVersion>4. artifactId and version elements are variables that will be substituted with the values provided by the developer running archetype:create.xml file looks like the following: <project xmlns="http://maven.0.Team Collaboration with Maven If you look at pom. the groupId.0</modelVersion> <groupId>$groupId</groupId> <artifactId>$artifactId</artifactId> <version>$version</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. but it is also possible to specify files for resources. The archetype descriptor describes how to construct a new project from the archetype-resources provided.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven. These files will be used to generate the template files when the archetype is run.apache.0.xml. you'll see that the archetype is just a normal JAR project – there is no special build configuration required.apache. refer to the documentation on the Maven web site. The files within the archetype-resources section are Velocity templates. so everything else is contained under src/main/resources.java</source> </sources> <testSources> <source>src/test/java/AppTest. you need to populate the template with the content that you'd like to have applied consistently to new projects.1</version> <scope>test</scope> </dependency> </dependencies> </project> As you can see. The example descriptor looks like the following: <archetype> <id>proficio-archetype</id> <sources> <source>src/main/java/App.apache. the pom.org/POM/4. testResources.java</source> </testSources> </archetype> Each tag is a list of files to process and generate in the created project. Better Builds With Maven 220 .8. and the template project in archetype-resources. For more information on creating an archetype. and siteResources. There are two pieces of information required: the archetype descriptor in META-INF/maven/archetype. From here. The example above shows the sources and test sources.0" xmlns:xsi="http://www. The JAR that is built is composed only of resources. For this example.0 http://maven.org/POM/4.
a previous release would be used instead). and does all of the project and source control manipulation that results in a tagged version. now however.Team Collaboration with Maven Once you have completed the content in the archetype. and to perform standard tasks. such as deployment to the remote repository.3 of this chapter. so you can run the following command: C:\mvnbook\proficio\proficio-archetype> mvn deploy The archetype is now ready to be used. Releasing a project is explained in section 7. you will use the "internal" repository. go to an empty directory and run the following command: C:\mvnbook> mvn archetype:create -DgroupId=com. Cutting a Release Releasing software is difficult. Worse. 7.9 of this chapter. since the archetype has not yet been released.8. Since the archetype inherits the Proficio parent. The release plugin takes care of a number of manual steps in updating the project POM. the content of the files will be populated with the values that you provided on the command line.mvnbook \ -DartifactId=proficio-example \ -DarchetypeGroupId=com. It is usually tedious and error prone. new release. and creating tags (or equivalent for your SCM). allowing them to be highly automated.mergere. Once the definition for a release has been set by a team. The release plugin operates in two steps: prepare and perform. The prepare step is run once for a release. However. full of manual steps that need to be completed in a particular order. To do so. it has the correct deployment settings already.mvnbook \ -DarchetypeArtifactId=proficio-archetype \ -DarchetypeVersion=1. once a release has been made. You now have the template project laid out in the proficio-example directory. updating the source control management system to check and commit release related changes. the required version would not be known (or if this was later development. releases should be consistent every time they are built. Better Builds With Maven 221 . Maven will build. The perform step could potentially be run multiple times to rebuild a release from a clean checkout of the tagged version. 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. which often leads to omissions or short cuts. Finally. install and deploy it like any other JAR. It will look very similar to the content of the archetype-resources directory you created earlier. Maven provides a release plugin that provides the basic functions of a standard release process. if omitted.mergere. Continuing from the example in section 7. the archetypeVersion argument is not required at this point. it is usually difficult or impossible to correct mistakes other than to make another.0-SNAPSHOT Normally.
Describe the SCM commit and tag operations 9. As the command runs. or creating and committing an announcement file) 8. This can be corrected by adding the plugin definition to your POM. as they will be committed for the next development iteration 10. 3. Describe the SCM commit operation 1. not ready to be used as a part of a release. or part of the project. This is because you are using a locally installed snapshot of a plugin (either built yourself. and released as 1. However. You'll notice that each of the modules in the project is considered. In some cases. the Proficio example will be revisited. 6. an error will appear. The prepare step ensures that there are no snapshots in the build. To review the steps taken in this release process: Check for correct version of the plugin and POM (for example. You can continue using the code that you have been working on in the previous sections. or check out the following: C:\mvnbook> svn co \ file://localhost/C:/mvnbook/svn/proficio/tags/proficio-final \ proficio To start the release process. other than those that will be released as part of the process (that is. 2. but this might include updating the metadata in your issue tracker. and setting the version to the latest release (But only after verifying that your project builds correctly with that version!). or obtained from the development repository of the Maven project) that is implied through the build life cycle. 5. all of the dependencies being used are releases. Better Builds With Maven 222 . if you are using a dependency that is a snapshot. In this project. 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. you will be prompted for values.0. other modules). even if the plugin is not declared in the POM. you may encounter a plugin snapshot. Modify all POM files in the build. 4. 7. without making any modifications to your project. run the following command: c:\mvnbook\proficio> mvn release:prepare -DdryRun=true This simulates a normal release preparation. This is because the prepare step is attempting to guarantee that the build will be reproducible in the future. 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. and snapshots are a transient build.Team Collaboration with Maven To demonstrate how the release plugin works. Accept the defaults in this instance (note that running Maven in "batch mode" avoids these prompts and will accept all of the defaults).
. The SCM information is also updated in the tag POM to reflect where it will reside once it is tagged.] <plugin> <groupId>org.xml and profiles. This is used by Maven..plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <prepareVerifyArgs>-DenableCiProfile=true</prepareVerifyArgs> </configuration> </plugin> [.xml You may have expected that inheritance would have been resolved by incorporating any parent elements that are used. use the following plugin configuration: [. For that reason. these changes are not enough to guarantee a reproducible build – it is still possible that the plugin versions will vary. In this POM. Having run through this process you may have noticed that only the unit and integration tests were run as part of the test build. However. you created a profile to enable those checks conditionally. including profiles from settings.xml in the same directory as pom. this file will be release-pom. To do so.xml.] Better Builds With Maven 223 . This contains a resolved version of the POM that Maven will use to build from if it exists. instead of the normal POM. a number of changes are made: • • • the explicit version of plugins and dependencies that were used are added any settings from settings..xml.tag file written out to each module directory.Team Collaboration with Maven You might like to review the POM files that are created for steps 4 and 6. and this is reverted in the next POM. or that different profiles will be applied. When the final run is executed. and is set based on the values for which you were prompted during the release process.xml.maven. This is not the case however.. Also.xml (both per-user and per-installation) are incorporated into the POM.next respectively in each module directory. as these can be established from the other settings already populated in the POM in a reproducible fashion. 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. to verify they are correct.5. named pom. recall that in section 7. you need to enable this profile during the verification step. there is also a release-pom. that resulting version ranges will be different.tag and pom. To include these checks as part of the release process. any active profiles are explicitly activated. You'll notice that the version is updated in both of these files. when a build is run from this tag to ensure it matches the same circumstances as the release build.apache.xml. or that expressions would have been resolved.
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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, 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, and the updated POM files are committed. You won't be prompted for values as you were the first time – since by the default, the release plugin will resume a previous attempt by reading the release.properties file that was created at the end of the last run. If you need to start from the beginning, you can remove that file, or run mvn -Dresume=false release:prepare instead. Once this is complete, you'll see in your SCM the new tag for the project (with the modified files), while locally, the version is now 1.1-SNAPSHOT. However, the release still hasn't been generated yet – for that, you need to deploy the build artifacts. This is achieved with the release:perform goal. This is run as follows: C:\mvnbook\proficio> mvn release:perform No special arguments are required, because the release.properties file still exists to tell the goal the version from which to release. To release from an older version, or if the release.properties file had been removed, you would run the following:
C:\mvnbook\proficio> mvn release:perform -DconnectionUrl=\ scm:svn:file://localhost/c:/mvnbook/svn/proficio/tags/proficio-1.0
If you follow the output above, you'll see that a clean checkout was obtained from the created tag, before running Maven from that location with the goals deploy site-deploy. This is the default for the release plugin – to deploy all of the built artifacts, and to deploy a copy of the site. If this is not what you want to run, you can change the goals used with the goals parameter: C:\mvnbook\proficio> mvn release:perform -Dgoals="deploy" However, this requires that you remember to add the parameter every time. Since the goal is for consistency, you want to avoid such problems. To do so, add the following goals to the POM:
[...] <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <goals>deploy</goals> </configuration> </plugin> [...]
Better Builds With Maven
Team Collaboration with Maven
You may also want to configure the release plugin to activate particular profiles, or to set certain properties. Refer to the plugin reference at http://maven.apache.org/plugins/maven-release-plugin/ for more information. It is important in these cases that you consider the settings you want, before you run the release:prepare goal, though. To ensure reproducibility, 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). When the release is performed, and the built artifacts are deployed, you can examine the files that are placed in the SCM repository. To do this, check out the tag:
C:\mvnbook> svn co \ file://localhost/mvnbook/svn/proficio/tags/proficio-1.0
You'll notice that the contents of the POM match the pom.xml file, and not the release-pom.xml file. 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, it is necessary to know what version ranges are allowed for a dependency, rather than the specific version used for the release. For the same reason, both the original pom.xml file and the release-pom.xml files are included in the generated JAR file. Also, 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. These are configured by default in the Maven POM as part of a profile that is activated when the release is performed. You can disable this profile by setting the useReleaseProfile parameter to false, as follows:
[...] <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <useReleaseProfile>false</useReleaseProfile> </configuration> </plugin> [...]
Instead, you may want to include additional actions in the profile, without having to declare and enable an additional profile. To do this, define a profile with the identifier release-profile, as follows:
[...] <profiles> <profile> <id>release-profile</id> <build> <!-- Extra plugin configuration would be inserted here --> </build> </profile> </profiles> [...]
After the release process is complete, the only step left is to clean up after the plugin, removing release.properties and any POM files generated as a result of the dry run. Simply run the following command to clean up:
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C:\mvnbook\proficio> mvn release:clean
7.9. Summary
As you've seen throughout this chapter, and indeed this entire book, Maven was designed to address issues that directly affect teams of developers. All of the features described in this chapter can be used by any development team. So, whether your team is large or small, Maven provides value by standardizing and automating the build process. There are also strong team-related benefits in the preceding chapters – for example, the adoption of reusable plugins can capture and extend build knowledge throughout your entire organization, rather than creating silos of information around individual projects. The site and reports you've created can help a team communicate the status of a project and their work more effectively. And all of these features build on the essentials demonstrated in chapters 1 and 2 that facilitate consistent builds. Lack of consistency is the source of many problems when working in a team, and while Maven focuses on delivering consistency in your build infrastructure through patterns, it can aid you in effectively using tools to achieve consistency in other areas of your development. This in turn can lead to and facilitate best practices for developing in a community-oriented, real-time engineering style, by making information about your projects visible and organized.
Better Builds With Maven
Migrating to Maven
Migrating to Maven
This chapter explains how to migrate (convert) an existing build in Ant, 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, testing and building jars with Maven, using both Java 1.4 and Java 5 Using Ant tasks from within Maven Using Maven with your current directory structure
This is your last chance. After this, there is no turning back. You take the blue pill - the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill - you stay in Wonderland and I show you how deep the rabbit-hole goes.
- Morpheus. The Matrix
Better Builds With Maven
Migrating to Maven
8.1. Introduction
The purpose of this chapter is to show a migration path from an existing build in Ant to Maven. The Maven migration example is based on the Spring Framework build, which uses an Ant script. This example will take you through the step-by-step process of migrating Spring to a modularized, component-based, Maven build. You will learn how to start building with Maven, while still running your existing, Ant-based build system. This will allow you to evaluate Maven's technology, while enabling you to continue with your required work. You will learn how to use an existing directory structure (though you will not be following the standard, recommended Maven directory structure), how to split your sources into modules or components, how to run Ant tasks from within Maven, and among other things, you will be introduced to the concept of dependencies.
8.1.1. Introducing the Spring Framework
The Spring Framework is one of today's most popular Java frameworks. For the purpose of this example, we will focus only on building version 2.0-m1 of Spring, which is the latest version at the time of writing. The Spring release is composed of several modules, 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
TLD files.).4 and 1. src and test: contain JDK 1. you can see graphically the dependencies between the modules.4 compatible source code and JUnit tests respectively tiger/src and tiger/test: contain additional JDK 1. etc. Optional dependencies are indicated by dotted lines.Migrating to Maven Figure 8-1: Dependency relationship between Spring modules In figure 8-1. The src and tiger/src directories are compiled to the same destination as the test and tiger/test directories. more or less.5 classes. using inclusions and exclusions that are based on the Java packages of each class. properties files.5 compatible source code and JUnit Better Builds With Maven 229 . with the Java package structure. 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. For Spring. the Ant script compiles each of these different source directories and then creates a JAR for each module. and each produces a JAR. Each of these modules corresponds. resulting in JARs that contain both 1.
you will create a subdirectory called 'm2' to keep all the necessary Maven changes clearly separated from the current build system. that means you will need to have a Maven project (a POM) for each of the modules listed above.Migrating to Maven 8. In the Spring example. WAR.) per Maven project file. you will need to create a directory for each of Spring's modules. the rule of thumb to use is to produce one artifact (JAR.2. etc. Inside the 'm2' directory. To start. Where to Begin? With Maven. Figure 8-2: A sample spring module directory Better Builds With Maven 230 .
in order to tag the release in your SCM.1</version> <scope>test</scope> </dependency> </dependencies> As explained previously. • it should mimic standard package naming conventions to avoid duplicate values. spring-parent) • version: this setting should always represent the next release version number appended with . you will need to create a parent POM. respectively.migrating. the version you are developing in order to release. each module will inherit the following values (settings) from the parent POM. Recall from previous chapters that during the release process.springframework.SNAPSHOT – that is. non-snapshot version for a short period of time. company. For example. Better Builds With Maven 231 . You will use the parent POM to store the common configuration settings that apply to all of the modules.mergere. and In this parent POM we can also add dependencies such as JUnit. you will use com. war. the main source and test directories are src and test. thereby eliminating the requirement to specify the dependency repeatedly across multiple modules.org</url> <organization> <name>The Spring Framework Project</name> </organization> groupId: this setting indicates your area of influence.8.m2book.0-m1-SNAPSHOT</version> <name>Spring parent</name> <packaging>pom</packaging> <description>Spring Framework</description> <inceptionYear>2002</inceptionYear> <url>http://www. Maven will convert to the definitive. 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. the Spring team would use org.springframework • artifactId: the setting specifies the name of this module (for example. project. • packaging: the jar. For this example. department. <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.mergere. which will be used for testing in every module.m2book. primary used for documentation purposes. Let's begin with these directories. in Spring.Migrating to Maven In the m2 directory. <groupId>com. etc.. however. as it is our 'unofficial' example version of Spring.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2.
maven.src}"/> <classpath refid="all-libs"/> </javac> As you can see these include the source and target compatibility (1.. For the debug attribute./. your build section will look like this: <build> <sourceDirectory>.apache.dir}"/> <!-.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.classes. in the buildmain target. <javac destdir="${target.. At this point. that Maven automatically manages the classpath from its list of dependencies. so there is no need for you to add the configuration parameters.debug=false to the mvn command (by default this is set to true). and failonerror (true) values.tempdir.3</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 232 . For now./test</testSourceDirectory> <plugins> <plugin> <groupId>org. you can retrieve some of the configuration parameters for the compiler. To specify the required debug function in Maven.Migrating to Maven Using the following code snippet from Spring's Ant build script.3</source> <target>1. Spring's Ant script uses a parameter. These last three properties use Maven's default values./src</sourceDirectory> <testSourceDirectory>. deprecation and optimize (false). you don't have to worry about the commons-attributes generated sources mentioned in the snippet..compiler. you will need to append -Dmaven. as you will learn about that later in this chapter. Recall from Chapter 2.3" debug="${debug}" deprecation="false" optimize="false" failonerror="true"> <src path="${src.attributes.3).Include Commons Attributes generated Java sources --> <src path="${commons./.dir}" source="1..3" target="1.
classes.awt. Maven uses the default value from the compiler plugin.Must go first to ensure any jndi. You will need to specify the value of the properties test. Maven sets the reports destination directory (todir) to target/surefire-reports. this value is read from the project.properties file loaded from the Ant script (refer to the code snippet below for details). and this doesn't need to be changed.properties files etc take precedence --> <classpath location="${target. formatter elements are not required as Maven generates both plain text and xml reports.testclasses. as Maven prints the test summary and stops for any test error or failure. You will not need any printsummary.excludes}"/> </batchtest> </junit> You can extract some configuration information from the previous code: • • • • • • • forkMode="perBatch" matches with Maven's forkMode parameter with a value of once. by default.testclasses.dir}"/> <classpath refid="all-libs"/> <formatter type="plain" usefile="false"/> <formatter type="xml"/> <batchtest fork="yes" todir="${reports.mockclasses. classpath is automatically managed by Maven from the list of dependencies. so you will not need to locate the test classes directory (dir).Migrating to Maven The other configuration that will be shared is related to the JUnit tests.dir}"/> <!-.excludes from the nested fileset. • Better Builds With Maven 233 . since the concept of a batch for testing does not exist.includes and test. From the tests target in the Ant script: <junit forkmode="perBatch" printsummary="yes" haltonfailure="yes" haltonerror="yes"> <jvmarg line="-Djava.includes}" excludes="${test.dir}"/> <classpath location="${target. haltonfailure and haltonerror settings.Need files loaded as resources --> <classpath location="${test.dir}"> <fileset dir="${target.dir}" includes="${test. by default. The nested element jvmarg is mapped to the configuration parameter argLine As previously noted.dir}"/> <classpath location="${target.headless=true -XX:MaxPermSize=128m -Xmx128m"/> <!-.
5 . When building only on Java 5 you could remove that option and the XML parser (Xerces) and APIs (xml-apis) dependencies.excludes=**/Abstract* #test. <plugin> <groupId>org. Since Maven requires JDK 1. # Second exclude needs to be used for JDK 1.headless=true -XX:MaxPermSize=128m -Xmx128m </argLine> <includes> <include>**/*Tests.class # # Wildcards to exclude among JUnit tests. Better Builds With Maven 234 .1 # being compiled with target JDK 1. Spring's Ant build script also makes use of the commons-attributes compiler in its compileattr and compiletestattr targets. The commons-attributes compiler processes javadoc style annotations – it was created before Java supported annotations in the core language on JDK 1.maven.includes=**/*Tests.excludes=**/Abstract* org/springframework/orm/hibernate3/** The includes and excludes referenced above. due to Hibernate 3.4 to run you do not need to exclude hibernate3 tests. It makes tests run using the standard classloader delegation instead of the default Maven isolated classloader.3.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.4. mandatory when building in JDK 1. test. translate directly into the include/exclude elements of the POM's plugin configuration.4.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <forkMode>once</forkMode> <childDelegation>false</childDelegation> <argLine> -Djava. test. # Convention is that our JUnit test classes have XXXTests-style names.Migrating to Maven # Wildcards to be matched by JUnit tests.apache.and generates sources from them that have to be compiled with the normal Java compiler. which are processed prior to the compilation.awt. 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.
Better Builds With Maven 235 . --> <attribute-compiler destdir="${commons. this same function can be accomplished by adding the commons-attributes plugin to the build section in the POM.java</include> </testIncludes> </configuration> <goals> <goal>compile</goal> <goal>test-compile</goal> </goals> </execution> </executions> </plugin> Later in this chapter you will need to modify these test configurations.java"/> <fileset dir="${test.dir}" includes="**/metadata/*.metadata package currently needs to be shipped with an attribute.codehaus.web. --> <fileset dir="${src.Compile to a temp directory: Commons Attributes will place Java Source here.tempdir.attributes.java"/> </attribute-compiler> In Maven. so you will only need to add the inclusions for the main source and test source compilation.tempdir.java"/> </attribute-compiler> From compiletestattr: <!-.src}"> <!-Only the PathMap attribute in the org.mojo</groupId> <artifactId>commons-attributes-maven-plugin</artifactId> <executions> <execution> <configuration> <includes> <include>**/metadata/*.Migrating to Maven From compileattr: <!-.java</include> <include>org/springframework/jmx/**/*. to support indexing. --> <attribute-compiler destdir="${commons.attributes.java</include> </includes> <testIncludes> <include>org/springframework/aop/**/*.Compile to a temp directory: Commons Attributes will place Java Source here. <plugin> <groupId>org.dir}" includes="org/springframework/jmx/**/*.springframework.dir}" includes="org/springframework/aop/**/*.servlet.handler. Maven handles the source and destination directories automatically.test}"> <fileset dir="${test.
review the following code snippet from Spring's Ant script.Migrating to Maven 8. or they will get included in the JAR.). As you saw before. you will need to tell Maven to pick the correct classes and resources from the core and util packages. version. you can determine which classes are included in the JAR and what attributes are written into the JAR's manifest.3. Compiling In this section.mergere. Creating POM files Now that you have the basic configuration shared by all modules (project information. Better Builds With Maven 236 .0-m1-SNAPSHOT</version> </parent> <artifactId>spring-core</artifactId> <name>Spring core</name> Again. To begin. as those values are inherited from parent POM. and organization name to the values in the POM. you will need to create a POM that extends the parent POM. 8. Maven will automatically set manifest attributes such as name. etc. The following is the POM for the spring-core module. since the sources and resources are in the same directory in the current Spring build.dir}"> <include name="org/springframework/core/**"/> <include name="org/springframework/util/**"/> </fileset> <manifest> <attribute name="Implementation-Title" value="${spring-title}"/> <attribute name="Implementation-Version" value="${spring-version}"/> <attribute name="Spring-Version" value="${spring-version}"/> </manifest> </jar> From the previous code snippet.m2book. setting the files you want to include (by default Maven will pick everything from the resource directory).java files from the resources. For the resources. you won't need to specify the version or groupId elements of the current module. This module is the best to begin with because all of the other modules depend on it. you need to create the POM files for each of Spring's modules. you will need to add a resources element in the build section. While manifest entries can also be customized with additional configuration to the JAR plugin. compiler configuration. in this case the defaults are sufficient.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2.dir}/modules/spring-core. you will need to exclude the *. description. you will start to compile the main Spring source.jar"> <fileset dir="${target. which centralizes and maintains information common to the project. JUnit test configuration. tests will be dealt with later in the chapter. <parent> <groupId>com. In each subdirectory. However.classes.4. where spring-core JAR is created: <jar jarfile="${dist.
.java</exclude> </excludes> </resource> </resources> <plugins> <plugin> <groupId>org. because as with resources./src</directory> <includes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*.maven.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 237 . Maven will by default compile everything from the source directory.Migrating to Maven For the classes.. you will need to configure the compiler plugin to include only those in the core and util packages. which is inherited from the parent POM. <build> <resources> <resource> <directory>.apache./.
artifactId and version should we use? For the groupId and artifactId.org/maven2/commons-logging/commons-logging/. 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 These are typical compiler messages.apache. If you check the repository. commons-logging groupId would become org.logging.34] package org. it's usually the JAR name without a version (in this case commonslogging). Specify site:www.java:[30.commons.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver.34] package org.commons. you will find all the available versions of commons-logging under http://www. the actual groupId is commons-logging.java:[19. beginning with the following: [INFO] -----------------------------------------------------------------------[ERROR] BUILD FAILURE [INFO] -----------------------------------------------------------------------[INFO] Compilation failure C:\dev\m2book\code\migrating\spring\m2\springcore\.apache.ibiblio..24] cannot find symbol symbol : class Log location: class org.io. changing dots to slashes.support. In the case of commons-logging.org/maven2 commons logging..core.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver.. Better Builds With Maven 238 .Migrating to Maven To compile your Spring build. for historical reasons some groupId values don't follow this convention and use only the name of the project.commons. From the previous output.. You will see a long list of compilation failures. Typically. But..apache.java:[107.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver.\src\org\springframework\util\xml\SimpleSaxErrorHandler. you can search the repository using Google.\.logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\.\.ibiblio. what groupid. located in the org/apache/commons/logging directory in the repository. Regarding the artifactId. and then choose from the search results..logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\.\. you can now run mvn compile.34] package org.commons..\. the option that is closest to what is required by your project. For example. As an alternative.. However.java:[31.apache. caused by the required classes not being on the classpath.PathMatchingResourcePatternResolver C:\dev\m2book\code\migrating\spring\m2\springcore\. you need to check the central repository at ibiblio. the convention is to use a groupId that mirrors the package name.springframework.
modular projects that are easier to maintain in the long term. and then search in Google prepending site:www.ibiblio. for the hibernate3.ibiblio.hibernate) An easier way to search for dependencies.1/hibernate-3.txt in the lib directory of the Spring source. When needed. the previous directory is the artifactId (hibernate) and the other directories compose the groupId. search the ibiblio repository through Google by calculating the MD5 checksum of the JAR file with a program such as md5sum.MF • For advanced users. you could search with: site:www.1.org/maven2 to the query. However. component-oriented. is under development (refer to the Maven Repository Manager project for details). <dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. using a web interface. explicit dependency management is one of the biggest benefits of Maven once you have invested the effort upfront.org/maven2/org/hibernate/hibernate/3. although you could simply follow the same behavior used in Ant (by adding all the dependencies in the parent POM so that. For instance. 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.jar. You can use this as a reference to determine the versions of each of the dependencies. during the process of migrating Spring to Maven. For example. we strongly encourage and recommend that you invest the time at the outset of your migration. we discovered that the commons-beanutils version stated in the documentation is wrong and that some required dependencies are missing from the documentation.org/maven2 78d5c38f1415efc64f7498f828d8069a • The search will return: www.Migrating to Maven With regard the version.jar provided with Spring under lib/hibernate.ibiblio. While adding dependencies can be the most painful part of migrating to Maven. with the slashes changed to dots (org. to make explicit the dependencies and interrelationships of your projects. all sub-modules would use the same dependencies).0.md5 You can see that the last directory is the version (3.1). through inheritance. you have to be careful as the documentation may contain mistakes and/or inaccuracies. you will find that there is documentation for all of Spring's dependencies in readme. Doing so will result in cleaner. Better Builds With Maven 239 . so you will have first hand knowledge about the dependencies and versions used. So.4</version> </dependency> </dependencies> Usually you will convert your own project.
so log4j will not be included in other projects that depend on this. In addition.properties file required for logging configuration.properties</include> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*. Using the optional tag does not affect the current project. After compiling the tests. you will notice that you also need Apache Commons Collections (aka commons-collections) and log4j.5. For the first step. Compiling Tests Setting the test resources is identical to setting the main resources. and it is just for the convenience of the users.1</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1. <testResources> <testResource> <directory>.java</exclude> </excludes> </testResource> </testResources> Better Builds With Maven 240 . This is because in other projects. with the exception of changing the location from which the element name and directory are pulled. run mvn compile again .Migrating to Maven Running again mvn compile and repeating the process previously outlined for commons-logging.5.1..9</version> <optional>true</optional> </dependency> Notice that log4j is marked as optional. Optional dependencies are not included transitively../.this time all of the sources for spring-core will compile./test</directory> <includes> <include>log4j. you will need to add the log4j. Testing Now you're ready to compile and run the tests.2. 8. setting which test resources to use. you will repeat the previous procedure for the main classes. and setting the JUnit test sources to compile. you may decide to use another log implementation. <dependency> <groupId>commons-collections</groupId> <artifactId>commons-collections</artifactId> <version>3. 8. Now. we will cover how to run the tests.
java</exclude> <exclude>org/springframework/util/SerializationTestUtils. Inside the mavencompiler-plugin configuration. you will see the following error: package javax. as well. org. but this time there is a special case where the compiler complains because some of the classes from the org.beans packages are missing. Better Builds With Maven 241 . you will see that their main classes. To exclude test classes in Maven.web and org.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2. In other words.4</version> <scope>test</scope> </dependency> The scope is set to test. <testExcludes> <exclude>org/springframework/util/comparator/ComparatorTests. you will need to add the testIncludes element. <testIncludes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </testIncludes> Now. it makes sense to exclude all the test classes that reference other modules from this one and include them elsewhere. not tests. which one do we build first? Impossible to know. but if you try to compile those other modules. It may appear initially that spring-core depends on spring-mock. the key here is to understand that some of the test classes are not actually unit tests for springcore.java</exclude> <exclude>org/springframework/util/ObjectUtilsTests.java</exclude> <exclude>org/springframework/core/io/ResourceTests. Therefore. add the testExcludes element to the compiler configuration as follows. as all the test classes compile correctly now. if you try to compile the test classes by running mvn test-compile. if spring-core depends on spring-beans and springbeans depends on spring-core. As a result.Migrating to Maven Setting the test sources for compilation follows the same procedure.servlet does not exist This means that the following dependency must be added to the POM.springframework.java</exclude> <exclude>org/springframework/util/ClassUtilsTests. we cannot add a dependency from spring-core without creating a circular dependency. depend on classes from spring-core. spring-web and spring-beans modules. as before.java</exclude> <exclude>org/springframework/util/ReflectionUtilsTests.mock.springframework. as this is not needed for the main sources. but rather require other modules to be present. when you run mvn test-compile.springframework.java</exclude> </testExcludes> Now. in order to compile the tests: <dependency> <groupId>javax. If you run mvn test-compile again you will have a successful build. So. you will get compilation errors.
PathMatchingResourcePatternResolverT ests. you will find the following: [surefire] Running org. so to resolve the problem add the following to your POM <dependency> <groupId>aopalliance</groupId> <artifactId>aopalliance</artifactId> <version>1. there is a section for each failed test called stacktrace. Failures: 1.txt.2.) Better Builds With Maven 242 . This indicates that there is something missing in the classpath that is required to run the tests.015 sec <<<<<<<< FAILURE !! This output means that this test has logged a JUnit failure and error.io. Time elapsed: 0.support. Failures: 1. 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. you will need to check the test logs under target/surefire-reports. for the test class that is failing org.io. when you run this command. Running Tests Running the tests in Maven.aopalliance package is inside the aopallience JAR.5. Errors: 1. To debug the problem.0</version> <scope>test</scope> </dependency> Now run mvn test again.springframework. you will get the following error report: Results : [surefire] Tests run: 113.Migrating to Maven 8. compile. as it will process all of the previous phases of the build life cycle (generate sources.springframework. is to run mvn install to make the resulting JAR available to other projects in your local Maven repository.PathMatchingResourcePatternResolverTests [surefire] Tests run: 5. simply requires running mvn test.core. The first section starts with java. [INFO] ------------------------------------------------------------------------ Upon closer examination of the report output. The org. Errors: 1 [INFO] -----------------------------------------------------------------------[ERROR] BUILD ERROR [INFO] -----------------------------------------------------------------------[INFO] There are test failures.core. run tests.support.io. etc.FileNotFoundException: class path resource [org/aopalliance/] cannot be resolved to URL because it does not exist. compile tests. This command can be used instead most of the time. However. Within this file.
In the same way. Using the parent POM to centralize this information makes it possible to upgrade a dependency version across all sub-projects from a single location.groupId}</groupId> <artifactId>spring-core</artifactId> <version>${project. For instance.0.4</version> </dependency> </dependencyManagement> The following are some variables that may also be helpful to reduce duplication: • • ${project. you will be adding the Surefire plugin configuration settings repeatedly for each module that you convert.6.6. each of the modules will be able to inherit the required Surefire configuration. 8. you will find that you are repeating yourself.1. move these configuration settings to the parent POM instead. otherwise you will find that the main classes from some of the modules reference classes from modules that have not yet been built. To avoid duplication. you can refer to spring-core from spring-beans with the following. since they have the same groupId and version: <dependency> <groupId>${project.Migrating to Maven 8. use the parent POM's dependencyManagement section to specify this information once. Avoiding Duplication As soon as you begin migrating the second module. instead of repeatedly adding the same dependency version information to each module. <dependencyManagement> <dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. and remove the versions from the individual modules (see Chapter 3 for more information).groupId}: groupId of the current POM being built For example.version}</version> </dependency> Better Builds With Maven 243 . If you follow the order of the modules described at the beginning of the chapter you will be fine. That way. See figure 8-1 to get the overall picture of the interdependencies between the Spring modules. Other Modules Now that you have one module working it is time to move on to the other modules.version}: version of the current POM being built ${project.
with only those classes related to spring-web.maven.4. 8. you will need to create a new spring-beans-tiger module.Migrating to Maven 8. To eliminate this problem. particularly in light of transitive dependencies.version}</version> <type>test-jar</type> <scope>test</scope> </dependency> A final note on referring to test classes from other modules: if you have all of Spring's mock classes inside the same module. By splitting them into different modules. First. there is a procedure you can use. you can use it as a dependency for other components. Building Java 5 Classes Some of Spring's modules include Java 5 classes from the tiger folder. Consider that if you include some classes compiled for Java 1. Better Builds With Maven 244 . So.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <executions> <execution> <goals> <goal>test-jar</goal> </goals> </execution> </executions> </plugin> Once that JAR is installed. in this case it is necessary to avoid refactoring the test source code. Referring to Test Classes from Other Modules If you have tests from one component that refer to tests from other modules.6.3 or 1. with only those classes related to spring-context module. and spring-web-mock. However. any users. attempting to use one of the Java 5 classes under Java 1. Although it is typically not recommended. by specifying the test-jar type.6. As the compiler plugin was earlier configured to compile with Java 1. Generally with Maven. users will know that if they depend on the module composed of Java 5 classes.5 sources be added? To do this with Maven. make sure that when you run mvn install.3 compatibility. be sure to put that JAR in the test scope as follows: <dependency> <groupId>${project. how can the Java 1.3. you can split Spring's mock classes into spring-context-mock.apache.2.groupId}</groupId> <artifactId>spring-beans</artifactId> <version>${project. they will need to run them under Java 5. would experience runtime errors.3 and some compiled for Java 5 in the same JAR. this can cause previously-described cyclic dependencies problem. it's easier to deal with small modules. 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. that a JAR that contains the test classes is also installed in the repository: <plugin> <groupId>org.
the Java 5 modules will share a common configuration for the compiler. The best way to split them is to create a tiger folder with the Java 5 parent POM. and then a directory for each one of the individual tiger modules.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 245 .
Migrating to Maven Figure 8-5: Dependency relationship. you will need to add a module entry for each of the directories.5</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 246 ./. 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>./..5</source> <target>1.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1././tiger/test</testSourceDirectory> <plugins> <plugin> <groupId>org..../tiger/src</sourceDirectory> <testSourceDirectory>.apache.maven. with all modules In the tiger POM./...
4. From Ant.rmi.4 you will add that module in a profile that will be triggered only when using 1.5 JDK. In this case.springframework. Maven can call Ant tasks directly from a POM using the maven-antrun-plugin.remoting. this is: <rmic base="${target.classes.remoting.6. but to still be able to build the other modules when using Java 1. you just need a new module entry for the tiger folder.dir}" classname="org.dir}" classname="org.Migrating to Maven In the parent POM.5</id> <activation> <jdk>1.RmiInvocationWrapper" iiop="true"> <classpath refid="all-libs"/> </rmic> Better Builds With Maven 247 .RmiInvocationWrapper"/> <rmic base="${target.classes. you need to use the Ant task in the spring-remoting module to use the RMI compiler. you may find that Maven does not have a plugin for a particular task or an Ant target is so small that it may not be worth creating a new plugin.springframework. <profiles> <profile> <id>jdk1. with the Spring migration.rmi. For example. Using Ant Tasks From Inside Maven In certain migration cases.5</jdk> </activation> <modules> <module>tiger</module> </modules> </profile> </profiles> 8.
plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <executions> <execution> <phase>process-classes</phase> <configuration> <tasks> <echo>Running rmic</echo> <rmic base="${project. To complete the configuration.rmi.directory}/classes" classname="org. there are some references available already. such as the reference to the tools. such as ${project.4</version> <systemPath>${java.Migrating to Maven To include this in Maven build. the most appropriate phase in which to run this Ant task is in the processclasses phase..RmiInvocationWrapper" iiop="true"> <classpath refid="maven. There are also references for anything that was added to the plugin's dependencies section.springframework. In this case.maven. which is a classpath reference constructed from all of the dependencies in the compile scope or lower.build.classpath"/> </rmic> </tasks> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> <dependencies> <dependency> <groupId>com.build. you will need to determine when Maven should run the Ant task.directory} and maven. Better Builds With Maven 248 .compile.build.jar</systemPath> </dependency> </dependencies> </plugin> As shown in the code snippet above.jar above. So. which is bundled with the JDK.rmi.home}/. add: <plugin> <groupId>org.classpath./lib/tools.apache.RmiInvocationWrapper"/> <rmic base="${project. stub and tie classes from them. will take the compiled classes and generate the rmi skeleton.springframework.sun</groupId> <artifactId>tools</artifactId> <scope>system</scope> <version>1.compile.directory}/classes" classname="org.remoting. and required by the RMI task. the rmic task.remoting. which applies to that plugin only.
6.6. which used relative paths in Log4JConfigurerTests 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. Sun's Activation Framework and JavaMail are not redistributable from the repository due to constraints in their licenses. There is some additional configuration required for some modules.6.2 -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. NamespaceHandlerUtilsTests. as these test cases will not work in both Maven and Ant. 8. see http://maven.apache. Some Special Cases In addition to the procedures outlined previously for migrating Spring to Maven. Using classpath resources is recommended over using file system resources. 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. which uses AspectJ for weaving the classes.5.3. to install JavaMail: mvn install:install-file -Dfile=mail.html. 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. there are two additional.mail -DartifactId=mail -Dversion=1. These issues were shared with the Spring developer community and are listed below: • • Moving one test class. Better Builds With Maven 249 . For more information on dealing with this issue.org/guides/mini/guide-coping-with-sun-jars. These can be viewed in the example code.Migrating to Maven 8. such as spring-aspects. You can then install them in your local repository with the following command. For example. mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging> For instance.jar -DgroupId=javax. special cases that must be handled.
Migrating to Maven
8.7. Restructuring the Code
If you finally decide to stick with Maven, you are encouraged to use the default directory structure to take advantage of For example, for the spring-core module, 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. All of the other files under those two packages would go to src/main/resources. The same for tests, these would move from the original test folder to src/test/java and src/test/resources respectively for Java sources and other files - just remember not to move the excluded tests (ComparatorTests, ClassUtilsTests, ObjectUtilsTests, ReflectionUtilsTests, SerializationTestUtils and ResourceTests). By adopting Maven's standard directory structure, you can simplify the POM significantly, reducing its size by two-thirds!
8.8. Summary
By following and completing this chapter, you will be able to take an existing Ant-based build, split it into modular components (if needed), compile and test the code, create JARs, and install those JARs in your local repository using Maven. At the same time, you will be able to keep your current build working. Once you decide to switch completely to Maven, you will be able to take advantage of the benefits of adopting Maven's standard directory structure. By doing this, you would eliminate the need to include and exclude sources and resources "by hand" in the POM files as shown in this chapter. Once you have spent this initial setup time Maven, you can realize Maven' other benefits - advantages such as built-in project documentation generation, reports, and quality metrics. Finally, in addition to the improvements to your build life cycle, Maven can eliminate the requirement of storing jars in a source code management system. In the case of the Spring example, as Maven downloads everything it needs and shares it across all your Maven projects automatically - you can delete that 80 MB lib folder. Now that you have seen how to do this for Spring, you can apply similar concepts to your own Ant based build.
Better Builds With Maven
Appendix A: Resources for Plugin Developers
Appendix A: Resources for Plugin Developers
In this appendix you will find: Mavens Life Cycles • Mojo Parameter Expressions • Plugin Metadata
Scotty: She's all yours, sir. All systems automated and ready. A chimpanzee and two trainees could run her! Kirk: Thank you, Mr. Scott, I'll try not to take that personally. - Star Trek
Better Builds With Maven
Appendix A: Resources for Plugin Developers
A.1. Maven's Life Cycles
Below is a discussion of Maven's three life cycles and their default mappings. It begins by listing the phases in each life cycles, along with a short description for the mojos which should be bound to each. It continues by describing the mojos bound to the default life cycle for both the jar and mavenplugin packagings. Finally, this section will describe the mojos bound by default to the clean and site life cycles.
A.1.1. The
default Life Cycle
Maven provides three life cycles, corresponding to the three major activities performed by Maven: building a project from source, cleaning a project of the files generated by a build, and generating a project web site. For the default life cycle, mojo-binding defaults are specified in a packaging-specific manner. This is necessary to accommodate the inevitable variability of requirements for building different types of projects. This section contains a listing of the phases in the default life cycle, along with a summary of bindings for the jar and maven-plugin packagings.
Life-cycle phases
The default life cycle is executed in order to perform a traditional build. In other words, it takes care of compiling the project's code, performing any associated tests, archiving it into a jar, and distributing it into the Maven repository system. It contains the following phases: 1. validate – verify that the configuration of Maven, and the content of the current set of POMs to be built is valid. 2. initialize – perform any initialization steps required before the main part of the build can start. 3. generate-sources – generate compilable code from other source formats. 4. process-sources – perform any source modification processes necessary to prepare the code for compilation. For example, a mojo may apply source code patches here. 5. generate-resources – generate non-code resources (such as configuration files, etc.) from other source formats. 6. process-resources – perform any modification of non-code resources necessary. This may include copying these resources into the target classpath directory in a Java build. 7. compile – compile source code into binary form, in the target output location. 8. process-classes – perform any post-processing of the binaries produced in the preceding step, such as instrumentation or offline code-weaving, as when using Aspect-Oriented Programming techniques. 9. generate-test-sources – generate compilable unit test code from other source formats.
Better Builds With Maven
Appendix A: Resources for Plugin Developers
10. process-test-sources – perform any source modification processes necessary to prepare the unit test code for compilation. For example, a mojo may apply source code patches here. 11. generate-test-resources – generate non-code testing resources (such as configuration files, etc.) from other source formats. 12. process-test-resources – perform any modification of non-code testing resources necessary. This may include copying these resources into the testing target classpath location in a Java build. 13. test-compile – compile unit test source code into binary form, in the testing target output location. 14. test – execute unit tests on the application compiled and assembled up to step 8 above. 15. package – assemble the tested application code and resources into a distributable archive. 16. preintegration-test – setup the integration testing environment for this project. This may involve installing the archive from the preceding step into some sort of application server. 17. integration-test – execute any integration tests defined for this project, using the environment configured in the preceding step. 18. post-integration-test – return the environment to its baseline form after executing the integration tests in the preceding step. This could involve removing the archive produced in step 15 from the application server used to test it. 19. verify – verify the contents of the distributable archive, before it is available or installation or deployment. 20. install – install the distributable archive into the local Maven repository. 21. deploy – deploy the distributable archive into the remove Maven repository configured in the distributionManagement section of the POM.
Better Builds With Maven
Appendix A: Resources for Plugin Developers
Bindings for the jar packaging
Below are the default life-cycle bindings for the jar packaging. Alongside each, you will find a short description of what that mojo does. 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. Filter variables if necessary. Compile project source code to the staging directory for jar creation. Copy non-source-code test resources to the test output directory for unit-test compilation. Compile unit-test source code to the test output directory. Execute project unit tests. Create a jar archive from the staging directory. Install the jar archive into the local Maven repository. Deploy the jar archive to a remote Maven repository, specified in the POM distribution Management section.
process-test- 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
maven-plugin-plugin Update the plugin registry. compiling source code. if one exists. As such. Better Builds With Maven 255 . to extract and format the metadata for the mojos within. for example). Indeed. and metadata references to latest plugin version. the maven-plugin packaging also introduces a few new mojo bindings. However. 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. to install reflect the new plugin installed in the local repository. addPluginArtifact Metadata updateRegistry maven-plugin-plugin Integrate current plugin information with plugin search metadata. and the rest. testing. packaging. they undergo the same basic processes of marshaling non-source-code resources. maven-plugin artifacts are in fact jar files.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. and generate a plugin descriptor.
Default life-cycle bindings Below are the clean life-cycle bindings for the jar packaging. Below is a listing of the phases in the clean life cycle. effective for all POM packagings. which perform the most common tasks involved in cleaning a project. pre-clean – execute any setup or initialization procedures to prepare the project for cleaning 2. you will find a short description of what that mojo does. Maven provides a set of default mojo bindings for this life cycle. the state of the project before it was built. along with a summary of the default bindings.2. 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. Life-cycle phases The clean life-cycle phase contains the following phases: 1. Alongside each. clean – remove all files that were generated during another build process 3. Better Builds With Maven 256 . The clean Life Cycle This life cycle is executed in order to restore a project back to some baseline state – usually.1.Appendix A: Resources for Plugin Developers A. along with any additional directories configured in the POM. post-clean – finalize the cleaning process.
Below is a listing of the phases in the site life cycle.Appendix A: Resources for Plugin Developers A. post-site – execute any actions required to finalize the site generation process. site-deploy deploy Better Builds With Maven 257 . 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. pre-site – execute any setup or initialization steps to prepare the project for site generation 2. you will find a short description of what that mojo does. and render documentation source files into HTML. Life-cycle phases The site life cycle contains the following phases: 1. Maven provides a set of default mojo bindings for this life cycle. and render documentation into HTML 3.1. Default Life Cycle Bindings Below are the site life-cycle bindings for the jar packaging.3. render your documentation source files into HTML. It will run any reports that are associated with your project. and prepare the generated web site for potential deployment 4. Deploy the generated web site to the web server path specified in the POM distribution Management section. Alongside each. along with a summary of the default bindings. effective for all POM packagings. and even deploy the resulting web site to your server. site – run all associated project reports. site-deploy – use the distributionManagement configuration in the project's POM to deploy the generated web site files to the web server. which perform the most common tasks involved in generating the web site for a project. The site Life Cycle This life cycle is executed in order to generate a web site for your project.
ArtifactRepository used to cache artifacts during a Maven build. it will describe the algorithm used to resolve complex parameter expressions. A. org.reporting.MavenReport> life cycle executes. ${reactorProjects} ${reports} ${executedProject} java.artifact. in addition to providing a mechanism for looking up Maven components on-demand.maven.2.1. It will summarize the root objects of the build state which are available for mojo expressions.MavenProject> processed as part of the current build.ma List of project instances which will be ven. which act as a shorthand for referencing commonly used build state objects.2.apache.List<org. They are summarized below: Table A-5: Primitive expressions supported by Maven's plugin parameter Expression Type Description ${localRepository} ${session} org.re This is a reference to the local repository pository. Simple Expressions Maven's plugin parameter injector supports several primitive expressions.maven.apache. java.apache.project.maven.apache. Using the discussion below. These expressions allow a mojo to traverse complex build state. mojo developers should have everything they need to extract the build state they require. Better Builds With Maven 258 . Mojo Parameter Expressions Mojo parameter values are resolved by way of parameter expressions when a mojo is initialized. Finally.util.project. This reduces the complexity of the code contained in the mojo. org.M The current build session. and extract only the information it requires.ma List of reports to be generated when the site ven. This section discusses the expression language used by Maven to inject build state and plugin configuration into mojos.util. and often eliminates dependencies on Maven itself beyond the plugin API. along with the published Maven API documentation. It is used for bridging results from forked life cycles back to the main line of execution.List<org.Appendix A: Resources for Plugin Developers A. This contains avenSession methods for accessing information about how Maven was called.Mav This is a cloned instance of the project enProject instance currently being built.apache.execution.
Sett The Maven settings.descri The descriptor instance for the current plugin. 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.Maven Project instance which is currently being built.apache. Complex Expression Roots In addition to the simple expressions above. unless specified otherwise.maven.maven.Appendix A: Resources for Plugin Developers A.m2/settings.File The current project's root directory.settings. ${plugin} org.xml in the maven application directory and from .apache. ptor. merged from ings conf/settings.project.PluginDescriptor including its dependency artifacts.maven. Project org. Maven supports more complex expressions that traverse the object graph starting at some root object that contains build state.xml in the user's home directory.io. Better Builds With Maven 259 . org.apache.2.plugin.2.
Maven will consult the current system properties. following standard JavaBeans naming conventions. --> <description>Sample Maven Plugin</description> <!-.2. and must correspond to one of the roots mentioned above.Appendix A: Resources for Plugin Developers A. if the expression matches one of the primitive expressions (mentioned above) exactly. then the string literal of the expression itself is used as the resolved value. if there is one.The description element of the plugin's POM. successive expression parts will extract values from deeper and deeper inside the build state. 2. Plugin descriptor syntax The following is a sample plugin descriptor. During this process. If the parameter is still empty after these two lookups. the expression is split at each '. Maven plugin parameter expressions do not support collection lookups. This root object is retrieved from the running application using a hard-wired mapping. the value that was resolved last will be returned as the expression's value. or an active profile. Plugin metadata Below is a review of the mechanisms used to specify metadata for plugins. an ancestor POM. The first is the root object. this reflective lookup process is aborted.' character.2. The Expression Resolution Algorithm Plugin parameter expressions are resolved using a straightforward algorithm. <plugin> <!-. resolved in this order: 1. an expression part named 'child' translates into a call to the getChild() method on that object. From there. Repeating this. as well the metadata formats which are translated into plugin descriptors from Java. Otherwise. Its syntax has been annotated to provide descriptions of the elements. much like a primitive expression would. If at this point Maven still has not been able to resolve a value for the parameter expression. |-> Better Builds With Maven 260 .and Ant-specific mojo source files. When there are no more expression parts. Currently.These are the identity elements (groupId/artifactId/version) | from the plugin POM. it will be resolved as the parameter value at this point. array index references. This includes properties specified on the command line using the -D commandline option. rendering an array of navigational directions. No advanced navigation can take place using is such expressions. First. the next expression part is used as a basis for reflectively traversing that object' state. The system properties. or method invocations that don't conform to standard JavaBean naming conventions. It includes summaries of the essential plugin descriptor. If the value is still empty. If a user has specified a property mapping this expression to a specific value in the current POM. The resulting value then becomes the new 'root' object for the next round of traversal. then the value mapped to that expression is returned. If at some point the referenced object doesn't contain a property that matches the next expression part. it will attempt to find a value in one of two remaining places. The POM properties.
| This allows the user to specify that this mojo be executed (via the | <execution> section of the plugin configuration in the POM). |-> <executeGoal>do-something-first</executeGoal> <!-.maven.Appendix A: Resources for Plugin Developers <groupId>org. It is a good idea to provide this. without | also having to specify which phase is appropriate for the mojo's | execution. |-> <inheritedByDefault>true</inheritedByDefault> <!-. | This is useful when the user will be invoking this mojo directly from | the command line. this plugin could be referred to from the command line using | the 'myplugin:' prefix.0-SNAPSHOT</version> <!-. unless the user specifies | <inherit>false</inherit>. |-> Better Builds With Maven 261 . This is | useful to inject specialized behavior in cases where the main life | cycle should remain unchanged.This element provides the shorthand reference for this plugin. but the mojo itself has certain life-cycle | prerequisites.apache. For | instance. It's restricted to this plugin to avoid creating inter-plugin | dependencies.Tells Maven that the this plugin's configuration should be inherted from | a parent POM by default. to give users a hint | at where this task should run. |-> <executeLifecycle>myLifecycle</executeLifecycle> <!-. |-> <executePhase>process-resources</executePhase> <!-.</description> <!-.This is optionally used in conjunction with the executePhase element.plugins</groupId> <artifactId>maven-myplugin-plugin</artifactId> <version>2.Which phase of the life cycle this mojo will bind to by default. |-> <goal>do-something</goal> <!-. |-> <phase>compile</phase> <!-. --> <description>Do something cool. |-> <goalPrefix>myplugin</goalPrefix> <!-. via the | command line. then execute that life cycle up to the specified phase. | and specifies a custom life-cycle overlay that should be added to the | cloned life cycle before the specified phase is executed.Ensure that this other mojo within the same plugin executes before | this one.This is a list of the mojos contained within this plugin. | this name allows the user to invoke this mojo from the command line | using 'myplugin:do-something'. --> <mojos> <mojo> <!-.Tells Maven that this mojo can ONLY be invoked directly.Description of what this mojo does.This tells Maven to create a clone of the current project and | life cycle. Combined with the 'goalPrefix' element above.The name of the mojo.
--> <type>java.The class or script path (within the plugin's jar) for this mojo's | implementation.plugins.maven. |-> <requiresOnline>false</requiresOnline> <!-.Tells Maven that the this plugin's configuration should be inherted | from a parent POM by default. In Java mojos. |-> <inheritedByDefault>true</inheritedByDefault> <!-. 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. | It will be used as a backup for retrieving the parameter value. If the mojo is not marked as an | aggregator. Better Builds With Maven 262 .Determines how Maven will execute this mojo in the context of a | multimodule build.The Java type for this parameter.site. |-> <alias>outputDirectory</alias> <!-. unless the user specifies | <inherit>false</inherit>. |-> <implementation>org. such mojos will | cause the build to fail.apache.File</type> <!-. |-> <name>inputDirectory</name> <!-. This flag controls whether the mojo requires | Maven to be online.This is a list of the parameters used by this mojo.This is an optional alternate parameter name for this parameter. it will be executed once for each project instance in the | current build. this will often reflect the | parameter field name in the mojo class.The implementation language for this mojo. If a mojo is marked as an aggregator. it will only | execute once. |-> <requiresProject>true</requiresProject> <!-.SiteDeployMojo</implementation> <!-.Tells Maven that a valid list of reports for the current project are | required before this plugin can execute. the | mojo (and the build) will fail when this parameter doesn't have a | value. |-> <requiresReports>false</requiresReports> <!-. If Maven is operating in offline mode.Appendix A: Resources for Plugin Developers <requiresDirectInvocation>false</requiresDirectInvocation> <!-. regardless of the number of project instances in the | current build. If true.Some mojos cannot execute if they don't have access to a network | connection. --> <language>java</language> <!-. |-> <aggregator>false</aggregator> <!-. --> <parameters> <parameter> <!-.io.Whether this parameter is required to have a value.The parameter's name.
as | compared to the descriptive specification above. The expression used to extract the | parameter value is ${project. and it | expects a type of java.apache. Finally.io. If set to | false.outputDirectory}. | | The general form is: | <param-name implementation="param-type">param-expr</param-name> | |-> <configuration> <!-. Each parameter must | have an entry here that describes the parameter name. specified in the javadoc comment | for the parameter field in Java mojo implementations.artifact.reporting.Use a component of type: org.manager.io. this parameter is named "inputDirectory". | along with an optional classifier for the specific component instance | to be used (role-hint). |-> <description>This parameter does something important.WagonManager</role> <!-.reporting. as in the case of the list of project dependencies.File">${project.maven. |-> <editable>true</editable> <!-.Appendix A: Resources for Plugin Developers |-> <required>true</required> <!-. | and the primary expression used to extract the parameter's value. |-> <inputDirectory implementation="java.This is the list of non-parameter component references used by this | mojo. Components are specified by their interface class name (role).maven.WagonManager |-> <role>org.apache.Description for this parameter.Whether this parameter's value can be directly specified by the | user. |-> <requirements> <requirement> <!-.File. either via command-line or POM configuration. parameter type. the requirement specification tells | Maven which mojo-field should receive the component instance.For example.outputDirectory}</inputDirectory> </configuration> <!-.This is the operational specification of this mojo's parameters. this parameter must be configured via some other section of | the POM.</description> </parameter> </parameters> <!-.Inject the component instance into the "wagonManager" field of | this mojo.manager.artifact. |-> <field-name>wagonManager</field-name> </requirement> </requirements> </mojo> </mojos> </plugin> Better Builds With Maven 263 .
2.4. executeLifecycle. 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 264 . Alphanumeric. phase. Classlevel annotations correspond to mojo-level metadata elements. 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. and field-level annotations correspond to parameter-level metadata elements. life cycle name. 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. Java Mojo Metadata: Supported Javadoc Annotations The Javadoc annotations used to supply metadata about a particular mojo come in two types. Table A-7: A summary of class-level javadoc annotations Descriptor Element Javadoc Annotation Values Required? aggregator description executePhase.Appendix A: Resources for Plugin Developers A.
Contains the list of mojos described by this metadata file.Whether this mojo requires a current project instance --> <requiresProject>true</requiresProject> <!-.The name for this mojo --> <goal>myGoal</goal> <!-. These metadata translate into elements within the parameter. 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. |-> <requiresDependencyResolution>compile</requiresDependencyResolution> <!-.Appendix A: Resources for Plugin Developers Field-level annotations The table below summarizes the field-level annotations which supply metadata about mojo parameters. 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. Table A-8: Field-level annotations Descriptor Element Javadoc Annotation Values Required? alias.5. and requirements sections of a mojo's specification in the plugin descriptor.The dependency scope required for this mojo. and Yes No No No No (recommended) No Requirements section required editable description deprecated usually left blank None None Anything Alternative parameter A. Ant Metadata Syntax The following is a sample Ant-based mojo metadata file.2. Its syntax has been annotated to provide descriptions of the elements. <pluginMetadata> <!-.The default life-cycle phase binding for this mojo --> <phase>compile</phase> <!-. NOTE: | multiple mojos are allowed here.Whether this mojo requires access to project reports --> <requiresReports>true</requiresReports> Better Builds With Maven 265 . |-> <mojos> <mojo> <!-.
|-> <hint>custom</hint> </component> </components> <!-. --> <role>org.ArtifactResolver</role> <!-.List of non-parameter application components used in this mojo --> <components> <component> <!-.Whether this mojo must be invoked directly from the command | line. --> <name>nom</name> <!-.The list of parameters this mojo uses --> <parameters> <parameter> <!-. |-> <property>prop</property> <!-.The phase of the forked life cycle to execute --> <phase>initialize</phase> <!-.Whether the configuration for this mojo should be inherited | from parent to child POMs by default.Another mojo within this plugin to execute before this mojo | executes.Whether this mojo requires Maven to execute in online mode --> <requiresOnline>true</requiresOnline> <!-.This is an optional classifier for which instance of a particular | component type should be used. |-> <execute> <!-.This is the type for the component to be injected.apache.The property name used by Ant tasks to reference this parameter | value.This describes the mechanism for forking a new life cycle to be | executed prior to this mojo executing.Whether this mojo operates as an aggregator --> <aggregator>true</aggregator> <!-.maven. |-> <inheritByDefault>true</inheritByDefault> <!-.The parameter name.resolver. |-> <goal>goal</goal> </execute> <!-.artifact.A named overlay to augment the cloned life cycle for this fork | only |-> <lifecycle>mine</lifecycle> <!-.Appendix A: Resources for Plugin Developers <!-.Whether this parameter is required for mojo execution --> <required>true</required> Better Builds With Maven 266 . |-> <requiresDirectInvocation>true</requiresDirectInvocation> <!-.
The description of what the mojo is meant to accomplish --> <description> This is a test.Appendix A: Resources for Plugin Developers <!-. it provides advice on which alternative mojo | to use.apache. </description> <!-.maven.When this is specified. this element will provide advice for an | alternative parameter to use instead.The default value provided when the expression won't resolve --> <defaultValue>${project. |-> <deprecated>Use another mojo</deprecated> </mojo> </mojos> </pluginMetadata> Better Builds With Maven 267 . |-> <deprecated>Use something else</deprecated> </parameter> </parameters> <!-.property}</expression> <!-.project.MavenProject</type> <!-.An alternative configuration name for this parameter --> <alias>otherProp</alias> <!-.The Java type of this mojo parameter --> <type>org.If this is specified.Whether the user can edit this parameter directly in the POM | configuration or the command line |-> <readonly>true</readonly> <!-.The expression used to extract this parameter's value --> <expression>${my.The description of this parameter --> <description>Test parameter</description> <!-.artifactId}</defaultValue> <!-.
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. .Star Trek Better Builds With Maven 268 .
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 files.xml LICENSE. which is always at the top-level of a project. Standard location for test resource filters. may generate some sources from a JavaCC grammar. target/generated-sources/<plugin-id> Standard location for generated sources. For example. A simple note which might help first time users and is optional. Standard Directory Structure Table B-1: Standard directory layout for maven project content Standard Location Description pom. Directory for all generated output.txt README.Appendix B: Standard Conventions B. generated sources that may be compiled. Standard location for resource filters. the generated site or anything else that might be generated as part of your build. This would include compiled classes. Better Builds With Maven 269 . Standard location for assembly descriptors. Standard location for test sources. Standard location for application resources. A license file is encouraged for easy identification by users and is optional.txt target/ Maven's POM. Standard location for test resources.1.
Plugin Repository Conventions --> <pluginRepositories> <pluginRepository> <id>central</id> <name>Maven Plugin Repository</name> <url>http://repo1.0</modelVersion> <name>Maven Default Project</name> <!-. </project> Better Builds With Maven 270 ..org/maven2</url> <layout>default</layout> <snapshots> <enabled>false</enabled> </snapshots> <releases> <updatePolicy>never</updatePolicy> </releases> </pluginRepository> </pluginRepositories> <!-.Reporting Conventions --> <reporting> <outputDirectory>target/site</outputDirectory> </reporting> ..2.maven.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> <!-.Appendix B: Standard Conventions B. Maven's Super POM <project> <modelVersion>4.Repository Conventions --> <repositories> <repository> <id>central</id> <name>Maven Repository Switchboard</name> <layout>default</layout> <url>http://repo1.0.org/maven2</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <!-.
for use as a dependency in other projects locally.3. Generate any test source code for inclusion in compilation. Perform actions required after integration tests have been executed.Appendix B: Standard Conventions B. Compile the source code of the project. Done in an integration or release environment. This may involve things such as setting up the required environment. Take the compiled code and package it in its distributable format. Perform actions required before integration tests are executed. Copy and process the resources into the destination directory. Install the package into the local repository. 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. Better Builds With Maven 271 . Description Validate the project is correct and all necessary information is available. Process the test source code. for example to do byte code enhancement on Java classes. Run any checks to verify the package is valid and meets quality criteria. Process the source code. Generate resources for inclusion in the package. These tests should not require the code be packaged or deployed. Compile the test source code into the test destination directory Run tests using a suitable unit testing framework. for example to filter any values. Post-process the generated files from compilation. Create resources for testing. ready for packaging. Process and deploy the package if necessary into an environment where integration tests can be run. such as a JAR. Copy and process the resources into the test destination directory. for example to filter any values. copies the final package to the remote repository for sharing with other developers and projects. Generate any source code for inclusion in compilation.
org/eclipse/development/java-api-evolution. 2001 http://www.org/axis/java/ AxisTools Reference Documentation .html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL Axis Tool Plugin . Effective Java.codehaus.http://cargo.codehaus.org/Deploying+to+a+running+container Cargo Plugin Configuration Options .sf.org/Merging+WAR+files Cargo Reference Documentation . Evolving Java-based APIs.eclipse.codehaus.org/ Checkstyle .http://mojo. June 8.apache.http://checkstyle.http://ws.http://cargo.sun. Jim.http://cargo.codehaus.net/config.apache.org/axistools-maven-plugin/ Cargo Containers Reference .codehaus.org/axis/java/userguide.html Better Builds With Maven 272 .com/docs/books/effective/ Web Sites Axis Building Java Classes from WSDLhttp://ws.http://cargo.org/Maven2+plugin Cargo Merging War Files Plugin . Joshua.http://java.html Bloch.org/Containers Cargo Container Deployments .http://cargo.Bibliography Bibliography Online Books des Rivieres. Sun Developer Network .codehaus.
http://xdoclet.http://tomcat.sf.apache.Bibliography Checkstyle Available Checks .org/plugins/ Mojo .net/ EJB Plugin Documentation .html Jdiff .org Maven Downloads .org/plugins/maven-clover-plugin/ DBUnit Java API .apache.org/download.html Maven Plugins .www.sun.apache.org/tomcat-5.http://maven.http://xdoclet.org/guides/introduction/introduction-to-archetypes.http://cobertura.http://pmd.http://www.http://maven.mortbay.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.codehaus.org/jdiff-maven-plugin Jetty 6 Plugin Documentation .net/availablechecks.html XDoclet Maven Plugin .sf.au/products/simian/ Tomcat Manager Web Application .apache.sourceforge.http://dbunit.sourceforge.0-doc/manager-howto.codehaus.http://maven.http://clirr.apache.ibiblio.net/ Clirr .sourceforge.http://maven.codehaus.maven.http://maven.org XDoclet2 Maven Plugin .net/ XDoclet EjbDocletTask .http://java.http://maven.org/xdoclet-maven-plugin/ XDoclet Reference Documentation http://xdoclet.com.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.http://jester.http://xdoclet.html Ruby on Rails .org/Maven2+Plugin Better Builds With Maven 273 .http://mojo.http://pmd.codehaus.org/ Simian .net/ Clover Plugin .org/jetty6/maven-plugin/index.rubyonrails.sourceforge.net/bestpractices.http://checkstyle.codehaus.apache.html Xdoclet2 .http://mojo.http://www.net J2EE Specification .html Introduction to the Build Life Cycle – Maven .sf.net/howtomakearuleset.redhillconsulting.org/guides/introduction/introduction-to-thelifecycle.apache.org/maven-model/maven.apache.www.http://jetty.org/ PMD Best Practices .html POM Reference .sf.http://maven.http://xdoclet.sf.org/plugins/maven-ejb-plugin/ ibiblio.html Xdoclet .sf.com/j2ee/reference/api/ Maven 2 Wiki .html Cobertura .com Introduction to Archetypes .apache.html PMD Rulesets .html Jester .http://mojo.
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