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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
Vincent.support. 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. To the authors Jason. for their copy editing. My most heartfelt thanks and all of my love go to my wife Laura. for loving me as I am despite all my flaws. test features. 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. and for leaving her native Michigan to live in a bizarre foreign land. 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. and to do so with such a number of my talented friends and colleagues. To Lisa Malgeri and Elena Renard. and without whom I would never have been able to get involved in the project in the first place.I'd like to start by thanking everyone who has been involved in the Maven community over the years. whose work made this book as professional and polished as it is. friends. formatting and development of the book's template. for trusting my judgment to use Maven on our projects. help and encouragement in everything that I do. for her great patience and sacrifice in allowing me to work at all hours from home. for her dedication to see this through. I'd like to say how much I appreciate all of my family. and submit fixes. and those of St Paul's Anglican church for all of their care. for sticking with it through some of the early development and for holding the development team to a higher standard. Maven is the cumulative work of nearly 40 committers and an even larger number of contributors who've taken the time to give feedback. I'd also like to thank Paul Russell and the development team during my time at Fairfax Digital. John and Carlos congratulations on a job well done. I'm grateful to have had the opportunity to finally write a book about Maven. but for the opportunity to work in such a tremendous environment. Personally. Brett Porter ii . contribute ideas. answer questions. doing additional copy editing and organizing its release. despite having all of the least enjoyable tasks of keeping the development on track. doing what you enjoy and being able to see your our own personal vision realized. To Natalie Burdick. I continue to hope that it was for me and not just because of the warmer climate. Both I and the Maven project owe you all a debt of gratitude.
Tim O'Brien. Allan Ramirez. Carlos Sanchez Many thanks to Jesse McConnell for his contributions to the book. Abel Rodriguez. I'd like to thank my family for their continuous support. Vincent.I would like to thank professor Fernando Bellas for encouraging my curiosity about the open source world. for accepting my crazy ideas about open source. especially my parents and my brother for helping me whenever I needed. Finally. Stephane Nicoll. and the teammates during my time at Softgal. John. Lester Ecarma. Elena Renard and Joakim Erdfelt for their many contributions to the book. It is much appreciated. Bill Dudney. Ramirez. Mark Hobson. Jerome Lacoste. Jerome Lacoste. David Blevins. All of us would like to thank Lisa Malgeri. Chris Berry. we would like to thank all the reviewers who greatly enhanced the content and quality of this book: Natalie Burdick. Brett and Carlos iii . Thanks also to all the people in Galicia for that delicious food I miss so much when traveling around the world. Fabrice Bellingard. Felipe Leme. Also. Emmanuel Venisse and John Tolentino. Jason. Napoleon Esmundo C. Ruel Loehr.
published by O'Reilly in 2005 (ISBN 0-596-00750-7). as well as to various Maven plugins. In addition to his work on Maven.. Jason van Zyl focuses on improving the Software Development Infrastructure associated with medium to large scale projects. Brett is a co-founder and the Director of Engineering at Mergere. discovering Maven while searching for a simpler way to define a common build process across projects. Immediately hooked. Additionally. where he is the technical director of Pivolis. of course. financial. and in 2005.0 major releases. When he's not working on Maven. He created his own company. Jason Van Zyl: As chief architect and co-founder of Mergere. Australia. Spain. iv . John Casey became involved in the Maven community in early 2002. roasting coffee. which has led to the founding of the Apache Maven project. and today a large part of John's job focus is to continue the advancement of Maven as a premier software development tool. supporting both European and American companies to deliver pragmatic solutions for a variety of business problems in areas like e-commerce. where he hopes to be able to make the lives of other developers easier. Inc. Brett has become involved in a variety of other open source projects. Since 2004. he founded the Jakarta Cactus project-a simple testing framework for server-side Java code and the Cargo project-a J2EE container manipulation framework. Inc. Vincent lives and works in Paris. John lives in Gainesville. his focus in the Maven project has been the development of Maven 2. Brett Porter has been involved in the Apache Maven project since early 2003. published by Manning in 2003 (ISBN 1-930-11099-5) and Maven: A Developer's Notebook.. specializing in open source consulting. He was invited to become a Maven committer in 2004. Emily. and working on his house. Carlos Sanchez received his Computer Engineering degree in the University of Coruña. CSSC. John was elected to the Maven Project Management Committee (PMC). John enjoys amateur astrophotography. when he began looking for something to make his job as Ant "buildmeister" simpler.0 and 2. He is grateful to work and live in the suburbs of Sydney. telecommunications and. and is a Member of the Apache Software Foundation. and started early in the open source technology world.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. Build management and open source involvement have been common threads throughout his professional career. This is Vincent's third book. a company which specializes in collaborative offshore software development using Agile methodologies. He enjoys cycling and raced competitively when he was younger. joining the Maven Project Management Committee (PMC) and directing traffic for both the 1. Vincent has directly contributed to Maven's core. he is a co-author of JUnit in Action. Florida with his wife. software development. He continues to work directly on Maven and serves as the Chair of the Apache Maven Project Management Committee. Brett became increasingly involved in the project's development.
..................2.......................................................................................................22 Standard naming conventions.......1.................................................................... 34 2......... Declarative Execution.................................................................26 Locating dependency artifacts...................................15 1..........................................................................................54 3.................................... Maven's Benefits......28 1........1............ Summary.................... 49 3...........................6...............8....... 42 2.....................................................................38 2...................................6........................................................... 45 2................. Maven's Origins........ Filtering Classpath Resources................3..................................... 49 3.................................4...................... 20 Standard directory layout for projects..................................... 12 1..............1........... Using Snapshots.....1........................................................................................................ 40 2.......... Introduction......................... 48 3..................... 23 Maven's project object model (POM)................................................................................................................ 29 2..............................................................5......................................................................2.....................31 2........2......2.......52 3.................... 16 1........................................................... 25 1.................. Getting Started with Maven....................................... Creating Applications with Maven....................... Introducing Maven........................... 47 3............................................................... 23 1.................... 30 2..........................................Table of Contents Preface........... What Does Maven Provide?.. 20 1............................................. Reuse of Build Logic......................................................................56 v ................... Handling Classpath Resources................................3...................................................1................................................................................................................................6...........................................................................................................................................1................................... 22 1...........2............2........................................46 2...................................4............ 32 2............................................................23 Maven's build life cycle..... Convention Over Configuration.............................. Handling Test Classpath Resources...................7.......................................... What is Maven?.......................................... 21 One primary output per project................ Maven Overview............3.....1...................5...2..................................... Packaging and Installation to Your Local Repository................ Managing Dependencies...... 17 1........................... Compiling Test Sources and Running Unit Tests................................................................................................................1.......... Setting Up an Application Directory Structure............................... Maven's Principles.......................3................................................1................................... Preparing to Use Maven........................................................................................ Compiling Application Sources.............................. 41 2............................................................................................. Creating Your First Maven Project......4.............. 16 1.....................................................................................................................................................................................2.........................................................................................................................................................................................2....................................................2..................................... 25 Local Maven repository....................................................... Using Maven Plugins......................... 36 2.............................................................. 18 1....................... Using Project Inheritance........................... Preventing Filtering of Binary Resources..... Coherent Organization of Dependencies...................................................................................3.6..................................................................................................3..............
........................................................................................................................................... Introducing the DayTrader Application.............................................................................................. 91 4...........89 4.....................................8.................10............ Resolving Dependency Conflicts and Using Version Ranges................................ 61 3.... Developing Your First Mojo................................................................................. 76 4........................................................................................................................................................................13.........................................5....57 3.....................................1............................. Deploying EJBs..68 3.............11....................11.......................66 3.............................................................................................................103 4................................................................................... Building an EJB Project......................6............. 132 Using the archetype plugin to generate a stub plugin project......11..............................................1........................ A Note on the Examples in this Chapter......................... Plugin Development Tools........... 127 Accessing build information........................................................ 137 vi ............................................................................................................................ 74 4................................128 5.........................................116 4...............................................14..............................2........................................1............................................................................................................. Deploying your Application.......................................9.................9................3........................... A Review of Plugin Terminology..........................................................60 3..... 66 3................................................... 125 5..........................4....................................4..........................7..............124 5...........................................4...........126 5..............1.................... 67 3....3......... 132 5......................................................................................................... Using Profiles.................................. Building a Web Application Project............. 123 5....... 76 4............................ 135 Binding to the life cycle............................................. 85 4............. Deploying to the File System........................ Summary...................10...... Developing Custom Maven Plugins............9........................................................................................................................................................67 3....................... Introduction.......107 4................................................ Summary.. 66 3............................... Creating a Web Site for your Application..................................7............................................. Building an EAR Project..... Deploying a J2EE Application............ 131 5.....................3.. Bootstrapping into Plugin Development................. 131 5..................... Testing J2EE Applications..........1................... 68 3..... 75 4............................................................................................................2............................................................................. 133 The plugin POM........................11...............................................................12.........................................................................................1............................................................................................................................... 95 4................................................. 128 The plugin descriptor..........................................................12..............................................13............................................................................................................................................ BuildInfo Example: Capturing Information with a Java Mojo ............ 78 4.......................................... Improving Web Development Productivity........................................... Building an EJB Module With Xdoclet..............3.......... The Plugin Framework.. Deploying with FTP............................................................................................................................ Deploying with an External SSH.......3................ Building a Web Services Client Project...................................................................................................................... Building J2EE Applications............................. Utilizing the Build Life Cycle.......6................ Deploying Web Applications...... Introduction...........113 4........................ Deploying with SFTP... Organizing the DayTrader Directory Structure........... 81 4...... 132 The mojo........................................................................................................................100 4..........2................................... 129 Choose your mojo implementation language............. 136 The output....3...........................................2.................. Deploying with SSH2.....................................8..................................... 125 5............................................................................................... 126 Participation in the build life cycle...........3.........................................
....145 5..................................................... Accessing Project Dependencies.................1.......2......................................................1................12........................................................................3............2.......... Continuous Integration with Continuum..................................................................................10...... 189 6......... 202 7..... 228 vii ......................6............... Introducing the Spring Framework...................3........186 6..................... 150 Note on testing source-roots and resources..........1...................... 143 Requiring dependency resolution............................................................................ How to Setup a Consistent Developer Environment..............1...................................................................................... Monitoring and Improving the Health of Your Releases............ BuildInfo Example: Notifying Other Developers with an Ant Mojo............................ 221 7.......219 7........................... Configuration of Reports... Creating an Organization POM............................ 160 6.................................... Attaching Artifacts for Installation and Deployment................................................199 7............................................................................. 195 7.149 Accessing the resource list..................................................................................................................................................... 143 Injecting the project dependency set....................................................................... Team Collaboration with Maven..................................... Separating Developer Reports From User Documentation.................................................................... 143 5............................................................................. Cutting a Release................. 226 8........................................................................ Introduction...................................................... The Issues Facing Teams................................................................................... Viewing Overall Project Health.... 194 7... Creating Reference Material.............. Creating a Shared Repository..........................1............... 169 6.................9......................... 171 6......4....................7........... 140 Binding the notify mojo to the life cycle..................................................................................................................................................................................7...................................................................................... 155 6....... 157 6..................................9...............................................11.... 156 6.................... Assessing Project Health with Maven.............8.... 227 8.................................................................................................................................................................................................... 152 5................ Summary............................................ Monitoring and Improving the Health of Your Source Code......................6................................... 174 6.......................... 144 BuildInfo example: logging dependency versions........5......................................................... 148 Accessing the source-root list................................. Team Dependency Management Using Snapshots...............................................................196 7.......................... 138 The Ant target.. 138 The mojo metadata file......... Advanced Mojo Development............4...................................................2............................193 6.............................................. Summary..............................1....... 228 8.......181 6................................................................... 146 Adding a source directory to the build.... 147 Adding a resource to the build.................. 138 Modifying the plugin POM for Ant mojos........................................ Adding Reports to the Project Web site............... 193 7........................................................................................ Accessing Project Sources and Resources.......... 205 7............................8....................................... 142 5......... Monitoring and Improving the Health of Your Tests................... 158 6.........................................5............................................................................................................................ Choosing Which Reports to Include....................................................2....................................................................................................................................................................... Monitoring and Improving the Health of Your Dependencies. 214 7....3.............................5.........6......................................................................................... What Does Maven Have to do With Project Health?...................5................................................... Summary........................5.....................................................................................................................................4............. Migrating to Maven...................163 6.....................................5...................... 153 5.................................5.................................... Creating a Standard Project Archetype.......................
............................................... Other Modules............................................................................................................................................................................................................................ 272 viii ................................ Some Special Cases....................... 258 A.................................................................................. 260 Plugin metadata................................................................2..................... 256 Life-cycle phases..............................252 Bindings for the jar packaging.....................................................................................................................4......................................................................................1..............236 8............................................................................ 249 8......................................................... The site Life Cycle......................................................................................................................... 249 8.................2.... 254 Bindings for the maven-plugin packaging........ Non-redistributable Jars..................................... 268 B........................3....6................................................................2...................................................... 243 8.......................... 271 Bibliography.1.... Maven's Default Build Life Cycle..............................3.....................................3..................................................................................................................................................2...........1...............................................................240 8.....................6................................................. 247 8............... Building Java 5 Classes.......... Running Tests..................2.........................................................................................2. 264 Class-level annotations.....................256 A................................................................................................................................ Standard Directory Structure........................................... 242 8... Compiling.................. 259 A..................257 Default Life Cycle Bindings...........1...... Maven's Super POM.5............................................................. Compiling Tests................. Mojo Parameter Expressions. 240 8............................................ 264 Field-level annotations...................... 270 B............................ The Expression Resolution Algorithm............. Summary...................... 258 A.........4.1............. 251 A........................................................................................................ Referring to Test Classes from Other Modules................................................................................................3......6......................................................6................ Restructuring the Code................. 244 8........................... Simple Expressions.....................................1........257 A...6....................1...........................................1........................................................................................................................................... Avoiding Duplication...........2.2.................................2.............................................................................................5. Ant Metadata Syntax...................................................................................................................5......................................................... 250 8...................................................................................... Using Ant Tasks From Inside Maven....................................................... 269 B... Testing.......................................................252 A.......................260 Plugin descriptor syntax..........................................................................4.......................................................... The clean Life Cycle...... The default Life Cycle.....................................................2.........................................8.............................6.......................................2............................................. Creating POM files...................................... 257 Life-cycle phases....................................................5..............................................................6........................1................ 265 Appendix B: Standard Conventions...........................2......................................................... 252 Life-cycle phases.............. 265 A..................................2........................................ 250 Appendix A: Resources for Plugin Developers.......................................................................................................................................................................................... Maven's Life Cycles.........................260 A......................................................... Complex Expression Roots................... Where to Begin?.............................255 A... 236 8..............................6.......256 Default life-cycle bindings...........230 8.......................................... 244 8.......................................................................... 243 8................................8. Java Mojo Metadata: Supported Javadoc Annotations...................................7.............................................5.
...............271 ix ................................................... 103 Table 5-1: Life-cycle bindings for jar packaging.........................................59 Table 3-3: Site descriptor.............................................................................................71 Table 4-1: WAR plugin configuration properties......................................................List of Tables Table 3-1: Module packaging types..............................152 Table 6-1: Project Web site content types...................................................................................................................................................................................................264 Table A-8: Field-level annotations................................................................................................ 256 Table A-4: The site life-cycle bindings for the jar packaging.............................................................................................................................................................................................. 51 Table 3-2: Examples of version ranges............ 94 Table 4-2: Axis generated classes............................................................................................................................ 180 Table A-1: The default life-cycle bindings for the jar packaging............................164 Table 6-2: Report highlights...............................................................................................................................................................................................................................................................................................................................................................................................................258 Table A-6: A summary of the valid root objects for plugin parameter expressions................................................ 257 Table A-5: Primitive expressions supported by Maven's plugin parameter........................................................ 127 Table 5-2: Key differences between compile-time and test-time mojo activities............................... 265 Table B-1: Standard directory layout for maven project content.................................................................................................................................. 169 Table 6-3: Built-in Checkstyle configurations...254 Table A-2: A summary of the additional mojo bindings......................................................................................... 255 Table A-3: The clean life-cycle bindings for the jar packaging..............................................................................................................259 Table A-7: A summary of class-level javadoc annotations.....269 Table B-2: Phases in Maven's life cycle............................................................
.................................... 33 Figure 2-2: Directory structure after adding the resources directory..................97 Figure 4-10: Directory structure of the wsappclient module.................................. 188 x .......................................................... 73 Figure 3-6: The sample generated site.................................................................................................................... 42 Figure 3-1: Proficio directory structure...........................................................................................................................................................................................................................................................................................................41 Figure 2-4: Directory structure after adding test resources.. 28 Figure 1-3: Sample directory structure............69 Figure 3-5: The target directory...................... 76 Figure 4-2: Module names and a simple flat directory structure...................................................................................................166 Figure 6-5: The new Web site............................................................................................186 Figure 6-12: The dependency convergence report.............................................................................................................................................................................................. 165 Figure 6-4: The directory layout with a user guide....................................171 Figure 6-7: An example PMD report........ 81 Figure 4-6: Directory structure for the DayTrader ejb module when using Xdoclet............................ 80 Figure 4-5: Directory structure for the DayTrader ejb module.................................................................................................................................. 103 Figure 4-11: Directory structure of the ear module........................................79 Figure 4-4: Nested directory structure for the EAR...................................................................................................................................... 107 Figure 4-12: Directory structure of the ear module showing the Geronimo deployment plan.......................................... 27 Figure 1-2: General pattern for the repository layout.............................................................................................................................................................. 96 Figure 4-9: Modified registration page automatically reflecting our source change.................. EJB and Web modules................................................. 50 Figure 3-2: Proficio-stores directory.................................182 Figure 6-11: An example dependency report..................... 159 Figure 6-3: The initial setup....................................................................................................................................................................................................................... 174 Figure 6-8: An example CPD report................................................................................................................................................................. 40 Figure 2-3: Directory structure of the JAR file created by Maven...51 Figure 3-3: Version parsing..........................................................................86 Figure 4-7: Directory structure for the DayTrader web module showing some Web application resources............................................................................................................................91 Figure 4-8: DayTrader JSP registration page served by the Jetty6 plugin....................................................................................................................................................List of Figures Figure 1-1: Artifact movement from remote to local repository...............................................................79 Figure 4-3: Modules split according to a server-side vs client-side directory organization................................................. 118 Figure 6-1: The reports generated by Maven............................................................................................................................................................................................................... 167 Figure 6-6: An example source code cross reference.....................59 Figure 3-4: The site directory structure.......................................................... 116 Figure 4-14: Directory structure for the functional-tests module...................178 Figure 6-9: An example Checkstyle report....................................................................................................................................113 Figure 4-13: The new functional-tests module amongst the other DayTrader modules .......................................... 158 Figure 6-2: The Surefire report................................................................................................................... 74 Figure 4-1: Architecture of the DayTrader application.................................................................................................................................... 179 Figure 6-10: An example Cobertura report...................................................................... 28 Figure 2-1: Directory structure after archetype generation..................................................................
.............................................................245 Figure 8-4: The final directory structure................ 211 Figure 7-5: Adding a build definition for site deployment.......................................................230 Figure 8-3: A tiger module directory.................. 208 Figure 7-3: Summary page after projects have built................ 212 Figure 7-6: Continuum configuration................................................................................................................................245 Figure 8-5: Dependency relationship........................................ 209 Figure 7-4: Schedule configuration...........................................................................................................................................................................................................................................................................................................................................................................246 xi ..................... 219 Figure 8-1: Dependency relationship between Spring modules..................................................................................................................206 Figure 7-2: Add project screen shot........................................................................................................................................................217 Figure 7-7: Archetype directory layout.................................... with all modules........Figure 6-13: An example Clirr report...................................189 Figure 7-1: The Continuum setup screen..................... 229 Figure 8-2: A sample spring module directory................................................................................................................................................................................................................................................................
Perhaps. 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. Better Builds With Maven 12 . it does not take long to realize those benefits. it is recommended that you step through the material in a sequential fashion. For users more familiar with Maven (including Maven 1. an indispensable guide to understand and use Maven 2.0. As you will soon find. this guide endeavors to provide a quick solution for the need at hand. which provides a wide range of topics from understanding Maven's build platform to programming nuances. Maven works equally well for small and large projects.Preface Preface Welcome to Better Builds with Maven. 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. reading this book will take you longer. We hope that this book will be useful for Java project managers as well. Maven 2 is a product that offers immediate value to many users and organizations.x). For first time users.
Better Builds With Maven 13 . Web Services). Chapter 4 shows you how to build a J2EE application and deploy it. looks at Maven as a set of practices and tools that enable effective team communication and collaboration. reporting tools. and install those JARs in your local repository using Maven. you will be revisiting the Proficio application that was developed in Chapter 3. After reading this chapter. It starts by describing fundamentals. illustrates Maven's best practices and advanced uses by working on a real-world example application. At this stage you'll pretty much become an expert Maven user. Chapter 7. EJB. and learning more about the health of the project. After reading this chapter. visualize. Migrating to Maven. At the same time. These tools aid the team to organize. goes through the background and philosophy behind Maven and defines what Maven is. From there. Chapter 3. The first two chapters are geared toward a new user of Maven 2. Finally. You will learn how to use Maven to ensure successful team development. Getting Started with Maven. the chapter covers the tools available to simplify the life of the plugin developer. you will be able to keep your current build working. Developing Custom Maven Plugins. and how to use Maven to deploy J2EE archives to a container. Team Collaboration with Maven. Assessing Project Health with Maven. Creating Applications with Maven. Chapter 5 focuses on developing plugins for Maven. EAR. Chapter 5. Chapter 6 discusses project monitoring issues and reporting.Preface Organization Here is how the book is organized. 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. Introducing Maven. you will be able to take an existing Ant-based build. you should be up and running with Maven. Chapter 1. Chapter 6. Chapter 7 discusses using Maven in a team development environment and Chapter 8 shows you how to migrate Ant builds to Maven. and compiling and packaging it. Chapter 8. Chapter 3 builds on that and shows you how to build a real-world project. shows how to use Maven to build J2EE archives (JAR. Building J2EE Applications. Chapter 4. gives detailed instructions on creating your first project. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. Chapter 2. compile and test the code. it discusses the various ways that a plugin can interact with the Maven build environment and explore some examples. split it into modular components if needed. and how to use Maven to generate a Web site for your project. create JARs. focuses on the task of writing custom plugins. WAR. explains a migration path from an existing build in Ant to Maven. discusses Maven's monitoring tools. In this chapter. shows how to create the build for a full-fledged J2EE application. and document for reuse the artifacts that result from a software project. they discuss what Maven is and get you started with your first Maven project.
mergere. How To Contact Us We want to hear about any errors you find in this book.com.0 installed. You can also click the Submit Errata link on this page to notify us of any errors that you might have found. Simply email the information to email@example.com Errata We have made every effort to ensure that there are no errors in the text or in the code. on the book details page. We'll check the information and.com. errata. To find the errata page for this book. We offer source code for download. Better Builds With Maven 14 . However. so occasionally something will come up that none of us caught prior to publication. then you're ready to go. we are human.com. Once at the site. simply locate the appropriate Download link on the page and you can obtain all the source code for the book. click the Book Errata link. So if you have Maven 2. On this page you will be able to view all errata that have been submitted for this book and posted by Maven editors. go to http://library. if appropriate. Then.mergere. and technical support from the Mergere Web site at http://library. post an update to the book's errata page and fix the problem in subsequent editions of the book. How To Download the Source Code All of the source code used in this book is available for download at http://library.mergere.com and locate the title in the title lists.
1.Convention over configuration .Coherent organization of dependencies .Maven's benefits • Things should be made as simple as possible. . Introducing Maven Introducing Maven This chapter covers: An overview of Maven • Maven's objectives • Maven's principles: . but not any simpler.Declarative execution .Albert Einstein Better Builds With Maven 15 .Reuse of build logic .
Introducing Maven 1. distribution. to view it in such limited terms is akin to saying that a web browser is nothing more than a tool that reads hypertext. but the term project management framework is a meaningless abstraction that doesn't do justice to the richness and complexity of Maven. Revolutionary ideas are often difficult to convey with words. When someone wants to know what Maven is.1. documentation. a framework that greatly simplifies the process of managing a software project. uninspiring words.1." Better Builds With Maven 16 . sound-bite answer. to team collaboration. 1. but this doesn't tell you much about Maven. In addition to solving straightforward. Perhaps you picked up this book because someone told you that Maven is a build tool. richer definition of Maven read this introduction. It simultaneously reduces your headcount and leads to remarkable operational efficiencies. From compilation. to documentation. It defines a standard life cycle for building. Maven 2. to distribution. a repository format. and many developers who have approached Maven as another build tool have come away with a finely tuned build system. What is Maven? Maven is a project management framework. While you are free to use Maven as "just another build tool". If Maven isn't a "project management framework". It's the most obvious three-word definition of Maven the authors could come up with. you can stop reading now and skip to Chapter 2. 1 You can tell your manager: "Maven is a declarative project management tool that decreases your overall time to market by effectively leveraging your synergies. it will prime you for the concepts that are to follow.1. and they expect a short. testing. You may have been expecting a more straightforward answer. Maven provides the necessary abstractions that encourage reuse and take much of the work out of project builds. Maven also brings with it some compelling second-order benefits. It provides a framework that enables easy reuse of common build logic for all projects following Maven's standards. and deploying project artifacts. "Well it is a build tool or a scripting framework" Maven is more than three boring. and a piece of software used to manage and describe projects. If you are reading this introduction just to find something to tell your manager1. and software. standards. It is a combination of ideas. Maven and the technologies related to the Maven project are beginning to have a transformative effect on the Java community. and it is impossible to distill the definition of Maven to simply digested sound-bites. Maven can be the build tool you are looking for. 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). This book focuses on the core tool produced by the Maven project. they will usually ask "What exactly is Maven?". Too often technologists rely on abstract phrases to capture complex topics in three or four words. first-order problems such as simplifying builds. and with repetition phrases such as project management and enterprise software start to lose concrete meaning. Maven Overview Maven provides a comprehensive approach to managing software projects. If you are interested in a fuller. what is it? Here's one attempt at a description: Maven is a set of standards. Don't worry. and the deployment process.
This lack of a common approach to building software meant that every new project tended to copy and paste another project's build system. and package. If you followed the Maven Way. Prior to Maven. and deploying. but Maven is an entirely different creature from Ant. they would not have to go through this process again when they moved on to the next project.1. Maven is not just a build tool. predictable way.2. every project at the ASF had a different approach to compilation. Maven's Origins Maven was borne of the practical desire to make several projects at the Apache Software Foundation (ASF) work in the same. In addition. such as Jakarta Commons. and it immediately sparked interest as a sort of Rosetta Stone for software project management. It is a way of approaching a set of software as a collection of interdependent components which can be described in a common format. Maven entered the scene by way of the Turbine project. Ultimately. Maven's standard formats enable a sort of "Semantic Web" for programming projects. 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. test. 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. If developers spent time understanding how one project was built. 1. the barrier to entry for a project with a difficult build system was extremely high. 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. Better Builds With Maven 17 . Many people come to Maven familiar with Ant so it's a natural association. your project gained a build by default. developers were building yet another build system. distribution. you will wonder how you ever developed without it. So to answer the original question: Maven is many things to many people. generating metrics and reports. generating documentation. and started focusing on component development. The same effect extended to testing. and not just a replacement for Ant. Maven's standards and central repository have defined a new naming system for projects. The build process for Tomcat was different from the build process used by Struts. knowing clearly how they all worked just by understanding how one of them worked. Etc. People stopped figuring out creative ways to compile. 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. the Turbine developers used a different approach to site generation than the developers of Jakarta Commons. Developers within the Turbine project could freely move between subcomponents. It is the next step in the evolution of how individuals and organizations collaborate to create software systems. It is a set of standards and an approach as much as it is a piece of software. Using Maven has made it easier to add external dependencies and publish your own components. the Codehaus community started to adopt Maven 1 as a foundation for project management. and Web site generation.Introducing Maven As more and more projects and products adopt Maven as a foundation for project management. Once you get up to speed on the fundamentals of Maven. The ASF was effectively a series of isolated islands of innovation. There were some common themes to each separate build.
which forms the basis of the entire Maven system.Introducing Maven Whereas Ant provides a toolbox for scripting builds. and output. assemble. and if you can apply a testing plugin to one project.3. and much more transparent. referred to as "building the build". Maven takes a similar approach to software projects: if you can build one Maven project you can build them all. test. Projects and systems that use this standard declarative approach tend to be more transparent. you can easily drive a Camry. and easier to comprehend. and the software tool named Maven is just a secondary side-effect of this model. the car provides a known interface. you can apply it to all projects. more maintainable. What Does Maven Provide? It provides a comprehensive model that can be applied to all software projects. existing Ant scripts and Make files can be complementary to Maven and used through Maven's plugin architecture. and you gain access to expertise and best-practices of an entire industry.1. Maven provides a useful abstraction in the same way an automobile provides an abstraction most of us are familiar with. to provide a common layout for project documentation. You describe your project using Maven's model. install) is effectively delegated to the POM and the appropriate plugins. and to retrieve project dependencies from a shared storage area makes the building process much less time consuming. Maven allows developers to declare goals and dependencies and rely on Maven's default structures and plugin capabilities to build the project. documentation. Make files and Ant are alternatives to Maven. if your project currently relies on an existing Ant build script that must be maintained. Maven is about the application of patterns in order to facilitate project management through the reuse of common build strategies. Plugins allow developers to call existing Ant scripts and Make files and incorporate those existing functions into the Maven build life cycle. Maven provides a common project "language". more reusable. However. Given the highly inter-dependent nature of projects in open source. Much of the project management and build orchestration (compile. The key value to developers from Maven is that it takes a declarative approach rather than developers creating the build process themselves. When you purchase a new car. Developers can build any given project without having to understand how the individual plugins work (scripts in the Ant world). Maven provides you with: A comprehensive model for software projects • Tools that interact with this Declarative Model • Better Builds With Maven 18 . An individual Maven project's structure and contents are declared in a Project Object Model (POM). Maven's ability to standardize locations for source files. if you've learned how to drive a Jeep. 1.
Maven lowers the barrier to reuse not only of build logic but of components.Introducing Maven Organizations and projects that adopt Maven benefit from: • Coherence . • • • Without these characteristics.Maven allows organizations to standardize on a set of best practices." Reusability . The definition of this term from the American Heritage dictionary captures the meaning perfectly: "Marked by an orderly. Because Maven projects adhere to a standard model they are less opaque. and aesthetically consistent relation of parts. Without visibility it is unlikely one individual will know what another has accomplished and it is likely that useful code will not be reused. As a result you end up with a lack of shared knowledge along with the commensurate degree of frustration among team members. logical. When code is not reused it is very hard to create a maintainable system. When everyone is constantly searching to find all the different bits and pieces that make up a project. Maven projects are more maintainable because they have fewer surprises and follow a common model.Maven is built upon a foundation of reuse. home-grown build system. there is little chance anyone is going to comprehend the project as a whole. Agility . it is improbable that multiple individuals will work productively together on a project. It is easier for developers to jump between different projects without a steep learning curve that accompanies a custom. Maintainability . and start focusing on the application. This is a natural effect when processes don't work the same way for everyone. Better Builds With Maven 19 .Organizations that adopt Maven can stop building the build. When you adopt Maven you are effectively reusing the best practices of an entire industry. When using Maven it is easier to create a component and integrate it into a multi-project build.
which all add up to make a huge difference in daily use. you gain an immense reward in terms of productivity that allows you to do more. With Rails. that we shouldn't pass judgment on one form of development over another.2. If you are happy to work along the golden path that I've embedded in Rails. We have a ton of examples like that. 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.Introducing Maven 1."2 2 O'Reilly interview with DHH Better Builds With Maven 20 . and better at the application level. As mentioned earlier Maven creates a sense of structure so that problems can be approached in terms of this structure. you're rewarded by not having to configure that link. 1. One of those ideals is flexibility. you trade flexibility at the infrastructure level to gain flexibility at the application level. Maven's Principles According to Christopher Alexander "patterns help create a shared language for communicating insight and experience about problems and their solutions". The class automatically knows which table to use for persistence. but the use of these sensible default strategies is encouraged and should be strayed from only when absolutely necessary. such as classes are singular and tables are plural (a person class relates to a people table).2. It eschews placing the old ideals of software in a primary position. Rails does. 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. One characteristic of opinionated software is the notion of "convention over configuration". the notion that we should try to accommodate as many approaches as possible.1. 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. sooner. 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. 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. If you follow basic conventions. This is not to say that you can't override them. Well. and I believe that's why it works.
If this saves you 30 minutes for each new project you look at. Maven encourages a common arrangement of project content so that once you are familiar with the standard locations. You don't want to spend time fiddling with building. and documentation. 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. It is a very simple idea but it can save you a lot of time. configuration files. 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. when you do this. You can override any of Maven's defaults to create a directory layout of your choosing. 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. 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 will be able to adapt your project to your customized layout at a cost. Better Builds With Maven 21 . and you will make it easier to communicate about your project. You shouldn't need to spend a lot of time getting your development infrastructure functioning. generating documentation. makes it easier to communicate to others. 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. In this case. you need to ask yourself if the extra configuration that comes with customization is really worth it. Follow the standard directory layout. project resources. 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. 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. even if you only look at a few new projects a year that's time better spent on your application. All of these things should simply work. you will be able to navigate within any Maven project you encounter in the future. and allows you to create value in your applications faster with less effort. he probably doesn't even know what Maven is and wouldn't like if he did because it's not written in Ruby yet!). or deploying. generated output. Using standard conventions saves time.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.
because the naming convention keeps them separate in a logical. which should be identified and separated to cope with complexity and to achieve the required engineering quality factors such as adaptability. In this scenario the code contained in each separate project has a different role to play. You could produce a single JAR file which contained all the compiled classes. is much easier to reuse. If you have placed all the sources together in a single project. and some shared utility code. A simple example of the naming convention might be commons-logging-1. maintainability.2 of Commons Logging. To illustrate this point consider a set of sources for a client/server-based application that contained the client code. in a separate JAR file. well. later in this chapter. easy to see manner. and they should be separated. The intent behind the naming conventions employed by Maven is that you can tell exactly what you are looking at by. The separation of concerns (SoC) principle states that a given problem involves different kinds of concerns. a set of conventions really. or concern.2. Standard naming conventions The third convention. Better Builds With Maven 22 .jar. It is immediately obvious that this is version 1. and a project for the shared utility code. Maven pushes you to think clearly about the separation of concerns when setting up your projects because modularity leads to reuse.Introducing Maven One primary output per project The second convention used by Maven is the concept of a Maven project producing one primary output. extendibility and reusability. is a standard naming convention for directories and a standard naming convention for the primary output of a project.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's happened to all of us and it doesn't have to. It doesn't make much sense to exclude pertinent information when you have it at hand to use. The conventions provide clarity and immediate comprehension. If the JAR were named commonslogging. but Maven would encourage you to have three separate projects: a project for the client portion of the application. This is illustrated in the Coherent Organization of Dependencies section. 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. looking at it. Having the utility code in a separate project.2. This is important if there are multiple projects involved.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. a project for the server portion of the application. Systems that cannot cope with information rich artifacts like commons-logging-1. the server code.
and many others. and generate basic documentation. a plugin for creating JARs. Maven can be thought of as a framework which coordinates the execution of plugins in a well defined way. 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. and the answer lies in Maven's implicit use of its Super POM. Plugins are the key building blocks for everything in Maven.2. Maven's project object model (POM) Maven is project-centric by design. a plugin for running tests. test. Maven encourages a separation of concerns because it promotes reuse. and the POM is Maven's description of a single project. Maven puts this principle into practice by encapsulating build logic into coherent modules called plugins. Reuse of Build Logic As you have already learned. 1. It's a very good and essential question in fact. Without POM.3. The POM is an XML document and looks like the following (very) simplified example: <project> <modelVersion>4. specifically from the plugin configurations contained in the POM.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. 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).Introducing Maven 1.mycompany. One important concept to keep in mind is that everything accomplished in Maven is the result of a plugin executing.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8. Maven is useless . It is the POM that drives execution in Maven and this approach can be described as model driven execution. a plugin for creating Javadocs.2.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM will allow you to compile. The POM below is an example of what you could use to build and test a project. being the observant reader. Better Builds With Maven 23 .2. will ask how this is possible using a 15 line file.the POM is Maven's currency. 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.0</modelVersion> <groupId>com.0. You. In Maven there is a plugin for compiling source code.
jar).This element indicates the display name used for the project.apache. A typical artifact produced by Maven would have the form <artifactId>-<version>. The default value for the packaging element is jar so you do not have to specify this in most cases. which indicates that a project is in a state of development.apache. For a complete reference of the elements available for use in the POM please refer to the POM reference at http://maven. WAR.Object class. In Java. The life cycle is a topic dealt with later in the chapter. • name . all objects have the implicit parent of java. and is the analog of the Java language's java.<extension> (for example. WAR. • • url .0. and during the build process for your project. • version .This element indicates the package type to be used by this artifact (JAR. or EAR. • groupId . This not only means that the artifact produced is a JAR.Object. artifactId . Additional artifacts such as source bundles also use the artifactId as part of their file name. Likewise. 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. • • project .This element provides a basic description of your project. The key feature to remember is the Super POM contains important default information so you don't have to repeat this information in the POMs you create. description . modelVersion .xml files.This is the top-level element in all Maven pom. Maven goes a long way to help you with version management and you will often see the SNAPSHOT designator in a version.This element indicates the version of the artifact generated by the project. This is often used in Maven's generated documentation.This element indicates the unique identifier of the organization or group that created the project.org/maven-model/maven. For example org. The POM shown above is a very simple POM.lang.plugins is the designated groupId for all Maven plugins.This element indicates where the project's site can be found. in Maven all POMs have an implicit parent which is Maven's Super POM. but it is mandatory in order to ensure stability when Maven introduces new features or other model changes. or other projects that use it as a dependency. The version of the model itself changes very infrequently. Better Builds With Maven 24 . • • packaging . myapp-1. but also indicates a specific life cycle to use as part of the build process.maven.lang. For now.html.This required element indicates the version of the object model this POM is using. The POM contains every important piece of information about your project. just keep in mind that the selected packaging of a project plays a part in customizing the build life cycle. The groupId is one of the key identifiers of a project and is typically based on the fully qualified domain name of your organization. EAR.Introducing Maven Maven's Super POM carries with it all the default conventions that Maven encourages. etc. but still displays the key elements every POM contains.This element indicates the unique base name of the primary artifact being generated by this project.).
or install. artifacts. Maven plugins provide reusable build logic that can be slotted into the standard build life cycle. which is straightforward. When you need to add some functionality to the build life cycle you do so with a plugin. related to that phase.8. or test. artifacts.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. which is for Junit: <project> <modelVersion>4. packaging. the compile phase invokes a certain set of goals to compile a set of classes. For example.0. In "Maven-speak" an artifact is a specific piece of software. If you recall.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM states that your project has a dependency on JUnit. 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. and compile phases will execute. In Maven you do day-to-day work by invoking particular phases in this standard build life cycle.Introducing Maven Maven's build life cycle Software projects generally follow a similar.4. the validate. compilation. or goals. The path that Maven moves along to accommodate an infinite variety of projects is called the build life cycle. 1.mycompany. our example POM has a single dependency listed. generate-resources. It is important to note that each phase in the life cycle will be executed up to and including the phase you specify. Chapter 2 includes a demonstrates the customization of a Maven build with a Maven plugin.0</modelVersion> <groupId>com. Coherent Organization of Dependencies We are now going to delve into how Maven resolves dependencies and discuss the intimately connected concepts of dependencies. Any time you need to customize the way your project builds you either employ the use of an existing plugin or create a custom plugin for the task at hand. Better Builds With Maven 25 .2. well-trodden paths: preparation. you tell Maven that you want to compile. The standard build life cycle consists of many phases and these can be thought of as extension points. or package. and repositories. installation. and repositories work. For example. process-sources. If you tell Maven to compile. testing. The actions you need to have performed are stated at a high level and Maven deals with the details behind the scenes. the build life cycle consists of a series of phases where each phase can perform one or more actions. generate-sources. In Maven.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. initialize.
SAR. At a basic level.1. Maven usually interacts with your local repository. artifactId and version. it depends on version 3.jar. 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.8. you are simply telling Maven what a specific project expects. In the POM you are not specifically telling Maven where the dependencies are physically. for artifacts that match the dependency request. When a dependency is declared.jar: Better Builds With Maven 26 . and it supplies these coordinates to its own internal dependency mechanisms. Maven tries to satisfy that dependency by looking in all of the remote repositories that are available.1 of the junit artifact produced by the junit group. but a Java artifact could also be a WAR. we can describe the process of dependency management as Maven reaching out into the world.8. Maven transports it from that remote repository to your local repository for general use. the most common artifact is a JAR file. Maven takes the dependency coordinates you provide in a POM. Your project doesn't require junit-3.Introducing Maven In Java. Maven has two types of repositories: local and remote.1.8. Read the following sections for specific details about where Maven searches for these dependencies. or EAR file. grabbing a dependency. By default. Maven needs to know what repository to look in as well as the dependency's coordinates. You must have a local repository in order for Maven to work. within the context of your project. instead you deal with logical dependencies.m2/repository. you stop focusing on a collection of JAR files. 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. If a matching artifact is located. A dependency is a reference to an specific artifact that resides in a repository. Dependency Management is one of the most easily understood and powerful features in Maven. The following folder structure shows the layout of a local Maven repository that has a few locally installed dependency artifacts such as junit-3. With Maven. but the key concept is that Maven dependencies are declarative. In order for Maven to attempt to satisfy a dependency. A dependency is uniquely identified by the following identifiers: groupId. Maven creates your local repository in ~/. There is more going on behind the scenes. and providing this dependency to your software project.
In theory a repository is just an abstract storage mechanism.8. Above you can see the directory structure that is created when the JUnit dependency is resolved.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. but in practice the repository is a directory structure in your file system.jar artifact that landed in your local repository. so you understand how the layout works. We'll stick with our JUnit example and examine the junit-3. On the next page is the general pattern used to create the repository layout: Better Builds With Maven 27 .1.
the artifact is downloaded and installed in your local repository.1. Maven will generate a path to the artifact in your local repository. Maven will attempt to download an artifact from each remote repository in the order defined in your POM.1" in ~/.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.apache. Locating dependency artifacts When satisfying dependencies.jar. artifactId of "junit".m2/repository/junit/unit/3. it will be fetched from a remote repository. Maven attempts to locate a dependency's artifact using the following process. for example. If this file is not present.y.maven. Maven will attempt to find the artifact with a groupId of "junit".8. If your project's POM contains more than one remote repository.8.8. Once the dependency is satisfied.1/junit-3. By default. Better Builds With Maven 28 . Maven will attempt to fetch an artifact from the central Maven repository at http://www. and a version of "3.Introducing Maven Figure 1-2: General pattern for the repository layout If the groupId is a fully qualified domain name (something Maven encourages) such as x.ibiblio.org/maven2. First.
Dependencies are not you projects code. modular project arrangements.jar for each project that needs it. you don't have to jump through hoops trying to get it to work. Maven is also a vibrant. there is no need to store the various spring JAR files in your project. Your local repository is one-stop-shopping for all artifacts that you need regardless of how many projects you are working on. Using Maven is more than just downloading another JAR file and a set of scripts.1. shielding you from complexity and allowing you to focus on your specific task. If you were coding a web application. if your project has ten web applications which all depend on version 1.0 by change your dependency declarations. and they don't deserve to be versioned in an SCM. you don't store a copy of junit3. Better Builds With Maven 29 . all project referencing this dependency share a single copy of this JAR. Storing artifacts in your SCM along with your project may seem appealing but it is incompatible with the concept of small. Each project relies upon a specific artifact via the dependencies listed in a POM. 1. Maven is a framework. be a part of your thought process. if ever. in the background. Like the engine in your car or the processor in your laptop.0 JARs to every project. While this approach works for a few project. In other words. you simply changed some configuration. To summarize. you would check in the 10-20 JAR files your project relies upon into a lib directory. it simplifies the process of development. Maven's Benefits A successful technology takes away a burden. a useful technology just works. in doing so. Instead of having to add the Spring 2. it should rarely.3. With Maven. Maven is a repository. it doesn't scale easily to support an application with a great number of small components. You don't have to worry about whether or not it's going to work. active open-source community that produces software focused on project management.8. it is the adoption of processes that allow you to take your software development to the next level. and.2.Introducing Maven From this point forward. Declare you dependencies and let Maven take care of details like compilation and testing classpaths. the common pattern in most project was to store JAR files in a project's subdirectory. Maven is a set of standards. Maven provides such a technology for project management. and Maven is software.6 of the Spring Framework. and you build would add these dependencies to your classpath. Before Maven. rather than imposing one. every project with a POM that references the same dependency will use this single copy installed in your local repository. and it is a trivial process to upgrade all of your ten web applications to Spring 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.Jon Bentley and Doug McIlroy Better Builds With Maven 30 . not battalions of special cases. .2.
Maven requires network access.m2/settings. it may be necessary to make a few more preparations for Maven to function correctly. it is assumed that you are a first time Maven user and have already set up Maven on your local system. Now you can perform the following basic check to ensure Maven is working correctly: mvn -version If Maven's version is displayed.xml file with the following content.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 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. <mirrors> <mirror> <id>maven.1. then you should be all set to create your first Maven project. Better Builds With Maven 31 .com/maven2</url> <mirrorOf>central</mirrorOf> </mirror> </mirrors> </settings> In its optimal mode. create a <your-homedirectory>/.xml file. Preparing to Use Maven In this chapter.m2/settings.mycompany. ask your administrator if there if there is an internal Maven proxy.Getting Started with Maven 2. If you are behind a firewall.xml file with the following content: <settings> <proxies> <proxy> <active>true</active> <protocol>http</protocol> <host>proxy. The settings.com</id> <name>My Company's Maven Proxy</name> <url>http://maven. then please refer to Maven's Download and Installation Instructions before continuing.mycompany. If there is an active Maven proxy running. Create a <your-home-directory>/. then note the URL and let Maven know you will be using a proxy. then you will have to set up Maven to understand that. To do this.mycompany. Depending on where your machine is located. so for now simply assume that the above settings will work. If you have not set up Maven yet.
execute the following: C:\mvnbook> mvn archetype:create -DgroupId=com. and it in fact adheres to Maven's standard directory layout discussed in Chapter 1. First.mycompany. you will use Maven's Archetype mechanism. and this directory contains your pom. This chapter will show you how the archetype mechanism works. please refer to the Introduction to Archetypes.0</modelVersion> <groupId>com.xml file. After the archetype generation has completed you will notice that the following directory structure has been created. an archetype is a template of a project. In Maven.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. which is combined with some user input to produce a fullyfunctional Maven project.1</version> <scope>test</scope> </dependency> </dependencies> </project> At the top level of every project is your pom.xml. Creating Your First Maven Project To create your first project. To create the Quick Start Maven project.0.8.apache. An archetype is defined as an original pattern or model from which all other things of the same kind are made. which looks like the following: <project> <modelVersion>4. you will notice that a directory named my-app has been created for the new project. Better Builds With Maven 32 . Whenever you see a directory structure which contains a pom. but if you would like more information about archetypes.xml file you know you are dealing with a Maven project.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.Getting Started with Maven 2.2.app \ -DartifactId=my-app You will notice a few things happened when you executed this command.mycompany.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven.
Now that you have a POM. Better Builds With Maven 33 . configuration files. and some test sources. documenting. but later in the chapter you will see how the standard directory layout is employed for other project content.Getting Started with Maven Figure 2-1: Directory structure after archetype generation The src directory contains all of the inputs required for building. various descriptors such as assembly descriptors. and so on). and deploying the project (source files. In this first stage you have Java source files only. the site. testing. some application sources. you are ready to build your project.
[INFO] [resources:resources] .Getting Started with Maven 2. Change into the <my-app> directory. for the my-app project.... in order to accomplish the desired task. Before you issue the command to compile the application sources.plugins:maven-resources-plugin: checking for updates from central . in one fell swoop. 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. 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. [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.maven.maven.plugins:maven-compiler-plugin: checking for updates from central .. The <my-app> directory is the base directory. Then.apache.apache. at a very high level. Compiling Application Sources As mentioned in the introduction. in a declarative way. 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. ${basedir}. [INFO] artifact org... you tell Maven what you need.3. Better Builds With Maven 34 .
if you poke around the standard Maven installation. or where your output should go. by default. it took almost 4 minutes with a broadband connection). now you know how Maven finds application sources. The first time you execute this (or any other) command. there is a form of mapping and it is called Maven's default build life cycle. in fact. inherited from the Super POM. By default. Maven will download all the plugins and related dependencies it needs to fulfill the command. is target/classes. From a clean installation of Maven this can take quite a while (in the output above. You can. the compiled classes were placed in target/classes. Even the simplest of POMs knows the default location for application sources. The next time you execute the same command again. how was Maven able to retrieve the compiler plugin? After all. and eliminates the requirement for you to explicitly tell Maven where any of your sources are. because Maven already has what it needs. Maven downloads plugins when they are needed. but there is very little reason to do so. What actually compiled the application sources? This is where Maven's second principle of "reusable build logic" comes into play. By following the standard Maven conventions you can get a lot done with very little effort! Better Builds With Maven 35 . The standard compiler plugin. In fact. The same build logic encapsulated in the compiler plugin will be executed consistently across any number of projects. along with its default configuration. is the tool used to compile your application sources. override this default location. what Maven uses to compile the application sources. If you're a keen observer you'll notice that using the standard conventions makes the POM above very small. it won't download anything new. Although you now know that the compiler plugin was used to compile the application sources.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. The same holds true for the location of the compiled classes which. This means you don't have to state this location at all in any of your POMs. As you can see from the output. This default value (though not visible in the POM above) was. which is specified by the standard directory layout. in the first place? You might be guessing that there is some background process that maps a simple command to a particular plugin. application sources are placed in src/main/java. you won't find the compiler plugin since it is not shipped with the Maven distribution. Instead. The next question is. Maven will execute the command much more quickly. how was Maven able to decide to use the compiler plugin. So. Therefore. if you use the default location for application sources. and how Maven invokes the compiler plugin. of course.
. Failures: 0.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 . Time elapsed: 0 sec Results : [surefire] Tests run: 1.app. you probably have unit tests that you want to compile and execute as well (after all. [INFO] [surefire:test] [INFO] Setting reports dir: C:\Test\Maven2\test\my-app\target/surefire-reports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running com.. 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 . Errors: 0.4.plugins:maven-surefire-plugin: checking for updates from central .maven. Compiling Test Sources and Running Unit Tests Now that you're successfully compiling your application's sources.mycompany. wink wink*). simply tell Maven you want to test your sources.. Failures: 0. [INFO] [resources:resources] [INFO] [compiler:compile] [INFO] Nothing to compile .AppTest [surefire] Tests run: 1. 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. This implies that all prerequisite phases in the life cycle will be performed to ensure that testing will be successful. programmers always write and execute their own unit tests *nudge nudge..Getting Started with Maven 2. Again.apache.
Better Builds With Maven 37 . remember that it isn't necessary to run this every time. compile the tests. Maven compiles the main code (all these classes are up-to-date. Now that you can compile the application sources. since we haven't changed anything since we compiled last). • If you simply want to compile your test sources (but not execute the tests). and execute the tests.Getting Started with Maven Some things to notice about the output: Maven downloads more dependencies this time. you can execute the following command: C:\mvnbook\my-app> mvn test-compile However. you'll want to move on to the next logical step. how to package your application. • Before compiling and executing the tests. 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). as well as all the others defined before it. mvn test will always run the compile and test-compile phases first.
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.0-SNAPSHOT\my-app-1. Now.m2/repository is the default location of the repository.0-SNAPSHOT.0-SNAPSHOT.mycompany. Failures: 0. The directory <your-homedirectory>/.you will notice the packaging element is set to jar.AppTest [surefire] Tests run: 1. Errors: 0 [INFO] [jar:jar] [INFO] Building jar: <dir>/my-app/target/my-app-1.jar to <localrepository>\com\mycompany\app\my-app\1. Take a look in the the target directory and you will see the generated JAR file.app.Getting Started with Maven 2.001 sec Results : [surefire] Tests run: 1. To install. It can then be used by other projects as a dependency.5.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 .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). you'll want to install the artifact (the JAR file) you've generated into your local repository.0-SNAPSHOT. Errors: 0. Failures: 0. Time elapsed: 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.
packaging. to get any more functionality out of an Ant build script. In this case. alternatively you might like to generate an Eclipse descriptor: C:\mvnbook\my-app> mvn eclipse:eclipse Better Builds With Maven 39 . and if you've noticed. there is far more functionality available to you from Maven without requiring any additions to the POM. 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. for example: C:\mvnbook\my-app> mvn clean This will remove the target directory with the old build data before starting. So. and installing a typical Maven project. the following tests are excluded: • • **/Abstract*Test. this POM has enough information to generate a Web site for your project! Though you will typically want to customize your Maven site. Without any work on your part. you must keep making error-prone additions. Or. everything done up to this point has been driven by an 18-line POM.Getting Started with Maven Note that the Surefire plugin (which executes the test) looks for tests contained in files with a particular naming convention. Of course. so it is fresh.java • **/Test*. 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. testing.java You have now completed the process for setting up. if you're pressed for time and just need to create a basic Web site for your project. it will update the settings rather than starting fresh.java **/Abstract*TestCase. building. By default.java • Conversely.java • **/*TestCase. For projects that are built with Maven. this covers the majority of tasks users perform. In contrast. This chapter will cover one in particular. the following tests are included: **/*Test. as it is one of the highly-prized features in Maven. what other functionality can you leverage. as it currently stands. there are a great number of Maven plugins that work out of the box. given Maven's re-usable build logic? With even the simplest POM.
Maven again uses the standard directory layout. For this common task. In the example following. you can package resources within JARs.Getting Started with Maven 2. This means that by adopting Maven's standard conventions. Handling Classpath Resources Another common use case which requires no changes to the POM shown previously. is the packaging of resources into a JAR file. If you unpacked the JAR that Maven created you would see the following: Better Builds With Maven 40 . simply by placing those resources in a standard directory structure.properties file within that directory. 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. you need to add the directory src/main/resources. 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.6. That is where you place any resources you wish to package in the JAR.
Handling Test Classpath Resources To add resources to the classpath for your unit tests. but Maven will generate one by default if you don't. These come standard with the creation of a JAR in Maven.1. except place resources in the src/test/resources directory.properties file. as well as a pom. You can create your own manifest if you choose. Operating on the POM file would require you to use Maven utilities. One simple use might be to retrieve the version of your application.MF. follow the same pattern as you do for adding resources to the JAR. You will also notice some other files there like META-INF/MANIFEST.properties file is there in the META-INF directory. should the need arise. 2.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.xml and pom. The pom.xml and pom. but the properties can be utilized using the standard Java APIs.6.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. At this point you have a project directory structure that should look like the following: Better Builds With Maven 41 .
xml.2. a value defined in the user's settings. // Do something with the resource [..properties" ). put a reference to the property that will contain the value into your resource file using the syntax ${<property name>}.6.] // Retrieve resource InputStream is = getClass().xml: <project> Better Builds With Maven 42 . The property can be either one of the values defined in your pom. you could use a simple snippet of code like the following for access to the resource required for testing: [.. only. Filtering Classpath Resources Sometimes a resource file will need to contain a value that can be supplied at build time.getResourceAsStream( "/test.xml. or a system property. simply set filtering to true for the resource directory in your pom..Getting Started with Maven Figure 2-4: Directory structure after adding test resources In a unit test.] 2. To have Maven filter resources when copying.. a property defined in an external properties file. To accomplish this in Maven.
To override the default value for filtering and set it to true.properties file. To reference a property defined in your pom.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. whose values will be supplied when the resource is filtered as follows: # application.name} application. ${project. To continue the example.name=${project. any element in your POM is available when filtering resources.8. In addition. and resource elements have been added. create an src/main/resources/application.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.0</modelVersion> <groupId>com.xml. resources. the property name uses the names of the XML elements that define the value.finalName} refers to the final name of the file created. when the built project is packaged. So ${project. and ${project. All of this information was previously provided as default values. In fact.properties application.version} With that in place.0. you can execute the following command (process-resources is the build life cycle phase where the resources are copied and filtered): mvn process-resources Better Builds With Maven 43 . this information had to be added to the pom.version=${project.version} refers to the version of the project.Getting Started with Maven <modelVersion>4.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven. which weren't there before.mycompany.name} refers to the name of the project.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.xml.build.apache. the POM has to explicitly state that the resources are located in the src/main/resources directory.
name=${project.version=1.properties file under target/classes.value=hello! Next.filter. First.properties either): Better Builds With Maven 44 .0-SNAPSHOT To reference a property defined in an external file.version} message=${my. As an alternative to defining the my..name=Maven Quick Start Archetype application.filter.properties</filter> </filters> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> [.properties application. add a reference to this new file in the pom. all you need to do is add a reference to this external file in your pom..xml file: [.properties file as follows: # application..value} The next execution of the mvn process-resources command will put the new property value into application. create an external properties file and call it src/main/filters/filter.name} application.filter.Getting Started with Maven The application.] Then.] <build> <filters> <filter>src/main/filters/filter.properties: # filter.properties.properties application..xml.xml and you'd get the same effect (notice you don't need the references to src/main/filters/filter. which will eventually go into the JAR looks like this: # application.value property in an external file. add a reference to this property in the application.properties my. you could have defined it in the properties section of your pom.version=${project.
This is most often the case with binary resources.0. then you would create one resource entry that handled the filtering of resources with an exclusion on the resources you wanted unfiltered. and an inclusion of your images directory.8.apache. Preventing Filtering of Binary Resources Sometimes there are classpath resources that you want included in your JAR. mvn process-resources "-Dcommand.0</modelVersion> <groupId>com.Getting Started with Maven <project> <modelVersion>4.prop=${command. To continue the example. or properties defined on the command line using the standard Java -D parameter.prop property on the command line).line.version or user.prop} Now.value>hello</my.line.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. either the system properties built into Java (like java. In addition you would add another resource entry.home). for example image files.prop=hello again" 2.line. The build element would look like the following: Better Builds With Maven 45 .3.value> </properties> </project> Filtering resources can also retrieve values from system properties.filter. change the application.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven.mycompany. the application. with filtering disabled.line.properties file to look like the following: # application. If you had a src/main/resources/images that you didn't want to be filtered.6. when you execute the following command (note the definition of the command.version=${java.properties file will contain the values from the system properties. but you do not want them filtered.1</version> <scope>test</scope> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> <properties> <my.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.filter.version} command.properties java.
Using Maven Plugins As noted earlier in the chapter. but in most cases these elements are not required.5</source> <target>1.7. This plugin will be downloaded and installed automatically. This is as simple as adding this following to your POM: <project> .and in some ways they are. if it is not present on your local system.. <build> <plugins> <plugin> <groupId>org... or configure parameters for the plugins already included in the build. To illustrate the similarity between plugins and dependencies. you may want to configure the Java compiler to allow JDK 5. in much the same way that a dependency would be handled.0 sources. to customize the build for a Maven project. </project> You'll notice that all plugins in Maven 2 look very similar to a dependency.apache. For example. <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> <excludes> <exclude>images/**</exclude> </excludes> </resource> <resource> <directory>src/main/resources</directory> <includes> <include>images/**</include> </include> </resource> </resources> </build> ...Getting Started with Maven <project> .0</version> <configuration> <source>1. you must include additional Maven plugins. </project> 2. Better Builds With Maven 46 ..plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2. the groupId and version elements have been shown.maven.5</target> </configuration> </plugin> </plugins> </build> ...
you'll know how to exercise the basic features of Maven: creating a project. read on. If someone gave you a project using Maven tomorrow.8. If someone throws a Maven project at you. The configuration element applies the given parameters to every goal from the compiler plugin. This is often the most convenient way to use a plugin.apache. 2. You've learned a new language and you've taken Maven for a test drive.apache. Summary After reading this chapter. use the mvn help:describe command. In seventeen pages. 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. and if you were just looking for a build tool. you would know enough to compile. plugin developers take care to ensure that new versions of plugins are backward compatible so you are usually OK with the latest release.Getting Started with Maven If you do not specify a groupId. but if you find something has changed . test. compiling a project.maven.mojo groupId label. If you do not specify a version then Maven will attempt to use the latest released version of the specified plugin.codehaus. If you want to find out what the plugin's configuration options are. and build it.xml. The chapter focused on Maven as a concrete build tool. or settings. it laid a good foundation for the rest of this book.you can lock down a specific version. 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.org/plugins/ and navigating to the plugin and goal you are using.apache. The next few chapters provide you with the tools to customize Maven's behavior and use Maven to manage interdependent software projects. If you are interested in learning how Maven builds upon the concepts introduced in the Introduction and the practical tools introduced in Chapter 2. use the following command: mvn help:describe -DgroupId=org. You can specify an additional groupId to search within your POM. but you may want to specify the version of a plugin to ensure reproducibility. testing a project. In the above case. and packaging a project. Better Builds With Maven 47 . then Maven will default to looking for the plugin with the org. By learning how to build a Maven project. For the most part. you should be up and running with Maven.maven.plugins or the org. you could safely stop reading this book now. You should also have some insight into how Maven handles dependencies and provides an avenue for customization using Maven plugins. you've seen how you can use Maven to build your project. you have gained access to every single project uses Maven.
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.Edward V. . Berard Better Builds With Maven 48 .
and they it clearly understands that convention. but you are free to name your modules in any fashion your team decides.Creating Applications with Maven 3. • Proficio API: The application programming interface for Proficio. Setting Up an Application Directory Structure In setting up the directory structure for Proficio. The guiding principle in determining how best to decompose your application is called the Separation of Concerns (SoC). each of which addresses one or more concerns. task. are discrete and coherent components. Introduction In the second chapter you stepped though the basics of setting up a simple project. and can easily identify what a particular module does simply by looking at its name.2. Proficio has a very simple memory-based store and a simple XStream-based store. A module is a reference to another Maven project. The natural outcome of this practice. SoC refers to the ability to identify. using a real-world example. 3. So. which consists of a set of interfaces. These are default naming conventions that Maven uses. The interfaces for the APIs of major components. • Proficio Core: The implementation of the API. encapsulate. In examining the top-level POM for Proficio. which is Latin for "help". or purpose. goal. In this chapter. you will see that the Proficio sample application is made up of several modules: Proficio Model: The data model for the Proficio application. which consists of all the classes that will be used by Proficio as a whole.1. Now you will delve in a little deeper. are also kept here. 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 . • • Proficio CLI: The code which provides a command line interface to Proficio. Concerns are the primary motivation for organizing and decomposing software into smaller. In doing so you will be guided through the specifics of setting up an application and managing that structure. The application that you are going to create is called Proficio. and operate on the pieces of software that are relevant to a particular concept. 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). it is important to keep in mind that Maven emphasizes the practice of discrete. • Proficio Stores: The module which itself houses all the store modules. coherent. The only real criterion to which to adhere is that your team has a single convention. which really means a reference to another POM. As such. you can see in the modules element all the modules that make up the Proficio application. a necessary goal for every software development project. like the store. and modular builds. which enables code reusability. more manageable and comprehensible parts. lets start by discussing the ideal directory structure for Proficio.
maven.x these were commonly referred to as multi-project builds and some of this vestigial terminology carried over to the Maven 2.proficio</groupId> <artifactId>proficio</artifactId> <packaging>pom</packaging> <version>1.0</modelVersion> <groupId>org. In Maven 1. but the Maven team is now trying to consistently refer to these setups as multimodule builds. <modules> <module>proficio-model</module> <module>proficio-api</module> <module>proficio-core</module> <module>proficio-stores</module> </modules> . Currently there is some variance on the Maven web site when referring to directory structures that contain more then one Maven project. 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. which has a value of pom.0-SNAPSHOT.Creating Applications with Maven <project> <modelVersion>4.x documentation. 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. For POMs that contain modules..0-SNAPSHOT</version> <name>Maven Proficio</name> <url>http://maven. </project> An important feature to note in the POM above is the value of the version element.. You should take note of the packaging element. 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.apache.org</url> .0. which you can see is 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 ...apache.
apache.0. Looking at the module names is how Maven steps into the right directory to process the POM located there. which is the proficio-stores module.proficio</groupId> <artifactId>proficio</artifactId> <version>1.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.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.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 . but the interesting thing here is that we have a another project with a packaging type of pom.maven. 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.
state your deployment information... which are all placed in one directory.1. in any of your child POMs. organizing your projects in groups according to concern. Using project inheritance allows you to do things like state your organizational information.proficio</groupId> <artifactId>proficio</artifactId> <version>1.8. Let's examine a case where it makes sense to put a resource in the top-level POM.enabling you to add resources where it makes sense in the hierarchy of your projects. </project> What specifically happens for each child POM. you never have to declare this dependency again. by stating the dependency in the top-level POM once. The dependency is stated as following: <project> . So. if you take a look at the POM for the proficio-core module you will see the following. You can nest sets of projects like this to any level. In this case the assumption being made is that JUnit will be used for testing in all our child projects.apache. If you look at the top-level POM for Proficio..8. you will see that in the dependencies section there is a declaration for JUnit version 3.. using our the top-level POM for the sample Proficio application. 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> ...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. <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.3. 3..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 .all in a single place. <parent> <groupId>org. 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 . or state your common dependencies . is that each one inherits the dependencies section of the top-level POM. just as has been done with Proficio's multiple storage mechanisms. So. Being the observant user..1</version> <scope>test</scope> </dependency> </dependencies> .
.proficio</groupId> <artifactId>proficio-api</artifactId> </dependency> <dependency> <groupId>org. Looking at the effective POM includes everything and is useful to view when trying to figure out what is going on when you are having problems.8.. which in turn inherits from the Super POM.proficio</groupId> <artifactId>proficio</artifactId> <version>1..0.1</version> <scope>test</scope> </dependency> .0-SNAPSHOT</version> </parent> <modelVersion>4..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. <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.apache. </dependencies> . </project> You will have noticed that the POM that you see when using the mvn help:effective-pom is bigger then you expected. the proficio-core project inherits from the toplevel Proficio project. So in this case. take a look at the resulting POM you will see the JUnit version 3.Creating Applications with Maven <project> <parent> <groupId>org..maven.maven.8. This command will show you the final result for a target POM.apache. But remember from Chapter 2 that the Super POM sits at the top of the inheritance hierarchy. <dependencies> ..codehaus. After you move into the proficio-core module and run the command.1 dependency: <project> . Better Builds With Maven 53 ..0</modelVersion> <artifactId>proficio-core</artifactId> <packaging>jar</packaging> <name>Maven Proficio Core</name> <dependencies> <dependency> <groupId>org..
proficio</groupId> <artifactId>proficio-core</artifactId> <version>${project. which is the application version.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1. To illustrate how this mechanism works. You don't want.proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project.apache. it is likely that some of those projects will share common dependencies. </project> Note that the ${project. Maven's strategy for dealing with this problem is to combine the power of project inheritance with specific dependency management elements in the POM. versions of dependencies across several projects.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project. for example.Creating Applications with Maven 3. <dependencyManagement> <dependencies> <dependency> <groupId>org.maven.0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> . making dependency management difficult to say the least...version}</version> </dependency> <dependency> <groupId>org. to end up with multiple versions of a dependency on the classpath when your application executes.maven. individual projects. When you write applications which consist of multiple.codehaus. Managing Dependencies When you are building applications you have many dependencies to manage and the number of dependencies only increases over time. When this happens it is critical that the same version of a given dependency is used for all your projects. as the results can be far from desirable. Better Builds With Maven 54 .version}</version> </dependency> <dependency> <groupId>org..apache. In order to manage.version}</version> </dependency> <dependency> <groupId>org. so that the final application works correctly.4. or align. you use the dependency management section in the top-level POM of an application. of all your dependencies.maven.. let's look at the dependency management section of the Proficio top-level POM: <project> . You want to make sure that all the versions.apache.version} specification is the version specified by the top-level POM's version element. across all of your projects are in alignment so that your testing accurately reflects what you will deploy as your final result.
.maven. whereas the top-level dependencies element does affect the dependency graph. Better Builds With Maven 55 . 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..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. <dependencies> <dependency> <groupId>org. 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.version}) for proficio-model so that version is injected into the dependency above.apache. you will see a single dependency declaration and that it does not specify a version: <project> . to make it complete. 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. The dependencyManagement declares a stated preference for the 1.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.0-SNAPSHOT (stated as ${project.
<version>1. and this is where Maven's concept of a snapshot comes into play.apache.0-SNAPSHOT</version> <dependencyManagement> <dependencies> <dependency> <groupId>org.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1.codehaus.5. so Maven will attempt to update them.proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project. </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. it is usually the case that each of the modules are in flux. Your build system needs to be able to easily deal with this real-time flux.version}</version> </dependency> <dependency> <groupId>org.. Your APIs might be undergoing some change or your implementations are undergoing change and are being fleshed out. When you specify a non-snapshot version of a dependency Maven will download that dependency once and never attempt to retrieve it again.Creating Applications with Maven 3. but you can use the -U command line option to force the search for updates. If you look at the top-level POM for Proficio you will see a snapshot version specified: <project> .maven.0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> . or you may be doing some refactoring. By default Maven will look for snapshots on a daily basis. Better Builds With Maven 56 .. Using Snapshots While you are developing an application with multiple modules.. Controlling how snapshots work will be explained in detail in Chapter 7.version}</version> </dependency> <dependency> <groupId>org.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project.maven.. A snapshot in Maven is an artifact which has been prepared using the most recent sources available.apache. Snapshot dependencies are assumed to be changing.
1 (selected for test) plexus-container-default:1.xml file as follows: Better Builds With Maven 57 .8. 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. see section 6. if you run mvn -X test on the proficio-core module.1-alpha-2 (selected for compile) junit:3. However. • If multiple versions are selected at the same depth. the output will contain something similar to: proficio-core:1. Resolving Dependency Conflicts and Using Version Ranges With the introduction of transitive dependencies in Maven 2. and more importantly ways to avoid it as the author of a reusable library. the least number of dependencies that were traversed to get this version. then the result is undefined. you can remove the incorrect version from the tree. there are ways to manually resolve these conflicts as the end user of a dependency. this has limitations: The version chosen may not have all the features required by the other dependency. To ensure this.0.4 (selected for compile) classworlds:1.8. you can exclude the dependency from the graph by adding an exclusion to the dependency that introduced it. However. or you can override both with the correct version. A dependency in the POM being built will be used over anything else. to compile.1 (selected for compile) Once the path to the version has been identified.that is.. To manually resolve conflicts. the version selected is the one declared "nearest" to the top of the tree . local scope test wins) proficio-api:1. and Proficio requires version 1. modify the plexus-container-default dependency in the proficio-core/pom. it is inevitable that two or more artifacts will require different versions of a particular dependency.1 be used. For example. Maven must choose which version to provide.6. In this example.9 in Chapter 6). In Maven 2.Creating Applications with Maven 3. In this case. as the graph grows.1 (not setting.0.0-SNAPSHOT (selected for compile) proficio-model:1. plexus-utils occurs twice. it became possible to simplify your own POM by only including the dependencies you need directly.0-SNAPSHOT (selected for compile) plexus-utils:1.0-alpha-9 (selected for compile) plexus-utils:1. and to allow Maven to calculate the full dependency graph..0-SNAPSHOT junit:3. • While further dependency management features are scheduled for the next release of Maven at the time of writing.
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. <dependencies> <dependency> <groupId>org.1. for a library or framework.. In fact. as shown above for plexus-utils. You'll notice here that the runtime scope is used. is to include it directly in the POM. In this case.1</version> <scope>runtime</scope> </dependency> </dependencies> .plexus</groupId> <artifactId>plexus-utils</artifactId> <version>1.1 version is used instead.0-alpha-9</version> <exclusions> <exclusion> <groupId>org.. the dependency is used only for packaging. The reason for this is that it distorts the true dependency graph.. so in the case of a conflict with another dependency.Creating Applications with Maven .1. you may require a feature that was introduced in plexus-utils version 1.regardless of whether another dependency introduces it. However. This is because in this situation..4 version of plexus-utils in the dependency graph. Neither of these solutions are ideal. as follows: .. if it were required for compilation.codehaus.. for stability it would always be declared in the current POM as a dependency . The alternate way to ensure that a particular version of a dependency is used. 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. <dependency> <groupId>org.. This is achieved using version ranges instead. However. but that other versions may be acceptable. not for compilation.plexus</groupId> <artifactId>plexus-utils</artifactId> </exclusion> </exclusions> </dependency> . so that the 1. Maven has no knowledge about what versions will definitely work. When a version is declared as 1. this indicates that the preferred version of the dependency is 1.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1. a WAR file). which will accumulate if this project is reused as a dependency itself.0. the dependency should be specified as follows: Better Builds With Maven 58 .1. Maven assumes that all versions are valid and uses the "nearest dependency" technique described previously to determine which version to use.codehaus. that will be used widely by others.codehaus.. This ensures that Maven ignores the 1.
while the build number is an increment after release to indicate patched builds. alpha-1.0] [1. and so on.3 (inclusive) Greater than or equal to 1.1. it is necessary to understand how versions are compared. then the qualifier and finally a build number.5. and table 3-2 shows some of the values that can be used. Better Builds With Maven 59 . the version that is used must fit the range given.5 Any version. the build will fail. the snapshot (as shown above) is a special case where the qualifier and build number are both allowed. or there were no conflicts originally.2.0 Between 1.1. minor and bug fix releases. 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.2.2 and 1.(1.plexus</groupId> <artifactId>plexus-utils</artifactId> <version>[1.0) [1. Finally. In a regular version. If the nearest version does not match. In the current version scheme. then the next nearest will be tested.1 By being more specific through the use of version ranges. If two ranges in a dependency graph do not intersect at all. beta-1. or only the build number. Table 3-2: Examples of version ranges Range Meaning (. The notation used above is set notation.1). but less than 2. will be retrieved from the repository.1.1. However.). rc1).0.0. the version you are left with is [1. if none of them match.) (. It is intended that the qualifier indicates a version prior to release (for example.1.1. Figure 3-3: Version parsing As you can see. that is greater than or equal to 1. a version is broken down into five parts: the major. while the nearest dependency technique will still be used in the case of a conflict.3] [1.)</version> </dependency> What this means is that.1. To understand how ranges work. except 1.0 Greater than or equal to 1. You can see how a version is partitioned by Maven in figure 3-1. you can provide only the qualifier. This means that the latest version. you also need to avoid being too specific.codehaus.) Less than or equal to 1.Creating Applications with Maven <dependency> <groupId>org.
7. the two versions are compared entirely as strings.). and the versions 1. Maven accommodates this requirement by allowing the declaration of a plugin.6. or forced from the command line using the -U option for a particular Maven execution. of course. if the build number exists. the versions will not match this syntax... typically. all projects have different requirements and it is sometimes necessary to augment the life cycle to satisfy these requirements. and finally. By default. through the use of a separate repository. the updatePolicy value is changed for releases.. Conversely. <repository> . so to avoid such a situation. or release betas as milestones along the way. So. In some cases. by build number. second .Creating Applications with Maven With regard to ordering. which means the plugin is bound to a specific phase in the default life cycle. In Proficio. If it will be configured for a particular repository. 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 .if the major versions were equal . This will ensure that the beta versions are used in a range only if the project has declared the snapshot (or development) repository explicitly. If a qualifier exists. For example: ..1. <releases> <updatePolicy>interval:60</updatePolicy> </releases> </repository> 3.first by major version. fourth by qualifier (using string comparison). Proficio has a requirement to generate Java sources from a model. the elements are considered in sequence to determine which is greater . Maven's default build life cycle will suffice for a great number of projects without any augmentation but. this can be configured perrepository to be on a more regular interval. which binds itself to a standard phase in Maven's default life cycle.1 and 1. the repository is checked once a day for updates to the versions of artifacts in use.2-beta-1 exist. In those case. A final note relates to how version updates are determined when a range is in use. it means that the version is older than if the qualifier didn't. you must structure your releases accordingly. Whether you use snapshots until the final release. the Modello plugin is used to generate the Java sources for Proficio's data model. 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. Often this is not desired. Plugins in Maven are created with a specific task in mind. However. that is considered newer than if it doesn't. if you use the range [1.2-beta-1 will be selected. For example. This mechanism is identical to that of the snapshots that you learned in section 3. Because all of these elements are considered part of the version. which is actually Maven's default build life cycle. you should deploy them to a snapshot repository as is discussed in Chapter 7 of this book. then 1.by minor version. the generate-sources phase. the ranges do not differentiate. third by bug fix version.
the path of the application server root in the development. A plugin in Maven may have several goals. so you need to specify which goal in the plugin you wish to run. testing with different databases.0-SNAPSHOT</version> </parent> <modelVersion>4. and production environments). and are meant to be used in complementary sets to give equivalent-but-different parameters for a set of target environments (providing.0-alpha-5</version> <executions> <execution> <goals> <goal>java</goal> </goals> </execution> </executions> <configuration> <version>1. by specifying the goal in the executions element.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. but sometimes you simply have to take into consideration variation across systems and this is why profiles were introduced in Maven.0. and can be activated in several ways.Creating Applications with Maven <project> <parent> <groupId>org. for example. but here you see an additional executions element. Profiles are specified using a subset of the elements available in the POM itself (plus one extra section). building with different JVMs. 3.apache.0</version> <packageWithVersion>false</packageWithVersion> <model>src/main/mdo/proficio.8. Profiles modify the POM at build time.codehaus.0</modelVersion> <artifactId>proficio-model</artifactId> <packaging>jar</packaging> <name>Proficio Model</name> <build> <plugins> <plugin> <groupId>org. Typically you try to encapsulate as much as possible in the POM to ensure that builds are portable.0. Better Builds With Maven 61 . or referencing the local file system. 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.proficio</groupId> <artifactId>proficio</artifactId> <version>1. testing.modello</groupId> <artifactId>modello-maven-plugin</artifactId> <version>1.
no profiles other than those specified in the option argument will be activated. called profiles.xml file as well.. Note that you must have defined the profiles in your settings.. For example: mvn -Pprofile1. profiles can easily lead to differing build results from different members of your team. When this option is specified. However. </profile> </profiles> <activeProfiles> <activeProfile>profile1</activeProfile> </activeProfiles> .Creating Applications with Maven As such.profile2 install Profiles can be activated in the Maven settings. For example: <settings> . which consists of: defaultGoal • resources • testResources • finalName • There are several ways that you can activate profiles: • Profiles can be specified explicitly using the -P CLI option.xml • The POM itself • In any of the above three profile sites. This option takes an argument that contains a comma-delimited list of profile-ids. • <profiles> <profile> <id>profile1</id> ..xml) • A file in the the same directory as the POM. </settings> Better Builds With Maven 62 . used properly. This section takes a list of activeProfile elements.. via the activeProfiles section. you can define the following elements: • • • • • • • • • repositories pluginRepositories dependencies plugins properties (not actually available in the main POM. 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. but used behind the scenes) modules reporting dependencyManagement distributionManagement A subset of the build element. each containing a profile-id.m2/settings..
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. "1. These activators are specified via an activation section in the profile itself.4</jdk> </activation> </profile> This activator will trigger the profile when the JDK's version starts with "1.2_07".. this detection is limited to prefix-matching of the JDK version.4").Creating Applications with Maven • Profiles can be triggered automatically based on the detected state of the build environment. "1. 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. Currently.. the presence of a system property.. <profile> <id>profile1</id> .0_08". Here are some examples: <profile> <id>profile1</id> ..4. <profile> <id>profile1</id> ..4" (eg. Now that you are familiar with profiles.. <activation> <property> <name>debug</name> </property> </activation> </profile> This will activate the profile when the system property "debug" is specified with any value.4. Better Builds With Maven 63 . "1. <activation> <jdk>1. <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". or the value of a system property.
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.Profiles for the two assemblies to create for deployment --> <profiles> <!-. <!-..Profile which creates an assembly using the xstream based store --> <profile> <id>xstream</id> <build> <plugins> <plugin> <artifactId>maven-assembly-plugin</artifactId> <configuration> <descriptors> <descriptor>src/main/assembly/assembly-store-xstream.xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>memory</name> </property> </activation> </profile> <!-..xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>xstream</name> </property> </activation> </profile> </profiles> </project> Better Builds With Maven 64 .Creating Applications with Maven If you take a look at the POM for the proficio-cli module you will see the profile definitions: <project> .
In each of these profiles you are configuring the assembly plugin to point at the assembly descriptor that will create a tailored assembly. 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. You will also notice that the profiles are activated using a system property. Better Builds With Maven 65 .jar file.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.jar file and the XStream-based store only contains the proficio-store-xstream-1.0-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.
.yourcompany. you'll want to share it with as many people as possible! So.. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scp://sshserver. 3.9. it is now time to deploy your application assembly. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>file://${basedir}/target/deploy</url> </repository> </distributionManagement> .. </project> Better Builds With Maven 66 ... which would typically be your top-level POM so that all child POMs can inherit this information.. FTP deployment. </project> 3. Deploying with SSH2 To deploy to an SSH2 server you would use something like the following: <project> . In order to deploy you need to correctly configure your distributionManagement element in your POM. SSH2 deployment. SFTP deployment.10.1. and external SSH deployment.Creating Applications with Maven 3. 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.9. Deploying to the File System To deploy to the file system you would use something like the following: <project> .. Currently Maven supports several methods of deployment include simple file-based deployment..
.apache.1.yourcompany. Wagon is the general purpose transport mechanism used throughout Maven.com/deploy</url> </repository> </distributionManagement> <build> <extensions> <extension> <groupId>org. so only the distributionManagement element is required. </project> The build extension specifies the use of the Wagon external SSH provider. but also a build extension.. Deploying with SFTP To deploy to an SFTP server you would use something like the following: <project> ..0-alpha-6</version> </extension> </extensions> </build> . </project> 3. which does the work of moving your files to the remote server.Creating Applications with Maven 3..11.... the first three methods illustrated are included with Maven.11.yourcompany. <project> .wagon</groupId> <artifactId>wagon-ssh-external</artifactId> <version>1. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scpexe://sshserver.com/deploy</url> </repository> </distributionManagement> . Better Builds With Maven 67 . <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>sftp://ftpserver. Deploying with an External SSH Now.. but to use an external SSH command to deploy you must configure not only the distributionManagment element.maven.
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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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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Creating Applications with Maven
<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 .
3. Summary In this chapter you have learned to setup a directory structure for a typical application and learned the basics of managing the application's development with Maven.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. augmenting your site to view quality metrics.13. how to manage your application's dependencies. Keeping in mind this simple rule you can add any resources you wish to your site. how to deploy your application. and using Maven in a collaborative environment. Better Builds With Maven 74 . 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. and how to create a simple Web site for your application. You should now have a grasp of how project inheritance works. 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. how to make small modifications to Maven's build life cycle.
EAR.4. 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 . . WAR. Building J2EE Applications Building J2EE Applications This chapter covers: • • • • • Organizing the directory structure Building J2EE archives (EJB.
EJBs.1. Introduction J2EE (or Java EE as it is now called) applications are everywhere. This chapter demonstrates how to use Maven on a real application to show how to address the complex issues related to automated builds. Introducing the DayTrader Application DayTrader is a real world application developed by IBM and then donated to the Apache Geronimo project. The functional goal of the DayTrader application is to buy and sell stock. 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. This chapter will take you through the journey of creating the build for a full-fledged J2EE application called DayTrader.2. Web services. As importantly. and it's architecture is shown in Figure . you'll learn how to build EARs. and Web applications.4 application and as a test bed for running performance tests. 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. As a consequence the Maven community has developed plugins to cover every aspect of building J2EE applications. Through this example. Figure 4-1: Architecture of the DayTrader application Better Builds With Maven 76 . Its goal is to serve as both a functional example of a full-stack J2EE 1. Whether you are using the full J2EE stack with EJBs or only using Web applications with frameworks such as Spring or Hibernate.Building J2EE Applications 4.
A new "open" order is saved in the database using the CMP Entity Beans. • • • A typical "buy stock" use case consists of the following steps that were shown in Figure : 1. and a JMS Server for interacting with the outside world. Once this happens the Trade Broker MDB is notified 6. The creation of the "open" order is confirmed for the user. and so on. Better Builds With Maven 77 . 5.Quote and AccountProfile). buy or sell a stock. The Web layer offers a view of the application for both the Web client and the Web services client. using Web services. The order is then queued for processing in the JMS Message Server. cancel an order. get a stock quote. 4. and Message-Driven Beans (MDB) to send purchase orders and get quote changes. Holding. The EJB layer is where the business logic is.Building J2EE Applications There are 4 layers in the architecture: • The Client layer offers 3 ways to access the application: using a browser. 2. The Data layer consists of a database used for storing the business objects and the status of each purchase. Asynchronously the order that was placed on the queue is processed and the purchase completed. and using the Quote Streamer. logout. It uses container-managed persistence (CMP) entity beans for storing the business objects (Order. Account. The Trade Session is a stateless session bean that offers the business services such as login. 3. The user gives a buy order (by using the Web client or the Web services client). The user is notified of the completed order on a subsequent request. It uses servlets and JSPs. The Trade Broker calls the Trade Session bean which in turn calls the CMP entity beans to mark the order as "completed". The Quote Streamer is a Swing GUI application that monitors quote information about stocks in real-time as the price changes. This request is handled by the Trade Session bean.
If there isn't a strong need you may find that managing several modules can be more cumbersome than useful. The next step is to give these modules names and map them to a directory structure. For example.the module containing the Web services client application ear . you may want to split the WAR module into 2 WAR modules: one for the browser client and one for the Web services client.Building J2EE Applications 4. another JAR that will contain the Web services client application. It is flat because you're locating all the modules in the same directory. Let's discuss the pros and cons of each layout. However. if you needed to physically locate the WARs in separate servlet containers to distribute the load.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. Thus you simply need to figure out what artifacts you need.the module containing the EJBs web . This EAR will be used to easily deploy the server code into a J2EE container. On the other hand. As a general rule. it is better to find functional names for modules. It is possible to come up with more.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. 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. For example. The easy answer is to follow Maven's artifact guideline: one module = one main artifact.3. Better Builds With Maven 78 . Figure 4-2 shows these modules in a flat directory structure. Note that this is the minimal number of modules required. Best practices suggest to do this only when the need arises. a JAR that will contain the Quote Streamer client application. a WAR which will contain the Web application. it is important to split the modules when it is appropriate for flexibility. it is usually easier to choose names that represent a technology instead.the module containing the Web application streamer . Organizing the DayTrader Directory Structure The first step to organizing the directory structure is deciding what build modules are required. For the DayTrader application the following names were chosen: • • • • • ejb .
you might separate the client side modules from the server side modules in the way shown in Figure 4-3.. and is the structure used in this chapter. not nested within each other. Better Builds With Maven 79 ..] <modules> <module>ejb</module> <module>web</module> <module>streamer</module> <module>wsappclient</module> <module>ear</module> </modules> [. Figure 4-3: Modules split according to a server-side vs client-side directory organization As before.xml file containing the shared POM elements and the list of modules underneath.xml file contains the POM elements that are shared between all of the modules. if you have many modules in the same directory you may consider finding commonalities between them and create subdirectories to partition them.Building J2EE Applications Figure 4-2: Module names and a simple flat directory structure The top-level daytrader/pom.. Note that in this case the modules are still separate. For example. However. for more details): [. 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.. each directory level containing several modules contains a pom.] This is the easiest and most flexible structure to use.
Now that you have decided on the directory structure for the DayTrader application. the three modules wouldn't be able to have different natures (Web application project. A flat layout is more neutral with regard to assembly and should thus be preferred. the ejb and web modules are nested in the ear module. EJB project. For example. This makes sense as the EAR artifact is composed of the EJB and WAR artifacts produced by the ejb and web modules. but then you'll be restricted in several ways. • These examples show that there are times when there is not a clear parent for a module. Or the ejb module might be producing a client EJB JAR which is not used by the EAR. You'd need to consider the three modules as one project. the nested strategy doesn't fit very well with the Assembler role as described in the J2EE specification. the ejb or web modules might depend on a utility JAR and this JAR may be also required for some other EAR. etc. starting with the EJB module. In those cases using a nested directory structure should be avoided. it has several drawbacks: Eclipse users will have issues with this structure as Eclipse doesn't yet support nested projects. 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. Better Builds With Maven 80 . Having this nested structure clearly shows how nested modules are linked to their parent. Figure 4-4: Nested directory structure for the EAR. even though the nested directory structure seems to work quite well here. For example. In addition. you're going to create the Maven build for each module. In this case. The Assembler has a pool of modules and its role is to package those modules for deployment. • It doesn't allow flexible packaging. but by some client-side application. as shown in Figure 4-4.Building J2EE Applications The other alternative is to use a nested directory structure. EJB and Web modules However. EAR project).
• • Unit tests in src/test/java and classpath resources for the unit tests in src/test/resources. More specifically. Unit tests are tests that execute in isolation from the container. the standard ejb-jar. 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.xml.xml deployment descriptor is in src/main/resources/META-INF/ejb-jar. Building an EJB Project Let's create a build for the ejb module.Building J2EE Applications 4. Tests that require the container to run are called integration tests and are covered at the end of this chapter. Any container-specific deployment descriptor should also be placed in this directory.
4_spec</artifactId> <version>1.specs</groupId> <artifactId>geronimo-j2ee_1.maven.apache.Building J2EE Applications Now. 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 .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. This is because the DayTrader build is a multi-module build and you are gathering common POM elements in a parent daytrader/pom.apache.samples.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean.0</modelVersion> <parent> <groupId>org. take a look at the content of this project's pom.geronimo.geronimo.xml file.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1.class</clientExclude> </clientExcludes> </configuration> </plugin> </plugins> </build> </project> As you can see.3</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.0.0.xml file: <project> <modelVersion>4.apache. you're extending a parent POM using the parent element.
Building J2EE Applications C:\dev\m2book\code\j2ee\daytrader>mvn -N install [INFO] Scanning for projects. **/*Session... this prevents the EAR module from including the J2EE JAR when it is packaged. so you must explicitly tell it to do so: <plugin> <groupId>org. the pom.m2\repository\org\apache\geronimo\samples\daytrader\daytrader\1.xml contains a configuration to tell the Maven EJB plugin to generate a Client EJB JAR file when mvn install is called.pom The ejb/pom. This is achieved by specifying a dependency element on the J2EE JAR.0\daytrad er-1. 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. Fortunately.]\.class</clientExclude> </clientExcludes> </configuration> </plugin> The EJB plugin has a default set of files to exclude from the client EJB JAR: **/*Bean. **/*CMP. it still needs to be listed in the POM so that the code can be compiled.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. The Client will be used in a later examples when building the web module. 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. this JAR is not redistributable and as such cannot be found on ibiblio. You should note that you're using a provided scope instead of the default compile scope. the Geronimo project has made the J2EE JAR available under an Apache license and this JAR can be found on ibiblio.xml to C:\[..apache. The reason is that this dependency will already be present in the environment (being the J2EE application server) where your EJB will execute.html. You make this clear to Maven by using the provided scope. Better Builds With Maven 83 .class.maven.class. Even though this dependency is provided at runtime. • Lastly. By default the EJB plugin does not generate the client JAR. You could instead specify a dependency on Sun's J2EE JAR..class and **/package.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean.0.
0. Note that it's also possible to specify a list of files to include using clientInclude elements. Errors: 0.samples. Failures: 0. Relax and type mvn install: C:\dev\m2book\code\j2ee\daytrader\ejb>mvn install [INFO] Scanning for projects.]\. Time elapsed: 0.0-client..0.0-client.jar to C:\[.jar [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.apache.FinancialUtilsTest [surefire] Tests run: 1.0.02 sec Results : [surefire] Tests run: 1.0-client.class pattern and which need to be present in the generated client EJB JAR..]\.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ejb\1..jar [INFO] [install:install] [INFO] Installing 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. [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.0-client [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ejb\1.0\daytrader-ejb-1.0\daytrader-ejb-1.jar to C:\[. 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. You're now ready to execute the build.geronimo.class). Errors: 0 [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1.jar Better Builds With Maven 84 .daytrader. Failures: 0.0 [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1. [INFO] ----------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [install] [INFO] ----------------------------------------------------------[INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources. 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..Building J2EE Applications In this example.
Stay tuned! 4. 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. you can safely skip this section – you won't need it! Better Builds With Maven 85 . the Remote and Local interfaces. There is a working prototype of an EJB3 Maven plugin. Early adopters of EJB3 may be interested to know how Maven supports EJB3. and the ejb-jar.org/plugins/maven-ejb-plugin/. the EJB3 specification is still not final. When writing EJBs it means you simply have to write your EJB implementation class and XDoclet will generate the Home interface.5. At the time of writing. 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.xml descriptor. the container-specific deployment descriptors. The EJB plugin has several other configuration elements that you can use to suit your exact needs. however in the future it will be added to the main EJB plugin after the specification is finalized. you can run the XDoclet processor to generate those files for you.apache. Note that if you're an EJB3 user.
ejb.daytrader. the project's directory structure is the same as in Figure 4-5.bean * display-name="TradeEJB" * name="TradeEJB" * view-type="remote" * impl-class-name= * "org.TradeBean" * @ejb.samples.transaction * type="RequiresNew" *[…] */ public void queueOrderOnePhase(Integer orderID) throws javax.ejb.home * generate="remote" * remote-class= * "org.Building J2EE Applications Here's an extract of the TradeBean session EJB using Xdoclet: /** * Trade Session EJB manages all Trading services * * @ejb.interface * generate="remote" * remote-class= * "org.samples.geronimo. Exception […] To demonstrate XDoclet.daytrader.daytrader. create a copy of the DayTrader ejb module called ejb-xdoclet.apache.ejb. As you can see in Figure 4-6.jms.xml file anymore as it's going to be generated by Xdoclet. but you don't need the ejb-jar.apache.interface-method * view-type="remote" * @ejb.geronimo.geronimo.apache.TradeHome" * @ejb.Trade" * […] */ public class TradeBean implements SessionBean { […] /** * Queue the Order identified by orderID to be processed in a * One Phase commit […] * * @ejb.samples.JMSException. Figure 4-6: Directory structure for the DayTrader ejb module when using Xdoclet Better Builds With Maven 86 .
build. this has to be run before the compilation phase occurs. Since XDoclet generates source files.java classes and remove all of the Home. Now you need to tell Maven to run XDoclet on your project. This is achieved by using the Maven XDoclet plugin and binding it to the generate-sources life cycle phase.sourceforge.java"></include> <include name="**/*MDB.outputDirectory}/META-INF"/> </ejbdoclet> </tasks> </configuration> </execution> </executions> </plugin> The XDoclet plugin is configured within an execution element. Finally. It also tells Maven that this directory contains sources that will need to be compiled when the compile phase executes.directory}/generated-sources/xdoclet"> <fileset dir="${project.java"></include> </fileset> <homeinterface/> <remoteinterface/> <localhomeinterface/> <localinterface/> <deploymentdescriptor destDir="${project. but here the need is to use the ejbdoclet task to instrument the EJB class files. In addition.mojo</groupId> <artifactId>xdoclet-maven-plugin</artifactId> <executions> <execution> <phase>generate-sources</phase> <goals> <goal>xdoclet</goal> </goals> <configuration> <tasks> <ejbdoclet verbose="true" force="true" ejbSpec="2.1" destDir= "${project.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask. The plugin generates sources by default in ${project. This is required by Maven to bind the xdoclet goal to a phase.sourceDirectory}"> <include name="**/*Bean. in the tasks element you use the ejbdoclet Ant task provided by the XDoclet project (for reference documentation see http://xdoclet.Building J2EE Applications The other difference is that you only need to keep the *Bean. Local and Remote interfaces as they'll also get generated. Better Builds With Maven 87 . the XDoclet plugin will also trigger Maven to download the XDoclet libraries from Maven's remote repository and add them to the execution classpath.build.build.html).codehaus.build.xml that configures the plugin: <plugin> <groupId>org. Here's the portion of the pom.directory}/generated-sources/xdoclet (you can configure this using the generatedSourcesDirectory configuration element). In practice you can use any XDoclet task (or more generally any Ant task) within the tasks element.
nor does it boast all the plugins that XDoclet1 has.apache.daytrader.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. it should be noted that XDoclet2 is a work in progress and is not yet fully mature. 2006 16:53:50 xdoclet.codehaus.AccountBean'. However. 2006 16:53:50 xdoclet.daytrader.ejb.daytrader.org/Maven2+Plugin. […] [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1.samples.XDocletMain start INFO: Running <homeinterface/> Generating Home interface for 'org.TradeBean'.geronimo.geronimo. It's based on a new architecture but the tag syntax is backwardcompatible in most cases.geronimo.0 […] You might also want to try XDoclet2.apache. Better Builds With Maven 88 .TradeBean'.AccountBean'. […] INFO: Running <remoteinterface/> Generating Remote interface for 'org. […] 10 janv. 2006 16:53:51 xdoclet. There's also a Maven 2 plugin for XDoclet2 at http://xdoclet.ejb.daytrader.geronimo.XDocletMain start INFO: Running <localhomeinterface/> Generating Local Home interface for 'org. […] 10 janv.XDocletMain start INFO: Running <deploymentdescriptor/> Generating EJB deployment descriptor (ejb-jar.samples. 2006 16:53:51 xdoclet.xml).apache.apache.samples.samples.XDocletMain start INFO: Running <localinterface/> Generating Local interface for 'org.ejb.ejb. […] 10 janv.
. 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.2. For example: <container> <containerId>jboss4x</containerId> <output>${project. the JBoss container will be used..directory}/jboss4x.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> </plugin> </plugins> </build> If you want to debug Cargo's execution. Better Builds With Maven 89 . Maven 1. you will need to have Maven start the container automatically.x (containerId element) and that you want Cargo to download the JBoss 4.sourceforge.net/ sourceforge/jboss/jboss-4. In the container element you tell the Cargo plugin that you want to use JBoss 4.] <plugin> <groupId>org. Later. To do so you're going to use the Maven plugin for Cargo.org/Debugging for full details. Ant. configuring them and deploying modules to them. stopping. Let's discover how you can automatically start a container and deploy your EJBs into it.2 distribution from the specified URL and install it in ${installDir}. Cargo is a framework for manipulating containers.log</log> [.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <zipUrlInstaller> <url>http://internap. Netbeans.6. in the Testing J2EE Applications section of this chapter. The location where Cargo should install JBoss is a user-dependent choice and this is why the ${installDir} property was introduced.directory}/cargo. you will also learn how to test it automatically.build. Edit the ejb/pom.0.Building J2EE Applications 4.] See http://cargo.codehaus.0. First. IntelliJ IDEA. you will learn how to deploy it.. Maven 2..xml file and add the following Cargo plugin configuration: <build> <plugins> [. Deploying EJBs Now that you know how to build an EJB project. In order to build this project you need to create a Profile where you define the ${installDir} property's value.) for performing various actions on containers such as starting. It offers generic APIs (Java. etc.log</output> <log>${project. In this example.codehaus.dl.build.
Better Builds With Maven 90 .0.2 starting. you can define a profile in the POM.2</home> That's all you need to have a working build and to deploy the EJB JAR into JBoss.Building J2EE Applications As explained in Chapter 3. That's it! JBoss is running. For example: <home>c:/apps/jboss-4.0. [INFO] ----------------------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [cargo:start] [INFO] ----------------------------------------------------------------------[INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4. it detects that the Maven project is producing an EJB from the packaging element and it automatically deploys it when the container is started..xml file. so run mvn package to generate it.. 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. Nor should the content be shared with other Maven projects at large.xml file.xml file defines a profile named vmassol. In that case replace the zipURLInstaller element with a home element.xml file.. the EJB JAR should first be created. Of course.0. It's also possible to tell Cargo that you already have JBoss installed locally. [INFO] Searching repository for plugin with prefix: 'cargo'..2 started on port [8080] [INFO] Press Ctrl-C to stop the container. Thus the best place is to create a profiles. and the EJB JAR has been deployed. in a settings. as the content of the Profile is user-dependent you wouldn't want to define it in the POM. in a profiles.2] [INFO] [talledLocalContainer] JBoss 4. In this case. or in a settings.. activated by default and in which the ${installDir} property points to c:/apps/cargo-installs..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.0. The Cargo plugin does all the work: it provides a default JBoss configuration (using port 8080 for example). [INFO] [talledLocalContainer] JBoss 4.
you would run the cargo:deploy goal.Building J2EE Applications As you have told Cargo to download and install JBoss. Check the documentation at http://cargo. modifying various container parameters. Cargo has many other configuration options such as the possibility of using an existing container installation. etc. Building a Web Application Project Now. the first time you execute cargo:start it will take some time. WEB-INF configuration files.org/Maven2+plugin. Figure 4-7: Directory structure for the DayTrader web module showing some Web application resources Better Builds With Maven 91 . except that there is an additional src/main/webapp directory for locating Web application resources such as HTML pages.codehaus.7. 4. The layout is the same as for a JAR module (see the first two chapters of this book). (see Figure 4-7). especially if you are on a slow connection. and more. Finally. deploying on a remote machine. let's focus on building the DayTrader web module. If the container was already started and you wanted to just deploy the EJB. to stop the container call mvn cargo:stop. Subsequent calls will be fast as Cargo will not download JBoss again. JSPs.
apache.xml: <dependency> <groupId>org. Therefore.samples.geronimo.0</modelVersion> <parent> <groupId>org.geronimo.xml. Depending on the main EJB JAR would also work. you need to add a dependency on the ejb module in web/pom.0. then the WAR you generate will be overlaid with the Better Builds With Maven 92 .apache.xml file: <project> <modelVersion>4.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1.0</version> <type>ejb-client</type> </dependency> Note that you're specifying a type of ejb-client and not ejb.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.geronimo.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.specs</groupId> <artifactId>geronimo-j2ee_1.daytrader</groupId> <artifactId>daytrader-ejb</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.geronimo.4_spec</artifactId> <version>1.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1. It's always cleaner to depend on the minimum set of required classes.apache.samples. Therefore.0</version> <type>ejb-client</type> </dependency> <dependency> <groupId>org. you specify the required dependencies. for example to prevent coupling. This is because the servlets are a client of the EJBs. the servlets only need the EJB client JAR in their classpath to be able to call the EJBs. If you add a dependency on a WAR. but it's not necessary and would increase the size of the WAR file.samples.apache.
] [INFO] [war:war] [INFO] Exploding webapp.0\daytrader-web-1. allowing the aggregation of multiple WAR files. The configuration is very simple because the defaults from the WAR plugin are being used.war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. Otherwise it would have surfaced in the WEB-INF/lib directory of the generated WAR.org/Merging+WAR+files). unless their scope is test or provided. the Geronimo J2EE specifications JAR is used with a provided scope (as seen previously when building the EJB).Building J2EE Applications content of that dependent WAR. Maven 2 supports transitive dependencies.]\.0. The final dependency listed is the J2EE JAR as your web module uses servlets and calls EJBs... Again..0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1..war to C:\[. An alternative is to use the uberwar goal from the Cargo Maven Plugin (see http://cargo.codehaus. However. As seen in the introduction.0.war [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. and files such as web. [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-web\1.war Better Builds With Maven 93 . As you know.xml file and reduces maintenance. Running mvn install generates the WAR and installs it in your local repository: C:\dev\m2book\code\j2ee\daytrader\web>mvn install [.xml.0.0...xml won't be merged. it recursively adds your module's dependencies. only files not in the existing Web application will be added. When it generates your WAR.0 [INFO] Assembling webapp daytrader-web in C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. it's a good practice to use the default conventions as much as possible. This is why we defined the J2EE JAR using a provided scope in the web module's pom. as it reduces the size of the pom.
xml Location of Web application resources to include in the WAR.apache.finalName} For the full list. warSourceIncludes/war All files are included SourceExcludes warName ${project. Specify where to find the web.xml file. Name of the generated WAR.build. Table 4-1: WAR plugin configuration properties Configuration property Default value Description warSourceDirectory webXml ${basedir}/src/main/webapp The web. Specify the files to include/exclude from the generated WAR. see the reference documentation for the WAR plugin at http://maven.Building J2EE Applications Table 4-1 lists some other parameters of the WAR plugin that you may wish to configure. Better Builds With Maven 94 .xml file found in ${warSourceDirectory}/WEBINF/web.org/plugins/maven-war-plugin/.
specs</groupId> <artifactId>geronimo-j2ee_1.Building J2EE Applications 4. You execute the Jetty6 plugin by typing mvn jetty6:run: Better Builds With Maven 95 .jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> <scanIntervalSeconds>10</scanIntervalSeconds> </configuration> <dependencies> <dependency> <groupId>org. the plugin reloads the Web application in Jetty. Add the following to the web/pom. The Jetty6 plugin creates a custom Jetty 6 configuration that is wired to your source tree. Fortunately. 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. 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).4_spec</artifactId> <version>1. Let's try the Jetty6 plugin on the DayTrader web module. Since the Web application earlier declared that the specification must be provided through the provided scope.apache. the web. Thus any recompilation in your IDE will trigger a redeploy of your Web application in Jetty. Maven can help. the src/main/webapp tree. and it adds the compiled classes in target/classes to its execution classpath. The plugin monitors the source tree for changes. 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.geronimo. the project dependencies and the compiled classes and classpath resources in target/classes. JSP or servlet code.mortbay. including the pom. There are two plugins that can alleviate this problem: the Cargo plugin and the Jetty6 plugin. If any change is detected.xml file.0</version> <scope>provided</scope> </dependency> </dependencies> </plugin> […] The scanIntervalSeconds configuration property tells the plugin to monitor for changes every 10 seconds. The plugin is configured by default to look for resource files in src/main/webapp. 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.8. providing an extremely fast turnaround time for development. adding this dependency to the plugin adds it to the classpath for Jetty.xml file: […] <build> <plugins> <plugin> <groupId>org.xml file.
.log .mortbay.Started SelectChannelConnector @ 0. using defaults: org.log.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 ..SelectChannelConnector listening on 8080 with maxIdleTime 30000 0 [main] INFO org.jetty. [INFO] Finished setting up classpath [INFO] Started configuring web.impl. listening for changes.slf4j.xml..SimpleLogger@1242b11 via org.xml 681 [main] INFO org. [INFO] No connectors configured.mortbay. As you can see.log .Slf4jLog [INFO] Context path = /daytrader-web [INFO] Webapp directory = C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Setting up classpath .Logging to org.0.. Maven pauses as Jetty is now started. Your Web application has been deployed and the plugin is waiting.0:8080 [INFO] Starting scanner at interval of 10 seconds.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. resource base= C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Finished configuring web.xml file located at: C:\dev\m2book\code\j2ee\daytrader\ web\src\main\webapp\WEB-INF\web.mortbay.mortbay.jsp URL as shown in Figure 4-8 to see the Web application running.0.nio. Open a browser with the http://localhost:8080/daytrader-web/register. Figure 4-8: DayTrader JSP registration page served by the Jetty6 plugin Better Builds With Maven 96 .
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. Edit web/src/main/webapp/register. but the EJBs and all the back end code has not been deployed.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.properties. In order to make it work you'd need to have your EJB container started with the DayTrader code deployed in it. In practice it's easier to deploy a full EAR as you'll see below. There are various configuration parameters available for the Jetty6 plugin such as the ability to define Connectors and Security realms. The Jetty container automatically recompiled the JSP when the page was refreshed. you would use: Better Builds With Maven 97 .jsp. isn't it? What happened is that the Jetty6 plugin realized the page was changed and it redeployed the Web application automatically. For example if you wanted to run Jetty on port 9090 with a user realm defined in etc/realm. The reason is that we have only deployed the Web application here.
SelectChannelConnector"> <port>9090</port> <maxIdleTime>60000</maxIdleTime> </connector> </connectors> <userRealms> <userRealm implementation= "org.mortbay. Then it deploys the unpacked Web application located in target/ (whereas the jetty6:run-war goal deploys the WAR file). any change to those files results in a hot redeployment.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. WEB-INF/classes.mortbay.jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> […] <connectors> <connector implementation= "org.nio.xml. WEB-INF/web. 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.jetty. By default the plugin uses the module's artifactId from the POM.security. 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. For a reference of all configuration options see the Jetty6 plugin documentation at http://jetty.jetty. possibly generating some files. Now imagine that you have an awfully complex Web application generation process.xml configuration file using the jettyConfig configuration element.xml file will be applied first.mortbay. 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. In that case anything in the jetty.xml file is modified.html. The WAR plugin has an exploded goal which produces an expanded Web application in the target directory. The plugin then watches the following files: WEB-INF/lib.xml and pom. Calling this goal ensures that the generated Web application is the correct one.org/jetty6/mavenplugin/index. and so on. • jetty6:run-exploded: The plugin runs the package phase as with the jetty6:run-war goal. Better Builds With Maven 98 .HashUserRealm"> <name>Test Realm</name> <config>etc/realm. that you have custom plugins that do all sorts of transformations to Web application resource files. It's also possible to pass in a jetty. for example) or when the pom.Building J2EE Applications <plugin> <groupId>org. Fortunately there's a solution.
.. Restarting webapp ...0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1.] [INFO] [war:war] [INFO] Exploding webapp. [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.0. 0 [main] INFO org...log.slf4j.0.0:8080 [INFO] Scanning .Slf4jLog [INFO] Context path = /daytrader-web 2214 [main] INFO org..war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1. [INFO] Scan complete at Wed Feb 15 11:59:00 CET 2006 [INFO] Starting scanner at interval of 10 seconds..war [INFO] [jetty6:run-exploded] [INFO] Configuring Jetty for project: DayTrader :: Web Application [INFO] Starting Jetty Server .. Stopping webapp .. As you can see the WAR is first assembled in the target directory and the Jetty plugin is now waiting for changes to happen.mortbay..Logging to org.SimpleLogger@78bc3b via org.... execute mvn jetty6:run-exploded goal on the web module: C:\dev\m2book\code\j2ee\daytrader\web>mvn jetty6:run-exploded [.0.. Scanning ..log . Reconfiguring webapp .impl.mortbay. Restart completed.. Listeners completed.0 [INFO] Assembling webapp daytrader-web in C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.Building J2EE Applications To demonstrate.. No more excuses! Better Builds With Maven 99 .mortbay. You're now ready for productive web development.log .Started SelectChannelConnector @ 0. 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 .0.
the containerId and url properties should be shared for all users of the build.servlet. Those properties will be defined in a Profile.port>8280</cargo.org/Containers).9. This example uses the Cargo Maven plugin to deploy to any container supported by Cargo (see http://cargo. First. so now the focus will be on deploying a packaged WAR to your target container. add the following profiles to the web/pom. Thus.xml file.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>${containerId}</containerId> <zipUrlInstaller> <url>${url}</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <configuration> <properties> <cargo. edit the web module's pom.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. As seen in the Deploying EJBs section the installDir property is user-dependent and should be defined in a profiles.servlet. There are two differences though: • • Two new properties have been introduced (containerId and url) in order to make this build snippet generic. Deploying Web Applications You have already seen how to deploy a Web application for in-place Web development in the previous section. However. This is very useful when you're developing an application and you want to verify it works on several containers.xml file: Better Builds With Maven 100 . This is very useful if you have containers already running your machine and you don't want to interfere with them.xml file and add the Cargo configuration: <plugin> <groupId>org.Building J2EE Applications 4.servlet.codehaus.codehaus. 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.
org/dist/jakarta/tomcat-5/v5.0...30..2..sourceforge.0..net/sourceforge/jboss/jboss4.0.. [INFO] [talledLocalContainer] Tomcat 5. [INFO] [talledLocalContainer] JBoss 4..30 starting..dl..30 started on port [8280] [INFO] Press Ctrl-C to stop the container.0.] [INFO] [cargo:start] [INFO] [talledLocalContainer] Tomcat 5..0. You could add as many profiles as there are containers you want to execute your Web application on.] </build> <profiles> <profile> <id>jboss4x</id> <activation> <activeByDefault>true</activeByDefault> </activation> <properties> <containerId>jboss4x</containerId> <url>http://ovh.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)..]\Temp\cargo\50866\webapps]..30/bin/ jakarta-tomcat-5...2 starting.0.2] [INFO] [talledLocalContainer] JBoss 4.2 started on port [8280] [INFO] Press Ctrl-C to stop the container.zip</url> </properties> </profile> <profile> <id>tomcat5x</id> <properties> <containerId>tomcat5x</containerId> <url>http://www. [INFO] [CopyingLocalDeployer] Deploying [C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.0.0...0.] [INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4. 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 [. starts the JBoss container and deploys the WAR into it: C:\dev\m2book\code\j2ee\daytrader\web>mvn install cargo:start [.war] to [C:\[. Better Builds With Maven 101 .apache..Building J2EE Applications [.. Executing mvn install cargo:start generates the WAR.
servlet. At this stage you have learned how to build and deploy EJBs and WARs. • 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.xml file) for those user-dependent.username> <cargo. Better Builds With Maven 102 .codehaus.org/Deploying+to+a+running+container.password>${remotePassword}</cargo.hostname> <cargo. once this is verified you'll want a solution to deploy your WAR into an integration platform. One solution is to have your container running on that integration platform and to perform a remote deployment of your WAR to it.username>${remoteUsername}</cargo. Let's now discover how to build Web services modules.password> </properties> </configuration> </configuration> </plugin> When compared to the configuration for a local deployment above. Note that there was no need to specify a deployment URL as it is computed automatically by Cargo.port>${remotePort}</cargo.Building J2EE Applications This is useful for development and to test that your code deploys and works.remote.port> <cargo. However. To deploy the DayTrader's WAR to a running JBoss server on machine remoteserver and executing on port 80. All the properties introduced need to be declared inside the POM for those shared with other users and in the profiles.codehaus.remote.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <type>remote</type> </container> <configuration> <type>runtime</type> <properties> <cargo.hostname>${remoteServer}</cargo.servlet.remote. • Check the Cargo reference documentation for all details on deployments at http://cargo. the changes are: A remote container and configuration type to tell Cargo that the container is remote and not under Cargo's management.xml: <plugin> <groupId>org. you would need the following Cargo plugin configuration in web/pom.xml file (or the settings.remote.
10. the Maven plugin called Axis Tools plugin takes WSDL files and generates the Java files needed to interact with the Web services it defines.apache. see http://ws. As you may notice. the plugin uses the Axis framework (http://ws.org/axis/java/userguide. and Maven's ability to integrate toolkits can make them easier to add to the build process. which is the default used by the Axis Tools plugin: Figure 4-10: Directory structure of the wsappclient module Better Builds With Maven 103 .html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL.org/axis/java/). For example.apache. Figure 4-10 shows the directory structure of the wsappclient module. the WSDL files are in src/main/wsdl. Building a Web Services Client Project Web services are a part of many J2EE applications. and this will be used from DayTrader's wsappclient module.Building J2EE Applications 4. 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. As the name suggests.
Better Builds With Maven 104 .. This is because after the sources are generated.codehaus. Similarly.codehaus.xml.xml file must declare and configure the Axis Tools plugin: <project> [. 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.] In order to generate the Java source files from the TradeServices.wsdl file.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. it would fail. and more importantly. At this point f you were to execute the build...] <build> <plugins> [. you will require a dependency on Axis and Axis JAXRPC in your pom. any tools that report on the POM will be able to recognize the dependency. it allows users of your project to automatically get the dependency transitively. For example: [.. While you might expect the Axis Tools plugin to define this for you.Building J2EE Applications The location of WSDL source can be customized using the sourceDirectory property.] <plugin> <groupId>org. the wsappclient/pom...mojo</groupId> <artifactId>axistools-maven-plugin</artifactId> <configuration> <sourceDirectory> src/main/resources/META-INF/wsdl </sourceDirectory> </configuration> [..] <plugin> <groupId>org..
they are not present on ibiblio and you'll need to install them manually.Building J2EE Applications As before. Run mvn install and Maven will fail and print the installation instructions. Thus add the following two dependencies to your POM: <dependencies> <dependency> <groupId>axis</groupId> <artifactId>axis</artifactId> <version>1.geronimo.0</version> <scope>provided</scope> </dependency> </dependencies> The Axis JAR depends on the Mail and Activation Sun JARs which cannot be redistributed by Maven. Better Builds With Maven 105 .specs</groupId> <artifactId>geronimo-j2ee_1.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>axis</groupId> <artifactId>axis-jaxrpc</artifactId> <version>1. Thus.4_spec</artifactId> <version>1.apache.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>org. you need to add the J2EE specifications JAR to compile the project's Java sources.
] Note that the daytrader-wsappclient JAR now includes the class files compiled from the generated source files.0.org/axistoolsmaven-plugin/..wsdl [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources.codehaus.0. The Axis Tools reference documentation can be found at http://mojo.0.. [INFO] [jar:jar] [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1.0\daytrader-wsappclient-1. The Axis Tools plugin boasts several other goals including java2wsdl that is useful for generating the server-side WSDL file from handcrafted Java classes. The generated WSDL file could then be injected into the Web Services client module to generate client-side Java files.jar [..jar [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1. Better Builds With Maven 106 ..] [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. But that's another story..Building J2EE Applications Running the build with mvn install leads to: C:\dev\m2book\code\j2ee\daytrader\wsappclient>mvn install [. [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. in addition to the sources from the standard source directory.m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-wsappclient\1..jar to C:\[.]\. [INFO] [compiler:testCompile] [INFO] No sources to compile [INFO] [surefire:test] [INFO] No tests to run...
Start by defining that this is an EAR project by using the packaging element: <project> <modelVersion>4. 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.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.apache. The ear module's directory structure can't be any simpler.0. Building an EAR Project You have now built all the individual modules. Figure 4-11: Directory structure of the ear module As usual the magic happens in the pom.11.geronimo.samples.0</modelVersion> <parent> <groupId>org.xml file.Building J2EE Applications 4. It's time to package the server module artifacts (EJB and WAR) into an EAR for convenient deployment.0</version> </parent> <artifactId>daytrader-ear</artifactId> <name>DayTrader :: Enterprise Application</name> <packaging>ear</packaging> <description>DayTrader EAR</description> Next.xml file (see Figure 4-11)...
the description to use. jar.apache. ejb3. At the time of writing.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1. the EAR plugin supports the following module types: ejb.daytrader</groupId> <artifactId>daytrader-web</artifactId> <version>1.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <version>1. war.samples.0</version> <type>war</type> </dependency> <dependency> <groupId>org. and EJB modules.0</version> </dependency> </dependencies> Finally.geronimo. Better Builds With Maven 108 . ejb-client.0</version> </dependency> <dependency> <groupId>org. par.geronimo. you need to configure the Maven EAR plugin by giving it the information it needs to automatically generate the application. rar.xml deployment descriptor file.samples.apache.samples.geronimo. sar and wsr.Building J2EE Applications <dependencies> <dependency> <groupId>org.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <version>1.0</version> <type>ejb</type> </dependency> <dependency> <groupId>org.apache.samples. This includes the display name to use.geronimo. and the J2EE version to use.apache. It is also necessary to tell the EAR plugin which of the dependencies are Java modules. Web modules.
daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <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. 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.Building J2EE Applications By default. with the exception of those that are optional.geronimo. or those with a scope of test or provided. all dependencies are included. However.apache.4</version> <modules> <javaModule> <groupId>org.apache.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <webModule> <groupId>org. You should also notice that you have to specify the includeInApplicationXml element in order to include the streamer and wsappclient libraries into the EAR.plugins</groupId> <artifactId>maven-ear-plugin</artifactId> <configuration> <displayName>Trade</displayName> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <version>1.samples. only EJB client JARs are included when specified in the Java modules list.xml file.daytrader</groupId> <artifactId>daytrader-web</artifactId> <contextRoot>/daytrader</contextRoot> </webModule> </modules> </configuration> </plugin> </plugins> </build> </project> Here.maven.samples.apache.geronimo.apache. By default.geronimo. Better Builds With Maven 109 .samples.
] There are some other configuration elements available in the EAR plugin which you can find out by checking the reference documentation on http://maven.samples.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: [.] <defaultBundleDir>lib</defaultBundleDir> <modules> <javaModule> [.] </javaModule> [..apache. Run mvn install in daytrader/streamer. For example.org/plugins/maven-ear-plugin...apache.apache..Building J2EE Applications It is also possible to configure where the JARs' Java modules will be located inside the generated EAR.geronimo..geronimo. Better Builds With Maven 110 . 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. if you wanted to put the libraries inside a lib subdirectory of the EAR you would use the bundleDir element: <javaModule> <groupId>org.samples.. The streamer module's build is not described in this chapter because it's a standard build generating a JAR.
geronimo.geronimo.Building J2EE Applications To generate the EAR.samples. run mvn install: C:\dev\m2book\code\j2ee\daytrader\ear>mvn install […] [INFO] [ear:generate-application-xml] [INFO] Generating application.samples.daytrader: daytrader-ejb:1.apache.samples.xml [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources.0.ear Better Builds With Maven 111 .samples.jar] [INFO] Copying artifact [war:org.0] to [daytrader-web-1.ear to C:\[.jar] [INFO] Copying artifact [jar:org.apache.0.geronimo.0.daytrader: daytrader-web:1.geronimo.jar] [INFO] Copying artifact [ejb-client:org.0] to [daytrader-wsappclient-1.war] [INFO] Copying artifact [ejb:org.samples.apache.jar] [INFO] Could not find manifest file: C:\dev\m2book\code\j2ee\daytrader\ear\src\main\application\ META-INF\MANIFEST.]\.0.apache.0] to [daytrader-ejb-1.Generating one [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1..0.apache.0.MF .0] to[daytrader-ejb-1.0\daytrader-ear-1..0.daytrader: daytrader-ejb:1.daytrader: daytrader-wsappclient:1.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ear\1.ear [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1.0-client.geronimo.daytrader: daytrader-streamer:1. [INFO] [ear:ear] [INFO] Copying artifact [jar:org.0] to [daytrader-streamer-1.
Better Builds With Maven 112 .com/xml/ns/j2ee" xmlns:xsi="http://www.Building J2EE Applications You should review the generated application.0.sun.com/xml/ns/j2ee http://java.0" encoding="UTF-8"?> <application xmlns="http://java.w3.jar</ejb> </module> </application> This looks good.4"> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <display-name>Trade</display-name> <module> <java>daytrader-streamer-1.jar</java> </module> <module> <web> <web-uri>daytrader-web-1.0.com/xml/ns/j2ee/application_1_4.sun. The next section will demonstrate how to deploy this EAR into a container.war</web-uri> <context-root>/daytrader</context-root> </web> </module> <module> <ejb>daytrader-ejb-1.0.xsd" version="1.xml to prove that it has everything you need: <?xml version="1.0.sun.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.jar</java> </module> <module> <java>daytrader-wsappclient-1.
The DayTrader application does not deploy correctly when using the JDK 5 or newer. store the deployment plan in ear/src/main/deployment/geronimo/plan. To get started. it is recommended that you use an external plan file so that the deployment configuration is independent from the archives getting deployed. In this example.Building J2EE Applications 4. as shown on Figure 4-2.xml. Like any other container. Geronimo also supports having this deployment descriptor located within the J2EE archives you are deploying. etc. You would need the following pom. how to map J2EE resources in the container. Geronimo is somewhat special among J2EE containers in that deploying requires calling the Deployer tool with a deployment plan.4 for this section and the following. you'll deploy the DayTrader EAR into Geronimo. Deploying EARs follows the same principle.12. 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. A plan is an XML file containing configuration information such as how to map CMP entity beans to a specific database. However. Deploying a J2EE Application You have already learned how to deploy EJBs and WARs into a container individually.xml configuration snippet: Better Builds With Maven 113 . You'll need to use the JDK 1. enabling the Geronimo plan to be modified to suit the deployment environment.
apache.codehaus.xml </argument> </arguments> </configuration> </plugin> Better Builds With Maven 114 . or when Cargo doesn't support the container you want to deploy into. This plugin can execute any process. Modify the ear/pom.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <deployer> <deployables> <deployable> <properties> <plan>${basedir}/src/main/deployment/dayTrader-plan. You'll use it to run the Geronimo Deployer tool to deploy your EAR into a running Geronimo container.0/ geronimo-tomcat-j2ee-1. learning how to use the Exec plugin is useful in situations where you want to do something slightly different.0.org/dist/geronimo/1.ear </argument> <argument> ${basedir}/src/main/deployment/geronimo/plan.directory}/${project.xm</plan> </properties> </deployable> </deployables> </deployer> </configuration> </plugin> However.mojo</groupId> <artifactId>exec-maven-plugin</artifactId> <configuration> <executable>java</executable> <arguments> <argument>-jar</argument> <argument>${geronimo.home}/bin/deployer.jar</argument> <argument>--user</argument> <argument>system</argument> <argument>--password</argument> <argument>manager</argument> <argument>deploy</argument> <argument> ${project. in this section you'll learn how to use the Maven Exec plugin.build.finalName}.build. Even though it's recommended to use a specific plugin like the Cargo plugin.Building J2EE Applications <plugin> <groupId>org.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www.xml to configure the Exec plugin: <plugin> <groupId>org.codehaus.
jar [INFO] [INFO] `-> daytrader-streamer-1.home> </properties> </profile> </profiles> At execution time. 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. put the following profile in a profiles.xml First..0-tomcat</geronimo.jar –user system –password manager deploy C:\dev\m2book\code\j2ee\daytrader\ear\target/daytrader-ear-1. Better Builds With Maven 115 .0-SNAPSHOT.0.home>c:/apps/geronimo-1.Building J2EE Applications You may have noticed that you're using a geronimo. the Exec plugin will transform the executable and arguments elements above in the following command line: java -jar c:/apps/geronimo-1.home property that has not been defined anywhere. start your preinstalled version of Geronimo and run mvn exec:exec: C:\dev\m2book\code\j2ee\daytrader\ear>mvn exec:exec [. As the location where Geronimo is installed varies depending on the user.xml file: <profiles> <profile> <id>vmassol</id> <properties> <geronimo.0-SNAPSHOT.0-tomcat/bin/deployer.jar [INFO] [INFO] `-> TradeDataSource [INFO] [INFO] `-> TradeJMS You can now access the DayTrader application by opening your browser to http://localhost:8080/daytrader/.0-SNAPSHOT.0-SNAPSHOT.jar [INFO] [INFO] `-> daytrader-wsappclient-1.war [INFO] [INFO] `-> daytrader-ejb-1.xml or settings.] [INFO] [exec:exec] [INFO] Deployed Trade [INFO] [INFO] `-> daytrader-web-1..ear C:\dev\m2book\code\j2ee\daytrader\ear/src/main/deployment/geronimo/plan.
0-tomcat\bin>deploy undeploy Trade 4.13. To achieve this.Building J2EE Applications You will need to make sure that the DayTrader application is not already deployed before running the exec:exec goal or it will fail. Testing J2EE Applications In this last section you'll learn how to automate functional testing of the EAR built previously. modify the daytrader/pom. so you can define a profile to build the functional-tests module only on demand.0 comes with the DayTrader application bundled. At the time of writing. 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. create a functional-tests module as shown in Figure 4-12. Since Geronimo 1. Maven only supports integration and functional testing by creating a separate module. by creating a new execution of the Exec plugin or run the following: C:\apps\geronimo-1. Functional tests can take a long time to execute. you should first stop it.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.xml file as follows: Better Builds With Maven 116 .xml so that it's built along with the others. For example.0-tomcat\bin>deploy stop geronimo/daytrader-derby-tomcat/1.
Building J2EE Applications <modules> <module>ejb</module> <module>web</module> <module>streamer</module> <module>wsappclient</module> <module>ear</module> </modules> <profiles> <profile> <id>functional-test</id> <activation> <property> <name>enableCiProfile</name> <value>true</value> </property> </activation> <modules> <module>functional-tests</module> </modules> </profile> </profiles> For more information on the ciProfile configuration. • The Geronimo deployment Plan file is located in src/deployment/geronimo/plan. Now. • Classpath resources required for the tests are put in src/it/resources (this particular example doesn't have any resources). but running mvn install-Pfunctional-test will. see Chapter 7. take a look in the functional-tests module itself.xml. Figure 4-1 shows how it is organized: Functional tests are put in src/it/java. This means that running mvn install will not build the functional-tests module. • Better Builds With Maven 117 .
the packaging should be defined as pom. so these need to be configured in the functional-tests/pom. However.Building J2EE Applications Figure 4-14: Directory structure for the functional-tests module As this module does not generate an artifact.xml file: Better Builds With Maven 118 . the compiler and Surefire plugins are not triggered during the build life cycle of projects with a pom packaging.
.apache.0-SNAPSHOT</version> <type>ear</type> <scope>provided</scope> </dependency> [.geronimo.apache.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <executions> <execution> <phase>integration-test</phase> <goals> <goal>test</goal> </goals> </execution> </executions> </plugin> [.daytrader</groupId> <artifactId>daytrader-ear</artifactId> <version>1.0</modelVersion> <parent> <groupId>org.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <executions> <execution> <goals> <goal>testCompile</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.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.maven.samples.apache..] </dependencies> <build> <testSourceDirectory>src/it</testSourceDirectory> <plugins> <plugin> <groupId>org.maven..Building J2EE Applications <project> <modelVersion>4..daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.geronimo.apache.samples.0.] </plugins> </build> </project> Better Builds With Maven 119 .
so DBUnit is not needed to perform any database operations. and it is started automatically by Geronimo. in the case of the DayTrader application. thus ensuring the proper order of execution. As the Surefire plugin's test goal has been bound to the integration-test phase above. 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/. You're going to use the Cargo plugin to start Geronimo and deploy the EAR into it.cargo</groupId> <artifactId>cargo-ant</artifactId> <version>0.8</version> <scope>test</scope> </dependency> </dependencies> Better Builds With Maven 120 .codehaus. For integration and functional tests. This is because the EAR artifact is needed to execute the functional tests.xml file: <project> [.net/). there's a DayTrader Web page that loads test data into the database.] <dependency> <groupId>org.] <dependencies> [..codehaus. Start by adding the Cargo dependencies to the functional-tests/pom. To set up your database you can use the DBUnit Java API (see http://dbunit.. However. You may be asking how to start the container and deploy the DayTrader EAR into it.cargo</groupId> <artifactId>cargo-core-uberjar</artifactId> <version>0.8</version> <scope>test</scope> </dependency> <dependency> <groupId>org.sourceforge.. you will usually utilize a real database in a known state.. 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. Derby is the default database configured in the deployment plan.Building J2EE Applications As you can see there is also a dependency on the daytrader-ear module. In addition.
] The deployer element is used to configure the Cargo plugin's deploy goal....apache.codehaus.samples.0/ geronimo-tomcat-j2ee-1. a pingURL element is specified so that Cargo will ping the specified URL till it responds. Better Builds With Maven 121 . In addition.Building J2EE Applications Then create an execution element to bind the Cargo plugin's start and deploy goals: <build> <plugins> [. thus ensuring that the EAR is ready for servicing when the tests execute.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <wait>false</wait> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www.geronimo.0.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> <executions> <execution> <id>start-container</id> <phase>pre-integration-test</phase> <goals> <goal>start</goal> <goal>deploy</goal> </goals> <configuration> <deployer> <deployables> <deployable> <groupId>org.] <plugin> <groupId>org.daytrader</groupId> <artifactId>daytrader-ear</artifactId> <type>ear</type> <properties> <plan>${basedir}/src/deployment/geronimo/plan.apache.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.org/dist/geronimo/1.
.sourceforge.Building J2EE Applications Last.6.] <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. by wrapping it in a JUnit TestSetup class to start the container in setUp() and stop it in tearDown(). An alternative to using Cargo's Maven plugin is to use the Cargo Java API directly from your tests. Add the JUnit and HttpUnit dependencies. as you're only using them for testing: <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.1</version> <scope>test</scope> </dependency> Better Builds With Maven 122 .net/) to call a Web page from the DayTrader application and check that it's working.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: [.8. The only thing left to do is to add the tests in src/it/java. You're going to use the HttpUnit testing framework (http://httpunit. with both defined using a test scope.
import junit. type mvn install and relax: C:\dev\m2book\code\j2ee\daytrader\functional-tests>mvn install [.*. Errors: 0.FunctionalTest [surefire] Tests run: 1.meterware.14. add a JUnit test class called src/it/java/org/apache/geronimo/samples/daytrader/FunctionalTest. In the class.apache. 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. deploying J2EE archives and implementing functional tests. WebRequest request = new GetMethodWebRequest( "http://localhost:8080/daytrader").geronimo.httpunit.samples. how to effectively set up Maven in a team. } } It's time to reap the benefits from your build. In addition you've discovered how to automate starting and stopping containers. response. public class FunctionalTest extends TestCase { public void testDisplayMainPage() throws Exception { WebConversation wc = new WebConversation(). WebResponse response = wc. Failures: 0.] [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. 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.. Change directory into functional-tests. Better Builds With Maven 123 . import com.daytrader.531 sec [INFO] [cargo:stop {execution: stop-container}] 4.framework.samples. and more..*.getResponse(request). the http://localhost:8080/daytrader URL is called to verify that the returned page has a title of "DayTrader": package org.getTitle()).java. Time elapsed: 0.geronimo. assertEquals("DayTrader".daytrader.apache.Building J2EE Applications Next. how to gather project health information from your builds.
.5. source directories. Developing Custom Maven Plugins Developing Custom Maven Plugins This chapter covers: • • • • • How plugins execute in the Maven life cycle Tools and languages available to aid plugin developers Implementing a basic plugin using Java and Ant Working with dependencies. for Nature cannot be fooled. reality must take precedence over public relations. and resources from a plugin Attaching an artifact to the project For a successful technology.Richard Feynman Better Builds With Maven 124 .
Even if a project requires a special task to be performed. 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). it may be necessary to write a custom plugin to integrate these tasks into the build life cycle. With most projects. Recall that a mojo represents a single task in the build process. From there. Packaging these mojos inside a single plugin provides a consistent access mechanism for users. resolving dependencies. Each mojo can leverage the rich infrastructure provided by Maven for loading projects. A Review of Plugin Terminology Before delving into the details of how Maven plugins function and how they are written. When a number of mojos perform related tasks. Such supplemental plugins can be found at the Apache Maven project the loosely affiliated CodeHaus Mojo project.2. let's begin by reviewing the terminology used to describe a plugin and its role in the build. It starts by describing fundamentals. well-defined order. For example. the chapter will cover the tools available to simplify the life of the plugin developer. called phases. This ordering is called the build life cycle. The actual functional tasks. injecting runtime parameter information. It executes an atomic build task that represents a single step in the build process. Maven is actually a platform that executes plugins within a build life cycle. of the build process are executed by the set of plugins associated with the phases of a project's build life-cycle. they are packaged together into a plugin. but also extending a project's build to incorporate new functionality. This chapter will focus on the task of writing custom plugins. or work. and is defined as a set of task categories. the common theme for these tasks is the function of compiling code. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. the build process for a project is comprised of set of mojos executing in a particular. When Maven executes a build. A mojo is the basic unit of work in the Maven application. allowing shared configuration to be added to a single section of the POM.Developing Custom Maven Plugins 5.1. However. in order to perform the tasks necessary to build a project. refer to the Plugin Matrix. Introduction As described in Chapter 2. resolving project dependencies. This makes Maven's plugin framework extremely important as a means of not only building a project. Better Builds With Maven 125 . Finally. Maven's core APIs handle the "heavy lifting" associated with loading project definitions (POMs). 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. plugins provide a grouping mechanism for multiple mojos that serve similar functions within the build life cycle. and organizing and running plugins. it traverses the phases of the life cycle in order. and more. 5. it will discuss the various ways that a plugin can interact with the Maven build environment and explore some examples. such as integration with external tools and systems. In this case. the maven-compiler-plugin incorporates two mojos: compile and testCompile. if your project requires tasks that have no corresponding plugin. it is still likely that a plugin already exists to perform this task. This association of mojos to phases is called binding and is described in detail below. Correspondingly. Additionally. Just like Java packages. executing all the associated mojos at each phase of the build. it enables these mojos to share common code more easily.
dependency management. 5. Together. While mojos usually specify a default phase binding. and as such. they can be bound to any phase in the life cycle. Better Builds With Maven 126 . Using the life cycle. Understanding this framework will enable you to extract the Maven build-state information that each mojo requires. the discussion in this chapter is restricted to the default life cycle.1. or even create the directory structure for a new project. and parameter resolution and injection.Developing Custom Maven Plugins Together with phase binding. plus much more. Maven also provides a well-defined procedure for building a project's sources into a distributable archive. While Maven does in fact define three different lifecycles. using the plugin executions section of the project's POM. However. including a well-defined build life cycle. Bootstrapping into Plugin Development In addition to understanding Maven's plugin terminology. since they often perform tasks for the POM maintainer. These mojos are meant to be used by way of direct invocation. Since phase bindings provide a grouping mechanism for mojos within the life cycle. sequencing the various build operations. it may still require that certain activities have already been completed. Most mojos fall into a few general categories. Therefore. will not have a life-cycle phase binding at all since they don't fall into any natural category within a typical build process. you must understand the mechanics of life-cycle phase binding and parameter injection.3. in addition to determining its appropriate phase binding. 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).3. which correspond to the phases of the build life cycle. so be sure to check the documentation for a mojo before you re-bind it. to ensure compatibility with other plugins. Each execution can specify a separate phase binding for its declared set of mojos. A discussion of all three build life cycles can be found in Appendix A. 5. a mojo can pick and choose what elements of the build state it requires in order to execute its task. In some cases. The Plugin Framework Maven provides a rich framework for its plugins. it is important to provide the appropriate phase binding for your mojos. parameter injection and life-cycle binding form the cornerstone for all mojo development. As a plugin developer. Such mojos may be meant to check out a project from version control. a mojo may be designed to work outside the context of the build life cycle. Binding to a phase of the Maven life cycle allows a mojo to make assumptions based upon what has happened in the preceding phases. the ordered execution of Maven's life cycle gives coherence to the build process. Using Maven's parameter injection infrastructure. a given mojo can even be bound to the life cycle multiple times during a single build. successive phases can make assumptions about what work has taken place in the previous phases. mojos have a natural phase binding which determines when a task should execute within the life cycle. you will also need a good understanding of how plugins are structured and how they interact with their environment. Think of these mojos as tangential to the the Maven build process. Indeed. or aid integration with external development tools. As a result. before a mojo can execute.
at least two of the above mojos will be invoked. validation of project content. Depending on the needs of a given project. Instead. This level of extensibility is part of what makes Maven so powerful. and much more. consider a very basic Maven build: a project with source code that should be compiled and archived into a jar file for redistribution. none of the mojos from the maven-resources-plugin will be executed. The testCompile mojo from the maven-compiler-plugin will compile the test sources. Indeed. During this build process. Only those mojos with tasks to perform are executed during this build. Maven's plugin framework ensures that almost anything can be integrated into the build life cycle. These mojos were always present in the life-cycle definition. If this basic Maven project also includes source code for unit tests. 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. did not execute. providing functions as varied as deployment into the repository system. is often as important as the modifications made during execution itself. Maven will execute a default life cycle for the 'jar' packaging. Then. then two additional mojos will be triggered to handle unit testing. 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. determining when not to execute. but until now they had nothing to do and therefore. the jar mojo from the maven-jarplugin will harvest these class files and archive them into a jar file. 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. then the test mojo from the maven-surefire-plugin will execute those compiled tests. First. This is not a feature of the framework. Better Builds With Maven 127 .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. In good mojo design. but a requirement of a well-designed mojo. generation of the project's website. Since our hypothetical project has no "non-code" resources. the compile mojo from the maven-compiler-plugin will compile the source code into binary class files in the output directory.
the expression to retrieve that information might look as follows: ${patchDirectory} For more information about which mojo expressions are built into Maven. how do you associate mojo parameters with their expression counterparts. For example. and what methods Maven uses to extract mojo parameters from the build state. whether it is required for the mojo's execution. The Maven plugin descriptor is a file that is embedded in the plugin jar archive. That is to say. To gain access to the current build state. 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. each declared mojo parameter includes information about the various expressions used to resolve its value.xml. The plugin descriptor Though you have learned about binding mojos to life-cycle phases and resolving parameter values using associated expressions.and machine-level Maven settings. a mojo can keep its dependency list to a bare minimum. they require information about the state of the current build. the set of parameters the mojo declares. and consists of the user. the life-cycle phase to which the mojo should be bound. under the path /META-INF/maven/plugin. For the complete plugin descriptor syntax. At runtime. This mojo would retrieve the list of source directories from the current build information using the following expression: ${project. Maven allows mojos to specify parameters whose values are extracted from the build state using expressions.compileSourceRoots} Then. and the resulting value is injected into the mojo. whether it is editable. thereby avoiding traversal of the entire build-state object graph. Better Builds With Maven 128 . Using the correct parameter expressions. Within this descriptor. until now you have not seen exactly how a life-cycle binding occurs. and once resolved. how do you instruct Maven to inject those values into the mojo instance? Further. how do you instruct Maven to instantiate a given mojo in the first place? The answers to these questions lie in the plugin descriptor. see Appendix A. using a language-appropriate mechanism. Environment information – which is more static. a mojo that applies patches to the project source code will need to know where to find the project source and patch files.Developing Custom Maven Plugins Accessing build information In order for mojos to execute effectively. The descriptor is an XML file that informs Maven about the set of mojos that are contained within the plugin. see Appendix A. 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. It contains information about the mojo's implementation class (or its path within the plugin jar). and the mechanism for injecting the parameter value into the mojo instance. and more. in addition to any programmatic modifications made by previous mojo executions.
By abstracting many of these details away from the plugin developer. it uses a complex syntax. 5. • Of course. This is where Maven's plugin development tools come into play. POM configurations. this flexibility comes at a price. The clean mojo also defines the following: Better Builds With Maven 129 . it consists of a framework library which is complemented by a set of provider libraries (generally. Plugin Development Tools To simplify the creation of plugin descriptors. the format used to write a mojo's metadata is dependent upon the language in which the mojo is implemented. To accommodate the extensive variability required from the plugin descriptor.Developing Custom Maven Plugins The plugin descriptor is very powerful in its ability to capture the wiring information for a wide variety of mojos. In short.3. so it can be referenced from lifecycle mappings. one per supported mojo language). except when configuring the descriptor. The maven-plugin-plugin – which uses the plugin extractor framework. to generate the plugin descriptor). Maven provides plugin tools to parse mojo metadata from a variety of formats. 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. Maven's development tools expose only relevant specifications in a format convenient for a given plugin's implementation language. Using Java. 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. However.2. 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. and orchestrates the process of extracting metadata from mojo implementations. it's a simple case of providing special javadoc annotations to identify the properties and parameters of the mojo. Maven's plugindevelopment tools remove the burden of maintaining mojo metadata by hand. For example. and direct invocations (as from the command line). 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. This metadata is embedded directly in the mojo's source code where possible. This framework generates both plugin documentation and the coveted plugin descriptor.
However. Here. Remember. it's impossible to initialize the Java field with the value you need. For instance. this value is resolved based on the POM and injected into this field. Moreover. default-value and expression.Developing Custom Maven Plugins /** * Be verbose in the debug log-level? * * @parameter expression="${clean. which references the output directory for the current project. The first specifies that this parameter's default value should be set to true. For a complete list of javadoc annotations available for specifying mojo metadata. the underlying principles remain the same. consider the following field annotation from the resources mojo in the maven-resources-plugin: /** * Directory containing the classes. But consider what would happen if the default value you wanted to inject contained a parameter expression. However. it's implicit when using the @parameter annotation. see Appendix A. then the mechanism for specifying mojo metadata such as parameter definitions will be different.outputDirectory}" */ private File classesDirectory. namely the java. Since the plugin tools can also generate documentation about plugins based on these annotations. * * @parameter default-value="${project. these annotations are specific to mojos written in Java. When the mojo is instantiated. In this case.build.io. it's a good idea to consistently specify the parameter's default value in the metadata. 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. rather than in the Java field initialization code. Better Builds With Maven 130 . it might seem counter-intuitive to initialize the default value of a Java field using a javadoc annotation. If you choose to write mojos in another language.verbose=true At first. The second specifies that this parameter can also be configured from the command line as follows: -Dclean. especially when you could just declare the field as follows: private boolean verbose = true.File instance.verbose}" default=value="false" */ private boolean verbose. the annotation identifies this field as a mojo parameter. like Ant. this parameter annotation also specifies two attributes.
Otherwise. you risk confusing the issue at hand – namely. this chapter will also provide an example of basic plugin development using Ant. During the early phases of such a migration. This is especially important during migration. Whatever language you use. To make Ant scripts reusable.Developing Custom Maven Plugins Choose your mojo implementation language Through its flexible plugin descriptor format and invocation framework. In these cases. the particular feature of the mojo framework currently under discussion. it's important to keep the examples clean and relatively simple. and because many Maven-built projects are written in Java. A Note on the Examples in this Chapter When learning how to interact with the different aspects of Maven from within a mojo. However.3. this technique also works well for Beanshell-based mojos. it also provides good alignment of skill sets when developing mojos from scratch. Java is the language of choice. in certain cases you may find it easier to use Ant scripts to perform build tasks. when translating a project build from Ant to Maven (refer to Chapter 8 for more discussion about migrating from Ant to Maven). Such information might include details about the system environment. Maven can accommodate mojos written in virtually any language. This project can be found in the source code that accompanies this book. it is often simpler to wrap existing Ant build targets with Maven mojos and bind them to various phases in the life cycle. the examples in this chapter will focus on a relatively simple problem space: gathering and publishing information about a particular build. and Beanshell. individual mojos each mapped to separate scripts. you will need to work with an external project. this chapter will focus primarily on plugin development in this language. 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. For example. To facilitate these examples. Since it provides easy reuse of third-party APIs from within your mojo. and so on. Therefore. 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. This relieves you of the burden associated with traversing a large object graph in your code. mojo mappings and parameters definitions are declared via an associated metadata file. In addition. called mavenbuildinfo. and minimizes the number of dependencies you will have on Maven's core APIs. For many mojo developers. You can install it using the following simple command: mvn install Better Builds With Maven 131 . Ant. Since Beanshell behaves in a similar way to standard Java. due to the mitigation value of Ant-based mojos when converting a build to Maven. or any combination thereof. 5. Plugin parameters can be injected via either field reflection or setter methods. Maven currently supports mojos written in Java. Maven can wrap an Ant build target and use it as if it were a mojo. the specific snapshot versions of dependencies used in the build. Since Java is currently the easiest language for plugin development. Maven lets you select pieces of the build state to inject as mojo parameters. which is used to read and write build information metadata files.3.
• Better Builds With Maven 132 . you will need to disseminate the build to the rest of the development team. Developing Your First Mojo For the purposes of this chapter. you will look at the development effort surrounding a sample project. BuildInfo Example: Capturing Information with a Java Mojo To begin. • Remove the url element.Developing Custom Maven Plugins 5. This development effort will have the task of maintaining information about builds that are deployed to the development repository.4. This information should capture relevant details about the environment used to build the Guinea Pig artifacts. 5. In addition to simply capturing build-time information. this profile adds a new dependency on a Linux-specific library. For the purposes of this plugin. the values of system properties used in the build are clearly very important.4. which allows the build to succeed in that environment. a default profile injects a dependency on a windows-specific library. Inside.archetypes \ -DarchetypeArtifactId=maven-archetype-mojo \ -DarchetypeVersion=1. it's helpful to use the archetype plugin to create a simple stub project.1.0-alpha-4 This will create a project with the standard layout under a new subdirectory called mavenbuildinfo-plugin within the current working directory. and has no impact on transitive dependencies for users of this project. which will be deployed to the Maven repository system. Once you have the plugin's project structure in place. 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).mergere. then the value of the triggering system property – and the profile it triggers – could reasonably determine whether the build succeeds or fails. writing your custom mojo is simple. and this dependency is injected by one of the aforementioned profiles. Capturing this information is key. you will need to modify the POM as follows: Change the name element to Maven BuildInfo Plugin. Therefore. When this profile is not triggered. called Guinea Pig. 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. if the system property os. simply execute the following: mvn archetype:create -DgroupId=com.name is set to the value Linux (for more information on profiles. Using the archetype plugin to generate a stub plugin project To jump-start the process of writing a new plugin. Here. If you have a test dependency which contains a defect. this dependency is used only during testing.apache. consider a case where the POM contains a profile. For simplicity. which will be triggered by the value of a given system property – say. To generate a stub plugin project for the buildinfo plugin.maven. since this plugin doesn't currently have an associated web site. you'll find a basic POM and a sample mojo. refer to Chapter 3). When triggered.plugins \ -DartifactId=maven-buildinfo-plugin \ -DarchetypeGroupId=org. for the purposes of debugging.mvnbook. since it can have a critical effect on the build process and the composition of the resulting Guinea Pig artifacts.
MISSING_INFO_PLACEHOLDER ). Finally. fairly simple Java-based mojo: [.getProperty( key.addSystemProperty( key. i < keys. i++ ) { String key = keys[i]. public void execute() throws MojoExecutionException { BuildInfo buildInfo = new BuildInfo().length. under the following path: src/main/java/org/codehaus/mojo/MyMojo.trim(). /** * The location to write the buildinfo file. The mojo You can handle this scenario using the following. for ( int i = 0.Developing Custom Maven Plugins You will modify the POM again later." ).split( ". * @goal extract * @phase package */ public class WriteBuildInfoMojo extends AbstractMojo { /** * Determines which system properties are added to the file. this simple version will suffice for now. value ).] /** * Write environment information for the current build to file. * @parameter expression="${buildinfo.outputDirectory}/${project. * This is a comma-delimited list. } try Better Builds With Maven 133 .build. as you know more about your mojos' dependencies. * @parameter expression="${systemProperties}" */ private String systemProperties. It can be found in the plugin's project directory. String value = sysprops. since you will be creating your own mojo from scratch. if ( systemProperties != null ) { String[] keys = systemProperties. Properties sysprops = System. } buildInfo...xml" * @required */ private File outputFile.java.version}buildinfo.artifactId}-${project. However. BuildInfoConstants.outputFile}" defaultvalue="${project.getProperties(). you should remove the sample mojo.
since you have more specific requirements for this parameter. However. it's worthwhile to take a closer look at the javadoc annotations. Each offers a slightly different insight into parameter specification. consider the systemProperties parameter: /** * @parameter expression="${buildinfo.user. you may want to allow a user to specify which system properties to include in the build information file.systemProperties=java. In the class-level javadoc comment. Reason: " + e. In this case. } While the code for this mojo is fairly straightforward. In general. First.version. Using the @parameter annotation by itself. you have several field-level javadoc comments. as follows: localhost $ mvn buildinfo:java-write \ -Dbuildinfo. there are two special annotations: /** * @goal extract * @phase package */ The first annotation.getMessage(). will allow this mojo field to be configured using the plugin configuration specified in the POM. with no attributes. so they will be considered separately. it makes sense to execute this mojo in the package phase. you're collecting information from the environment with the intent of distributing it alongside the main project artifact in the repository.Developing Custom Maven Plugins { } } BuildInfoUtils. the expression attribute allows you to specify a list of system properties on-the-fly. the complexity is justified. 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. Aside from the class-level comment. outputFile ). Using the expression attribute. Therefore. When you invoke this mojo. you can specify the name of this parameter when it's referenced from the command line.writeXml( buildInfo. @goal. the outputFile parameter presents a slightly more complex example of parameter annotation. } catch ( IOException e ) { throw new MojoExecutionException( "Error writing buildinfo XML file. However. you will use this name. In this case. This is where the expression attribute comes into play. Take another look: Better Builds With Maven 134 . so it will be ready to attach to the project artifact. which are used to specify the mojo's parameters. e ).systemProperties}" */ This is one of the simplest possible parameter specifications. The second annotation tells Maven where in the build life cycle this mojo should be executed. tells the plugin tools to treat this class as a mojo named extract.dir Finally.
the mojo uses the @required annotation.0-SNAPSHOT</version> </dependency> </dependencies> </project> This POM declares the project's identity and its two dependencies. the mojo cannot function unless it knows where to write the build information file.Developing Custom Maven Plugins /** * The location to write the buildinfo file. you can see why the normal Java field initialization is not used. the build will fail with an error.artifactId}-${project. you can construct an equally simple POM which will allow you to build the plugin. which provides the parsing and formatting utilities for the build information file. as execution without an output file would be pointless.mvnbook.0-SNAPSHOT</version> <packaging>maven-plugin</packaging> <dependencies> <dependency> <groupId>org.mergere. Note the dependency on the buildinfo project. using several expressions to extract project information on-demand. To ensure that this parameter has a value.0</version> </dependency> <dependency> <groupId>com. In addition.outputDirectory}/${project.version}buildinfo.outputFile}" defaultvalue="${project.plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <version>1. Also.maven</groupId> <artifactId>maven-plugin-api</artifactId> <version>2.apache. * * @parameter expression="${buildinfo. In this example.xml" * * @required */ In this case.0</modelVersion> <groupId>com. The plugin POM Once the mojo has been written. as follows: <project> <modelVersion>4. which simply adds plugin descriptor extraction and generation to the build process. The default output path is constructed directly inside the annotation. Better Builds With Maven 135 . If this parameter has no value when the mojo is configured.mvnbook.shared</groupId> <artifactId>buildinfo</artifactId> <version>1. This mapping is a slightly modified version of the one used for the jar packaging.mergere.build. you want the mojo to use a certain value – calculated from the project's information – as a default value for this parameter. note the packaging – specified as maven-plugin – which means that this plugin build will follow the maven-plugin life-cycle mapping.0.
..name</systemProperty> </systemProperties> </configuration> <goals> <goal>extract</goal> </goals> </execution> </executions> </plugin> . Better Builds With Maven 136 .plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> <configuration> <systemProperties> <systemProperty>os. which you can do by adding the configuration of the new plugin to the Guinea Pig POM..mergere. as follows: <build> ..mvnbook. <plugins> <plugin> <groupId>com. you need to ensure that every build captures this information. </plugins> . </build> The above binding will execute the extract mojo from your new maven-buildinfo-plugin during the package phase of the life cycle.. This involves modification of the standard jar lifecycle.Developing Custom Maven Plugins Binding to the life cycle Now that you have a method of capturing build-time environmental information. so that every build triggers it.name system property. and capture the os.. The easiest way to guarantee this is to bind the extract mojo to the life cycle.
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. build the buildinfo plugin with the following commands: > C:\book-projects\maven-buildinfo-plugin > mvn clean install Next.xml In the file.. you should see output similar to the following: [.] [INFO] [INFO] [INFO] [INFO] [.name> </systemProperties> </buildinfo> Formatting aside.Developing Custom Maven Plugins The output Now that you have a mojo and a POM. you can build the plugin and try it out! First. test the plugin by building Guinea Pig with the buildinfo plugin bound to its life cycle as follows: > C:\book-projects\guinea-pig > mvn package When the Guinea Pig build executes. Better Builds With Maven 137 .. there should be a file named: guinea-pig-1.] [buildinfo:extract {execution:extract}] ------------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------------- Under the target directory.name>Linux</os.0" encoding="UTF-8"?><buildinfo> <systemProperties> <os. the output of of the generated build information is clear enough..0-SNAPSHOT-buildinfo. a property that can have profound effects on binary compatibility.
such a task could be handled using a Java-based mojo and the JavaMail API from Sun. BuildInfo Example: Notifying Other Developers with an Ant Mojo Now that some important information has been captured. In this example. The corresponding metadata file will be called notify. From here. Of course. However. The mojo metadata file Unlike the prior Java examples. and should look similar to the following: <project> <target name="notify-target"> <mail from="maven@localhost" replyto="${listAddr}" subject="Build Info for Deployment of ${project. you need to share it with others in your team when the resulting project artifact is deployed.name}" mailhost="${mailHost}" mailport="${mailPort}" messagefile="${buildinfo.mojos. given the amount of setup and code required. For now. metadata for an Ant mojo is stored in a separate file. it might be enough to send a notification e-mail to the project development mailing list. it's simpler to use Ant.Developing Custom Maven Plugins 5. therefore. which is associated to the build script using a naming convention.build. mature tasks available for build script use (including one specifically for sending e-mails).xml. Your new mojo will be in a file called notify. 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. After writing the Ant target to send the notification e-mail. simply declare mojo parameters for them.4. you'll notice that this mojo expects several project properties. It's important to remember that in the Maven world.build. so that other team members have access to it. you just need to write a mojo definition to wire the new target into Maven's build process. and how. the build script was called notify.2. it should be extracted directly from the POM for the project we're building. To ensure these project properties are in place within the Ant Project instance.xml. Information like the to: address will have to be dynamic. "deployment" is defined as injecting the project artifact into the Maven repository system.outputFile}"> <to>${listAddr}</to> </mail> </target> </project> If you're familiar with Ant. it's a simple matter of specifying where the email should be sent. and the dozens of well-tested.xml and should appear as follows: Better Builds With Maven 138 .
]]></description> <parameters> <parameter> <name>buildinfo.build. the contents of this file may appear different than the metadata used in the Java mojo.name</name> <defaultValue>${project.xml </defaultValue> <required>true</required> <readonly>false</readonly> </parameter> <parameter> <name>listAddr</name> <required>true</required> </parameter> <parameter> <name>project.directory}/${project.name}</defaultValue> <required>true</required> <readonly>true</readonly> </parameter> <parameter> <name>mailHost</name> <expression>${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.version}-buildinfo.outputFile</name> <defaultValue> ${project.Developing Custom Maven Plugins <pluginMetadata> <mojos> <mojo> <call>notify-target</call> <goal>notify</goal> <phase>deploy</phase> <description><![CDATA[ Email environment information from the current build to the development mailing list when the artifact is deployed. however.artifactId}${project. you will see many similarities. Better Builds With Maven 139 . upon closer examination.
Also. with its use of the MojoDescriptorExtractor interface from the maven-plugin-tools-api library. then its value is injected as a property. its value is injected as a project reference. a more in-depth discussion of the metadata file for Ant mojos is available in Appendix A. Modifying the plugin POM for Ant mojos Since Maven 2. This allows developers to generate descriptors for Java.0 shipped without support for Ant-based mojos (support for Ant was added later in version 2. In this example. notice that this mojo is bound to the deploy phase of the life cycle. parameter injection takes place either through direct field assignment. metadata specify a list of parameters for the mojo. but expressed in XML. in order to capture the parameter's type in the specification. and more. parameters are injected as properties and references into the Ant Project instance. expression.String. all of the mojo's parameter types are java. since you now have a good concept of the types of metadata used to describe a mojo. otherwise. by binding the mojo to the deploy phase of life cycle. you will have to add support for Ant mojo extraction to the maven-plugin-plugin. so it's pointless to spam the mailing list with notification e-mails every time a jar is created for the project. The rule for parameter injection in Ant is as follows: if the parameter's type is java.Developing Custom Maven Plugins First of all. or through JavaBeans-style setXXX() methods. you'd have to add a <type> element alongside the <name> element. because you're going to be sending e-mails to the development mailing list. the notification e-mails will be sent only when a new artifact becomes available in the remote repository. The maven-plugin-plugin is a perfect example. Finally. In Java. Any build that runs must be deployed for it to affect other development team members. In an Ant-based mojo however. Better Builds With Maven 140 .or Beanshell-based mojos with no additional configuration. Instead. When this mojo is executed. Maven allows POM-specific injection of plugin-level dependencies in order to accommodate plugins that take a framework approach to providing their functionality. default value. This is an important point in the case of this mojo.lang. each with its own information like name. 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. The expression syntax used to extract information from the build state is exactly the same. the overall structure of this file should be familiar. some special configuration is required to allow the maven-plugin-plugin to recognize Ant mojos. Fortunately.0. and parameter flags such as required are still present. the difference here is the mechanism used for this injection. Maven still must resolve and inject each of these parameters into the mojo. mojo-level metadata describes details such as phase binding and mojo name. As with the Java example.lang. to develop an Ant-based mojo. If one of the parameters were some other object type. However. The maven-plugin-plugin ships with the Java and Beanshell provider libraries which implement the above interface. As with the Java example.2).String (the default).
since the plugin now contains an Ant-based mojo. If you don't have Ant in the plugin classpath.apache.maven</groupId> <artifactId>maven-script-ant</artifactId> <version>2.maven</groupId> <artifactId>maven-plugin-tools-ant</artifactId> <version>2.0...2</version> </dependency> </dependencies> </plugin> </plugins> </build> [. 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.. 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> [. Better Builds With Maven 141 ..] <dependency> <groupId>org.. it will be quite difficult to execute an Ant-based plugin...] </dependencies> The first of these new dependencies is the mojo API wrapper for Ant build scripts. quite simply. The second new dependency is.0.] <build> <plugins> <plugin> <artifactId>maven-plugin-plugin</artifactId> <dependencies> <dependency> <groupId>org.5</version> </dependency> [.2</version> </dependency> <dependency> <groupId>ant</groupId> <artifactId>ant</artifactId> <version>1. it requires a couple of new dependencies.Developing Custom Maven Plugins To accomplish this. a dependency on the core Ant library (whose necessity should be obvious).6.] </project> Additionally..apache.
Better Builds With Maven 142 . execute the following command: > mvn deploy The build process executes the steps required to build and deploy a jar . Instead.. you should add a configuration section to the new execution section..except in this case.. Adding a life-cycle binding for the new Ant mojo in the Guinea Pig POM should appear as follows: <build> [.] <plugins> <plugin> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> [.] </plugins> </build> The existing <execution> section – the one that binds the extract mojo to the build – is not modified. Again.org</listAddr> </configuration> </execution> </executions> </plugin> [.codehaus.. Now. and send them to the Guinea Pig development mailing list in the deploy phase. which supplies the listAddr parameter value. it will also extract the relevant environmental details during the package phase.. it behaves like any other type of mojo to Maven. This is because an execution section can address only one phase of the build life cycle. and these two mojos should not execute in the same phase (as mentioned previously). notification happens in the deploy phase only.] </execution> <execution> <id>notify</id> <goals> <goal>notify</goal> </goals> <configuration> <listAddr>dev@guineapig. In order to tell the notify mojo where to send this e-mail. because non-deployed builds will have no effect on other team members.Developing Custom Maven Plugins Binding the notify mojo to the life cycle Once the plugin descriptor is generated for the Ant mojo. a new section for the notify mojo is created. Even its configuration is the same..
• Second. The next examples cover more advanced topics relating to mojo development. it must tell Maven that it requires access to that set of artifacts.5. 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. only the following two changes are required: First. the mojo must tell Maven that it requires the project's dependencies be resolved (this second requirement is critical. the compile mojo in the maven-compiler-plugin must have a set of dependency paths in order to build the compilation classpath. Maven makes it easy to inject a project's dependencies.Developing Custom Maven Plugins 5. This declaration should be familiar to you. if you want to know how to develop plugins that manage dependencies. project source code and resources. this declaration has another annotation. For example. which might not be as familiar: @readonly. Fortunately. the mojo must tell Maven that it requires the project dependency set. This annotation tells Maven not to allow the user to configure this parameter directly. and are not required for developing basic mojos.Set dependencies.artifacts}" * @required * @readonly */ private java. 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. Accessing Project Dependencies Many mojos perform tasks that require access to a project's dependencies.util.1. since it defines a parameter with a default value that is required to be present before the mojo can execute.</dependencies> </configuration> Better Builds With Maven 143 . As with all declarations. • Injecting the project dependency set As described above. if the mojo works with a project's dependencies. However. namely it disables configuration via the POM under the following section: <configuration> <dependencies>... and how to annotate the mojo with a name and a preferred phase binding. The following sections do not build on one another. To enable a mojo to work with the set of artifacts that comprise the project's dependencies. since the dependency resolution process is what populates the set of artifacts that make up the project's dependencies). Advanced Mojo Development The preceding examples showed how to declare basic mojo parameters. and artifact attachments.5. then read on! 5. However. In addition.
If a mojo doesn't need access to the dependency list. this is a direct result of the rigid dependency resolution design in Maven 1. if a mojo declares that it requires dependencies for the compile scope. If the project's dependencies aren't available.. so you configure this parameter by modifying that section directly.x term 'goal'). If this parameter could be specified separately from the main dependencies section. any dependencies specific to the test scope will remain unresolved. "How exactly can I configure this parameter?" The answer is that the mojos parameter value is derived from the dependencies section of the POM.. To gain access to the project's dependencies. such as: -Ddependencies=[. Maven 2. In this case.x. it will have to tell Maven to resolve them. the @readonly annotation functions to force users to configure the POM.] So. Maven 2 addresses this problem by deferring dependency resolution until the project's dependencies are actually required. Failure to do so will cause an empty set to be injected into the mojo's dependencies parameter. If you've used Maven 1. In other words. if your mojo needs to work with the project's dependencies. rather than configuring a specific plugin only.0 uses the term 'mojo' as roughly equivalent to the Maven 1. Maven 2 will not resolve project dependencies until a mojo requires it. the build process doesn't incur the added overhead of resolving them. It's important to note that your mojo can require any valid dependency scope to be resolved prior to its execution. your mojo must declare that it needs them. the clean process will fail – though not because the clean goal requires the project dependencies. and if so. Better Builds With Maven 144 . Even then. Maven encounters another mojo that declares a requirement for test-scoped dependencies. at which scope. Rather. it will force all of the dependencies to be resolved (test is the widest possible scope. Returning to the example. the mojo is missing one last important step. Maven will resolve only the dependencies that satisfy the requested scope. users could easily break their builds – particularly if the mojo in question compiled project source code. Maven provides a mechanism that allows a mojo to specify whether it requires the project dependencies to be resolved. direct configuration could result in a dependency being present for compilation. but being unavailable for testing.x. encapsulating all others). if later in the build process. Consider the case where a developer wants to clean the project directory using Maven 1. Requiring dependency resolution Having declared a parameter that injects the projects dependencies into the mojo. you may be wondering. 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. However.Developing Custom Maven Plugins It also disables configuration via system properties. Therefore.
one of the dependency libraries may have a newer snapshot version available. you will need to iterate through the set.isEmpty() ) { for ( Iterator it = dependencies.. In this case. rd.getArtifactId() ).setResolvedVersion( artifact. ) { Artifact artifact = (Artifact) it.] */ Now.setScope( artifact. you will want to log the versions of the dependencies used during the build.setClassifier( artifact.addResolvedDependency( rd ). Once you have access to the project dependency set. To that end. This will result in the addition of a new section in the buildinfo file.setGroupId( artifact.setType( artifact. rd.getVersion() ). } Better Builds With Maven 145 .. you'll add the dependency-set injection code discussed previously to the extract mojo in the maven-buildinfo-plugin.next().hasNext(). knowing the specific set of snapshots used to compile a project can lend insights into why other builds are breaking.Developing Custom Maven Plugins You can declare the requirement for the test-scoped project dependency set using the following classlevel annotation: /** * @requiresDependencyResolution test [. rd.setArtifactId( artifact. rd. it.getClassifier() != null ) { rd. BuildInfo example: logging dependency versions Turning once again to the maven-buildinfo-plugin.iterator(). rd.setOptional( artifact.getGroupId() ). For example. This is critical when the project depends on snapshot versions of other libraries. so it can log the exact set of dependencies that were used to produce the project artifact. along with their versions – including those dependencies that are resolved transitively. adding the information for each individual dependency to your buildinfo object. ResolvedDependency rd = new ResolvedDependency().getType() ). rd.getClassifier() ). } } buildInfo. if ( artifact.getScope() ).isOptional() ). the mojo should be ready to work with the dependency set. The code required is as follows: if ( dependencies != null && !dependencies. which enumerates all the dependencies used in the build.
For instance.0-alpha-SNAPSHOT in the POM. it's possible that a plugin may be introduced into the build process when a profile is activated. Therefore.094434-1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>compile</scope> </resolvedDependency> [. Accessing Project Sources and Resources In certain cases.guineapig</groupId> <artifactId>guinea-pig-api</artifactId> <resolvedVersion>1. Better Builds With Maven 146 .. with an additional section called resolvedDependencies that looks similar to the following: <resolvedDependencies> <resolvedDependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <resolvedVersion>3. Once this new source directory is in place..8.] </resolvedDependencies> The first dependency listed here. This won't add much insight for debuggers looking for changes from build to build. This dependency is part of the example development effort. 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.0-alpha-SNAPSHOT.2.Developing Custom Maven Plugins When you re-build the plugin and re-run the Guinea Pig build.0-20060210. the compile mojo will require access to it. and is still listed with the version 1. or new source code directories to the build.mergere. junit.. but consider the next dependency: guinea-pigapi. it may be necessary to augment a project's code base with an additional source directory. If this plugin adds resources like images.1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>test</scope> </resolvedDependency> [. has a static version of 3. when a project is built in a JDK 1. The actual snapshot version used for this artifact in a previous build could yield tremendous insight into the reasons for a current build failure.5.mvnbook. particularly if the newest snapshot version is different.] <resolvedDependency> <groupId>com. If you were using a snapshot version from the local repository which has not been deployed.8. 5. the resolvedVersion in the output above would be 1. and other mojos may need to produce reports based on those same source directories. This is because snapshot time-stamping happens on deployment only. the extract mojo should produce the same buildinfo file.1.4 environment.. it can have dramatic effects on the resulting project artifact.
This declaration identifies the project field as a required mojo parameter that will inject the current MavenProject instance into the mojo for use. or simply need to augment the basic project code base. 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. Better Builds With Maven 147 . This can be very useful when plugins generate source code. This annotation tells Maven that users cannot modify this parameter.addCompileSourceRoot( sourceDirectoryPath ).directory}/generated-sources/<plugin-prefix> While conforming with location standards like this is not required.build. Further. Maven's project API bridges this gap. it's a simple matter of adding a new source root to it. So. as in the following example: project. Chapter 3 of this book).6. Maven's concept of a project can accommodate a whole list of directories. it does improve the chances that your mojo will be compatible with other plugins bound to the same life cycle. Once the current project instance is available to the mojo. which tells Maven that it's OK to execute this mojo in the absence of a POM. this parameter also adds the @readonly annotation. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project. Maven will fail the build if it doesn't have a current project instance and it encounters a mojo that requires one. The current project instance is a great example of this. mojos require a current project instance to be available. as in the case where the mavenarchetype-plugin is used to create a stub of a new project. when generating source code. which can be injected into a mojo using the following code: /** * Project instance. 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. unless declared otherwise. allowing plugins to add new source directories as they execute. Mojos that augment the source-root list need to ensure that they execute ahead of the compile phase. instead. and no other project contains current state information for this build. the accepted default location for the generated source is in: ${project. However. It requires access to the current MavenProject instance only. any normal build will have a current project. As in the prior project dependencies discussion.Developing Custom Maven Plugins Adding a source directory to the build Although the POM supports only a single sourceDirectory entry. It is possible that some builds won't have a current project. used to add new source directory to the build. The generally-accepted binding for this type of activity is in the generate-sources life-cycle phase.
and abstract the associated complexities away from the mojo developer. the unadorned @component annotation – like the above code snippet – is adequate. in some special cases. Namely. However. However. used to make addition of resources * simpler. * @component */ private MavenProjectHelper helper. the mojo also needs access to the MavenProjectHelper component. this is what Maven calls a component requirement (it's a dependency on an internal component of the running Maven application). This declaration will inject the current project instance into the mojo. you should notice something very different about this parameter. For example. Normally. or it could be added to help identify some key attribute about the artifact to other developers. the project helper is not a build state. used to add new source directory to the build. Just as the current project instance is required in order to add a new source root. To be clear. so your mojo simply needs to ask for it. the process of adding a new resource directory to the current build is straightforward. Right away. which means it's always present. as in the case of Maven itself. the MavenProjectHelper is provided to standardize the process of augmenting the project instance. Whatever the purpose of the mojo. that it's not a parameter at all! In fact. Component requirements are not available for configuration by users. This could be some sort of descriptor for binding the project artifact into an application framework. to make it simpler to add resources to a project. This component is part of the Maven application. Better Builds With Maven 148 . However. Component requirements are simple to declare.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. The project helper component can be injected as follows: /** * project-helper instance. the Maven application itself is well-hidden from the mojo developer. as discussed previously. it does require a new type of parameter declaration: a requirement based on another component within the Maven application. the project is also required to achieve this. It provides methods for attaching artifacts and adding new resource definitions to the current project. The project parameter is declared as follows: /** * Project instance. Maven components can make it much simpler to interact with the build process. it is a utility. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project. in most cases. which will be packaged up in the same jar as the project classes.
these values would come from other mojo parameters. along with inclusion and exclusion patterns for resources within that directory. * @parameter default-value="${project. which actually compiles the source code contained in these root directories into classes in the project output directory. as in the following example: /** * List of source roots containing non-test code. The code should look similar to the following: String directory = "relative/path/to/some/directory". they have to modify the sourceDirectory element in the POM. With these two objects at your disposal. it will need to execute ahead of this phase. it's important to understand where resources should be added during the build life cycle. the entire build will fail. Accessing the source-root list Just as some mojos add new source directories to the build. Other examples include javadoc mojo in the maven-javadoc-plugin. adding a new resource couldn't be easier. Again. as it is particularly useful to mojo developers. The parameter is also required for this mojo to execute. helper. this parameter declaration states that Maven does not allow users to configure this parameter directly. excludes).compileSourceRoots}" * @required * @readonly */ private List sourceRoots. Resources are copied to the classes directory of the build during the process-resources phase. includes. however. List includes = Collections. instead. if it's missing. conforming with these standards improves the compatibility of your plugin with other plugins in the build. Similar to the parameter declarations from previous sections. If your mojo is meant to add resources to the eventual project artifact. and then call a utility method on the project helper. Again. The classic example is the compile mojo in the maven-compiler-plugin.addResource(project. the MavenProjectHelper component is worth mentioning here. In a typical case. which may or may not be directly configurable.singletonList("**/*"). and the jar mojo in the maven-source-plugin. others must read the list of active source directories. The prior example instantiates the resource's directory. for the sake of brevity. Better Builds With Maven 149 . List excludes = null. or else bind a mojo to the life-cycle phase that will add an additional source directory to the build. and exclusion patterns as local variables.Developing Custom Maven Plugins A complete discussion of Maven's architecture – and the components available – is beyond the scope of this chapter. all you have to do is declare a single parameter to inject them. Simply define the resources directory to add. Gaining access to the list of source root directories for a project is easy. in order to perform some operation on the source code. inclusion patterns. The most common place for such activities is in the generate-resources life-cycle phase. directory.
binding to any phase later than compile should be acceptable. In order to make this information more generally applicable.iterator(). applying whatever processing is necessary.addSourceRoot( makeRelative( sourceRoot ) ).hasNext(). This is the mechanism used by the resources mojo in the maven-resources-plugin. it could be critically important to track the list of source directories used in a particular build. it can iterate through them. 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. Better Builds With Maven 150 . it can be bound to any phase in the life cycle. then this profile would dramatically alter the resulting project artifact when activated. you need to add the following code: for ( Iterator it = sourceRoots. since compile is the phase where source files are converted into classes. One thing to note about this code snippet is the makeRelative() method. it's better to bind it to a later phase like package if capturing a complete picture of the project is important. it. any reference to the path of the project directory in the local file system should be removed. let's learn about how a mojo can access the list of resources used in a build. You've already learned that mojos can modify the list of resources included in the project artifact. for eventual debugging purposes. If a certain profile injects a supplemental source directory into the build (most likely by way of a special mojo binding).next(). However. Returning to the buildinfo example. } buildInfo.Developing Custom Maven Plugins Now that the mojo has access to the list of project source roots. in order to incorporate list of source directories to the buildinfo object. To be clear. the ${basedir} expression refers to the location of the project directory in the local file system. Therefore. ) { String sourceRoot = (String) it. Remember. Accessing the resource list Non-code resources complete the picture of the raw materials processed by a Maven build. When you add this code to the extract mojo in the maven-buildinfo-plugin. In this case however. now. source roots are expressed as absolute file-system paths. as in the case of the extract mojo. 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. which copies all non-code resources to the output directory for inclusion in the project artifact. This involves subtracting ${basedir} from the source-root paths. By the time the mojo gains access to them.
Developing Custom Maven Plugins
Much like the source-root list, the resources list is easy to inject as a mojo parameter. The parameter appears as follows:
/** * List of Resource objects for the current build, containing * directory, includes, and excludes. * @parameter default-value="${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
Samuel Butler Better Builds With Maven 156 .6. it is an art. 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. .
In this chapter. and what the nature of that activity is. and using a variety of tools. Maven takes all of the information you need to know about your project and brings it together under the project Web site. there will be too many failed builds. if the build fails its checks? The Web site also provides a permanent record of a project's health. In this chapter. Conversely. But. It provides additional information to help determine the reasons for a failed build. Maven has access to the information that makes up a project. unzip the Code_Ch03. new tools that can assess its health are easily integrated. This is important. Through the POM. The next three sections demonstrate how to set up an effective project Web site.finding out whether there is any activity on the project. and whether the conditions for the checks are set correctly. because if the bar is set too high. What Does Maven Have to do With Project Health? In the introduction. if the bar is set too low. there are two aspects to consider: • • Code quality . you'll learn how to use a number of these tools effectively. and learning more about the health of the project. you will be revisiting the Proficio application that was developed in Chapter 3. and display that information in a single place. to get a build to pass. 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.Assessing Project Health with Maven 6. 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!). relate. and how well it adapts to change. Because the POM is a declarative model of the project. Better Builds With Maven 157 . When referring to health. Maven can analyze.zip for convenience as a starting point. and then run mvn install from the proficio subdirectory to ensure everything is in place. why have a site. To begin.determining how well the code works. For this reason. This is unproductive as minor changes are prioritized over more important tasks. the project will meet only the lowest standard and go no further.zip file into C:\mvnbook or your selected working directory. The code that concluded Chapter 3 is also included in Code_Ch03. it was pointed out that Maven's application of patterns provides visibility and comprehensibility. how well it is tested. Project vitality . It is these characteristics that assist you in assessing the health of your project.1. which everyone can see at any time.
adding a new report is easy. review the project Web site shown in figure 6-1. These reports are useful for sharing information with others. and to reference as links in your mailing lists. To start. by including the following section in proficio/pom. For example.2. These reports provide a variety of insights into the quality and vitality of the project. SCM. The second menu (shown opened in figure 6-1). issue tracker. Adding Reports to the Project Web site This section builds on the information on project Web sites in Chapter 2 and Chapter 3. Project Reports. you can add the Surefire report to the sample application. this menu doesn't appear as there are no reports included.xml: Better Builds With Maven 158 . and so on. However. The Project Info menu lists the standard reports Maven includes with your site by default. On a new project. and now shows how to integrate project health information.Assessing Project Health with Maven 6. For newcomers to the project. Figure 6-1: The reports generated by Maven You can see that the navigation on the left contains a number of reports. is the focus of the rest of this chapter. unless you choose to disable them. having these standard reports means that those familiar with Maven Web sites will always know where to find the information they need.
.apache.maven. and is shown in figure 62. Figure 6-2: The Surefire report Better Builds With Maven 159 .html. C:\mvnbook\proficio\proficio-core> mvn site This can now be found in the file target/site/surefire-report. </project> This adds the report to the top level project. it will be inherited by all of the child modules... You can now run the following site task in the proficio-core directory to regenerate the site. and as a result. <reporting> <plugins> < plugin> <groupId>org.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> </plugin> </plugins> </reporting> .Assessing Project Health with Maven ..
plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <showSuccess>false</showSuccess> </configuration> </plugin> </plugins> </reporting> . Configuration of Reports Before stepping any further into using the project Web site. the report can be modified to only show test failures by adding the following configuration in pom. the defaults are sufficient to get started with a useful report.maven. The addition of the plugin element triggers the inclusion of the report in the Web site.. <build> <plugins> <plugin> <groupId>org..3. and due to using convention over configuration. it is important to understand how the report configuration is handled in Maven.Assessing Project Health with Maven As you may have noticed in the summary... for example: . the report shows the test results of the project. while the configuration can be used to modify its appearance or behavior. <reporting> <plugins> <plugin> <groupId>org.5</target> </configuration> </plugin> </plugins> </build> ... Better Builds With Maven 160 . For example. as seen in the previous section.apache.apache. For a quicker turn around. however it is added to the reporting section of the POM..5</source> <target>1.xml.. the report can also be run individually using the following standalone goal: C:\mvnbook\proficio\proficio-core> mvn surefire-report:report That's all there is to generating the report! This is possible thanks to key concepts of Maven discussed in Chapter 2: through a declarative project model. You might recall from Chapter 2 that a plugin is configured using the configuration element inside the plugin declaration in pom. Maven knows where the tests and test results are. 6.xml: .maven. Configuration for a reporting plugin is very similar.
and not site generation. The configuration value is specific to the build stage Better Builds With Maven 161 . even though it is not specific to the execution. the plugin would need to be configured in the build section instead of. always place the configuration in the reporting section – unless one of the following is true: 1. When you configure a reporting plugin.. "Executions" such as this were introduced in Chapter 3. <build> <plugins> <plugin> <groupId>org. they will all be included.build.. is used only during the build.Assessing Project Health with Maven If a plugin contains multiple reports. or in addition to. The reports will not be included in the site 2.maven. this isn't the case – adding the configuration to the reporting section is sufficient.directory}/surefire-reports </outputDirectory> </configuration> <executions> <execution> <phase>test</phase> <goals> <goal>report</goal> </goals> </execution> </executions> </plugin> </plugins> </build> . Any plugin configuration declared in the reporting section is also applied to those declared in the build section.. the reporting section: . 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. Fortunately. Plugins and their associated configuration that are declared in the build section are not used during site generation. you might think that you'd need to configure the parameter in both sections. The plugin is included in the build section to ensure that the configuration. and the build. some reports apply to both the site. However. To continue with the Surefire report.apache.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <outputDirectory> ${project. consider if you wanted to create a copy of the HTML report in the directory target/surefirereports every time the build ran. However. To do this..
xml: . Running mvn site with this addition will generate two Surefire reports: target/site/surefire-reportunit.directory}/surefire-reports/perf </reportsDirectory> <outputName>surefire-report-perf</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> </reportSets> </plugin> </plugins> </reporting> . Better Builds With Maven 162 .html. However. by default all reports available in the plugin are executed once. and that you had had generated its XML results to target/surefire-reports/unit and target/surefire-reports/perf respectively. Both of these cases can be achieved with the reportSets element. Each report set can contain configuration.build. once for unit tests and once for a set of performance tests.. To generate two HTML reports for these results. consider if you had run Surefire twice in your build.Assessing Project Health with Maven When you are configuring the plugins to be used in the reporting section. each time with a different configuration.. For example.html and target/site/surefire-report-perf.. you would include the following section in your pom. and a list of reports to include. there are cases where only some of the reports that the plugin produces will be required..apache. and cases where a particular report will be run more than once.directory}/surefire-reports/unit </reportsDirectory> <outputName>surefire-report-unit</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> <reportSet> <id>perf</id> <configuration> <reportsDirectory> ${project.maven. <reporting> <plugins> <plugin> <groupId>org.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <reportSets> <reportSet> <id>unit</id> <configuration> <reportsDirectory> ${project. which is the reporting equivalent of the executions element in the build section.build.
The reports element in the report set is a required element. • The open source reusable library. where the end user documentation is on a completely different server than the developer information. who isn't interested in the state of the source code.. this customization will allow you to configure reports in a way that is just as flexible as your build. where the developer information is available. there's something subtly wrong with the project Web site. add the following to the reporting section of the pom. as with executions. <plugin> <groupId>org. Consider the following: The commercial product.xml file: .4.. 6. It is also possible to include only a subset of the reports in a plugin. which are targeted at the developers. If you want all of the reports in a plugin to be generated. The reports in this list are identified by the goal names that would be used if they were run from the command line.. Separating Developer Reports From User Documentation After adding a report. This may be confusing for the first time visitor. When a report is executed individually.Assessing Project Health with Maven However.maven. Maven will use only the configuration that is specified in the plugin element itself. This approach to balancing these competing requirements will be vary. • Better Builds With Maven 163 . they must be enumerated in this list. While the defaults are usually sufficient. which are targeted at an end user.plugins</groupId> <artifactId>maven-project-info-reports-plugin</artifactId> <reportSets> <reportSet> <reports> <report>mailing-list</report> <report>license</report> </reports> </reportSet> </reportSets> </plugin> .. and most likely doesn't use Maven to generate it. On the entrance page there are usage instructions for Proficio. but in the navigation there are reports about the health of the project. For example. depending on the project. but quite separate to the end user documentation. running mvn surefire-report:report will not use either of these configurations. where much of the source code and Javadoc reference is of interest to the end user.apache. • The open source graphical application. 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. to generate only the mailing list and license pages of the standard reports. outside of any report sets.
but usually not distributed or displayed in an application. This is reference material (for example. This is true of the news and FAQs. and sometimes they are available for download separately. regardless of releases. For a single module library. the Javadoc and other reference material are usually distributed for reference as well. Some standard reports. and not introducing incorrect documentation. It is important not to include documentation for features that don't exist in the last release. It refers to a particular version of the software. and to maintain only one set of documentation. While there are some exceptions. 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. Javadoc) that in a library or framework is useful to the end user. It is good to update the documentation on the Web site between releases. 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 Updated column indicates whether the content is regularly updated. Table 6-1 lists the content that a project Web site may contain. including the end user documentation in the normal build is reasonable as it is closely tied to the source code reference. The Distributed column in the table indicates whether that form of documentation is typically distributed with the project. like mailing list information and the location of the issue tracker and SCM are updated also. and the content's characteristics. that can be updated between releases without risk of including new features. The situation is different for end user documentation. This is typically true for the end user documentation. which are continuously published and not generally of interest for a particular release. You can maintain a stable branch. each section of the site needs to be considered. The Separated column indicates whether the documentation can be a separate module or project. For libraries and frameworks.Assessing Project Health with Maven To determine the correct balance. which are based on time and the current state of the project. Sometimes these are included in the main bundle. Yes Yes No Yes Yes No No Yes No Yes No No In the table. Features that are available only in more recent releases should be marked to say when they were introduced. source code references should be given a version and remain unchanged after being released. It is also true of the project quality and vitality reports. Better Builds With Maven 164 . Table 6-1: Project Web site content types Content Description Updated Distributed Separated News. in some cases down to individual reports. and a development branch where new features can be documented for when that version is released. These are the reports discussed in this chapter that display the current state of the project to the developers. is to branch the end user documentation in the same way as source code. the source code reference material and reports are usually generated from the modules that hold the source code and perform the build. However. This is documentation for the end user including usage instructions and guides.
This is done using the site archetype : C:\mvnbook\proficio> mvn archetype:create -DartifactId=user-guide \ -DgroupId=com. In this case. the documentation and Web site should be kept in a separate module dedicated to generating a site. In Proficio. which you can later add content to. you will learn how to separate the content and add an independent project for the news and information Web site. You would make it a module when you wanted to distribute it with the rest of the project. This separated documentation may be a module of the main project.mvnbook. Figure 6-3: The initial setup The first step is to create a module called user-guide for the end user documentation.mergere. Better Builds With Maven 165 . or maybe totally independent. It is important to note that none of these are restrictions placed on a project by Maven. This avoids including inappropriate report information and navigation elements. The resulting structure is shown in figure 6-4. in most cases.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple This archetype creates a very basic site in the user-guide subdirectory. While these recommendations can help properly link or separate content according to how it will be used.Assessing Project Health with Maven However. a module is created since it is not related to the source code reference material. but make it an independent project when it forms the overall site with news and FAQs. you are free to place content wherever it best suits your project. In the following example. The current structure of the project is shown in figure 6-3. and is not distributed with the project. the site currently contains end user documentation and a simple report.
com/www/library/mvnbook/proficio/reference/${project. and the user guide to http://library. Adding the version to the development documentation. 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. whether to maintain history or to maintain a release and a development preview.version} </url> </site> </distributionManagement> . First. edit the top level pom.xml file to change the site deployment url: . <distributionManagement> <site> . Previously.. Under the current structure.... <url> scp://mergere. while optional.mergere. the development documentation would go to that location.. the URL and deployment location were set to the root of the Web site: http://library.com/mvnbook/proficio/user-guide.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.com/mvnbook/proficio. is useful if you are maintaining multiple public versions..mergere. In this example. Better Builds With Maven 166 .
site</id> <url> scp://mergere.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple The resulting structure is shown in figure 6-5. edit the user-guide/pom. you can create a new site using the archetype. This will include news and FAQs about the project that change regularly. As before. 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.mergere.mergere.com/mvnbook/proficio/user-guide/ • http://library.. a top level site for the project is required. This time.com/www/library/mvnbook/proficio/user-guide </url> </site> </distributionManagement> . Now that the content has moved.com/mvnbook/proficio/reference/1...mergere.com/www/library/mvnbook/proficio/user-guide and it is included here only for illustrative purposes. C:\mvnbook> mvn archetype:create -DartifactId=proficio-site \ -DgroupId=com.xml as follows: Better Builds With Maven 167 .0-SNAPSHOT/ • You will not be able to deploy the Web site to the location scp://mergere. <distributionManagement> <site> <id>mvnbook. in the ch06-1 directory.mvnbook.xml file to set the site deployment url for the module: . There are now two sub-sites ready to be deployed: http://library. run it one directory above the proficio directory.Assessing Project Health with Maven Next..
add some menus to src/site/site. You can now run mvn site in proficio-site to see how the separate site will look.....6 of this chapter. * News * <16 Jan 2006> . Generating reference documentation is covered in section 6. so that link won't work even if the site is deployed...] Next..com/mvnbook/proficio</url> [.xml that point to the other documentation as follows: . Note that you haven't produced the apidocs directory yet. Better Builds With Maven 168 .] <distributionManagement> <site> <id>mvnbook.apt file with a more interesting news page.website</id> <url>scp://mergere..Assessing Project Health with Maven [.] <url>http://library.. like the following: ----Proficio ----Joe Blogs ----2 February 2006 ----Proficio Proficio is super. replace the src/site/apt/index.0-SNAPSHOT/apidocs/" /> <item name="Developer Info" href="/reference/1.com/www/library/mvnbook/proficio</url> </site> </distributionManagement> [. If you deploy both sites to a server using mvn site-deploy as you learned in Chapter 3.Proficio project started Finally. you will then be able to navigate through the links and see how they relate..0-SNAPSHOT/" /> </menu> . <menu name="Documentation"> <item name="User's Guide" href="/user-guide/" /> </menu> <menu name="Reference"> <item name="API" href="/reference/1. The rest of this chapter will focus on using the developer section of the site effectively and how to build in related conditions to regularly monitor and improve the quality of your project.mergere.
it is possible in the future that reports for other languages will be available. Table 6-2 covers the reports discussed in this chapter and reasons to use them. JXR Yes N/A Checkstyle Checks your source code against a standard descriptor for formatting issues.5. See Chapter 7. for more information. 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. is an important decision that will determine the effectiveness of your build reports. the performance of your build will be affected by this choice. For each report. You may notice that many of these tools are Java-centric. and an applicable build check (for testing a certain condition and failing the build if it doesn't pass). such as Checkstyle Doesn't handle JDK 5. in addition to the generic reports such as those for dependencies and change tracking. and which checks to perform during the build. While these aren't all the reports available for Maven. the guidelines should help you to determine whether you need to use other reports. 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. the reports that utilize unit tests often have to re-run the tests with new parameters. Not useful if there are a lot of errors to be fixed – it will be slow and the result unhelpful.Assessing Project Health with Maven 6. it is recommended that these checks be constrained to the continuous integration and release environments if they cause lengthy builds. While future versions of Maven will aim to streamline this. Yes Yes ✔ ✔ ✗ Better Builds With Maven 169 . Recommended to enhance readability of the code. Team Collaboration with Maven. Table 6-2: Report highlights Report Description Visual Check Notes ✔ ✔ ✔ ✔ ✗ Javadoc Produces an API reference from Javadoc. While this is certainly the case at present. there is also a note about whether it has an associated visual report (for project site inclusion). Report results and checks performed should be accurate and conclusive – every developer should know what they mean and how to address them. In particular. Produces a source cross reference for any Java code.0 features Use to enforce a standard code style. or you can walk through all of the examples one by one. In some instances. and look at the output to determine which reports to use. Choosing Which Reports to Include Choosing which reports to include.
Some overlap with Checkstyle rules Can be used to identify lazy copy/pasted code that might be refactored into a shared method. Simple report on outstanding tasks or other markers in source code Analyze code statement coverage during unit tests or other code execution. Yes Yes Should be used to improve readability and identify simple and common bugs. CPD Yes No ✔ ✔ Tag List Yes No ✔ ✔ ✔ ✔ ✔ ✗ Cobertura Yes Yes Surefire Report Yes Yes ✔ ✔ ✔ Dependency Examine the state of Convergence dependencies in a multiple module build Clirr Compare two versions of a JAR for binary compatibility Yes No ✔ ✔ Yes Yes ✔ ✔ Changes Produce release notes and road maps from issue tracking systems Yes N/A ✔ ✔ Better Builds With Maven 170 . Doesn't identify all missing or inadequate tests. Recommended for teams with a focus on tests Can help identify untested or even unused code. Can help find snapshots prior to release. 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. Should be used for keeping teams up to date on internal projects also. convenient set up Can be implemented using Checkstyle rules instead. Recommended for easier browsing of results. Recommended for all publicly released projects. Recommended for multiple module builds where consistent versions are important. Can also show any tests that are long running and slowing the build. Avoids issues when one piece of code is fixed/updated and the other forgotten Useful for tracking TODO items Very simple. Part of PMD. Show the results of unit tests visually. so additional tools may be required. checks for duplicate source code blocks that indicates it was copy/pasted.Assessing Project Health with Maven Report Description Visual Check Notes ✔ ✔ PMD Checks your source code against known rules for code smells. Check already performed by surefire:test.
Assessing Project Health with Maven 6.html created. Figure 6-6: An example source code cross reference Figure 6-6 shows an example of the cross reference. This page links to the two sets of cross references: one for the main source tree. and one for the unit tests. and. because it is often of interest to the end user of a library or framework. as well as to the developer of the project itself. The hyper links in the content pane can be used to navigate to other classes and interfaces within the cross reference.6. however the content pane is now replaced with a syntax-highlighted. crossreferenced Java source file for the selected class. Creating Reference Material Source code reference materials are usually the first reports configured for a new project. Better Builds With Maven 171 . Javadoc – the Java documentation tool You can get started with JXR on the example project very quickly. by running the following command: C:\mvnbook\proficio\proficio-core> mvn jxr:jxr You should now see a target/site/jxr. The two reports this section illustrates are: • • JXR – the Java source cross reference. Those familiar with Javadoc will recognize the framed navigation layout.
. browsing source code is too cumbersome for the developer if they only want to know about how the API works. Better Builds With Maven 172 .maven. However. you should include it in proficio/pom. in target/site/apidocs. the links can be used to quickly find the source belonging to a particular exception. <plugin> <groupId>org. with most of the command line options of the Javadoc tool available. Using Javadoc is very similar to the JXR report and most other reports in Maven. and can be done by adding the following to proficio/pom.plugins</groupId> <artifactId>maven-jxr-plugin</artifactId> </plugin> ..xml: . the default JXR configuration is sufficient. and if possible use Checkstyle to ensure they are documented.... so an equally important piece of reference material is the Javadoc report.plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> </plugin> .apache. </plugins> </reporting> . The end result is the familiar Javadoc output. many of the other reports demonstrated in this chapter will be able to link to the actual code to highlight an issue. Or. 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... Again.apache. <reporting> <plugins> <plugin> <groupId>org. see the plugin reference at http://maven.. Unlike JXR.. Now that you have a source cross reference.xml as a site report to ensure it is run every time the site is regenerated: .maven. In most cases.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. the Javadoc report is quite configurable. A Javadoc report is only as good as your Javadoc! Make sure you document the methods you intend to display in the report. 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.apache. if you don't have the project open in your IDE. Including JXR as a permanent fixture of the site for the project is simple.org/plugins/maven-jxr-plugin/.. however if you'd like a list of available configuration options.
. However. Edit the configuration of the existing Javadoc plugin in proficio/pom.lang.apache.4. this will link to an external Javadoc reference at a given URL.sun. but this would still limit the available classes in the navigation as you hop from module to module..maven.. When built from the top level project. as well as any references to classes in Plexus. One option would be to introduce links to the other modules (automatically generated by Maven based on dependencies.html. the next section will allow you to start monitoring and improving its health.com/j2se/1. when added to proficio/pom. In the online mode.xml by adding the following line: . but it results in a separate set of API documentation for each library in a multi-module build.2/docs/api</link> <link>http://plexus. Setting up Javadoc has been very convenient. Try running mvn clean javadoc:javadoc in the proficio directory to produce the aggregated Javadoc in target/site/apidocs/index. Better Builds With Maven 173 ..org/ref/1. For example. this simple change will produce an aggregated Javadoc and ignore the Javadoc report in the individual modules... Since it is preferred to have discreet functional pieces separated into distinct modules. the Javadoc plugin provides a way to produce a single set of API documentation for the entire project.4 API documentation and the Plexus container API documentation used by Proficio: .. will link both the JDK 1. of course!).plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> <configuration> <links> <link>http://java. are linked to API documentation on the Sun website..Assessing Project Health with Maven One useful option to configure is links.Object. <plugin> <groupId>org..lang. this is not sufficient. ensuring that the deployed Javadoc corresponds directly to the artifact with which it is deployed for use in an IDE. </configuration> . Now that the sample application has a complete reference for the source code.String and java. If you regenerate the site in proficio-core with mvn site again. This setting must go into the reporting section so that it is used for both reports and if the command is executed separately. this setting is always ignored by the javadoc:jar goal. but conversely to have the Javadoc closely related. you'll see that all references to the standard JDK classes such as java.0-alpha-9/apidocs</link> </links> </configuration> </plugin> . Instead. <configuration> <aggregate>true</aggregate> .xml. the following configuration.codehaus..
such as unused methods and variables.net/) • Checkstyle (http://checkstyle. this is important for both the efficiency of other team members and also to increase the overall level of code comprehension. which is obtained by running mvn pmd:pmd. some source files are identified as having problems that could be addressed. Better Builds With Maven 174 . and this section will look at three: PMD (http://pmd. 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. Figure 6-7 shows the output of a PMD report on proficio-core. copy-and-pasted code. which in turn reduces the risk that its accuracy will be affected by change) • Maven has reports that can help with each of these health factors.net/) • Tag List • PMD takes a set of either predefined or user-defined rule sets and evaluates the rules across your Java source code. The result can help identify bugs.sf. since the JXR report was included earlier. and violations of a coding standard.7.sf. Figure 6-7: An example PMD report As you can see. the line numbers in the report are linked to the actual source code so you can browse the issues.Assessing Project Health with Maven 6. Also.
In either case..xml file: .. For example. but exclude the "unused private field" rule. methods.. you can choose to create a custom rule set. The "imports" rule set will detect duplicate. create a file in the proficio-core directory of the sample application called src/main/pmd/custom.maven. you may use the same rule sets in a number of projects. The "basic" rule set includes checks on empty blocks. by passing the rulesets configuration to the plugin. you must configure all of them – including the defaults explicitly. The "unused code" rule set will locate unused private fields..xml</ruleset> <ruleset>/rulesets/unusedcode. unnecessary statements and possible bugs – such as incorrect loop variables. <plugin> <groupId>org. to include the default rules. and imports rule sets.apache.. For example.apache. The default PMD report includes the basic. You may find that you like some rules in a rule set. change the configuration by overriding it in the proficio-core/pom. However. if you configure these. adding: Better Builds With Maven 175 . you could create a rule set with all the default rules. and the finalizer rule sets.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>/rulesets/basic.. variables and parameters. Adding new rule sets is easy. no unused private field warning </description> <rule ref="/rulesets/basic.xml</ruleset> </rulesets> </configuration> </plugin> . Or. unused code. add the following to the plugin configuration you declared earlier: . but not others. redundant or unused import declarations..xml file.xml"> <exclude name="UnusedPrivateField" /> </rule> </ruleset> To use this rule set.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. <plugin> <groupId>org.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> </plugin> .xml. To try this.xml</ruleset> <ruleset>/rulesets/imports.xml" /> <rule ref="/rulesets/unusedcode. with the following content: <?xml version="1.0"?> <ruleset name="custom"> <description> Default rules.maven..xml</ruleset> <ruleset>/rulesets/finalizers.xml" /> <rule ref="/rulesets/imports.
html.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>${basedir}/src/main/pmd/custom.net/howtomakearuleset. If you've done all the work to select the right rules and are correcting all the issues being discovered. see the instructions on the PMD Web site at http://pmd. Start small.... 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. unusedcode.maven.apache. and imports are useful in most scenarios and easily fixed.xml</ruleset> </rulesets> </configuration> </plugin> </plugins> </reporting> ..net/bestpractices.html: • • Pick the rules that are right for you. There is no point having hundreds of violations you won't fix. you need to make sure it stays that way.sf. One important question is how to select appropriate rules. From this starting. For PMD. and add more as needed. basic. select the rules that apply to your own project. [INFO] --------------------------------------------------------------------------- Better Builds With Maven 176 .Assessing Project Health with Maven . try the following guidelines from the Web site at http://pmd. Try this now by running mvn pmd:check on proficio-core. For more examples on customizing the rule sets. It is also possible to write your own rules if you find that existing ones do not cover recurring problems in your source code. <reporting> <plugins> <plugin> <groupId>org.
plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> . you should include the check in the build... try running mvn verify in the proficio-core directory. but mandatory in an integration environment.. </plugins> </build> You may have noticed that there is no configuration here.java file by adding a //NOPMD comment to the unused variables and method: . the pmd:check goal is run in the verify phase.. 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 build will succeed. To do so. adding the check to a profile..xml file: <build> <plugins> <plugin> <groupId>org.. To correct this. which is executed only in an appropriate environment. While this check is very useful.. // Trigger PMD and checkstyle int i. int j. This is done by binding the goal to the build life cycle.apache. but recall from Configuring Reports and Checks section of this chapter that the reporting configuration is applied to the build as well. add the following section to the proficio/pom. fix the errors in the src/main/java/com/mergere/mvnbook/proficio/DefaultProficio.. If you need to run checks earlier. By default.maven.Assessing Project Health with Maven Before correcting these errors. If you run mvn verify again. so that it is regularly tested. For that reason. Better Builds With Maven 177 . can make the check optional for developers. See Continuous Integration with Continuum section in the next chapter for information on using profiles and continuous integration. // NOPMD .. You will see that the build fails. // NOPMD . which occurs after the packaging phase. private void testMethod() // NOPMD { } . it can be slow and obtrusive during general development..
Simian can also be used through Checkstyle and has a larger variety of configuration options for detecting duplicate source code. Better Builds With Maven 178 . Whether to use the report only. An example report is shown in figure 6-8.This report is included by default when you enable the PMD plugin in your reporting section. such as Checkstyle. However. pmd:cpd-check can be used to enforce a failure if duplicate source code is found. and it includes a list of duplicate code fragments discovered across your entire source base. There are other alternatives for copy and paste detection. This is the CPD.redhillconsulting. or copy/paste detection report. resulting in developers attempting to avoid detection by making only slight modifications. and a commercial product called Simian (http://www. With this setting you can fine tune the size of the copies detected. there is one that is in a separate report. 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.Assessing Project Health with Maven While the PMD report allows you to run a number of different rules. rather than identifying a possible factoring of the source code. This may not give you enough control to effectively set a rule for the source code. or to enforce a check will depend on the environment in which you are working. and will appear as "CPD report" in the Project Reports menu.au/products/simian/). which defaults to 100.com.
similar to PMD. the rules used are those of the Sun Java coding conventions. Better Builds With Maven 179 . Figure 6-9 shows the Checkstyle report obtained by running mvn checkstyle:checkstyle from the proficio-core directory. with a link to the corresponding source line – if the JXR report was enabled. and rely on other tools for detecting other problems. and then the errors are shown. in many ways. Depending on your environment. Some of the extra summary information for overall number of errors and the list of checks used has been trimmed from this display. • Use it to check code formatting and to detect other problems exclusively • This section focuses on the first usage scenario. but has more recently added checks for other code issues. If you need to learn more about the available modules in Checkstyle.html.sf.net/availablechecks. warnings or errors are listed in a summary. and still rely on other tools for greater coverage. That's a lot of errors! By default. you may choose to use it in one of the following ways: Use it to check code formatting only. It was originally designed to address issues of format and style. but Proficio is using the Maven team's code style. refer to the list on the Web site at http://checkstyle. Figure 6-9: An example Checkstyle report You'll see that each file with notices.Assessing Project Health with Maven Checkstyle is a tool that is. • Use it to check code formatting and selected other problems.
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.apache.0.xml: . one or the other will be suitable for most people.xml config/avalon_checks.sun.. Before completing this section it is worth mentioning the Tag List plugin. While this chapter will not go into an example of how to do this. and to parameterize the Checkstyle configuration for creating a baseline organizational standard that can be customized by individual projects. and typically. will look through your source code for known tags and provide a report on those it finds. This report. By default. or would like to use the additional checks introduced in Checkstyle 3. Table 6-3: Built-in Checkstyle configurations Configuration config/sun_checks.apache.xml config/turbine_checks. as explained at http://maven. known as "Task List" in Maven 1.Assessing Project Health with Maven This style is also bundled with the Checkstyle plugin. filter the results.plugins</groupId> <artifactId>maven-checkstyle-plugin</artifactId> <configuration> <configLocation>config/maven_checks. The configLocation parameter can be set to a file within your build. then it is likely to be more readable and easily learned by people joining your project. Better Builds With Maven 180 .html#Maven%20Code%20Style http://jakarta.0 and above. <plugin> <groupId>org. the Checkstyle documentation provides an excellent reference at http://checkstyle.org/plugins/maven-checkstyle-plugin/tips.com/docs/codeconv/ http://maven. These checks are for backwards compatibility only..html. a URL.apache.apache.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.org/turbine/common/codestandards. you will need to create a Checkstyle configuration.html No longer online – the Avalon project has closed. so to include the report in the site and configure it to use the Maven style.html. The Checkstyle plugin itself has a large number of configuration options that allow you to customize the appearance of the report.xml config/maven_checks. The built-in Sun and Maven standards are quite different. this will identify the tags TODO and @todo in the comments of your source code. or a resource within a special dependency also.xml</configLocation> </configuration> </plugin> Table 6-3 shows the configurations that are built into the Checkstyle plugin. It is also possible to share a Checkstyle configuration among multiple projects.sf. However. if you have developed a standard that differs from these.net/config.org/guides/development/guidem2-development.maven.
2. 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.8. 6.xml: . based on the theory that you shouldn't even try to use something before it has been tested. you saw that tests are run before the packaging of the library or application for distribution. 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. Cobertura (http://cobertura. have beta versions of plugins available from the http://mojo.. This configuration will locate any instances of TODO. add the following to the reporting section of proficio/pom... <plugin> <groupId>org. 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. Another critical technique is to determine how much of your source code is covered by the test execution. In the build life cycle defined in Chapter 2. and more plugins are being added every day. or XXX in your source code.sf. Some other similar tools.mojo</groupId> <artifactId>taglist-maven-plugin</artifactId> <configuration> <tags> <tag>TODO</tag> <tag>@todo</tag> <tag>FIXME</tag> <tag>XXX</tag> </tags> </configuration> </plugin> .codehaus. 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. PMD. or as part of the site). To see what Cobertura is able to report. 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.net) is the open source tool best integrated with Maven. using this report on a regular basis can be very helpful in spotting any holes in the test plan. In addition to that. FIXME. run mvn cobertura:cobertura in the proficio-core directory of the sample application. the report (run either on its own. While you are writing your tests. will ignore these failures when generated to show the current test state. At the time of writing. It is actually possible to achieve this using Checkstyle or PMD rules.Assessing Project Health with Maven To try this plugin. Figure 6-10 shows the output that you can view in target/site/cobertura/index. Checkstyle. As you learned in section 6.html. it is easy to add a report to the Web site that shows the results of the tests that have been run. for assessing coverage.. and Tag List are just three of the many tools available for assessing the health of your project's source code.codehaus. @todo. Setting Up the Project Web Site. Better Builds With Maven 181 . Knowing whether your tests pass is an obvious and important assessment of their health.org/ project at the time of this writing. JavaNCSS and JDepend.
Lines in red are statements that were not executed (if the count is 0). This includes method and class declarations. comments and white space. a branch is an if statement that can behave differently depending on whether the condition is true or false. For example.Assessing Project Health with Maven The report contains both an overall summary. in the familiar Javadoc style framed layout. Figure 6-10: An example Cobertura report Better Builds With Maven 182 . 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. and a line-by-line coverage analysis of each source file. For a source file. you'll notice the following markings: • • • Unmarked lines are those that do not have any executable code associated with them. or for which all possible branches were not executed. Unmarked lines with a green number in the second column are those that have been completely covered by the test execution.
ser..codehaus. there is another useful setting to add to the build section.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> </plugin> . High numbers (for example. so including it in the site is simple.xml: .. <build> <plugins> <plugin> <groupId>org. might indicate a method should be re-factored into simpler pieces. While not required. The Cobertura report doesn't have any notable configuration.. If you now run mvn site under proficio-core.. Better Builds With Maven 183 .html. which measures the number of branches that occur in a particular method. If you now run mvn clean in proficio-core.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> <executions> <execution> <id>clean</id> <goals> <goal>clean</goal> </goals> </execution> </executions> </plugin> </plugins> </build> . 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.. To ensure that this happens.Assessing Project Health with Maven The complexity indicated in the top right is the cyclomatic complexity of the methods in the class.ser file is deleted.. the database used is stored in the project directory as cobertura. Add the following to the reporting section of proficio/pom. you might consider having PMD monitor it. you'll see that the cobertura.xml: . <plugin> <groupId>org.codehaus. over 10). the report will be generated in target/site/cobertura/index. add the following to the build section of proficio/pom. as well as the target directory. Due to a hard-coded path in Cobertura. If this is a metric of interest. as it can be hard to visualize and test the large number of alternate code paths... and is not cleaned with the rest of the project.
. 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.. You can do this for Proficio to have the tests pass by changing the setting in proficio/pom. the check passes. these are instrumented in a separate directory. the check will be performed. you would add unit tests for the functions that are missing tests.. Better Builds With Maven 184 .xml: .. If you now run mvn verify under proficio-core. <configuration> <check> <totalLineRate>100</totalLineRate> <totalBranchRate>100</totalBranchRate> </check> </configuration> <executions> . This is because Cobertura needs to instrument your class files. Note that the configuration element is outside of the executions. the configuration will be applied. This wouldn't be the case if it were associated with the life-cycle bound check execution. This ensures that if you run mvn cobertura:check from the command line. If you run mvn verify again. and decide to reduce the overall average required. You'll notice that your tests are run twice. add a configuration and another execution to the build plugin definition you added above when cleaning the Cobertura database: . Normally. <configuration> <check> <totalLineRate>80</totalLineRate> ..Assessing Project Health with Maven To configure this goal for Proficio. <execution> <id>check</id> <goals> <goal>check</goal> </goals> </execution> </executions> . However... so are not packaged in your application). and the tests are re-run using those class files instead of the normal ones (however.. you may decide that only some exceptional cases are untested. The rules that are being used in this configuration are 100% overall line coverage rate. so running the check fails. and 100% branch coverage rate. as in the Proficio example. looking through the report... You would have seen in the previous examples that there were some lines not covered.
Remain flexible – consider changes over time rather than hard and fast rules. If you have another tool that can operate under the Surefire framework. Set some known guidelines for what type of code can remain untested. may be of assistance there. 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. These reports won't tell you if all the features have been implemented – this requires functional or acceptance testing. For example. as it will become a minimum benchmark to attain and rarely more. Better Builds With Maven 185 . Choosing appropriate settings is the most difficult part of configuring any of the reporting metrics in Maven. and setting the total rate higher than both. although not yet integrated with Maven directly. such as handling checked exceptions that are unexpected in a properly configured system and difficult to test. or as the average across each package. and at the time of writing experimental JUnit 4.apache. Don't set it too low. there is more to assessing the health of tests than success and coverage. Remember. It also won't tell you whether the results of untested input values produce the correct results. For more information. The best known commercial offering is Clover. This will allow for some constructs to remain untested. Tools like Jester (http://jester. so that they understand and agree with the choice.sf. Surefire supports tests written with TestNG.org/cobertura-maven-plugin. It behaves very similarly to Cobertura. Don't set it too high. only allowing a small number of lines to be untested. it is possible for you to write a provider to use the new tool. see the Clover plugin reference on the Maven Web site at http://maven. and you can evaluate it for 30 days when used in conjunction with Maven. these reports work unmodified with those test types. the easiest way to increase coverage is to remove code that handles untested. Some helpful hints for determining the right code coverage settings are: • • • • • • Like all metrics. using lineRate and branchRate. exceptional cases – and that's certainly not something you want! The settings above are requirements for averages across the entire source tree. refer to the Cobertura plugin configuration reference at http://mojo.Assessing Project Health with Maven These settings remain quite demanding though. as it will discourage writing code to handle exceptional cases that aren't being tested. involve the whole development team in the decision.net).codehaus. using packageLineRate and packageBranchRate. Choose to reduce coverage requirements on particular classes or packages rather than lowering them globally.org/plugins/maven-clover-plugin/. Consider setting any package rates higher than the per-class rate. In both cases. and get integration with these other tools for free. It is just as important to allow these exceptions. To conclude this section on testing. as it is to require that the other code be tested. You may want to enforce this for each file individually as well. 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. Cobertura is not the only solution available for assessing test coverage. Of course.0 support is also available. It is also possible to set requirements on individual packages or classes using the regexes parameter. For more information. which is very well integrated with Maven as well.
but does introduce a drawback: poor dependency maintenance or poor scope and version selection affects not only your own project. The first step to effectively maintaining your dependencies is to review the standard report included with the Maven site.Assessing Project Health with Maven 6. Left unchecked. the full graph of a project's dependencies can quickly balloon in size and start to introduce conflicts.9.0 introduced transitive dependencies. Figure 6-11: An example dependency report Better Builds With Maven 186 .html. used well it is a significant time saver. This brought much more power to Maven's dependency mechanism. If you haven't done so already. and a number of other features such as scoping and version selection. While this is only one of Maven's features. Maven 2. run mvn site in the proficio-core directory. The result is shown in figure 6-11. Monitoring and Improving the Health of Your Dependencies Many people use Maven primarily as a dependency manager. where the dependencies of dependencies are included in a build. and browse to the file generated in target/site/dependencies. but any projects that depend on your project.
8. To see the report for the Proficio project. and why. Whether there are outstanding SNAPSHOT dependencies in the build. local scope test wins) proficio-api:1. This can be quite difficult to read. The report shows all of the dependencies included in all of the modules within the project. run mvn site from the base proficio directory. This will output the dependency tree as it is calculated. • Better Builds With Maven 187 . This helps ensure your build is consistent and reduces the probability of introducing an accidental incompatibility. an incorrect version.0.0-SNAPSHOT junit:3. For example. using indentation to indicate which dependencies introduce other dependencies.Assessing Project Health with Maven This report shows detailed information about your direct dependencies. This report is also a standard report. here is the resolution process of the dependencies of proficio-core (some fields have been omitted for brevity): proficio-core:1. Another report that is available is the "Dependency Convergence Report". A dependency graphing plugin that will render a graphical representation of the information. or an incorrect scope – and choose to investigate its inclusion.8.4 (selected for compile) classworlds:1.1 (not setting scope to: compile. The file target/site/dependencyconvergence. for example. such as mvn -X package. and must be updated before the project can be released.0-alpha-9 (selected for compile) plexus-utils:1. Currently. proficio-model is introduced by proficio-api. which indicates dependencies that are in development. 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.0-SNAPSHOT (selected for compile) Here you can see that.1 (selected for test) plexus-container-default:1.1-alpha-2 (selected for compile) junit:3. and that plexus-container-default attempts to introduce junit as a compile dependency. this requires running your build with debug turned on. 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.0-SNAPSHOT (selected for compile) proficio-model:1. but appears in a multi-module build only. as well as comments about what versions and scopes are selected. but more importantly in the second section it will list all of the transitive dependencies included through those dependencies. It also includes some statistics and reports on two important factors: • Whether the versions of dependencies used for each module is in alignment.html will be created. and is shown in figure 6-12.
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). 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. You can control what version is actually used by declaring the dependency version in a project that packages or runs the application. Better Builds With Maven 188 . However. To improve your project's health and the ability to reuse it as a dependency itself. they can provide basic help in identifying the state of your dependencies once you know what to find. declaring the absolute minimum supported as the lower boundary.Assessing Project Health with Maven Figure 6-12: The dependency convergence report These reports are passive – there are no associated checks for them.
Libraries will often be substituted by newer versions to obtain new features or bug fixes.10. 6. Figure 6-13: An example Clirr report This is particularly important if you are building a library or framework that will be consumed by developers outside of your own project. and the information released with it. 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. Better Builds With Maven 189 . this section will focus on improving the quality of the code released. Monitoring and Improving the Health of Your Releases Releasing a project is one of the most important procedures you will perform. and more. An important tool in determining whether a project is ready to be released is Clirr (http://clirr.sf. This is particularly the case for dependencies that are optional and unused by your project.net/). Catching these before a release can eliminate problems that are quite difficult to resolve once the code is "in the wild". but then expected to continue working as they always have. Given the importance of this task.Assessing Project Health with Maven • Add exclusions to dependencies to remove poorly defined dependencies from the tree. Two that are in progress were listed above. While the next chapter will go into more detail about how Maven can help automate that task and make it more reliable. An example Clirr report is shown in figure 6-13. specification dependencies that let you depend on an API and manage the implementation at runtime. but it is often tedious and error prone. more tools are needed in Maven. there is no verification that a library is binary-compatible – incompatibility will be discovered only when there's a failure. Clirr detects whether the current version of a library has introduced any binary incompatibilities with the previous release. Because existing libraries are not recompiled every time a version is changed.
Different modules may use different versions. or a quick patch may need to be made and a new version deployed into an existing application. back to the first release. If you run mvn site in proficio-api. As a project grows. To see this in action.9 of proficio-api against which to compare (and that it is downloaded if you don't have it already): . the interactions between the project's own components will start behaving as if they were externally-linked. You can change the version used with the comparisonVersion parameter.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <minSeverity>info</minSeverity> </configuration> </plugin> </plugins> </reporting> .. This gives you an overview of all the changes since the last release...codehaus. you can configure the plugin to show all informational messages.9 ------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------- This version is determined by looking for the newest release in repository..8 release. For example. the answer here is clearly – yes.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. the report will be generated in target/site/clirrreport. You can obtain the same result by running the report on its own using mvn clirr:clirr. While methods of marking incompatibility are planned for future versions. by setting the minSeverity parameter. where the dependency mechanism is based on the assumption of binary compatibility between versions. However. to compare the current code to the 0. <reporting> <plugins> <plugin> <groupId>org. even if they are binary compatible.8 Better Builds With Maven 190 . run the following command: mvn clirr:clirr -DcomparisonVersion=0.. If you run either of these commands..xml: . [INFO] [INFO] [INFO] [INFO] [INFO] . the Clirr report shows only errors and warnings.. By default.. you'll notice that Maven reports that it is using version 0. [clirr:clirr] Comparing to version: 0.html. add the following to the reporting section of proficio-api/pom. that is before the current development version. Maven currently works best if any version of an artifact is backwards compatible. This is particularly true in a Maven-based environment.
and to check them automatically. and later was redesigned to make sure that version 1. rather than removing or changing the original API and breaking binary compatibility. it is important to agree up front. and it can assist in making your own project more stable. It is best to make changes earlier in the development cycle. the harder they are to change as adoption increases. The longer poor choices remain. <build> <plugins> <plugin> <groupId>org.zip file. Better Builds With Maven 191 . since this early development version had a different API. delegating the code.codehaus. Like all of the quality metrics. You'll notice there are a more errors in the report. to discuss and document the practices that will be used. add the following to the build section: . This is the most important one to check. there is nothing in Java preventing them from being used elsewhere.. you are monitoring the proficio-api component for binary compatibility changes only. However. as it will be used as the interface into the implementation by other applications. so that fewer people are affected. To add the check to the proficio-api/pom. if the team is prepared to do so. If it is the only one that the development team will worry about breaking... Even if they are designed only for use inside the project. </plugins> </build> ..0 would be more stable in the long run. it is a good idea to monitor as many components as possible. In this instance. 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.xml file. The Clirr plugin is also capable of automatically checking for introduced incompatibilities through the clirr:check goal. it is almost always preferable to deprecate an old API and add a new one.Assessing Project Health with Maven These versions of proficio-api are retrieved from the repository. however you can see the original sources by extracting the Codeh_Ch06-2.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> .. on the acceptable incompatibilities.. Once a version has been released that is intended to remain binary-compatible going forward.
and then act accordingly. A limitation of this feature is that it will eliminate a class entirely. so the report still lists the incompatibility. This allows the results to be collected over time to form documentation about known incompatibilities for applications using the library. However. With this simple setup. </plugin> This will prevent failures in the Proficio class from breaking the build in the future. A similar tool to Clirr that can be used for analyzing changes between releases is JDiff. it is listed only in the build configuration. Built as a Javadoc doclet. it takes a very different approach.9 preview release and the final 1.Assessing Project Health with Maven If you now run mvn verify. and so is most useful for browsing. the following articles and books can be recommended: • • Evolving Java-based APIs contains a description of the problem of maintaining binary compatibility. which is available at http://mojo. you can create a very useful mechanism for identifying potential release disasters much earlier in the development process.codehaus..codehaus. Effective Java describes a number of practical rules that are generally helpful to writing code in Java. Hopefully a future version of Clirr will allow acceptable incompatibilities to be documented in the source code. Better Builds With Maven 192 . you can choose to exclude that from the report by adding the following configuration to the plugin: . Since this was an acceptable incompatibility due to the preview nature of the 0.9 release..mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <excludes> <exclude>**/Proficio</exclude> </excludes> </configuration> . you will see that the build fails due to the binary incompatibility introduced between the 0. Note that in this instance. and ignored in the same way that PMD does. and particularly so if you are designing a public API. taking two source trees and comparing the differences in method signatures and Javadoc annotations.0 version.org/jdiff-maven-plugin.. This can be useful in getting a greater level of detail than Clirr on specific class changes. not just the one acceptable failure. it will not pinpoint potential problems for you. It has a functional Maven 2 plugin. While the topic of designing a strong public API and maintaining binary compatibility is beyond the scope of this book. as well as strategies for evolving an API without breaking it.. <plugin> <groupId>org.
0 (for example. it should be noted that the Maven reporting API was written with these requirements in mind specifically. 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. as there is a constant background monitor that ensures the health of the project is being maintained. and have not yet been implemented for Maven 2. a large amount of information was presented about a project.11. each in discrete reports. These are all important features to have to get an overall view of the health of a project. The purpose. In the absence of these reports. enforcing good.xml).0. the model remains flexible enough to make it easy to extend and customize the information published on your project web site. and will be used as the basis for the next chapter. they did not address all of these requirements. to a focus on quality. Once established. then. and run in the appropriate environment. and as the report set stabilizes – summary reports will start to appear. Better Builds With Maven 193 . but none related information from another report to itself. it requires a shift from a focus on time and deadlines. will reduce the need to gather information from various sources about the health of the project.12. However. Finally. so that they feel that they are achievable. In some cases. How well this works in your own projects will depend on the development culture of your team. Most Maven plugins allow you to integrate rules into the build that check certain constraints on that piece information once it is well understood. the Dashboard plugin).Assessing Project Health with Maven 6. The additions and changes to Proficio made in this chapter can be found in the Code_Ch06-1. While some attempts were made to address this in Maven 1. individual checks that fail the build when they're not met. However.zip source archive. Viewing Overall Project Health In the previous sections of this chapter. of the visual display is to aid in deriving the appropriate constraints to use. and incorporates the concepts learned in this chapter. It is important that developers are involved in the decision making process regarding build constraints. 6. along with techniques to ensure that the build checks are now automated. Summary The power of Maven's declarative project model is that with a very simple setup (often only 4 lines in pom. it is important that your project information not remain passive. none of the reports presented how the information changes over time other than the release announcements. regularly scheduled. this focus and automated monitoring will have the natural effect of improving productivity and reducing time of delivery again. Some of the reports linked to one another. and few of the reports aggregated information across a multiple module build. Best of all. The next chapter examines team development and collaboration.
7.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. .
it does encompass a set of practices and tools that enable effective team communication and collaboration. further contributing to the problem. iterative cycles.Team Collaboration with Maven 7. An organizational and technology-based framework.1. repeating errors previously solved or duplicating efforts already made. every other member (and particularly new members). rapid development. and that existing team members become more productive and effective. or forgotten. This value is delivered to development teams by supporting project transparency. CoRE enables globally distributed development teams to cohesively contribute to high-quality software. CoRE emphasizes the relationship between project information and project members. and dealing with differences in opinions. misinterpreted. it's just as important that they don't waste valuable time researching and reading through too many information sources simply to find what they need. However. CoRE is based on accumulated learnings from open source projects that have achieved successful. working on complex. in rapid. one of the biggest challenges relates to the sharing and management of development information. whether it is 2 people or 200 people. faces a number of challenges to the success of the effort. However. component-based projects despite large. The Issues Facing Teams Software development as part of a team. Better Builds With Maven 195 . real-time stakeholder participation. These tools aid the team to organize. Using the model of a community. and document for reuse the artifacts that result from a software project. Many of these challenges are out of any given technology's control – for instance finding the right people for the team. although a distributed team has a higher communication overhead than a team working in a single location. Even though teams may be widely distributed. As teams continue to grow. the key to the information issue in both situations is to reduce the amount of communication necessary to obtain the required information in the first place. Even when it is not localized. 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. web-based communication channels and web-based project management tools. A Community-oriented Real-time Engineering (CoRE) process excels with this information challenge. widely-distributed teams. This problem gets exponentially larger as the size of the team increases. project information can still be misplaced. As each member retains project information that isn't shared or commonly accessible. visualize. This problem is particularly relevant to those working as part of a team that is distributed across different physical locations and timezones. resulting in shortened development cycles. The CoRE approach to development also means that new team members are able to become productive quickly. but also to incorporate feedback. will inevitably have to spend time obtaining this localized information. and asynchronous engineering. which is enabled by the accessibility of consistently structured and organized information such as centralized code repositories. 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. While it's essential that team members receive all of the project information required to be productive. While Maven is not tied directly to the CoRE framework.
Maven can gather and share the knowledge about the health of a project. varying operating systems. error-prone and full of omissions. demonstrating how Maven provides teams with real-time information on the builds and health of a project. How to Setup a Consistent Developer Environment Consistency is important when establishing a shared development environment. Without it. Common configuration settings are included in the installation directory. and the use of archetypes to ensure consistency in the creation of new projects. you learned how to create your own settings. While one of Maven's objectives is to provide suitable conventions to reduce the introduction of inconsistencies in the build environment. The settings. it's a good idea to leverage Maven's two different settings files to separately manage shared and user-specific settings. This file can be stored in the conf directory of your Maven installation. and other discrete settings such as user names and passwords. Additionally. multiple JDK versions. such as proxy settings. This chapter also looks at the adoption and use of a consistent development environment. To maintain build consistency. <maven home>/conf/settings. In a shared development environment. and to effectively define and declare them. and to user-specific profiles. it will be the source of timeconsuming development problems in the future. or in the . this is taken a step further. such as different installation locations for software.xml file.xml file contains a number of settings that are user-specific. while still allowing for this natural variability. the key is to minimize the configuration required by each individual developer. the set up process for a new developer can be slow. through the practice of continuous integration.2. In Chapter 2. 7. In Maven. but also several that are typically common across users in a shared environment. In this chapter. while an individual developer's settings are stored in their home directory.m2 subdirectory of your home directory (settings in this location take precedence over those in the Maven installation directory).xml: Better Builds With Maven 196 . because the environment will tend to evolve inconsistently once started that way. these variables relate to the user and installation settings files. there are unavoidable variables that remain. The following is an example configuration file that you might use in the installation directory.Team Collaboration with Maven As described in Chapter 6.
mycompany.mycompany.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.username}</username> <filePermissions>664</filePermissions> <directoryPermissions>775</directoryPermissions> </server> </servers> <profiles> <profile> <repositories> <repository> <id>internal</id> <name>Internal Repository</name> <url>http://repo.plugins</pluginGroup> </pluginGroups> </settings> Better Builds With Maven 197 .com/internal/</url> </pluginRepository> </pluginRepositories> </profile> </profiles> <activeProfiles> <activeProfile>property-overrides</activeProfile> <activeProfile>default-repositories</activeProfile> </activeProfiles> <pluginGroups> <pluginGroup>com.com/internal/</url> </repository> </repositories> <pluginRepositories> <pluginRepository> <id>internal</id> <name>Internal Plugin Repository</name> <url>http://repo.mycompany.
at a single physical location. you can easily add and consistently roll out any new server and repository settings. See section 7.username>myuser</website. ${user. Using the basic template. The server settings will typically be common among a set of developers. the local repository is defined as the repository of single user.Team Collaboration with Maven There are a number of reasons to include these settings in a shared configuration: • • • • • • If a proxy server is allowed. such as ${website. The user-specific configuration is also much simpler as shown below: <settings> <profiles> <profile> <id>property-overrides</id> <properties> <website. See section 7. The profile defines those common. The plugin groups are necessary only if an organization has plugins. it would usually be set consistently across the organization or department. In Maven. across users. The mirror element can be used to specify a mirror of a repository that is closer to you. These repositories are independent of the central repository in this configuration. issues with inconsistently-defined identifiers and permissions are avoided.3 for more information on setting up an internal repository.username> </properties> </profile> </profiles> </settings> To confirm that the settings are installed correctly. Another profile. it is important that you do not configure this setting in a way that shares a local repository.3 of this chapter for more information on creating a mirror of the central repository within your own organization. The previous example forms a basic template that is a good starting point for the settings file in the Maven installation. which is typically one that has been set up within your own organization or department. without having to worry about integrating local changes made by individual developers. you can view the merged result by using the following help plugin command: C:\mvnbook> mvn help:effective-settings Better Builds With Maven 198 . which are run from the command line and not defined in the POM. internal repositories that contain a given organization's or department's released artifacts. with only specific properties such as the user name defined in the user's settings.home}/maven-repo).username}. This profile will be defined in the user's settings file to set the properties used in the shared file. While you may define a standard location that differs from Maven's default (for example. The active profiles listed enable the profile defined previously in every environment. You'll notice that the local repository is omitted in the prior example. By placing the common configuration in the shared settings. property-overrides is also enabled by default.
xml file. see Chapter 2. While any of the available transport protocols can be used.Team Collaboration with Maven Separating the shared settings from the user-specific settings is helpful. Apache Tomcat. If this infrastructure is available. While it can be stored anywhere you have permissions. see Chapter 3. doing so will prevent Maven from being available off-line. Now that each individual developer on the team has a consistent set up that can be customized as needed. You can use an existing HTTP server for this. or if there are network problems. If necessary. 7. Place the Maven installation on a read-only shared or network drive from which each developer runs the application. if M2_HOME is not set. To set up Jetty. by one of the following methods: Using the M2_HOME environment variable to force the use of a particular installation. and when possible.1. download the Jetty 5. developers must use profiles in the profiles. To do this. Setting up an internal repository is simple. Change to that directory.10-bundle.xml file covers the majority of use cases for individual developer customization. Subversion.3. and run: C:\mvnbook\repository> java -jar jetty-5. For more information on profiles. To set up your organization's internal repository using Jetty. Use an existing desktop management solution. or other custom solution. each execution will immediately be up-to-date. The following are a few methods to achieve this: • • • • Rebuild the Maven release distribution to include the shared configuration file and distribute it internally. the next step is to establish a repository to and from which artifacts can be published and dependencies downloaded. For an explanation of the different types of repositories. the most popular is HTTP. located in the project directory.10 server bundle from the book's Web site and copy it to the repository directory. Each developer can check out the installation into their own machines and run it from there. • Configuring the settings. or other source control management (SCM) system.1. it is possible to maintain multiple Maven installations. Jetty. Check the Maven installation into CVS. In some circumstances however. organization's will typically want to set up what is referred to as an internal repository. Creating a Shared Repository Most organizations will need to set up one or more shared repositories. since not everyone can deploy to the central Maven repository. however it applies to all projects that are built in the developer's environment. just as any other external repository would be. in this example C:\mvnbook\repository will be used. an individual will need to customize the build of an individual project. Retrieving an update from an SCM will easily update the configuration and/or installation. create a new directory in which to store the files. easily updated.jar 8081 Better Builds With Maven 199 . or any number of other servers. but requires a manual procedure. However. This internal repository is still treated as a remote repository in Maven. or create a new server using Apache HTTPd. so that multiple developers and teams can collaborate effectively. • Adjusting the path or creating symbolic links (or shortcuts) to the desired Maven executable. but it is also important to ensure that that the shared settings are easily and reliably installed with Maven. To publish releases for use across different environments within their network. A new release will be required each time the configuration is changed.
This creates an empty repository. but rather than set up multiple web servers. Use rsync to take a copy of the central repository and regularly update it. configured securely and monitored to ensure it remains running at all times. refer to Chapter 3. and reporting. accessible location. You can create a separate repository under the same server. create a subdirectory called internal that will be available at http://localhost:8081/internal/. it provides faster performance (as most downloads to individual developers come from within their own network). In addition. by avoiding any reliance on Maven's relatively open central repository. The server is set up on your own workstation for simplicity in this example. However. scp.org/repositorymanager/. and keep a copy in your internal repository for others on your team to reuse. While this isn't required.2. sftp and more. This chapter will assume the repositories are running from http://localhost:8081/ and that artifacts are deployed to the repositories using the file system. Better Builds With Maven 200 . you can store the repositories on this single server. and gives full control over the set of artifacts with which your software is built.Team Collaboration with Maven You can now navigate to http://localhost:8081/ and find that there is a web server running displaying that directory. using the following command: C:\mvnbook\repository> mkdir central This repository will be available at http://localhost:8081/central/. it is common in many organizations as it eliminates the requirement for Internet access or proxy configuration. as well as friendly repository browsing. At the time of writing. Later in this chapter you will learn that there are good reasons to run multiple. the size of the Maven repository was 5.apache. To populate the repository you just created. However. separate repositories. ftp. This will download anything that is not already present. It is deployed to your Jetty server (or any other servlet container) and provides remote repository proxies. For more information. searching. and is all that is needed to get started. 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. you will want to set up or use an existing HTTP server that is in a shared. For the first repository.8G. it is possible to user a repository on another server with any combination of supported protocols including http. 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. The setting for using this was shown in the mirror element of the settings file in section 7. Your repository is now set up. The repository manager can be downloaded from http://maven. • The Maven Repository Manager (MRM) is a new addition to the Maven build platform that is designed to administer your internal repository.
or hierarchy. However. Repositories such as the one above are configured in the POM usually. to configure the repository from the project level instead of in each user's settings (with one exception that will be discussed next). for a situation where a developer might not have configured their settings and instead manually installed the POM. otherwise Maven will fail to download any dependencies that are not in your local repository. or to include your own artifacts in the same repository. If you have multiple repositories. 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. or have it override the central repository. On the other hand. so that a project can add repositories itself for dependencies located out of those repositories configured initially. and as a result. To override the central repository with your internal repository. Better Builds With Maven 201 . and if it's acceptable to have developers configure this in their settings as demonstrated in section 7. there are two choices: use it as a mirror. it must retrieve the parent from the repository. You would use it as a mirror if it is intended to be a copy of the central repository exclusively. unless you have mirrored the central repository using one the techniques discussed previously. 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 necessary to declare only those that contain an inherited POM. or had it in their source code check out. if you want to prevent access to the central repository for greater control. It is still important to declare the repositories that will be used in the top-most POM itself. This makes it impossible to define the repository in the parent.2.2.Team Collaboration with Maven When using this repository for your projects. this must be defined as both a regular repository and a plugin repository to ensure all access is consistent. Usually. it would need to be declared in every POM. that declares shared settings within an organization and its departments. Developers may choose to use a different mirror. Not only is this very inconvenient. The next section discusses how to set up an "organization POM". you must define a repository in a settings file and/or POM that uses the identifier central. you should override the central repository.xml file. there is a problem – when a POM inherits from another POM that is not in the central repository. as shown in section 7. or the original central repository directly without consequence to the outcome of the build.
project inheritance can be used to assist in ensuring project consistency. has a number of sub-projects (Maven. While project inheritance was limited by the extent of a developer's checkout in Maven 1. </modules> </project> If you were to review the entire POM.org/maven-scm/</url> . depending on the information that needs to be shared. its departments.0 – that is. It is important to recall. there are three levels to consider when working with any individual module that makes up the Maven project. and then the teams within those departments. Maven SCM. then that repository will need to be added to the settings. etc.apache.scm</groupId> <artifactId>maven-scm</artifactId> <url>http://maven..maven</groupId> <artifactId>maven-parent</artifactId> <version>1</version> </parent> <groupId>org.. As an example. consider the Maven project itself. This project structure can be related to a company structure. or the organization as a whole. and is a project that. that if your inherited projects reside in an internal repository. as this is consistent information.). itself.. which is shared across all Maven projects through inheritance. To continue the Maven example. You may have noticed the unusual version declaration for the parent project.0</modelVersion> <parent> <groupId>org. It is a part of the Apache Software Foundation.. so it's possible to have one or more parents that define elements common to several projects.4.apache.maven. As a result. the easiest way to version a POM is through sequential numbering.apache. <modules> <module>maven-scm-api</module> <module>maven-scm-providers</module> . Maven Continuum. you'd find that there is very little deployment or repositoryrelated information.0. Future versions of Maven plan to automate the numbering of these types of parent projects to make this easier. from section 7. These parents (levels) may be used to define departments. Creating an Organization POM As previously mentioned in this chapter. Since the version of the POM usually bears no resemblance to the software.xml file in the shared installation (or in each developer's home directory). consistency is important when setting up your build infrastructure. consider the POM for Maven SCM: <project> <modelVersion>4.Team Collaboration with Maven 7. wherein there's the organization. By declaring shared elements in a common parent POM. Better Builds With Maven 202 . Any number of levels (parents) can be used.3. the current project – Maven 2 now retrieves parent projects from the repository.
.0.maven</groupId> <artifactId>maven-parent</artifactId> <version>5</version> <url>http://maven. you'd see it looks like the following: <project> <modelVersion>4..Team Collaboration with Maven If you look at the Maven project's parent POM.0</modelVersion> <parent> <groupId>org...apache.apache..apache. <mailingLists> <mailingList> <name>Maven Announcements List</name> <post>announce@maven. </developer> </developers> </project> Better Builds With Maven 203 .org/</url> . </mailingList> </mailingLists> <developers> <developer> .apache</groupId> <artifactId>apache</artifactId> <version>1</version> </parent> <groupId>org..org</post> .
org/</url> </organization> <url>http://www.. An issue that can arise. the Maven Repository Manager will allow POM updates from a web interface). In fact.apache. These parent POM files are likely to be updated on a different. </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. and less frequent schedule than the projects themselves. and the deployment locations..Team Collaboration with Maven The Maven parent POM includes shared elements. it is best to store the parent POM files in a separate area of the source control tree.apache. <repositories> <repository> <id>apache. most of the elements are inherited from the organization-wide parent project. where they can be checked out.0.0</modelVersion> <groupId>org. </repository> <snapshotRepository> . and deployed with their new version as appropriate.apache.. is regarding the storage location of the source POM files.org/maven-snapshot-repository</url> <releases> <enabled>false</enabled> </releases> </repository> </repositories> ..apache</groupId> <artifactId>apache</artifactId> <version>1</version> <organization> <name>Apache Software Foundation</name> <url>http://www. <distributionManagement> <repository> . 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.snapshots</id> <name>Apache Snapshot Repository</name> <url>http://svn. Again. such as the announcements mailing list and the list of developers that work across the whole project...org/</url> .. when working with this type of hierarchy. in this case the Apache Software Foundation: <project> <modelVersion>4. modified. Better Builds With Maven 204 . you can retain the historical versions in the repository if it is backed up (in the future. there is no best practice requirement to even store these files in your source control management system..6). For this reason.
3> bin\win32\run There are scripts for most major platforms.0. continuous integration can enable a better development culture where team members can make smaller. rather than close to a release. Continuum is Maven's continuous integration and build server. which you can obtain for your operating system from http://subversion. some additional steps are required. if you are running Continuum on your desktop and want to try the examples in this section.3. You can verify the installation by viewing the web site at http://localhost:8080/continuum/.org/. The first screen to appear will be the one-time setup page shown in figure 7-1.3. you will need to install Continuum.Team Collaboration with Maven 7. these additional configuration requirements can be set only after the previous step has been completed. The examples discussed are based on Continuum 22.214.171.124. For most installations this is all the configuration that's required. continuous integration is a key element of effective collaboration. press Ctrl-C in the window that is running Continuum). and the company information for altering the logo in the top left of the screen. This is very simple – once you have downloaded it and unpacked it. you will pick up the Proficio example from earlier in the book. First. continuous integration enables automated builds of your project on a regular interval. and learn how to use Continuum to build this project on a regular basis. however newer versions should be similar. In this chapter. The examples also assumes you have Subversion installed. however. as well as the generic bin/plexus. and you must stop the server to make the changes (to stop the server. you can run it using the following command: C:\mvnbook\continuum-1. 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. Better Builds With Maven 205 . As such.sh for use on other Unix-based platforms. As of Continuum 1. ensuring that conflicts are detected earlier in a project's release life cycle.tigris. More than just nightly builds. iterative changes that can more easily support concurrent development processes. Continuous Integration with Continuum If you are not already familiar with it.
After these steps are completed.. refer to http://maven.validation.UrlValidator </implementation> <configuration> <allowedSchemes> . POM files will be read from the local hard disk where the server is running. edit apps/continuum/conf/application. If you do not have this set up on your machine. For instructions. since paths can be entered from the web interface. To have Continuum send you e-mail notifications.Team Collaboration with Maven Figure 7-1: The Continuum setup screen In the following examples. By default. this is disabled as a security measure. To enable this setting.. you will also need an SMTP server to which to send the messages. <allowedScheme>file</allowedScheme> </allowedSchemes> </configuration> . edit the file above to change the smtp-host setting. The default is to use localhost:25.plexus.html.apache.formica.org/continuum/guides/mini/guide-configuration.codehaus. <implementation> org. Better Builds With Maven 206 ... you can start Continuum again.xml and uncomment the following line: ...
xml to correct the e-mail address to which notifications will be sent.. 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.zip archive and unpacking it in your environment. <ciManagement> <system>continuum</system> <url>http://localhost:8080/continuum <notifiers> <notifier> <type>mail</type> <configuration> <address>firstname.lastname@example.com} </url> </site> </distributionManagement> . <scm> <connection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </connection> <developerConnection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </developerConnection> </scm> . Better Builds With Maven 207 ...com</address> </configuration> </notifier> </notifiers> </ciManagement> .... You can then check out Proficio from that location. Edit proficio/pom. <distributionManagement> <site> <id>website</id> <url> file://localhost/c:/mvnbook/repository/sites/proficio /reference/${project. and edit the location of the Subversion repository.. This requires obtaining the Code_Ch07.. The ciManagement section can be used to configure a project for easier integration with Continuum.Team Collaboration with Maven The next step is to set up the Subversion repository for the examples. by uncommenting and modifying the following lines: . since not all of the required details were known at the time of its creation.
Better Builds With Maven 208 . or a Subversion HTTP server. you will see an empty project list. from the directory C:\mvnbook\repository. When you set up your own system later. or with another account you have since created with appropriate permissions. Initially. Figure 7-2: Add project screen shot This is all that is required to add a Maven 2 project to Continuum. commit the file with the following command: C:\mvnbook\proficio> svn ci -m 'my settings' pom. enter the file:// URL as shown. under the Continuum logo. Continuum will return to the project summary page.Team Collaboration with Maven The distributionManagement setting will be used in a later example to deploy the site from your continuous integration environment. you must either log in with the administrator account you created during installation.xml You should build all these modules to ensure everything is in order. Instead.0.3 for information on how to set this up. If you return to the http://localhost:8080/continuum/ location that was set up previously. Before you can add a project to the list. The result is shown in figure 7-3.0+ Project from the Add Project menu. with the following command: C:\mvnbook\proficio> mvn install You are now ready to start using Continuum.3 this does not work when the POM contains modules. in Continuum 1. Once you have logged in. and each of the modules will be added to the list of projects. While uploading is a convenient way to configure from your existing check out. This will present the screen shown in figure 7-2. If you haven't done so already. You have two options: you can provide the URL for a POM. a ViewCVS installation. you will enter either a HTTP URL to a POM in the repository. you can now select Maven 2. the builds will be marked as New and their checkouts will be queued. or upload from your local drive. or perform other tasks. The login link is at the top-left of the screen. refer to section 7. as in the Proficio example. Once these settings have been edited to reflect your setup. After submitting the URL. This assumes that you are still running the repository Web server on localhost:8081.
go to your earlier checkout and introduce an error into Proficio.. restore the file above to its previous state and commit it again. but you may wish to go ahead and try them. MSN and Google Talk are all supported. you should receive an e-mail at the address you configured earlier. Jabber. Better Builds With Maven 209 ... remove the interface keyword: [. To avoid receiving this error every hour. press Build Now on the Continuum web interface next to the Proficio API module. for example. The Build History link can be used to identify the failed build and to obtain a full output log. and then fail. check the file in: C:\mvnbook\proficio\proficio-api> svn ci -m 'introduce error' \ src/main/java/com/mergere/mvnbook/proficio/Proficio. For example. the build will show an "In progress" status. and send an e-mail notification if there are any problems. 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). First. If you want to put this to the test.] Now.java.] public Proficio [.. you might want to set up a notification to your favorite instant messenger – IRC. In addition.java Finally. The build in Continuum will return to the successful state. This chapter will not discuss all of the features available in Continuum.Team Collaboration with Maven Figure 7-3: Summary page after projects have built Continuum will now build the project hourly.
For these reports to be of value. operating system and other variables. it is often ignored. This is another way continuous integration can help with project collaboration and communication. When a failure occurs in the continuous integration environment. While this seems obvious. Consider a regular. Though it would be overkill to regenerate the site on ever commit. if the source control repository supports post-commit hooks. and independent of the environment being used. If multiple branches are in development. clean build. it is important that it can be isolated to the change that caused it. for example. not just that the project still compiles after one or more changes occur. Fix builds as soon as possible. iterative builds are helpful in some situations. run a servlet container to which the application can be deployed from the continuous integration environment. This doesn't mean committing incomplete code. Establish a stable environment. • • • • • • • In addition to the above best practices. Run comprehensive tests. separate from QA and production releases.Team Collaboration with Maven Regardless of which continuous integration server you use. Continuum has preliminary support for system profiles and distributed testing. This also means that builds should be fast – long integration and performance tests should be reserved for periodic builds. before the developer moves on or loses focus. there are two additional topics that deserve special attention: automated updates to the developer web site. it is also important that failures don't occur due to old build state. test and production environments. This can be helpful for non-developers who need visibility into the state of the application. This will be constrained by the length of the build and the available resources on the build machine. Continuous integration is most beneficial when tests are validating that the code is working as it always has. if it isn't something already in use in other development. it is beneficial to test against all different versions of the JDK. but rather keeping changes small and well tested. periodically. commit often. you learned how to create an effective site containing project information and reports about the project's health and vitality. and your team will become desensitized to the notifications in the future. based on selected schedules. In Chapter 6. Continuous integration will be pointless if developers repetitively ignore or delete broken build notifications. Run builds as often as possible. Continuous integration is most effective when developers commit regularly. Better Builds With Maven 210 . there are a few tips for getting the most out of the system: • Commit early. it is recommend that a separate. or local settings. Build all of a project's active branches. Run clean builds. and profile usage. but it is best to detect a failure as soon as possible. the continuous integration environment should be set up for all of the active branches. they need to be kept up-todate. Run a copy of the application continuously. but regular schedule is established for site generation. Continuum currently defaults to doing a clean build. enhancements that are planned for future versions. This will make it much easier to detect the source of an error when the build does break. Avoid customizing the JDK. If the application is a web application. Continuum can be configured to trigger a build whenever a commit occurs. and a future version will allow developers to request a fresh checkout. While rapid. In addition.
and select the top-most project. Once you add this schedule.Team Collaboration with Maven Verify that you are still logged into your Continuum instance.3. from the Administration menu on the left-hand side. The downside to this approach is that Continuum will build any unchanged modules. The example above runs at 8:00:00.com/quartz/api/org/quartz/CronTrigger. since commits are not atomic and a developer might be committing midway through a update.html. so you will need to add the definition to each module individually. Maven Proficio. In Continuum 1.. In addition to building the sites for each module. The appropriate configuration is shown in figure 7-4...opensymphony. there is no way to make bulk changes to build definitions. 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. The "quiet period" is a setting that delays the build if there has been a commit in the defined number of seconds prior. This is useful when using CVS.. Better Builds With Maven 211 . as well – if this is a concern. and add the same build definition to all of the modules. it can aggregate changes into the top-level site as required. use the non-recursive mode instead. The project information shows just one build on the default schedule that installs the parent POM. which will be configured to run every hour during business hours (8am – 4pm weekdays). Click the Add button to add a new schedule. 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. but does not recurse into the modules (the -N or --non-recursive argument). return to the project list. You will see that currently. 9:00:00. It is not typically needed if using Subversion. 16:00:00 from Monday to Friday. Next.0. only the default schedule is available.
The site will be deployed to the file system location you specified in the POM. Click this for the site generation build definition. Better Builds With Maven 212 . which means that Build Now from the project summary page will not trigger this build. The arguments provided are --batch-mode. if you want to fail the build based on these checks as well. To add a new build definition. when you first set up the Subversion repository earlier in this chapter. the generated site can be used as reference for what caused the failure. The --non-recursive option is omitted. However.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. verify or integrationtest goal to the list of goals. and view the generated site from http://localhost:8081/sites/proficio/. and -DenableCiProfile=true. Any of these test goals should be listed after the site-deploy goal. You can see also that the schedule is set to use the site generation schedule created earlier. to ensure these checks are run. which sets the given system property. on the business hours schedule. The Add Build Definition screen is shown in figure 7-5. It is rare that the site build will fail. which will be visible from http://localhost:8081/sites/proficio/. click the Add button below the default build definition. However. and that it is not the default build definition. so that if the build fails because of a failed check. you can add the test. which is essential for all builds to ensure they don't block for user input. since most reports continue under failure conditions. 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. The meaning of this system property will be explained shortly. Figure 7-5: Adding a build definition for site deployment The goals to run are clean and site-deploy.
However. The first is to adjust the default build definition for each module. please refer to Chapter 3..xml file in <maven home>/conf/settings.. add the following configuration to the settings.m2/settings.maven. ... Profiles are a means for selectively enabling portions of the build.. which can be a discouragement to using them. To enable this profile by default from these settings. for all projects in Continuum. none of the checks added in the previous chapter are executed. it reads the ${user. Better Builds With Maven 213 ... as well as the settings in the Maven installation.apache. In this particular case. As Maven 2 is still executed as normal.xml file in your Subversion checkout to that used in Chapter 6. such as the percentage of code covered in the unit tests dropping below a certain value.. by going to the module information page. In Chapter 6.Team Collaboration with Maven In the previous example. <activeProfiles> . you'll see that these checks have now been moved to a profile. at least in the version of Continuum current at the time of writing. it is necessary to do this for each module individually. However. If you compare the example proficio/pom. and clicking Edit next to the default build definition. <profiles> <profile> <id>ciProfile</id> <activation> <property> <name>enableCiProfile</name> <value>true</value> </property> </activation> <plugins> <plugin> <groupId>org.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> . As you saw before. the profile is enabled only when the enableCiProfile system property is set to true. a system property called enableCiProfile was set to true.home}/. The other alternative is to set this profile globally. You'll find that when you run the build from the command line (as was done in Continuum originally).. these checks delayed the build for all developers.xml file for the user under which it is running.. if you run mvn -DenableCiProfile=true verify. they will be. There are two ways to ensure that all of the builds added in Continuum use this profile.xml: . a number of plugins were set up to fail the build if certain project health checks failed. If you haven't previously encountered profiles. <activeProfile>ciProfile</activeProfile> </activeProfiles> .
rather than the property used to enable it. these artifacts will be updated frequently. you'll see that the repository was defined in proficio/pom. The guidelines discussed in this chapter will help point your team in the right direction. indicates that the profile is always active when these settings are read. which are not changed.8 of this chapter. the verify goal may need to be added to the site deployment build definition. Additionally. Instead. in an environment where a number of modules are undergoing concurrent development. it may be necessary to schedule them separately for each module. the build involves checking out all of the dependent projects and building them yourself.Team Collaboration with Maven In this case the identifier of the profile itself. you will learn about using snapshots more effectively in a team environment. and how to enable this within your continuous integration environment. 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. In this section. While building all of the modules from source can work well and is handled by Maven inherently. but the timing and configuration can be changed depending upon your circumstances. this is achieved by regularly deploying snapshots to a shared repository. Team Dependency Management Using Snapshots Chapter 3 of this book discussed how to manage your dependencies in a multi-module build. 7. So far in this book. which can be error-prone. In Maven. and while dependency management is fundamental to any Maven build. For example. it can lead to a number of problems: • • • • It relies on manual updates from developers. Considering that example.3. The generated artifacts of the snapshot are stored in the local repository. or for the entire multi-module project to run the additional checks after the site has been generated. 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. as discussed previously. is preferred. building from source doesn't fit well with an environment that promotes continuous integration. which is discussed in section 7. and in contrast to regular dependencies. in some cases. Projects in Maven stay in the snapshot state until they are released. using binary snapshots that have been built and tested already. Usually. you must build all of the modules simultaneously from a master build. the team dynamic makes it critical. such as the internal repository set up in section 7.xml: Better Builds With Maven 214 . where projects are closely related. Snapshots were designed to be used in a team environment as a means for sharing development versions of artifacts that have already been built. if the additional checks take too much time for frequent continuous integration builds.6. snapshots have been used to refer to the development version of an individual module.
131114-1. Currently. the time stamp would change and the build number would increment to 2. In this case. While this is not usually the case..0SNAPSHOT... Now. This technique allows you to continue using the latest version by declaring a dependency on 1. but rather relying on the other modules to be built first. <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> </repository> </repositories> ..0-20060211.Team Collaboration with Maven . though it may have been configured as part of your settings files. you may also want to add this as a pluginRepository element as well. If you were to deploy again. 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. proficio-api:1. If you are developing plugins. to see the updated version downloaded. To add the internal repository to the list of repositories used by Proficio regardless of settings. locking the version in this way may be important if there are recent changes to the repository that need to be ignored temporarily. the Proficio project itself is not looking in the internal repository for dependencies. the version used is the time that it was deployed (in the UTC timezone) and the build number. <distributionManagement> <repository> <id>internal</id> <url>file://localhost/c:/mvnbook/repository/internal</url> </repository> . you will see that some of the dependencies are checked for updates..0-SNAPSHOT: checking for updates from internal .. or to lock down a stable version by declaring the dependency version to be the specific equivalent such as 1. Better Builds With Maven 215 .. similar to the example below (note that this output has been abbreviated): ..jar..131114-1. The filename that is used is similar to proficio-api-1.0-20060211. add the following to proficio/pom.xml: . build proficio-core with the following command: C:\mvnbook\proficio\proficio-core> mvn -U install During the build.. </distributionManagement> Now...
However. To deploy from your server. the updates will still occur only as frequently as new versions are deployed to the repository.. <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> . In this example.. How you implement this will depend on the continuous integration server that you use. Whenever you use the -U argument.. by default. this feature is enabled by default in a build definition. to check for an update the first time that particular dependency is used after midnight local time. but you can also change the interval by changing the repository configuration. The settings that can be used for the update policy are never. In section 6. Better Builds With Maven 216 . shown in figure 7-6. add the following configuration to the repository configuration you defined above in proficio/pom.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. as well. and interval:minutes. You can always force the update using the -U command. all that is being saved is some time. as you saw earlier. always. This is because the default policy is to update snapshots daily – that is. no update would be performed. as well as updating any version ranges. you must ensure that the distributionManagement section of the POM is correctly configured. This technique can ensure that developers get regular updates. Log in as an administrator and go to the following Configuration screen. without having to manually intervene. it updates both releases and snapshots. <repository> .. If it were omitted. and without slowing down the build by checking on every access (as would be the case if the policy were set to always). To see this. However. A much better way to use snapshots is to automate their creation. This causes many plugins to be checked for updates. it makes sense to have it build snapshots. However. Continuum can be configured to deploy its builds to a Maven snapshot repository automatically. so let's go ahead and do it now. If there is a repository configured to which to deploy them. you were not asked to apply this setting. It is possible to establish a policy where developers do an update from the source control management (SCM) system before committing. deployed with uncommitted code.xml: . daily (the default). Several of the problems mentioned earlier still exist – so at this point. or deployed without all the updates from the SCM. Since the continuous integration server regularly rebuilds the code from a known state. making it out-of-date. any snapshot dependencies will be checked once an hour to determine if there are updates in the remote repository..5 of this chapter. assuming that the other developers have remembered to follow the process. and then deploy the snapshot to share with the other team members.. this introduces a risk that the snapshot will not be deployed at all.
This relies on your internal repository and Continuum server being in the same location. Better Builds With Maven 217 . enter the location of your internal repository: C:\mvnbook\repository\internal. 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. follow the Show Projects link. you can avoid all of the problems discussed previously. but still keep a full archive of releases. If this is not the case. Better yet. and click Build Now on the Proficio API project. you can either lock a dependency to a particular build. To try this feature. 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. With this setup.Team Collaboration with Maven Figure 7-6: Continuum configuration In Deployment Repository field. This can be useful if you need to clean up snapshots on a regular interval. when necessary. with an updated time stamp and build number. you can enter a full repository URL such as scp://repositoryhost/www/repository/internal. while you get regular updates from published binary dependencies. Once the build completes. or build from source.
. this separation is achieved by adding an additional repository to the distributionManagement section of your POM.. you would add the following: . and deploy to the regular repository you listed earlier.snapshots</id> <url>file://localhost/www/repository/snapshots</url> </snapshotRepository> </distributionManagement> ..snapshots</id> <url>http://localhost:8081/snapshots</url> <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> </repositories> . <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> <repository> <id>internal. Better Builds With Maven 218 .....Team Collaboration with Maven If you are using the regular deployment mechanism (instead of using Continuum). if you had a snapshot-only repository in /www/repository/snapshots. you can make the snapshot update process more efficient by not checking the repository that has only releases for updates. For example. The replacement repository declarations in your POM would look like this: . Given this configuration.. <snapshotRepository> <id>internal. when it doesn't... This will deploy to that repository whenever the version contains SNAPSHOT. <distributionManagement> .
you can create one or more of your own archetypes. Creating a Standard Project Archetype Throughout this book.mvnbook \ -DartifactId=proficio-archetype \ -DarchetypeArtifactId=maven-archetype-archetype The layout of the resulting archetype is shown in figure 7-7. and replacing the specific values with parameters. Writing an archetype is quite like writing your own project. using an archetype. you have seen the archetypes that were introduced in Chapter 2 used to quickly lay down a project structure.mergere. There are two ways to create an archetype: one based on an existing project using mvn archetype:create-from-project. archetypes give you the opportunity to start a project in the right way – that is. Figure 7-7: Archetype directory layout Better Builds With Maven 219 . As you saw in this chapter. To avoid this. While this is convenient. by hand.Team Collaboration with Maven 7. the requirement of achieving consistency is a key issue facing teams. there is always some additional configuration required. in a way that is consistent with other projects in your environment. run the following command: C:\mvnbook\proficio> mvn archetype:create \ -DgroupId=com. Beyond the convenience of laying out a project structure instantly. and the other.7. To get started with the archetype. either in adding or removing content from that generated by the archetypes.
These files will be used to generate the template files when the archetype is run.1</version> <scope>test</scope> </dependency> </dependencies> </project> As you can see. and siteResources.xml file looks like the following: <project xmlns="http://maven.org/POM/4.java</source> </testSources> </archetype> Each tag is a list of files to process and generate in the created project. From here. The archetype descriptor describes how to construct a new project from the archetype-resources provided.0" xmlns:xsi="http://www.org/POM/4. The example descriptor looks like the following: <archetype> <id>proficio-archetype</id> <sources> <source>src/main/java/App. the groupId.0.xsd"> <modelVersion>4.xml.8.w3.xml at the top level.0. The files within the archetype-resources section are Velocity templates. you'll see that the archetype is just a normal JAR project – there is no special build configuration required. Better Builds With Maven 220 . The example above shows the sources and test sources. and the template project in archetype-resources. but it is also possible to specify files for resources.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache. so everything else is contained under src/main/resources.org/maven-v4_0_0.0</modelVersion> <groupId>$groupId</groupId> <artifactId>$artifactId</artifactId> <version>$version</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. There are two pieces of information required: the archetype descriptor in META-INF/maven/archetype. the pom. you need to populate the template with the content that you'd like to have applied consistently to new projects.Team Collaboration with Maven If you look at pom. For this example. testResources. The JAR that is built is composed only of resources.apache. For more information on creating an archetype. refer to the documentation on the Maven web site. artifactId and version elements are variables that will be substituted with the values provided by the developer running archetype:create.0 http://maven.0.java</source> </sources> <testSources> <source>src/test/java/AppTest.apache.
However. full of manual steps that need to be completed in a particular order. the content of the files will be populated with the values that you provided on the command line. allowing them to be highly automated. install and deploy it like any other JAR. the archetypeVersion argument is not required at this point.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. you will use the "internal" repository. Maven provides a release plugin that provides the basic functions of a standard release process. Continuing from the example in section 7. Better Builds With Maven 221 . Cutting a Release Releasing software is difficult. It will look very similar to the content of the archetype-resources directory you created earlier. The release plugin takes care of a number of manual steps in updating the project POM. such as deployment to the remote repository.mvnbook \ -DartifactId=proficio-example \ -DarchetypeGroupId=com. the required version would not be known (or if this was later development.mvnbook \ -DarchetypeArtifactId=proficio-archetype \ -DarchetypeVersion=1.8. releases should be consistent every time they are built. which often leads to omissions or short cuts. 7. Maven will build. Worse. The release plugin operates in two steps: prepare and perform.mergere. 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. The perform step could potentially be run multiple times to rebuild a release from a clean checkout of the tagged version. It is usually tedious and error prone. The prepare step is run once for a release.Team Collaboration with Maven Once you have completed the content in the archetype.9 of this chapter. Once the definition for a release has been set by a team. it has the correct deployment settings already.0-SNAPSHOT Normally. if omitted. Finally. You now have the template project laid out in the proficio-example directory. a previous release would be used instead). and creating tags (or equivalent for your SCM). Since the archetype inherits the Proficio parent. and does all of the project and source control manipulation that results in a tagged version. Releasing a project is explained in section 7. updating the source control management system to check and commit release related changes.mergere. since the archetype has not yet been released. and to perform standard tasks. new release. now however. go to an empty directory and run the following command: C:\mvnbook> mvn archetype:create -DgroupId=com. once a release has been made. it is usually difficult or impossible to correct mistakes other than to make another. To do so.
6. 3. In some cases. but this might include updating the metadata in your issue tracker. an error will appear. even if the plugin is not declared in the POM. 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. This is because you are using a locally installed snapshot of a plugin (either built yourself. 4. you will be prompted for values. all of the dependencies being used are releases. In this project. You'll notice that each of the modules in the project is considered. you may encounter a plugin snapshot. This is because the prepare step is attempting to guarantee that the build will be reproducible in the future. and released as 1. You can continue using the code that you have been working on in the previous sections.0. without making any modifications to your project. Better Builds With Maven 222 . not ready to be used as a part of a release. Describe the SCM commit operation 1. This can be corrected by adding the plugin definition to your POM. 7. However. 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. or check out the following: C:\mvnbook> svn co \ file://localhost/C:/mvnbook/svn/proficio/tags/proficio-final \ proficio To start the release process. Accept the defaults in this instance (note that running Maven in "batch mode" avoids these prompts and will accept all of the defaults). Describe the SCM commit and tag operations 9. To review the steps taken in this release process: Check for correct version of the plugin and POM (for example. or creating and committing an announcement file) 8. or part of the project.Team Collaboration with Maven To demonstrate how the release plugin works. other modules). 5. as they will be committed for the next development iteration 10. Modify all POM files in the build. the Proficio example will be revisited. other than those that will be released as part of the process (that is. The prepare step ensures that there are no snapshots in the build. 2. 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. run the following command: c:\mvnbook\proficio> mvn release:prepare -DdryRun=true This simulates a normal release preparation. and snapshots are a transient build. if you are using a dependency that is a snapshot. As the command runs.
you created a profile to enable those checks conditionally. this file will be release-pom. To do so. To include these checks as part of the release process.. there is also a release-pom.] <plugin> <groupId>org.Team Collaboration with Maven You might like to review the POM files that are created for steps 4 and 6.5. For that reason.xml. any active profiles are explicitly activated.tag file written out to each module directory. The SCM information is also updated in the tag POM to reflect where it will reside once it is tagged. use the following plugin configuration: [. a number of changes are made: • • • the explicit version of plugins and dependencies that were used are added any settings from settings. Having run through this process you may have noticed that only the unit and integration tests were run as part of the test build. including profiles from settings. and this is reverted in the next POM.xml in the same directory as pom. 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. when a build is run from this tag to ensure it matches the same circumstances as the release build.xml (both per-user and per-installation) are incorporated into the POM. This is used by Maven.xml You may have expected that inheritance would have been resolved by incorporating any parent elements that are used..xml and profiles.xml. you need to enable this profile during the verification step.xml.next respectively in each module directory.. these changes are not enough to guarantee a reproducible build – it is still possible that the plugin versions will vary.xml. However. as these can be established from the other settings already populated in the POM in a reproducible fashion. This contains a resolved version of the POM that Maven will use to build from if it exists. named pom. In this POM. Also.. instead of the normal POM.maven. to verify they are correct.plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <prepareVerifyArgs>-DenableCiProfile=true</prepareVerifyArgs> </configuration> </plugin> [.] Better Builds With Maven 223 . When the final run is executed.tag and pom. You'll notice that the version is updated in both of these files. or that expressions would have been resolved. that resulting version ranges will be different. and is set based on the values for which you were prompted during the release process. recall that in section 7.apache. or that different profiles will be applied. This is not the case however.
Team Collaboration with Maven
Try the dry run again: C:\mvnbook\proficio> mvn release:prepare -DdryRun=true Now that you've gone through the test run and are happy with the results, 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
5 classes.Migrating to Maven Figure 8-1: Dependency relationship between Spring modules In figure 8-1.4 and 1. For Spring. the Ant script compiles each of these different source directories and then creates a JAR for each module. 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. more or less.4 compatible source code and JUnit tests respectively tiger/src and tiger/test: contain additional JDK 1.). and each produces a JAR.5 compatible source code and JUnit Better Builds With Maven 229 . with the Java package structure. etc. Optional dependencies are indicated by dotted lines. TLD files. The src and tiger/src directories are compiled to the same destination as the test and tiger/test directories. you can see graphically the dependencies between the modules. Each of these modules corresponds. src and test: contain JDK 1. using inclusions and exclusions that are based on the Java packages of each class. properties files. resulting in JARs that contain both 1.
Figure 8-2: A sample spring module directory Better Builds With Maven 230 . To start. In the Spring example.Migrating to Maven 8.2. Where to Begin? With Maven. you will need to create a directory for each of Spring's modules. that means you will need to have a Maven project (a POM) for each of the modules listed above. WAR.) per Maven project file. Inside the 'm2' directory. you will create a subdirectory called 'm2' to keep all the necessary Maven changes clearly separated from the current build system. the rule of thumb to use is to produce one artifact (JAR. etc.
Recall from previous chapters that during the release process.springframework. <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.0-m1-SNAPSHOT</version> <name>Spring parent</name> <packaging>pom</packaging> <description>Spring Framework</description> <inceptionYear>2002</inceptionYear> <url>http://www. etc.m2book. project. however. thereby eliminating the requirement to specify the dependency repeatedly across multiple modules. the main source and test directories are src and test.springframework • artifactId: the setting specifies the name of this module (for example. For example. in Spring. spring-parent) • version: this setting should always represent the next release version number appended with .. company. • it should mimic standard package naming conventions to avoid duplicate values. non-snapshot version for a short period of time.1</version> <scope>test</scope> </dependency> </dependencies> As explained previously. the Spring team would use org. respectively.SNAPSHOT – that is. each module will inherit the following values (settings) from the parent POM. you will need to create a parent POM. which will be used for testing in every module.m2book. You will use the parent POM to store the common configuration settings that apply to all of the modules.migrating. the version you are developing in order to release. 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.org</url> <organization> <name>The Spring Framework Project</name> </organization> groupId: this setting indicates your area of influence. you will use com.mergere.8. primary used for documentation purposes. • packaging: the jar. Better Builds With Maven 231 . Maven will convert to the definitive. in order to tag the release in your SCM. war.Migrating to Maven In the m2 directory. <groupId>com. as it is our 'unofficial' example version of Spring.mergere. Let's begin with these directories. and In this parent POM we can also add dependencies such as JUnit.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2. For this example. department.
Recall from Chapter 2.3</source> <target>1.. that Maven automatically manages the classpath from its list of dependencies. <javac destdir="${target.apache./... you will need to append -Dmaven. as you will learn about that later in this chapter. you don't have to worry about the commons-attributes generated sources mentioned in the snippet./test</testSourceDirectory> <plugins> <plugin> <groupId>org. Spring's Ant script uses a parameter. These last three properties use Maven's default values.attributes./.compiler./src</sourceDirectory> <testSourceDirectory>.Include Commons Attributes generated Java sources --> <src path="${commons. deprecation and optimize (false). so there is no need for you to add the configuration parameters.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.src}"/> <classpath refid="all-libs"/> </javac> As you can see these include the source and target compatibility (1. in the buildmain target.3</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 232 . you can retrieve some of the configuration parameters for the compiler.3).3" debug="${debug}" deprecation="false" optimize="false" failonerror="true"> <src path="${src. To specify the required debug function in Maven. For now. and failonerror (true) values.dir}"/> <!-.debug=false to the mvn command (by default this is set to true). For the debug attribute.tempdir.classes.maven.3" target="1.dir}" source="1.Migrating to Maven Using the following code snippet from Spring's Ant build script. your build section will look like this: <build> <sourceDirectory>.. At this point.
dir}"/> <classpath location="${target. and this doesn't need to be changed.excludes from the nested fileset. by default. as Maven prints the test summary and stops for any test error or failure.classes.excludes}"/> </batchtest> </junit> You can extract some configuration information from the previous code: • • • • • • • forkMode="perBatch" matches with Maven's forkMode parameter with a value of once.mockclasses. From the tests target in the Ant script: <junit forkmode="perBatch" printsummary="yes" haltonfailure="yes" haltonerror="yes"> <jvmarg line="-Djava.properties files etc take precedence --> <classpath location="${target. You will need to specify the value of the properties test.Must go first to ensure any jndi. classpath is automatically managed by Maven from the list of dependencies. The nested element jvmarg is mapped to the configuration parameter argLine As previously noted. this value is read from the project.dir}"/> <classpath refid="all-libs"/> <formatter type="plain" usefile="false"/> <formatter type="xml"/> <batchtest fork="yes" todir="${reports. You will not need any printsummary.includes and test. so you will not need to locate the test classes directory (dir).dir}"/> <classpath location="${target. haltonfailure and haltonerror settings.dir}"> <fileset dir="${target.dir}"/> <!-.dir}" includes="${test. Maven sets the reports destination directory (todir) to target/surefire-reports.Migrating to Maven The other configuration that will be shared is related to the JUnit tests. • Better Builds With Maven 233 .properties file loaded from the Ant script (refer to the code snippet below for details).testclasses.testclasses.awt.headless=true -XX:MaxPermSize=128m -Xmx128m"/> <!-. formatter elements are not required as Maven generates both plain text and xml reports.includes}" excludes="${test. Maven uses the default value from the compiler plugin.Need files loaded as resources --> <classpath location="${test. since the concept of a batch for testing does not exist. by default.
When building only on Java 5 you could remove that option and the XML parser (Xerces) and APIs (xml-apis) dependencies. <plugin> <groupId>org.includes=**/*Tests. translate directly into the include/exclude elements of the POM's plugin configuration.maven.5 .4 to run you do not need to exclude hibernate3 tests. Spring's Ant build script also makes use of the commons-attributes compiler in its compileattr and compiletestattr targets.excludes=**/Abstract* org/springframework/orm/hibernate3/** The includes and excludes referenced above. test.Migrating to Maven # Wildcards to be matched by JUnit tests. test.4. The commons-attributes compiler processes javadoc style annotations – it was created before Java supported annotations in the core language on JDK 1. due to Hibernate 3.3. # Second exclude needs to be used for JDK 1. It makes tests run using the standard classloader delegation instead of the default Maven isolated classloader. # Convention is that our JUnit test classes have XXXTests-style names.excludes=**/Abstract* #test.awt.class # # Wildcards to exclude among JUnit tests.and generates sources from them that have to be compiled with the normal Java compiler. Note that it is possible to use another lower JVM to run tests if you wish – refer to the Surefire plugin reference documentation for more information. Better Builds With Maven 234 .apache. which are processed prior to the compilation.headless=true -XX:MaxPermSize=128m -Xmx128m </argLine> <includes> <include>**/*Tests. mandatory when building in JDK 1.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <forkMode>once</forkMode> <childDelegation>false</childDelegation> <argLine> -Djava.1 # being compiled with target JDK 1.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. Since Maven requires JDK 1.
web.src}"> <!-Only the PathMap attribute in the org.mojo</groupId> <artifactId>commons-attributes-maven-plugin</artifactId> <executions> <execution> <configuration> <includes> <include>**/metadata/*.dir}" includes="org/springframework/jmx/**/*.tempdir.attributes.dir}" includes="**/metadata/*. <plugin> <groupId>org. --> <attribute-compiler destdir="${commons. to support indexing. --> <attribute-compiler destdir="${commons.java"/> <fileset dir="${test.java</include> </includes> <testIncludes> <include>org/springframework/aop/**/*. so you will only need to add the inclusions for the main source and test source compilation. Better Builds With Maven 235 .java</include> </testIncludes> </configuration> <goals> <goal>compile</goal> <goal>test-compile</goal> </goals> </execution> </executions> </plugin> Later in this chapter you will need to modify these test configurations. this same function can be accomplished by adding the commons-attributes plugin to the build section in the POM.codehaus.springframework.test}"> <fileset dir="${test.tempdir. --> <fileset dir="${src.handler.metadata package currently needs to be shipped with an attribute. Maven handles the source and destination directories automatically.java"/> </attribute-compiler> In Maven.attributes.Migrating to Maven From compileattr: <!-.Compile to a temp directory: Commons Attributes will place Java Source here.java</include> <include>org/springframework/jmx/**/*.Compile to a temp directory: Commons Attributes will place Java Source here.java"/> </attribute-compiler> From compiletestattr: <!-.dir}" includes="org/springframework/aop/**/*.servlet.
you will need to exclude the *. In each subdirectory. JUnit test configuration.).classes. The following is the POM for the spring-core module.0-m1-SNAPSHOT</version> </parent> <artifactId>spring-core</artifactId> <name>Spring core</name> Again. you will start to compile the main Spring source. This module is the best to begin with because all of the other modules depend on it.4. you won't need to specify the version or groupId elements of the current module. in this case the defaults are sufficient. you can determine which classes are included in the JAR and what attributes are written into the JAR's manifest.m2book. as those values are inherited from parent POM. review the following code snippet from Spring's Ant script.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2. Maven will automatically set manifest attributes such as name.dir}/modules/spring-core. While manifest entries can also be customized with additional configuration to the JAR plugin. To begin. you will need to tell Maven to pick the correct classes and resources from the core and util packages. Creating POM files Now that you have the basic configuration shared by all modules (project information. and organization name to the values in the POM.dir}"> <include name="org/springframework/core/**"/> <include name="org/springframework/util/**"/> </fileset> <manifest> <attribute name="Implementation-Title" value="${spring-title}"/> <attribute name="Implementation-Version" value="${spring-version}"/> <attribute name="Spring-Version" value="${spring-version}"/> </manifest> </jar> From the previous code snippet.mergere. <parent> <groupId>com. Compiling In this section. tests will be dealt with later in the chapter. Better Builds With Maven 236 . or they will get included in the JAR.Migrating to Maven 8. However. description. where spring-core JAR is created: <jar jarfile="${dist. since the sources and resources are in the same directory in the current Spring build. setting the files you want to include (by default Maven will pick everything from the resource directory). compiler configuration. which centralizes and maintains information common to the project. For the resources. you will need to create a POM that extends the parent POM. you need to create the POM files for each of Spring's modules. you will need to add a resources element in the build section. etc. 8.jar"> <fileset dir="${target. As you saw before.3.java files from the resources. version.
Migrating to Maven For the classes../.apache. which is inherited from the parent POM.java</exclude> </excludes> </resource> </resources> <plugins> <plugin> <groupId>org.. Maven will by default compile everything from the source directory. you will need to configure the compiler plugin to include only those in the core and util packages.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 . because as with resources./src</directory> <includes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*.maven. <build> <resources> <resource> <directory>.
However.springframework. caused by the required classes not being on the classpath. you can search the repository using Google. artifactId and version should we use? For the groupId and artifactId. you now know that you need the Apache Commons Logging library (commons-logging) to be added to the dependencies section in the POM. Better Builds With Maven 238 .java:[19.Migrating to Maven To compile your Spring build.java:[107.io.java:[30. You will see a long list of compilation failures.ibiblio.commons.24] cannot find symbol symbol : class Log location: class org.PathMatchingResourcePatternResolver C:\dev\m2book\code\migrating\spring\m2\springcore\. Regarding the artifactId.34] package org. commons-logging groupId would become org. what groupid..commons.org/maven2 commons logging.. beginning with the following: [INFO] -----------------------------------------------------------------------[ERROR] BUILD FAILURE [INFO] -----------------------------------------------------------------------[INFO] Compilation failure C:\dev\m2book\code\migrating\spring\m2\springcore\..logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\.. you need to check the central repository at ibiblio..apache. the actual groupId is commons-logging.core.\. Specify site:www. For example.apache.apache.logging. for historical reasons some groupId values don't follow this convention and use only the name of the project.34] package org. As an alternative.\.logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\..\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver.java:[31.logging does not exist These are typical compiler messages.34] package org.support. If you check the repository.ibiblio.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver. In the case of commons-logging.\. the convention is to use a groupId that mirrors the package name.apache.\. you can now run mvn compile.. From the previous output.commons. the option that is closest to what is required by your project. located in the org/apache/commons/logging directory in the repository. it's usually the JAR name without a version (in this case commonslogging). Typically..commons. changing dots to slashes.\src\org\springframework\util\xml\SimpleSaxErrorHandler. But.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver. you will find all the available versions of commons-logging under http://www. and then choose from the search results.org/maven2/commons-logging/commons-logging/.
ibiblio.MF • For advanced users.4</version> </dependency> </dependencies> Usually you will convert your own project. during the process of migrating Spring to Maven.1/hibernate-3.org/maven2 to the query.org/maven2 78d5c38f1415efc64f7498f828d8069a • The search will return: www. through inheritance. using a web interface. For example.md5 You can see that the last directory is the version (3. So. However. 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.1). is under development (refer to the Maven Repository Manager project for details). you could search with: site:www. While adding dependencies can be the most painful part of migrating to Maven.ibiblio. all sub-modules would use the same dependencies).0. we strongly encourage and recommend that you invest the time at the outset of your migration. component-oriented. For instance.txt in the lib directory of the Spring source.hibernate) An easier way to search for dependencies. search the ibiblio repository through Google by calculating the MD5 checksum of the JAR file with a program such as md5sum. although you could simply follow the same behavior used in Ant (by adding all the dependencies in the parent POM so that.Migrating to Maven With regard the version.jar provided with Spring under lib/hibernate. to make explicit the dependencies and interrelationships of your projects. with the slashes changed to dots (org.jar.org/maven2/org/hibernate/hibernate/3. modular projects that are easier to maintain in the long term. you will find that there is documentation for all of Spring's dependencies in readme. and then search in Google prepending site:www.1. the previous directory is the artifactId (hibernate) and the other directories compose the groupId. You can use this as a reference to determine the versions of each of the dependencies. explicit dependency management is one of the biggest benefits of Maven once you have invested the effort upfront.ibiblio. we discovered that the commons-beanutils version stated in the documentation is wrong and that some required dependencies are missing from the documentation. When needed. Doing so will result in cleaner. <dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. for the hibernate3. Better Builds With Maven 239 . so you will have first hand knowledge about the dependencies and versions used. you have to be careful as the documentation may contain mistakes and/or inaccuracies.
After compiling the tests.this time all of the sources for spring-core will compile. run mvn compile again .Migrating to Maven Running again mvn compile and repeating the process previously outlined for commons-logging. For the first step. This is because in other projects. you will repeat the previous procedure for the main classes. Optional dependencies are not included transitively./. In addition. we will cover how to run the tests. Testing Now you're ready to compile and run the tests. 8. 8.. <testResources> <testResource> <directory>. and setting the JUnit test sources to compile. setting which test resources to use. you will notice that you also need Apache Commons Collections (aka commons-collections) and log4j.5. Using the optional tag does not affect the current project. so log4j will not be included in other projects that depend on this.properties</include> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*. and it is just for the convenience of the users. <dependency> <groupId>commons-collections</groupId> <artifactId>commons-collections</artifactId> <version>3. with the exception of changing the location from which the element name and directory are pulled.2.1</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1. you may decide to use another log implementation.properties file required for logging configuration. you will need to add the log4j.. Compiling Tests Setting the test resources is identical to setting the main resources./test</directory> <includes> <include>log4j. Now.5.9</version> <optional>true</optional> </dependency> Notice that log4j is marked as optional.java</exclude> </excludes> </testResource> </testResources> Better Builds With Maven 240 .1.
If you run mvn test-compile again you will have a successful build.springframework. the key here is to understand that some of the test classes are not actually unit tests for springcore.4</version> <scope>test</scope> </dependency> The scope is set to test.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2. not tests. To exclude test classes in Maven. which one do we build first? Impossible to know.servlet does not exist This means that the following dependency must be added to the POM. but this time there is a special case where the compiler complains because some of the classes from the org. if you try to compile the test classes by running mvn test-compile.java</exclude> <exclude>org/springframework/util/SerializationTestUtils. depend on classes from spring-core.springframework.java</exclude> <exclude>org/springframework/util/ReflectionUtilsTests. Therefore. you will see that their main classes. when you run mvn test-compile.web and org. you will see the following error: package javax. we cannot add a dependency from spring-core without creating a circular dependency.springframework.java</exclude> <exclude>org/springframework/util/ClassUtilsTests. Inside the mavencompiler-plugin configuration. As a result.Migrating to Maven Setting the test sources for compilation follows the same procedure. In other words.mock. as before. add the testExcludes element to the compiler configuration as follows. So. Better Builds With Maven 241 . as this is not needed for the main sources.beans packages are missing. but rather require other modules to be present.java</exclude> <exclude>org/springframework/util/ObjectUtilsTests.java</exclude> <exclude>org/springframework/core/io/ResourceTests. spring-web and spring-beans modules. It may appear initially that spring-core depends on spring-mock. if spring-core depends on spring-beans and springbeans depends on spring-core. you will need to add the testIncludes element.java</exclude> </testExcludes> Now. as all the test classes compile correctly now. <testExcludes> <exclude>org/springframework/util/comparator/ComparatorTests. as well. but if you try to compile those other modules. org. you will get compilation errors. it makes sense to exclude all the test classes that reference other modules from this one and include them elsewhere. <testIncludes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </testIncludes> Now. in order to compile the tests: <dependency> <groupId>javax.
txt. Failures: 1. compile tests.springframework. there is a section for each failed test called stacktrace.) Better Builds With Maven 242 .io. simply requires running mvn test. you will find the following: [surefire] Running org.Migrating to Maven 8.support.5. Running Tests Running the tests in Maven.FileNotFoundException: class path resource [org/aopalliance/] cannot be resolved to URL because it does not exist. Time elapsed: 0.2. Within this file. The org.0</version> <scope>test</scope> </dependency> Now run mvn test again. as it will process all of the previous phases of the build life cycle (generate sources.core. This indicates that there is something missing in the classpath that is required to run the tests. 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. for the test class that is failing org. run tests. Errors: 1 [INFO] -----------------------------------------------------------------------[ERROR] BUILD ERROR [INFO] -----------------------------------------------------------------------[INFO] There are test failures. However. The first section starts with java. To debug the problem. when you run this command.015 sec <<<<<<<< FAILURE !! This output means that this test has logged a JUnit failure and error. is to run mvn install to make the resulting JAR available to other projects in your local Maven repository. so to resolve the problem add the following to your POM <dependency> <groupId>aopalliance</groupId> <artifactId>aopalliance</artifactId> <version>1.io.aopalliance package is inside the aopallience JAR.springframework. This command can be used instead most of the time.support.core. you will need to check the test logs under target/surefire-reports. compile. [INFO] ------------------------------------------------------------------------ Upon closer examination of the report output.io. you will get the following error report: Results : [surefire] Tests run: 113. Errors: 1. etc.PathMatchingResourcePatternResolverTests [surefire] Tests run: 5.PathMatchingResourcePatternResolverT ests.
Migrating to Maven 8. Other Modules Now that you have one module working it is time to move on to the other modules. each of the modules will be able to inherit the required Surefire configuration. Avoiding Duplication As soon as you begin migrating the second module. Using the parent POM to centralize this information makes it possible to upgrade a dependency version across all sub-projects from a single location. In the same way.6.4</version> </dependency> </dependencyManagement> The following are some variables that may also be helpful to reduce duplication: • • ${project. To avoid duplication. instead of repeatedly adding the same dependency version information to each module. That way.0. 8. <dependencyManagement> <dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1.groupId}: groupId of the current POM being built For example.6. For instance. See figure 8-1 to get the overall picture of the interdependencies between the Spring modules.version}: version of the current POM being built ${project. since they have the same groupId and version: <dependency> <groupId>${project.1. use the parent POM's dependencyManagement section to specify this information once.groupId}</groupId> <artifactId>spring-core</artifactId> <version>${project. you will find that you are repeating yourself. move these configuration settings to the parent POM instead.version}</version> </dependency> Better Builds With Maven 243 . If you follow the order of the modules described at the beginning of the chapter you will be fine. otherwise you will find that the main classes from some of the modules reference classes from modules that have not yet been built. you will be adding the Surefire plugin configuration settings repeatedly for each module that you convert. and remove the versions from the individual modules (see Chapter 3 for more information). you can refer to spring-core from spring-beans with the following.
would experience runtime errors. 8. it's easier to deal with small modules. there is a procedure you can use. attempting to use one of the Java 5 classes under Java 1. with only those classes related to spring-web. Consider that if you include some classes compiled for Java 1. how can the Java 1. you can split Spring's mock classes into spring-context-mock.groupId}</groupId> <artifactId>spring-beans</artifactId> <version>${project. By splitting them into different modules. you will need to create a new spring-beans-tiger module. by specifying the test-jar type. However. Referring to Test Classes from Other Modules If you have tests from one component that refer to tests from other 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.2. be sure to put that JAR in the test scope as follows: <dependency> <groupId>${project. and spring-web-mock.6. Generally with Maven. this can cause previously-described cyclic dependencies problem. in this case it is necessary to avoid refactoring the test source code. make sure that when you run mvn install.6. particularly in light of transitive dependencies.4. So. you can use it as a dependency for other components.3.apache.3 and some compiled for Java 5 in the same JAR. Better Builds With Maven 244 . As the compiler plugin was earlier configured to compile with Java 1.3 or 1. Although it is typically not recommended. with only those classes related to spring-context module. they will need to run them under Java 5.5 sources be added? To do this with Maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <executions> <execution> <goals> <goal>test-jar</goal> </goals> </execution> </executions> </plugin> Once that JAR is installed. Building Java 5 Classes Some of Spring's modules include Java 5 classes from the tiger folder.Migrating to Maven 8. that a JAR that contains the test classes is also installed in the repository: <plugin> <groupId>org. First. users will know that if they depend on the module composed of Java 5 classes.3 compatibility.maven. any users. To eliminate this problem.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.
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 As with the other modules that have been covered. and then a directory for each one of the individual tiger modules. The best way to split them is to create a tiger folder with the Java 5 parent POM. the Java 5 modules will share a common configuration for the compiler.
plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1././tiger/test</testSourceDirectory> <plugins> <plugin> <groupId>org.. you will need to add a module entry for each of the directories. with all modules In the tiger POM.5</source> <target>1..5</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 246 .apache./tiger/src</sourceDirectory> <testSourceDirectory>.... 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>././..maven.Migrating to Maven Figure 8-5: Dependency relationship./.
4.classes.remoting.5</jdk> </activation> <modules> <module>tiger</module> </modules> </profile> </profiles> 8. <profiles> <profile> <id>jdk1.springframework. Maven can call Ant tasks directly from a POM using the maven-antrun-plugin.rmi.remoting. From Ant.springframework.RmiInvocationWrapper" iiop="true"> <classpath refid="all-libs"/> </rmic> Better Builds With Maven 247 .dir}" classname="org. with the Spring migration. 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. In this case.Migrating to Maven In the parent POM. you just need a new module entry for the tiger folder.classes.dir}" classname="org.6. but to still be able to build the other modules when using Java 1.5</id> <activation> <jdk>1.rmi.4 you will add that module in a profile that will be triggered only when using 1. this is: <rmic base="${target. For example.5 JDK.RmiInvocationWrapper"/> <rmic base="${target. you need to use the Ant task in the spring-remoting module to use the RMI compiler. Using Ant Tasks From Inside Maven In certain migration cases.
rmi.directory} and maven.. Better Builds With Maven 248 .directory}/classes" classname="org.compile.directory}/classes" classname="org.Migrating to Maven To include this in Maven build.RmiInvocationWrapper" iiop="true"> <classpath refid="maven. stub and tie classes from them.home}/. the most appropriate phase in which to run this Ant task is in the processclasses phase. So. you will need to determine when Maven should run the Ant task.build. and required by the RMI task. There are also references for anything that was added to the plugin's dependencies section.springframework. which is bundled with the JDK.classpath.build.apache.maven. add: <plugin> <groupId>org.springframework.jar</systemPath> </dependency> </dependencies> </plugin> As shown in the code snippet above. In this case.jar above. such as the reference to the tools./lib/tools. the rmic task. such as ${project.compile.rmi.classpath"/> </rmic> </tasks> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> <dependencies> <dependency> <groupId>com.plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <executions> <execution> <phase>process-classes</phase> <configuration> <tasks> <echo>Running rmic</echo> <rmic base="${project.remoting. which is a classpath reference constructed from all of the dependencies in the compile scope or lower.RmiInvocationWrapper"/> <rmic base="${project. To complete the configuration.sun</groupId> <artifactId>tools</artifactId> <scope>system</scope> <version>1. there are some references available already.4</version> <systemPath>${java. which applies to that plugin only.build. will take the compiled classes and generate the rmi skeleton.remoting.
2 -Dpackaging=jar You will only need to do this process once for all of your projects or you may use a corporate repository to share them across your organization. Better Builds With Maven 249 .Migrating to Maven 8. there are two additional. These issues were shared with the Spring developer community and are listed below: • • Moving one test class. which used relative paths in Log4JConfigurerTests class. mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging> For instance. You can then install them in your local repository with the following command. Sun's Activation Framework and JavaMail are not redistributable from the repository due to constraints in their licenses. see http://maven. 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.5. which uses AspectJ for weaving the classes. These can be viewed in the example code.apache. special cases that must be handled. There is some additional configuration required for some modules. For more information on dealing with this issue.jar -DgroupId=javax. as these test cases will not work in both Maven and Ant. such as spring-aspects. 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. Some Special Cases In addition to the procedures outlined previously for migrating Spring to Maven. NamespaceHandlerUtilsTests. to install JavaMail: mvn install:install-file -Dfile=mail.org/guides/mini/guide-coping-with-sun-jars. Using classpath resources is recommended over using file system resources.html.mail -DartifactId=mail -Dversion=1. 8.3.6. 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. For example.6.6.
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
for example). they undergo the same basic processes of marshaling non-source-code resources. to install reflect the new plugin installed in the local repository. Better Builds With Maven 255 . if one exists. Indeed. and metadata references to latest plugin version. 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. maven-plugin-plugin Update the plugin registry. the maven-plugin packaging also introduces a few new mojo bindings. and the rest. packaging. testing. addPluginArtifact Metadata updateRegistry maven-plugin-plugin Integrate current plugin information with plugin search metadata. However. to extract and format the metadata for the mojos within. 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. As such. compiling source code.
pre-clean – execute any setup or initialization procedures to prepare the project for cleaning 2.1. Maven provides a set of default mojo bindings for this life cycle. Life-cycle phases The clean life-cycle phase contains the following phases: 1. along with any additional directories configured in the POM. the state of the project before it was built. effective for all POM packagings. Alongside each. 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.2. Below is a listing of the phases in the clean life cycle. Default life-cycle bindings Below are the clean life-cycle bindings for the jar packaging. you will find a short description of what that mojo does. post-clean – finalize the cleaning process. The clean Life Cycle This life cycle is executed in order to restore a project back to some baseline state – usually. which perform the most common tasks involved in cleaning a project. clean – remove all files that were generated during another build process 3. Better Builds With Maven 256 . along with a summary of the default bindings.Appendix A: Resources for Plugin Developers A.
and render documentation source files into HTML.3. render your documentation source files into HTML. post-site – execute any actions required to finalize the site generation process. 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. Default Life Cycle Bindings Below are the site life-cycle bindings for the jar packaging. Deploy the generated web site to the web server path specified in the POM distribution Management section.1. site-deploy – use the distributionManagement configuration in the project's POM to deploy the generated web site files to the web server.Appendix A: Resources for Plugin Developers A. site – run all associated project reports. effective for all POM packagings. pre-site – execute any setup or initialization steps to prepare the project for site generation 2. and prepare the generated web site for potential deployment 4. Maven provides a set of default mojo bindings for this life cycle. and render documentation into HTML 3. site-deploy deploy Better Builds With Maven 257 . and even deploy the resulting web site to your server. It will run any reports that are associated with your project. Below is a listing of the phases in the site life cycle. Alongside each. along with a summary of the default bindings. Life-cycle phases The site life cycle contains the following phases: 1. The site Life Cycle This life cycle is executed in order to generate a web site for your project. you will find a short description of what that mojo does. which perform the most common tasks involved in generating the web site for a project.
and often eliminates dependencies on Maven itself beyond the plugin API.ma List of reports to be generated when the site ven.M The current build session. org.apache.1.ma List of project instances which will be ven. It will summarize the root objects of the build state which are available for mojo expressions. it will describe the algorithm used to resolve complex parameter expressions.ArtifactRepository used to cache artifacts during a Maven build. and extract only the information it requires. This contains avenSession methods for accessing information about how Maven was called.reporting. This section discusses the expression language used by Maven to inject build state and plugin configuration into mojos.apache. A.project. Better Builds With Maven 258 .util. These expressions allow a mojo to traverse complex build state. java. which act as a shorthand for referencing commonly used build state objects. Using the discussion below.maven. This reduces the complexity of the code contained in the mojo.maven. org.artifact.execution.util. mojo developers should have everything they need to extract the build state they require.2. Mojo Parameter Expressions Mojo parameter values are resolved by way of parameter expressions when a mojo is initialized. They are summarized below: Table A-5: Primitive expressions supported by Maven's plugin parameter Expression Type Description ${localRepository} ${session} org. ${reactorProjects} ${reports} ${executedProject} java.List<org.List<org. along with the published Maven API documentation. in addition to providing a mechanism for looking up Maven components on-demand.maven.MavenReport> life cycle executes.re This is a reference to the local repository pository. Finally. It is used for bridging results from forked life cycles back to the main line of execution.apache.project.Appendix A: Resources for Plugin Developers A.Mav This is a cloned instance of the project enProject instance currently being built.2.apache.MavenProject> processed as part of the current build.apache. Simple Expressions Maven's plugin parameter injector supports several primitive expressions.
Project org.apache.maven. org. 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.xml in the maven application directory and from .2. ${plugin} org.maven.Maven Project instance which is currently being built.io.maven.apache.2.PluginDescriptor including its dependency artifacts.project. merged from ings conf/settings.descri The descriptor instance for the current plugin.Appendix A: Resources for Plugin Developers A. Maven supports more complex expressions that traverse the object graph starting at some root object that contains build state. Better Builds With Maven 259 .Sett The Maven settings.m2/settings. Complex Expression Roots In addition to the simple expressions above. unless specified otherwise.xml in the user's home directory.plugin.settings.apache. ptor.File The current project's root directory.
It includes summaries of the essential plugin descriptor. it will attempt to find a value in one of two remaining places. Otherwise. the next expression part is used as a basis for reflectively traversing that object' state. rendering an array of navigational directions. if there is one. If a user has specified a property mapping this expression to a specific value in the current POM. resolved in this order: 1. This includes properties specified on the command line using the -D commandline option. if the expression matches one of the primitive expressions (mentioned above) exactly. this reflective lookup process is aborted.and Ant-specific mojo source files. it will be resolved as the parameter value at this point. Maven plugin parameter expressions do not support collection lookups. This root object is retrieved from the running application using a hard-wired mapping. If at this point Maven still has not been able to resolve a value for the parameter expression. the expression is split at each '. much like a primitive expression would. First. or an active profile. Its syntax has been annotated to provide descriptions of the elements. During this process. The first is the root object. successive expression parts will extract values from deeper and deeper inside the build state. 2. No advanced navigation can take place using is such expressions. The Expression Resolution Algorithm Plugin parameter expressions are resolved using a straightforward algorithm. --> <description>Sample Maven Plugin</description> <!-. an ancestor POM. or method invocations that don't conform to standard JavaBean naming conventions. Repeating this. Plugin descriptor syntax The following is a sample plugin descriptor. From there. The POM properties. If the value is still empty. array index references. |-> Better Builds With Maven 260 . Plugin metadata Below is a review of the mechanisms used to specify metadata for plugins. Currently. the value that was resolved last will be returned as the expression's value. following standard JavaBeans naming conventions. <plugin> <!-. The system properties.' character.The description element of the plugin's POM. and must correspond to one of the roots mentioned above.2.2.These are the identity elements (groupId/artifactId/version) | from the plugin POM. as well the metadata formats which are translated into plugin descriptors from Java.Appendix A: Resources for Plugin Developers A. then the string literal of the expression itself is used as the resolved value. The resulting value then becomes the new 'root' object for the next round of traversal. If the parameter is still empty after these two lookups. When there are no more expression parts. If at some point the referenced object doesn't contain a property that matches the next expression part. Maven will consult the current system properties. an expression part named 'child' translates into a call to the getChild() method on that object. then the value mapped to that expression is returned.
apache.The name of the mojo. It's restricted to this plugin to avoid creating inter-plugin | dependencies.</description> <!-. |-> <inheritedByDefault>true</inheritedByDefault> <!-. | This is useful when the user will be invoking this mojo directly from | the command line. |-> <executeGoal>do-something-first</executeGoal> <!-.0-SNAPSHOT</version> <!-. this plugin could be referred to from the command line using | the 'myplugin:' prefix.This element provides the shorthand reference for this plugin.Tells Maven that this mojo can ONLY be invoked directly. | and specifies a custom life-cycle overlay that should be added to the | cloned life cycle before the specified phase is executed. For | instance. |-> <executePhase>process-resources</executePhase> <!-. This is | useful to inject specialized behavior in cases where the main life | cycle should remain unchanged.Tells Maven that the this plugin's configuration should be inherted from | a parent POM by default. --> <description>Do something cool. |-> <goalPrefix>myplugin</goalPrefix> <!-.Description of what this mojo does. |-> <executeLifecycle>myLifecycle</executeLifecycle> <!-. --> <mojos> <mojo> <!-. |-> <phase>compile</phase> <!-. |-> Better Builds With Maven 261 .Ensure that this other mojo within the same plugin executes before | this one.This is a list of the mojos contained within this plugin. |-> <goal>do-something</goal> <!-. It is a good idea to provide this. unless the user specifies | <inherit>false</inherit>. to give users a hint | at where this task should run. | this name allows the user to invoke this mojo from the command line | using 'myplugin:do-something'. | This allows the user to specify that this mojo be executed (via the | <execution> section of the plugin configuration in the POM).Appendix A: Resources for Plugin Developers <groupId>org.maven.Which phase of the life cycle this mojo will bind to by default.This is optionally used in conjunction with the executePhase element.plugins</groupId> <artifactId>maven-myplugin-plugin</artifactId> <version>2.This tells Maven to create a clone of the current project and | life cycle. Combined with the 'goalPrefix' element above. but the mojo itself has certain life-cycle | prerequisites. then execute that life cycle up to the specified phase. without | also having to specify which phase is appropriate for the mojo's | execution. via the | command line.
plugins. |-> <aggregator>false</aggregator> <!-. regardless of the number of project instances in the | current build.File</type> <!-. Better Builds With Maven 262 .apache. it will be executed once for each project instance in the | current build.The implementation language for this mojo.maven. If a mojo is marked as an aggregator. If true.Appendix A: Resources for Plugin Developers <requiresDirectInvocation>false</requiresDirectInvocation> <!-.The parameter's name.site.The class or script path (within the plugin's jar) for this mojo's | implementation. If the mojo is not marked as an | aggregator. the | mojo (and the build) will fail when this parameter doesn't have a | value. it will only | execute once. |-> <implementation>org.Tells Maven that a valid list of reports for the current project are | required before this plugin can execute.The Java type for this parameter.Whether this parameter is required to have a value. If Maven is operating in offline mode. |-> <requiresOnline>false</requiresOnline> <!-. |-> <name>inputDirectory</name> <!-. In Java mojos.Determines how Maven will execute this mojo in the context of a | multimodule build. --> <parameters> <parameter> <!-.Tells Maven that a valid project instance must be present for this | mojo to execute.This is an optional alternate parameter name for this parameter. such mojos will | cause the build to fail.SiteDeployMojo</implementation> <!-. --> <language>java</language> <!-. This flag controls whether the mojo requires | Maven to be online. |-> <requiresReports>false</requiresReports> <!-. |-> <alias>outputDirectory</alias> <!-.Some mojos cannot execute if they don't have access to a network | connection.This is a list of the parameters used by this mojo.io. | It will be used as a backup for retrieving the parameter value. |-> <inheritedByDefault>true</inheritedByDefault> <!-. --> <type>java. Mojos that are marked as aggregators should use the | ${reactorProjects} expression to retrieve a list of the project | instances in the current build. this will often reflect the | parameter field name in the mojo class. unless the user specifies | <inherit>false</inherit>. |-> <requiresProject>true</requiresProject> <!-.Tells Maven that the this plugin's configuration should be inherted | from a parent POM by default.
artifact. |-> <requirements> <requirement> <!-.outputDirectory}</inputDirectory> </configuration> <!-.artifact.manager. | | The general form is: | <param-name implementation="param-type">param-expr</param-name> | |-> <configuration> <!-. |-> <editable>true</editable> <!-. the requirement specification tells | Maven which mojo-field should receive the component instance.manager. If set to | false.This is the operational specification of this mojo's parameters.apache. | along with an optional classifier for the specific component instance | to be used (role-hint). specified in the javadoc comment | for the parameter field in Java mojo implementations.This is the list of non-parameter component references used by this | mojo. parameter type. this parameter must be configured via some other section of | the POM.Whether this parameter's value can be directly specified by the | user.outputDirectory}. |-> <field-name>wagonManager</field-name> </requirement> </requirements> </mojo> </mojos> </plugin> Better Builds With Maven 263 . this parameter is named "inputDirectory". either via command-line or POM configuration. Finally.File">${project. |-> <inputDirectory implementation="java. | and the primary expression used to extract the parameter's value.maven.Use a component of type: org.Description for this parameter.Appendix A: Resources for Plugin Developers |-> <required>true</required> <!-. as in the case of the list of project dependencies.WagonManager</role> <!-.Inject the component instance into the "wagonManager" field of | this mojo.io.For example.apache.reporting. |-> <description>This parameter does something important.maven.</description> </parameter> </parameters> <!-. as | compared to the descriptive specification above. Each parameter must | have an entry here that describes the parameter name. and it | expects a type of java. Components are specified by their interface class name (role). The expression used to extract the | parameter value is ${project.File.reporting.io.WagonManager |-> <role>org.
2. 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. Table A-7: A summary of class-level javadoc annotations Descriptor Element Javadoc Annotation Values Required? aggregator description executePhase. 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. Java Mojo Metadata: Supported Javadoc Annotations The Javadoc annotations used to supply metadata about a particular mojo come in two types. Classlevel annotations correspond to mojo-level metadata elements.4. Alphanumeric.Appendix A: Resources for Plugin Developers A. 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 . life cycle name. phase. executeLifecycle.
The default life-cycle phase binding for this mojo --> <phase>compile</phase> <!-. and Yes No No No No (recommended) No Requirements section required editable description deprecated usually left blank None None Anything Alternative parameter A.The name for this mojo --> <goal>myGoal</goal> <!-. |-> <requiresDependencyResolution>compile</requiresDependencyResolution> <!-. corresponding to the ability to map | multiple mojos into a single build script. <pluginMetadata> <!-. Maven will resolve | the dependencies in this scope before this mojo executes.Appendix A: Resources for Plugin Developers Field-level annotations The table below summarizes the field-level annotations which supply metadata about mojo parameters.2.Contains the list of mojos described by this metadata file. NOTE: | multiple mojos are allowed here. Table A-8: Field-level annotations Descriptor Element Javadoc Annotation Values Required? alias.5. Ant Metadata Syntax The following is a sample Ant-based mojo metadata file.Whether this mojo requires access to project reports --> <requiresReports>true</requiresReports> Better Builds With Maven 265 . parameterconfiguration section @parameter expression="${expr}" alias="alias" default-value="val" @component roleHint="someHint" @required @readonly N/A (field comment) @deprecated Anything roleHint is optional.The dependency scope required for this mojo. |-> <mojos> <mojo> <!-. configuration. These metadata translate into elements within the parameter. Its syntax has been annotated to provide descriptions of the elements. and requirements sections of a mojo's specification in the plugin descriptor.Whether this mojo requires a current project instance --> <requiresProject>true</requiresProject> <!-.
The parameter name.Whether this mojo requires Maven to execute in online mode --> <requiresOnline>true</requiresOnline> <!-.Appendix A: Resources for Plugin Developers <!-.Whether this parameter is required for mojo execution --> <required>true</required> Better Builds With Maven 266 . |-> <hint>custom</hint> </component> </components> <!-.Whether this mojo must be invoked directly from the command | line. |-> <inheritByDefault>true</inheritByDefault> <!-.Whether this mojo operates as an aggregator --> <aggregator>true</aggregator> <!-.apache.The list of parameters this mojo uses --> <parameters> <parameter> <!-.A named overlay to augment the cloned life cycle for this fork | only |-> <lifecycle>mine</lifecycle> <!-.Whether the configuration for this mojo should be inherited | from parent to child POMs by default.resolver. |-> <property>prop</property> <!-. --> <role>org. |-> <goal>goal</goal> </execute> <!-. |-> <requiresDirectInvocation>true</requiresDirectInvocation> <!-.This is an optional classifier for which instance of a particular | component type should be used.Another mojo within this plugin to execute before this mojo | executes. --> <name>nom</name> <!-.The phase of the forked life cycle to execute --> <phase>initialize</phase> <!-.maven. |-> <execute> <!-.This is the type for the component to be injected.artifact.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.List of non-parameter application components used in this mojo --> <components> <component> <!-.ArtifactResolver</role> <!-.
The description of what the mojo is meant to accomplish --> <description> This is a test.apache.If this is specified.maven.MavenProject</type> <!-.property}</expression> <!-.The Java type of this mojo parameter --> <type>org.Whether the user can edit this parameter directly in the POM | configuration or the command line |-> <readonly>true</readonly> <!-.Appendix A: Resources for Plugin Developers <!-.An alternative configuration name for this parameter --> <alias>otherProp</alias> <!-. </description> <!-.The expression used to extract this parameter's value --> <expression>${my.The description of this parameter --> <description>Test parameter</description> <!-.The default value provided when the expression won't resolve --> <defaultValue>${project.project.artifactId}</defaultValue> <!-. it provides advice on which alternative mojo | to use. this element will provide advice for an | alternative parameter to use instead. |-> <deprecated>Use something else</deprecated> </parameter> </parameters> <!-. |-> <deprecated>Use another mojo</deprecated> </mojo> </mojos> </pluginMetadata> Better Builds With Maven 267 .When this is specified.
Star Trek Better Builds With Maven 268 . Spock: I find that remark insulting. .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.
xml LICENSE.txt README. This would include compiled classes. may generate some sources from a JavaCC grammar. target/generated-sources/<plugin-id> Standard location for generated sources. Standard location for test resources.1. Standard Directory Structure Table B-1: Standard directory layout for maven project content Standard Location Description pom. For example.Appendix B: Standard Conventions B. Standard location for test resource filters. which is always at the top-level of a project. generated sources that may be compiled.txt target/ Maven's POM. Standard location for resource filters. Standard location for application configuration files. the generated site or anything else that might be generated as part of your build. Standard location for application resources. Better Builds With Maven 269 . Standard location for assembly descriptors. A simple note which might help first time users and is optional. A license file is encouraged for easy identification by users and is optional. 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 test sources. Directory for all generated output.
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> <!-.Reporting Conventions --> <reporting> <outputDirectory>target/site</outputDirectory> </reporting> .Appendix B: Standard Conventions B. </project> Better Builds With Maven 270 .org/maven2</url> <layout>default</layout> <snapshots> <enabled>false</enabled> </snapshots> <releases> <updatePolicy>never</updatePolicy> </releases> </pluginRepository> </pluginRepositories> <!-.org/maven2</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <!-. Maven's Super POM <project> <modelVersion>4..0</modelVersion> <name>Maven Default Project</name> <!-.0.maven.Plugin Repository Conventions --> <pluginRepositories> <pluginRepository> <id>central</id> <name>Maven Plugin Repository</name> <url>http://repo1.maven..2.Repository Conventions --> <repositories> <repository> <id>central</id> <name>Maven Repository Switchboard</name> <layout>default</layout> <url>http://repo1.
Perform actions required after integration tests have been executed. Compile the source code of the project. 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 . for example to filter any values. for example to do byte code enhancement on Java classes. Copy and process the resources into the test destination directory. Done in an integration or release environment. Generate resources for inclusion in the package. Generate any source code for inclusion in compilation. ready for packaging. This may including cleaning up the environment. Process the source code. Compile the test source code into the test destination directory Run tests using a suitable unit testing framework. These tests should not require the code be packaged or deployed.Appendix B: Standard Conventions B. Process and deploy the package if necessary into an environment where integration tests can be run. Description Validate the project is correct and all necessary information is available. Generate any test source code for inclusion in compilation. Install the package into the local repository. such as a JAR.3. copies the final package to the remote repository for sharing with other developers and projects. for example to filter any values. Run any checks to verify the package is valid and meets quality criteria. Create resources for testing. Post-process the generated files from compilation. Perform actions required before integration tests are executed. Process the test source code. Copy and process the resources into the destination directory. for use as a dependency in other projects locally. Take the compiled code and package it in its distributable format. This may involve things such as setting up the required environment.
org/axistools-maven-plugin/ Cargo Containers Reference .http://ws. June 8.org/ Checkstyle .http://java.codehaus.html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL Axis Tool Plugin .codehaus.sf.apache.org/eclipse/development/java-api-evolution.org/axis/java/ AxisTools Reference Documentation . Evolving Java-based APIs.codehaus.eclipse.html Bloch.http://cargo.http://cargo.http://mojo. Jim.html Better Builds With Maven 272 .http://cargo.com/docs/books/effective/ Web Sites Axis Building Java Classes from WSDLhttp://ws.codehaus.apache.http://checkstyle.Bibliography Bibliography Online Books des Rivieres. 2001 http://www. Sun Developer Network .http://cargo.org/Containers Cargo Container Deployments . Joshua.http://cargo.sun.org/Deploying+to+a+running+container Cargo Plugin Configuration Options .codehaus.net/config.org/axis/java/userguide.org/Maven2+plugin Cargo Merging War Files Plugin . Effective Java.codehaus.org/Merging+WAR+files Cargo Reference Documentation .
http://tomcat.net/ Clirr .html Maven Plugins .www.org/Maven2+Plugin Better Builds With Maven 273 .http://dbunit.ibiblio.http://clirr.apache.sun.html Xdoclet2 .codehaus.apache.org/maven-model/maven.org/ PMD Best Practices .maven.mortbay.org/tomcat-5.apache.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.sf.html POM Reference .net/ XDoclet EjbDocletTask .http://mojo.http://pmd.html Jester .apache.http://jester.http://mojo.org/download.org/ Simian .org Maven Downloads .net/bestpractices.codehaus.codehaus.apache.http://maven.www.html XDoclet Maven Plugin .http://xdoclet.apache.redhillconsulting.html Introduction to the Build Life Cycle – Maven .org/guides/introduction/introduction-to-archetypes.sf.org/jetty6/maven-plugin/index.html Ruby on Rails .http://cobertura.rubyonrails.http://checkstyle.com.http://www.org/plugins/maven-ejb-plugin/ ibiblio.sourceforge.sf.Bibliography Checkstyle Available Checks .http://maven.com Introduction to Archetypes .net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.net/availablechecks.org XDoclet2 Maven Plugin .http://xdoclet.apache.http://pmd.au/products/simian/ Tomcat Manager Web Application .sf.http://maven.http://jetty.net/ EJB Plugin Documentation .org/xdoclet-maven-plugin/ XDoclet Reference Documentation http://xdoclet.org/guides/introduction/introduction-to-thelifecycle.com/j2ee/reference/api/ Maven 2 Wiki .0-doc/manager-howto.org/jdiff-maven-plugin Jetty 6 Plugin Documentation .html Cobertura .sf.http://maven.sourceforge.codehaus.org/plugins/maven-clover-plugin/ DBUnit Java API .http://maven.http://www.http://maven.net/ Clover Plugin .codehaus.apache.http://java.html PMD Rulesets .html Jdiff .sf.sourceforge.http://xdoclet.http://mojo.net/howtomakearuleset.http://maven.apache.net J2EE Specification .sourceforge.http://xdoclet.org/plugins/ Mojo .html Xdoclet .
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