text:
This action might not be possible to undo. Are you sure you want to continue?
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
and those of St Paul's Anglican church for all of their care. 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. for their copy editing. help and encouragement in everything that I do. To Natalie Burdick. John and Carlos congratulations on a job well done. and for leaving her native Michigan to live in a bizarre foreign land. My most heartfelt thanks and all of my love go to my wife Laura. and submit fixes. Maven is the cumulative work of nearly 40 committers and an even larger number of contributors who've taken the time to give feedback. for her dedication to see this through. and to do so with such a number of my talented friends and colleagues. contribute ideas. 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. but for the opportunity to work in such a tremendous environment. formatting and development of the book's template. I'm grateful to have had the opportunity to finally write a book about Maven.support. for trusting my judgment to use Maven on our projects. I continue to hope that it was for me and not just because of the warmer climate. doing what you enjoy and being able to see your our own personal vision realized. Brett Porter ii . doing additional copy editing and organizing its release. I'd like to say how much I appreciate all of my family. for sticking with it through some of the early development and for holding the development team to a higher standard. despite having all of the least enjoyable tasks of keeping the development on track. To the authors Jason. I'd also like to thank Paul Russell and the development team during my time at Fairfax Digital. friends. for loving me as I am despite all my flaws. Personally. whose work made this book as professional and polished as it is. To Lisa Malgeri and Elena Renard. 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. answer questions. and without whom I would never have been able to get involved in the project in the first place. for her great patience and sacrifice in allowing me to work at all hours from home. Vincent. Both I and the Maven project owe you all a debt of gratitude. test features.I'd like to start by thanking everyone who has been involved in the Maven community over the years.
Napoleon Esmundo C. Carlos Sanchez Many thanks to Jesse McConnell for his contributions to the book. Bill Dudney. I'd like to thank my family for their continuous support. Jerome Lacoste. and the teammates during my time at Softgal. David Blevins. Jerome Lacoste. Finally. It is much appreciated. for accepting my crazy ideas about open source. Jason. Chris Berry. Vincent. we would like to thank all the reviewers who greatly enhanced the content and quality of this book: Natalie Burdick. Abel Rodriguez. Fabrice Bellingard. Elena Renard and Joakim Erdfelt for their many contributions to the book. Felipe Leme. Lester Ecarma. Ruel Loehr. John. Tim O'Brien. Allan Ramirez. Mark Hobson. Stephane Nicoll. Brett and Carlos iii . especially my parents and my brother for helping me whenever I needed. Ramirez. Emmanuel Venisse and John Tolentino.I would like to thank professor Fernando Bellas for encouraging my curiosity about the open source world. Also. Thanks also to all the people in Galicia for that delicious food I miss so much when traveling around the world. All of us would like to thank Lisa Malgeri.
specializing in open source consulting. where he is the technical director of Pivolis. Inc. He created his own company. Jason Van Zyl: As chief architect and co-founder of Mergere.. roasting coffee. discovering Maven while searching for a simpler way to define a common build process across projects. He continues to work directly on Maven and serves as the Chair of the Apache Maven Project Management Committee. and is a Member of the Apache Software Foundation. financial. and in 2005. This is Vincent's third book. John lives in Gainesville. John was elected to the Maven Project Management Committee (PMC). published by Manning in 2003 (ISBN 1-930-11099-5) and Maven: A Developer's Notebook. software development. CSSC.. of course. joining the Maven Project Management Committee (PMC) and directing traffic for both the 1. When he's not working on Maven. Immediately hooked. Australia. his focus in the Maven project has been the development of Maven 2.0 major releases. Brett is a co-founder and the Director of Engineering at Mergere. Brett became increasingly involved in the project's development. and started early in the open source technology world. Build management and open source involvement have been common threads throughout his professional career. and working on his house. as well as to various Maven plugins. Carlos Sanchez received his Computer Engineering degree in the University of Coruña. telecommunications and. Vincent lives and works in Paris. Brett has become involved in a variety of other open source projects. He was invited to become a Maven committer in 2004. In addition to his work on Maven. Emily. published by O'Reilly in 2005 (ISBN 0-596-00750-7). Florida with his wife. He enjoys cycling and raced competitively when he was younger. Spain. Brett Porter has been involved in the Apache Maven project since early 2003. He is grateful to work and live in the suburbs of Sydney. he founded the Jakarta Cactus project-a simple testing framework for server-side Java code and the Cargo project-a J2EE container manipulation framework. when he began looking for something to make his job as Ant "buildmeister" simpler. 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. Vincent has directly contributed to Maven's core. iv . John enjoys amateur astrophotography. which has led to the founding of the Apache Maven project. he is a co-author of JUnit in Action. Jason van Zyl focuses on improving the Software Development Infrastructure associated with medium to large scale projects.0 and 2.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. a company which specializes in collaborative offshore software development using Agile methodologies. Inc. Since 2004. Additionally. John Casey became involved in the Maven community in early 2002. where he hopes to be able to make the lives of other developers easier.
..............................................................................................3................................. Creating Applications with Maven............................ Summary........6.... Getting Started with Maven. 34 2...............1............................23 Maven's build life cycle.........26 Locating dependency artifacts...................4.... 48 3.........................................................6............................6............ Reuse of Build Logic................................................................................................................................................................. Coherent Organization of Dependencies........................2.....2............................... 25 1.........................................1..................................................Table of Contents Preface....................................4....... Handling Test Classpath Resources...................................................3........................................................................ 23 Maven's project object model (POM)............................................................................................................................................................... 40 2.................................................................................. Using Project Inheritance................4........1..................1........................ 49 3.......................................46 2......................................................2......................2...................... Managing Dependencies......................................... 42 2..... Preventing Filtering of Binary Resources.. Using Maven Plugins......................................................22 Standard naming conventions.................................................................................... Declarative Execution................... 23 1.......... 16 1..2..................................1................................... 49 3...................................................................................................................................3......................................................... Compiling Application Sources................................................................................................... Handling Classpath Resources... Using Snapshots....................................5................................... 45 2.......................8................. 36 2............. What is Maven?............................. 17 1................................... Packaging and Installation to Your Local Repository.................................52 3........................................................................................31 2................................2....................... 21 One primary output per project..... Maven's Origins........56 v .............................................2.............. Convention Over Configuration...................... 29 2.......................................28 1.................................... Preparing to Use Maven......... Maven's Principles.......................................................................... 25 Local Maven repository...... Introduction....................................................................................................38 2................ Setting Up an Application Directory Structure............ Maven Overview.................................................................................................................................................2.................3.. Creating Your First Maven Project.............1.......................................................................................................................................15 1.......2......................................................................................1.............. 41 2........... Introducing Maven...............6.....................................................1........ Filtering Classpath Resources..............................................................................................54 3.......................................................... Compiling Test Sources and Running Unit Tests..........................3................... 30 2.............. 32 2................................................... 20 1....................................................................................................................... 22 1.......... 47 3..................3........................................ 16 1........................................................................................................5...................1..........7............. What Does Maven Provide?.......................... Maven's Benefits...... 18 1................................................................................................................................ 12 1........ 20 Standard directory layout for projects.......................................................................................2.....................
................................ BuildInfo Example: Capturing Information with a Java Mojo .... 125 5.............................................................................. Introducing the DayTrader Application............................................................... Summary..........................................................................100 4..........................................................................................................9........................................ 137 vi ... 76 4..................................... Deploying EJBs.... 75 4..............................................................................11.....................103 4..3................................. 91 4..........1.............................................................3..........................4....4.... 136 The output...... 66 3...........................................................1.................................11....................................................................................124 5................................................. Utilizing the Build Life Cycle................................................................... 128 The plugin descriptor..........................................................11..................................................................... Deploying to the File System.......................................................... 78 4..........................................107 4................ Developing Custom Maven Plugins....................................... 125 5.................................................... 135 Binding to the life cycle....................... 67 3....2............................13...........................................................................................................................9................................................................................ Deploying with FTP.........................................3.........6..............6................1............................. 132 5.....................................................................9..14...... 95 4......................... 61 3...................12...67 3.............. 76 4..............................................................................................10......................................................57 3... Building an EJB Module With Xdoclet.............................................. Using Profiles........................3....................................... A Review of Plugin Terminology...... The Plugin Framework................................................................................................................ 66 3.................................................................................................................................................1....................... Building J2EE Applications.................. Bootstrapping into Plugin Development................................................................ Improving Web Development Productivity..................... Deploying with an External SSH....... Deploying with SFTP..........................................................................................................................116 4............ A Note on the Examples in this Chapter.............12............................................................................2....................... 81 4.................................................................................... 126 Participation in the build life cycle....................5....... Organizing the DayTrader Directory Structure............................................. 74 4..........................................3..... Developing Your First Mojo......8.................................................................... 131 5....... Building a Web Application Project. Building an EJB Project... Plugin Development Tools.................................... 68 3.....................................................3.............. 85 4.......................................... Resolving Dependency Conflicts and Using Version Ranges.............................. Building a Web Services Client Project................ 123 5....................8.4..126 5................................................................................................. Building an EAR Project.....................13...................................................................................................................................................................................................... Deploying Web Applications...................1................. Deploying with SSH2.......................................................113 4.........................................................................7.............. Deploying a J2EE Application............. 129 Choose your mojo implementation language......................... Deploying your Application.................................. 131 5...........11....66 3.............................................................................. 127 Accessing build information.........1......89 4.........................................10........................................................................................................................................................................................... Creating a Web Site for your Application................3............................................... Introduction................................................128 5.......2........................................................................ 133 The plugin POM......... 132 The mojo.... Introduction.. Testing J2EE Applications............................................................2............................... Summary...... 132 Using the archetype plugin to generate a stub plugin project.................................................60 3.........................68 3..7...
... 228 vii ................. 155 6......7....................................................... 228 8...................................................................................... Introduction.............. Migrating to Maven...............................................6............................ Configuration of Reports.................................... 189 6.........................................................................................................................................................9.................................................. Creating a Shared Repository............................................................................ 153 5..................................................................5........... 138 The Ant target.........1................................................ Monitoring and Improving the Health of Your Releases......... Monitoring and Improving the Health of Your Source Code............................................................................................. 174 6......................... 214 7................................ 143 5................................................................ 150 Note on testing source-roots and resources...............................................................................................4............................149 Accessing the resource list............................................1...........................................................................11............................................................ How to Setup a Consistent Developer Environment.......................... Accessing Project Sources and Resources......................... Monitoring and Improving the Health of Your Dependencies.... 156 6.....................1................................................. 138 The mojo metadata file................. Summary.........199 7...................................................10......................8............................ Team Dependency Management Using Snapshots...........5........................................................................................... 194 7........................................................ 171 6....9. Monitoring and Improving the Health of Your Tests........ 227 8............................ 202 7..................................5.......................................................................................... 148 Accessing the source-root list............................................................. Cutting a Release.................................2...................... 205 7............................. 152 5......................................5..... Separating Developer Reports From User Documentation... Attaching Artifacts for Installation and Deployment......................................................6......... Advanced Mojo Development......7.................................................................................. 160 6........................ 158 6............................... 144 BuildInfo example: logging dependency versions....... Assessing Project Health with Maven..................181 6....2..........................................................3................5................................................................................................................4...........................................5.................... Creating Reference Material........................ 193 7...................12........................................................................................................................................... Continuous Integration with Continuum............ 140 Binding the notify mojo to the life cycle......................................... 169 6.............................................3............................... 195 7........ 226 8....1..193 6. 143 Requiring dependency resolution.......................................4.............. Summary....................................................................................... Viewing Overall Project Health................... 147 Adding a resource to the build................................ Creating a Standard Project Archetype..................219 7........................................ Introducing the Spring Framework......................... Accessing Project Dependencies............................................................ BuildInfo Example: Notifying Other Developers with an Ant Mojo.....................1................................1.................2...........................................................8.. 138 Modifying the plugin POM for Ant mojos....................................2...........................3.............................................186 6....................................163 6........................ Creating an Organization POM........................ 157 6....................................................................................6............................................................................5........................................................................... 142 5.................196 7......... 143 Injecting the project dependency set.................................. 146 Adding a source directory to the build........................145 5......... Adding Reports to the Project Web site.......... Summary...................................... What Does Maven Have to do With Project Health?...................... Choosing Which Reports to Include.................................. Team Collaboration with Maven........................................... 221 7................................................................................................ The Issues Facing Teams................
........................ Java Mojo Metadata: Supported Javadoc Annotations.....................................2.....260 Plugin descriptor syntax..6.....................................................................................................................1.................................... Building Java 5 Classes............1.......................................................................................................................................... 249 8. Mojo Parameter Expressions. 243 8... 252 Life-cycle phases......................1........................................................ Maven's Default Build Life Cycle......6.................................................4................. 258 A.... 265 Appendix B: Standard Conventions................... Non-redistributable Jars....... Maven's Life Cycles.................................................................................................................. Summary................................................. The site Life Cycle.......................................................... Testing......... 257 Life-cycle phases.......................................... Avoiding Duplication.......................... 242 8............2...230 8.........236 8.....1................................................... 236 8......................................................................................................................8........................................................................ 270 B.................. 260 Plugin metadata.............. Creating POM files....................................................................................... 254 Bindings for the maven-plugin packaging......................................................6...................3......4........................................8........................................................................ Standard Directory Structure........... Ant Metadata Syntax......................................................................................................6..................................... 256 Life-cycle phases..............................................2.................3................................................................................................240 8...............................................................................2.............................255 A...1......................................................2. Compiling.............................................2.......................................5................................................................................................2...........6.............. 240 8................................ 264 Field-level annotations....256 Default life-cycle bindings................................................... Restructuring the Code.................................. 244 8....................................................................................................................................................................................................................................................................................................................................... 249 8.................... The clean Life Cycle.............................................................................. 272 viii .256 A.... Complex Expression Roots.................................5..................................................1............................... Some Special Cases................3.......... 271 Bibliography................................................................3..................... Maven's Super POM............................................................257 A..........2............... 268 B...................................................................................................................2..........252 Bindings for the jar packaging..............................................................................................................................7..........1...................................................................... 265 A................................................................................................................................. 264 Class-level annotations.....................................2...................................................................................... Referring to Test Classes from Other Modules..........................................2...........................6........... 247 8............. 259 A........................... 269 B............4............................ 251 A........................................................................................................ 244 8.260 A..5......................................................................................5................................................................ 243 8............1...........................5..................................... Using Ant Tasks From Inside Maven.....257 Default Life Cycle Bindings................................................................................................................................... 250 Appendix A: Resources for Plugin Developers.....................1.......................................... Compiling Tests... Where to Begin?..................6...............................6................ Running Tests............................ Other Modules...................................................................................................... 258 A.......................252 A........ 250 8......... Simple Expressions................................................ The Expression Resolution Algorithm. The default Life Cycle.........................2........2..........................................
................................................................................................................................................................................264 Table A-8: Field-level annotations.......................164 Table 6-2: Report highlights.......................................................................... 51 Table 3-2: Examples of version ranges...List of Tables Table 3-1: Module packaging types................................... 103 Table 5-1: Life-cycle bindings for jar packaging.................71 Table 4-1: WAR plugin configuration properties................................................................................................................................................................................... 127 Table 5-2: Key differences between compile-time and test-time mojo activities......................................................................152 Table 6-1: Project Web site content types.......................................................................................................................................................................................................................................................................... 256 Table A-4: The site life-cycle bindings for the jar packaging.................................................................................................271 ix .............................. 169 Table 6-3: Built-in Checkstyle configurations......................... 180 Table A-1: The default life-cycle bindings for the jar packaging.........................................................................................................................................................254 Table A-2: A summary of the additional mojo bindings..................................................................................................................................258 Table A-6: A summary of the valid root objects for plugin parameter expressions......................................................... 255 Table A-3: The clean life-cycle bindings for the jar packaging.........269 Table B-2: Phases in Maven's life cycle................................................................................................................................................................................................................................................. 265 Table B-1: Standard directory layout for maven project content......................................................259 Table A-7: A summary of class-level javadoc annotations................................................................ 257 Table A-5: Primitive expressions supported by Maven's plugin parameter...................... 94 Table 4-2: Axis generated classes.........................................................59 Table 3-3: Site descriptor..............................................................................
......................................... 165 Figure 6-4: The directory layout with a user guide...........................................................................86 Figure 4-7: Directory structure for the DayTrader web module showing some Web application resources...................................................................................97 Figure 4-10: Directory structure of the wsappclient module...................................................... 188 x .................................................................................................................................................................................................................................................... 174 Figure 6-8: An example CPD report..................................................................... 40 Figure 2-3: Directory structure of the JAR file created by Maven.............................................................................41 Figure 2-4: Directory structure after adding test resources......................................................................79 Figure 4-4: Nested directory structure for the EAR.............List of Figures Figure 1-1: Artifact movement from remote to local repository....................166 Figure 6-5: The new Web site...................................................................................................................................... 73 Figure 3-6: The sample generated site........................................................ 76 Figure 4-2: Module names and a simple flat directory structure................................. 33 Figure 2-2: Directory structure after adding the resources directory......................................................................................................................................................................................................51 Figure 3-3: Version parsing.......................... 74 Figure 4-1: Architecture of the DayTrader application................................................................... 80 Figure 4-5: Directory structure for the DayTrader ejb module..........69 Figure 3-5: The target directory.................................... 158 Figure 6-2: The Surefire report................................. 28 Figure 2-1: Directory structure after archetype generation...................79 Figure 4-3: Modules split according to a server-side vs client-side directory organization..................................................................................................................................................................................................... EJB and Web modules...................178 Figure 6-9: An example Checkstyle report..................................................................................................................................................................................................................................................................................................................... 103 Figure 4-11: Directory structure of the ear module...91 Figure 4-8: DayTrader JSP registration page served by the Jetty6 plugin................................................................................................................................................. 179 Figure 6-10: An example Cobertura report........................................................................................................................ 116 Figure 4-14: Directory structure for the functional-tests module............................................................................................. 27 Figure 1-2: General pattern for the repository layout..................................................................................................................................................................................................................... 159 Figure 6-3: The initial setup.....................................................................................113 Figure 4-13: The new functional-tests module amongst the other DayTrader modules ............171 Figure 6-7: An example PMD report...............................................................................................182 Figure 6-11: An example dependency report.................................................................................... 81 Figure 4-6: Directory structure for the DayTrader ejb module when using Xdoclet................................................................ 50 Figure 3-2: Proficio-stores directory........................ 118 Figure 6-1: The reports generated by Maven................................................ 167 Figure 6-6: An example source code cross reference............186 Figure 6-12: The dependency convergence report............................................59 Figure 3-4: The site directory structure.................................................................. 42 Figure 3-1: Proficio directory structure................................................................................................................................................... 28 Figure 1-3: Sample directory structure.................................................................................................................................. 96 Figure 4-9: Modified registration page automatically reflecting our source change.................................................... 107 Figure 4-12: Directory structure of the ear module showing the Geronimo deployment plan......................................................
.................................. 211 Figure 7-5: Adding a build definition for site deployment....................................................................................217 Figure 7-7: Archetype directory layout.................................................................................245 Figure 8-5: Dependency relationship.................................................................................................................................................................................. 219 Figure 8-1: Dependency relationship between Spring modules.................................................................................................................206 Figure 7-2: Add project screen shot........................................245 Figure 8-4: The final directory structure......................................................... 212 Figure 7-6: Continuum configuration......................... 208 Figure 7-3: Summary page after projects have built. with all modules............................................................. 229 Figure 8-2: A sample spring module directory.......................................................................................................................................................................Figure 6-13: An example Clirr report..................................................... 209 Figure 7-4: Schedule configuration..............230 Figure 8-3: A tiger module directory...........................................................................................................................................................................................................................189 Figure 7-1: The Continuum setup screen..............................................................................246 xi .......................................................................................................................................
0. 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. which provides a wide range of topics from understanding Maven's build platform to programming nuances. reading this book will take you longer. it does not take long to realize those benefits. As you will soon find. 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. this guide endeavors to provide a quick solution for the need at hand.x).Preface Preface Welcome to Better Builds with Maven. Better Builds With Maven 12 . Perhaps. it is recommended that you step through the material in a sequential fashion. We hope that this book will be useful for Java project managers as well. an indispensable guide to understand and use Maven 2. Maven 2 is a product that offers immediate value to many users and organizations. For first time users. For users more familiar with Maven (including Maven 1. Maven works equally well for small and large projects.
illustrates Maven's best practices and advanced uses by working on a real-world example application. Finally. Chapter 7 discusses using Maven in a team development environment and Chapter 8 shows you how to migrate Ant builds to Maven. Web Services). Chapter 4. and compiling and packaging it. create JARs. Chapter 7. and document for reuse the artifacts that result from a software project. In this chapter you will learn to setup a directory structure for a typical application and the basics of managing the application's development with Maven. you should be up and running with Maven. explains a migration path from an existing build in Ant to Maven. shows how to create the build for a full-fledged J2EE application. Better Builds With Maven 13 . and install those JARs in your local repository using Maven. visualize. Chapter 8. looks at Maven as a set of practices and tools that enable effective team communication and collaboration. Chapter 4 shows you how to build a J2EE application and deploy it. Chapter 2. compile and test the code. After reading this chapter. shows how to use Maven to build J2EE archives (JAR. From there. EJB. Chapter 1. Introducing Maven. These tools aid the team to organize. 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. you will be able to keep your current build working. Getting Started with Maven. you will be revisiting the Proficio application that was developed in Chapter 3.Preface Organization Here is how the book is organized. they discuss what Maven is and get you started with your first Maven project. Chapter 5. In this chapter. goes through the background and philosophy behind Maven and defines what Maven is. WAR. and learning more about the health of the project. Chapter 6. Developing Custom Maven Plugins. Creating Applications with Maven. the chapter covers the tools available to simplify the life of the plugin developer. You will learn how to use Maven to ensure successful team development. At this stage you'll pretty much become an expert Maven user. Chapter 6 discusses project monitoring issues and reporting. After reading this chapter. and how to use Maven to deploy J2EE archives to a container. reporting tools. Chapter 3 builds on that and shows you how to build a real-world project. Team Collaboration with Maven. Migrating to Maven. Chapter 5 focuses on developing plugins for Maven. Building J2EE Applications. It starts by describing fundamentals. At the same time. EAR. discusses Maven's monitoring tools. and how to use Maven to generate a Web site for your project. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. you will be able to take an existing Ant-based build. The first two chapters are geared toward a new user of Maven 2. gives detailed instructions on creating your first project. Chapter 3. Assessing Project Health with Maven. focuses on the task of writing custom plugins.
On this page you will be able to view all errata that have been submitted for this book and posted by Maven editors. So if you have Maven 2. Then.0 installed. simply locate the appropriate Download link on the page and you can obtain all the source code for the book.mergere. You can also click the Submit Errata link on this page to notify us of any errors that you might have found.com. How To Contact Us We want to hear about any errors you find in this book.mergere. We offer source code for download. We'll check the information and. if appropriate. To find the errata page for this book. so occasionally something will come up that none of us caught prior to publication.Preface Errata We have made every effort to ensure that there are no errors in the text or in the code. and technical support from the Mergere Web site at http://library.com and locate the title in the title lists.mergere. errata. click the Book Errata link. on the book details page. Once at the site.com. How To Download the Source Code All of the source code used in this book is available for download at http://library. go to http://library. However. then you're ready to go. post an update to the book's errata page and fix the problem in subsequent editions of the book. we are human. Better Builds With Maven 14 .com. Simply email the information to community@mergere.
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: .Convention over configuration .Albert Einstein Better Builds With Maven 15 .Reuse of build logic .1. . but not any simpler.Coherent organization of dependencies .Declarative execution .
Revolutionary ideas are often difficult to convey with words. In addition to solving straightforward. distribution. Maven Overview Maven provides a comprehensive approach to managing software projects. This book focuses on the core tool produced by the Maven project. It is a combination of ideas. and deploying project artifacts. it will prime you for the concepts that are to follow. to team collaboration. standards. Maven provides the necessary abstractions that encourage reuse and take much of the work out of project builds. Too often technologists rely on abstract phrases to capture complex topics in three or four words. Perhaps you picked up this book because someone told you that Maven is a build tool.Introducing Maven 1. sound-bite answer. "Well it is a build tool or a scripting framework" Maven is more than three boring.1. Don't worry. Maven and the technologies related to the Maven project are beginning to have a transformative effect on the Java community. to view it in such limited terms is akin to saying that a web browser is nothing more than a tool that reads hypertext. When someone wants to know what Maven is. If you are interested in a fuller. to documentation. and the deployment process. and a piece of software used to manage and describe projects. but the term project management framework is a meaningless abstraction that doesn't do justice to the richness and complexity of Maven. It simultaneously reduces your headcount and leads to remarkable operational efficiencies. Maven 2. From compilation.1. what is it? Here's one attempt at a description: Maven is a set of standards. Maven can be the build tool you are looking for. and many developers who have approached Maven as another build tool have come away with a finely tuned build system. you can stop reading now and skip to Chapter 2. It provides a framework that enables easy reuse of common build logic for all projects following Maven's standards. uninspiring words. richer definition of Maven read this introduction. and software." Better Builds With Maven 16 . a repository format. If you are reading this introduction just to find something to tell your manager1. to distribution. Maven also brings with it some compelling second-order benefits. It's the most obvious three-word definition of Maven the authors could come up with. The Maven project at the Apache Software Foundation is an open source community which produces software tools that understand a common declarative Project Object Model (POM). and it is impossible to distill the definition of Maven to simply digested sound-bites. If Maven isn't a "project management framework". documentation. testing. It defines a standard life cycle for building. and with repetition phrases such as project management and enterprise software start to lose concrete meaning. You may have been expecting a more straightforward answer. first-order problems such as simplifying builds. a framework that greatly simplifies the process of managing a software project. but this doesn't tell you much about Maven. they will usually ask "What exactly is Maven?".1. 1 You can tell your manager: "Maven is a declarative project management tool that decreases your overall time to market by effectively leveraging your synergies. While you are free to use Maven as "just another build tool". 1. What is Maven? Maven is a project management framework. and they expect a short.
and started focusing on component development. Maven's Origins Maven was borne of the practical desire to make several projects at the Apache Software Foundation (ASF) work in the same. If you followed the Maven Way.1. the barrier to entry for a project with a difficult build system was extremely high. developers were building yet another build system. Maven is not just a build tool. Once you get up to speed on the fundamentals of Maven. the Turbine developers used a different approach to site generation than the developers of Jakarta Commons. It is a set of standards and an approach as much as it is a piece of software. every project at the ASF had a different approach to compilation. Developers within the Turbine project could freely move between subcomponents. Many people come to Maven familiar with Ant so it's a natural association. such as Jakarta Commons. Maven's standards and central repository have defined a new naming system for projects. distribution. Soon after the creation of Maven other projects. but Maven is an entirely different creature from Ant. It is the next step in the evolution of how individuals and organizations collaborate to create software systems. and not just a replacement for Ant. predictable way. The ASF was effectively a series of isolated islands of innovation. So to answer the original question: Maven is many things to many people. 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. knowing clearly how they all worked just by understanding how one of them worked. It is a way of approaching a set of software as a collection of interdependent components which can be described in a common format. Ultimately. The same effect extended to testing. If developers spent time understanding how one project was built.2.Introducing Maven As more and more projects and products adopt Maven as a foundation for project management. you will wonder how you ever developed without it. they would not have to go through this process again when they moved on to the next project. Maven's standard formats enable a sort of "Semantic Web" for programming projects. and deploying. this copy and paste approach to build reuse reached a critical tipping point at which the amount of work required to maintain this collection of build systems was distracting from the central task of developing high-quality software. Using Maven has made it easier to add external dependencies and publish your own components. There were some common themes to each separate build. Etc. Prior to Maven. Maven entered the scene by way of the Turbine project. People stopped figuring out creative ways to compile. and it immediately sparked interest as a sort of Rosetta Stone for software project management. test. In addition. and Web site generation. and package. 1. The build process for Tomcat was different from the build process used by Struts. but different communities were creating different build systems of varied complexity and there was no reuse of build logic between projects. it becomes easier to build relationships between projects and to build systems that navigate and report on these relationships. This lack of a common approach to building software meant that every new project tended to copy and paste another project's build system. generating documentation. the Codehaus community started to adopt Maven 1 as a foundation for project management. Better Builds With Maven 17 . Instead of focusing on creating good component libraries or MVC frameworks. generating metrics and reports. your project gained a build by default.
and much more transparent. existing Ant scripts and Make files can be complementary to Maven and used through Maven's plugin architecture. assemble.1. if your project currently relies on an existing Ant build script that must be maintained. more reusable.3. Make files and Ant are alternatives to Maven. The key value to developers from Maven is that it takes a declarative approach rather than developers creating the build process themselves. You describe your project using Maven's model. and the software tool named Maven is just a secondary side-effect of this model. Maven allows developers to declare goals and dependencies and rely on Maven's default structures and plugin capabilities to build the project. and if you can apply a testing plugin to one project. Given the highly inter-dependent nature of projects in open source. test. to provide a common layout for project documentation. more maintainable. Maven provides a useful abstraction in the same way an automobile provides an abstraction most of us are familiar with. if you've learned how to drive a Jeep. which forms the basis of the entire Maven system. Maven provides a common project "language". However. and to retrieve project dependencies from a shared storage area makes the building process much less time consuming. the car provides a known interface. Developers can build any given project without having to understand how the individual plugins work (scripts in the Ant world). An individual Maven project's structure and contents are declared in a Project Object Model (POM). 1. and easier to comprehend. Maven's ability to standardize locations for source files. Much of the project management and build orchestration (compile. and output. referred to as "building the build". install) is effectively delegated to the POM and the appropriate plugins. Maven takes a similar approach to software projects: if you can build one Maven project you can build them all. Maven is about the application of patterns in order to facilitate project management through the reuse of common build strategies. you can easily drive a Camry. Projects and systems that use this standard declarative approach tend to be more transparent. and you gain access to expertise and best-practices of an entire industry.Introducing Maven Whereas Ant provides a toolbox for scripting builds. documentation. you can apply it to all projects. Maven provides you with: A comprehensive model for software projects • Tools that interact with this Declarative Model • Better Builds With Maven 18 . What Does Maven Provide? It provides a comprehensive model that can be applied to all software projects. When you purchase a new car. Plugins allow developers to call existing Ant scripts and Make files and incorporate those existing functions into the Maven build life cycle.
When everyone is constantly searching to find all the different bits and pieces that make up a project.Introducing Maven Organizations and projects that adopt Maven benefit from: • Coherence .Maven allows organizations to standardize on a set of best practices. When you adopt Maven you are effectively reusing the best practices of an entire industry. it is improbable that multiple individuals will work productively together on a project.Organizations that adopt Maven can stop building the build. Because Maven projects adhere to a standard model they are less opaque. • • • Without these characteristics. When using Maven it is easier to create a component and integrate it into a multi-project build.Maven lowers the barrier to reuse not only of build logic but of components. The definition of this term from the American Heritage dictionary captures the meaning perfectly: "Marked by an orderly. Agility . This is a natural effect when processes don't work the same way for everyone. Better Builds With Maven 19 . there is little chance anyone is going to comprehend the project as a whole. It is easier for developers to jump between different projects without a steep learning curve that accompanies a custom. logical." Reusability . home-grown build system. Without visibility it is unlikely one individual will know what another has accomplished and it is likely that useful code will not be reused. Maintainability . and aesthetically consistent relation of parts.Maven is built upon a foundation of reuse. Maven projects are more maintainable because they have fewer surprises and follow a common model. and start focusing on the application. As a result you end up with a lack of shared knowledge along with the commensurate degree of frustration among team members. When code is not reused it is very hard to create a maintainable system.
that we shouldn't pass judgment on one form of development over another."2 2 O'Reilly interview with DHH Better Builds With Maven 20 . you gain an immense reward in terms of productivity that allows you to do more. As mentioned earlier Maven creates a sense of structure so that problems can be approached in terms of this structure. One of those ideals is flexibility.2. 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. It eschews placing the old ideals of software in a primary position. Rails does. With Rails. One characteristic of opinionated software is the notion of "convention over configuration". If you are happy to work along the golden path that I've embedded in Rails. you're rewarded by not having to configure that link. the notion that we should try to accommodate as many approaches as possible. 1. Well. such as classes are singular and tables are plural (a person class relates to a people table). 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. 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. you trade flexibility at the infrastructure level to gain flexibility at the application level. and I believe that's why it works. The class automatically knows which table to use for persistence. and better at the application level. but the use of these sensible default strategies is encouraged and should be strayed from only when absolutely necessary.Introducing Maven 1. Maven's Principles According to Christopher Alexander "patterns help create a shared language for communicating insight and experience about problems and their solutions". which all add up to make a huge difference in daily use. We have a ton of examples like that. 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.1.2. If you follow basic conventions. This is not to say that you can't override them. 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.
In this case. You shouldn't need to spend a lot of time getting your development infrastructure functioning. 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. but. and this is what Maven provides for you. Standard directory layout for projects The first convention used by Maven is a standard directory layout for project sources. 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. or deploying. 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. and you will make it easier to communicate about your project. he probably doesn't even know what Maven is and wouldn't like if he did because it's not written in Ruby yet!). 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. You can override any of Maven's defaults to create a directory layout of your choosing. 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. Follow the standard directory layout. 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. project resources. If this saves you 30 minutes for each new project you look at. and allows you to create value in your applications faster with less effort. These components are generally referred to as project content. Better Builds With Maven 21 . generated output. when you do this. 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. Maven encourages a common arrangement of project content so that once you are familiar with the standard locations. you will be able to navigate within any Maven project you encounter in the future. even if you only look at a few new projects a year that's time better spent on your application. you need to ask yourself if the extra configuration that comes with customization is really worth it. and documentation. makes it easier to communicate to others. generating documentation. It is a very simple idea but it can save you a lot of time. You don't want to spend time fiddling with building. All of these things should simply work.
later in this chapter. Having the utility code in a separate project. 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. Standard naming conventions The third convention.jar are inherently flawed because there will come a time when something is misplaced and you'll track down a ClassNotFound exception which resulted from the wrong version of a JAR file being used. This is illustrated in the Coherent Organization of Dependencies section. If you have placed all the sources together in a single project.2 of Commons Logging. easy to see manner.2. and a project for the shared utility code. It's happened to all of us and it doesn't have to. extendibility and reusability. It doesn't make much sense to exclude pertinent information when you have it at hand to use. In this scenario the code contained in each separate project has a different role to play.jar. because the naming convention keeps them separate in a logical. or concern. The separation of concerns (SoC) principle states that a given problem involves different kinds of concerns. which should be identified and separated to cope with complexity and to achieve the required engineering quality factors such as adaptability. To illustrate this point consider a set of sources for a client/server-based application that contained the client code. is a standard naming convention for directories and a standard naming convention for the primary output of a project. A simple example of the naming convention might be commons-logging-1. a set of conventions really. maintainability.Introducing Maven One primary output per project The second convention used by Maven is the concept of a Maven project producing one primary output.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. looking at it. is much easier to reuse. and some shared utility code. and they should be separated. The conventions provide clarity and immediate comprehension. It is immediately obvious that this is version 1. well. You could produce a single JAR file which contained all the compiled classes. Maven pushes you to think clearly about the separation of concerns when setting up your projects because modularity leads to reuse. in a separate JAR file. Systems that cannot cope with information rich artifacts like commons-logging-1. the boundaries between our three separate concerns can easily become blurred and a simple desire to reuse the utility code could prove to be difficult. the server code. a project for the server portion of the application. This is important if there are multiple projects involved. The intent behind the naming conventions employed by Maven is that you can tell exactly what you are looking at by. Better Builds With Maven 22 .2.
app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.2. will ask how this is possible using a 15 line file. 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. Maven encourages a separation of concerns because it promotes reuse. test. a plugin for creating Javadocs. 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. The POM below is an example of what you could use to build and test a project.8. and generate basic documentation.3. The POM is an XML document and looks like the following (very) simplified example: <project> <modelVersion>4.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM will allow you to compile. It's a very good and essential question in fact. Plugins are the key building blocks for everything in Maven. In Maven there is a plugin for compiling source code. being the observant reader. One important concept to keep in mind is that everything accomplished in Maven is the result of a plugin executing. 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).2. a plugin for creating JARs. You.2.Introducing Maven 1.mycompany. Maven's project object model (POM) Maven is project-centric by design.0.the POM is Maven's currency. and the answer lies in Maven's implicit use of its Super POM. It is the POM that drives execution in Maven and this approach can be described as model driven execution. Better Builds With Maven 23 . Maven is useless . Maven can be thought of as a framework which coordinates the execution of plugins in a well defined way.0</modelVersion> <groupId>com. specifically from the plugin configurations contained in the POM. and many others. and the POM is Maven's description of a single project. 1. Maven puts this principle into practice by encapsulating build logic into coherent modules called plugins. a plugin for running tests. Reuse of Build Logic As you have already learned. Without POM.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.
xml files. which indicates that a project is in a state of development.lang. The POM contains every important piece of information about your project.This element indicates the display name used for the project.maven. Maven goes a long way to help you with version management and you will often see the SNAPSHOT designator in a version. description .html. etc. Better Builds With Maven 24 . 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.This element indicates the unique base name of the primary artifact being generated by this project.This element indicates the version of the artifact generated by the project. For a complete reference of the elements available for use in the POM please refer to the POM reference at http://maven. The default value for the packaging element is jar so you do not have to specify this in most cases. in Maven all POMs have an implicit parent which is Maven's Super POM. but still displays the key elements every POM contains. all objects have the implicit parent of java. In Java.apache.).Object. • name . but it is mandatory in order to ensure stability when Maven introduces new features or other model changes. myapp-1. The life cycle is a topic dealt with later in the chapter. This not only means that the artifact produced is a JAR.This required element indicates the version of the object model this POM is using. and is the analog of the Java language's java.This element indicates where the project's site can be found. Additional artifacts such as source bundles also use the artifactId as part of their file name. For now.<extension> (for example. The Super POM can be rather intimidating at first glance so if you wish to find out more about it you can refer to Appendix B.This is the top-level element in all Maven pom.Object class. For example org. The POM shown above is a very simple POM. • • url .org/maven-model/maven. Likewise.Introducing Maven Maven's Super POM carries with it all the default conventions that Maven encourages. • groupId . but also indicates a specific life cycle to use as part of the build process. The groupId is one of the key identifiers of a project and is typically based on the fully qualified domain name of your organization.lang. WAR. The version of the model itself changes very infrequently. • version . EAR. or EAR.jar). or other projects that use it as a dependency.This element indicates the unique identifier of the organization or group that created the project.plugins is the designated groupId for all Maven plugins. A typical artifact produced by Maven would have the form <artifactId>-<version>.This element indicates the package type to be used by this artifact (JAR. and during the build process for your project. just keep in mind that the selected packaging of a project plays a part in customizing the build life cycle.This element provides a basic description of your project.apache. modelVersion . This is often used in Maven's generated documentation. • • packaging . WAR.0. • • project . artifactId .
In Maven. 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. In "Maven-speak" an artifact is a specific piece of software. 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. 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. artifacts. If you tell Maven to compile. related to that phase. It is important to note that each phase in the life cycle will be executed up to and including the phase you specify. Coherent Organization of Dependencies We are now going to delve into how Maven resolves dependencies and discuss the intimately connected concepts of dependencies. For example. the compile phase invokes a certain set of goals to compile a set of classes. The standard build life cycle consists of many phases and these can be thought of as extension points. packaging. generate-sources. the validate. and repositories work. installation. well-trodden paths: preparation. The path that Maven moves along to accommodate an infinite variety of projects is called the build life cycle.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. or package. Maven plugins provide reusable build logic that can be slotted into the standard build life cycle. Better Builds With Maven 25 . generate-resources. you tell Maven that you want to compile. our example POM has a single dependency listed. and repositories.4.2. In Maven you do day-to-day work by invoking particular phases in this standard build life cycle. When you need to add some functionality to the build life cycle you do so with a plugin. For example. which is for Junit: <project> <modelVersion>4.mycompany. artifacts. compilation. which is straightforward. initialize.1</version> <scope>test</scope> </dependency> </dependencies> </project> This POM states that your project has a dependency on JUnit. or install. testing. or test. or goals. If you recall.0</modelVersion> <groupId>com. process-sources.0.Introducing Maven Maven's build life cycle Software projects generally follow a similar.8.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. 1. Chapter 2 includes a demonstrates the customization of a Maven build with a Maven plugin. and compile phases will execute.
Introducing Maven In Java. instead you deal with logical dependencies. In the POM you are not specifically telling Maven where the dependencies are physically.1. for artifacts that match the dependency request. we can describe the process of dependency management as Maven reaching out into the world. The following folder structure shows the layout of a local Maven repository that has a few locally installed dependency artifacts such as junit-3. By default. You must have a local repository in order for Maven to work.8. within the context of your project. In order for Maven to attempt to satisfy a dependency. If a matching artifact is located.jar: Better Builds With Maven 26 . 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. you stop focusing on a collection of JAR files. but the key concept is that Maven dependencies are declarative.8. Local Maven repository When you install and run Maven for the first time your local repository will be created and populated with artifacts as a result of dependency requests. Dependency Management is one of the most easily understood and powerful features in Maven. or EAR file. and it supplies these coordinates to its own internal dependency mechanisms. the most common artifact is a JAR file. SAR. and providing this dependency to your software project. At a basic level. Read the following sections for specific details about where Maven searches for these dependencies. There is more going on behind the scenes. you are simply telling Maven what a specific project expects. A dependency is uniquely identified by the following identifiers: groupId. When a dependency is declared. Your project doesn't require junit-3. Maven takes the dependency coordinates you provide in a POM. Maven usually interacts with your local repository. Maven creates your local repository in ~/.1 of the junit artifact produced by the junit group. grabbing a dependency.m2/repository. but a Java artifact could also be a WAR. With Maven.1. Maven transports it from that remote repository to your local repository for general use.jar.8. Maven needs to know what repository to look in as well as the dependency's coordinates. it depends on version 3. Maven has two types of repositories: local and remote. A dependency is a reference to an specific artifact that resides in a repository. Maven tries to satisfy that dependency by looking in all of the remote repositories that are available. artifactId and version.
jar artifact that landed in your local repository. In theory a repository is just an abstract storage mechanism.1. We'll stick with our JUnit example and examine the junit-3. but in practice the repository is a directory structure in your file system. so you understand how the layout works.8. On the next page is the general pattern used to create the repository layout: Better Builds With Maven 27 . 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.
1" in ~/. Maven will attempt to find the artifact with a groupId of "junit".org/maven2. If your project's POM contains more than one remote repository.y. Better Builds With Maven 28 .m2/repository/junit/unit/3.1/junit-3.8. Once the dependency is satisfied. Maven will generate a path to the artifact in your local repository. it will be fetched from a remote repository. Maven will attempt to download an artifact from each remote repository in the order defined in your POM.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.1. By default. the artifact is downloaded and installed in your local repository. Maven attempts to locate a dependency's artifact using the following process. artifactId of "junit".8.ibiblio. for example. Locating dependency artifacts When satisfying dependencies. If this file is not present.jar.apache.8.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. First. Maven will attempt to fetch an artifact from the central Maven repository at http://www. and a version of "3.maven.
Instead of having to add the Spring 2. it should rarely. Dependencies are not you projects code. and you build would add these dependencies to your classpath. To summarize.jar for each project that needs it. every project with a POM that references the same dependency will use this single copy installed in your local repository. and they don't deserve to be versioned in an SCM.6 of the Spring Framework. you don't store a copy of junit3. Storing artifacts in your SCM along with your project may seem appealing but it is incompatible with the concept of small. Maven is a repository.0 JARs to every project. it doesn't scale easily to support an application with a great number of small components. Maven is a framework. and it is a trivial process to upgrade all of your ten web applications to Spring 2. Your local repository is one-stop-shopping for all artifacts that you need regardless of how many projects you are working on. While this approach works for a few project. you simply changed some configuration. be a part of your thought process. Maven is also a vibrant. modular project arrangements.0 by change your dependency declarations. Using Maven is more than just downloading another JAR file and a set of scripts. Better Builds With Maven 29 . If you were coding a web application. active open-source community that produces software focused on project management. Each project relies upon a specific artifact via the dependencies listed in a POM. it simplifies the process of development. 220.127.116.11. You don't have to worry about whether or not it's going to work. With Maven. a useful technology just works. In other words. rather than imposing one. shielding you from complexity and allowing you to focus on your specific task. Maven is a set of standards.Introducing Maven From this point forward. all project referencing this dependency share a single copy of this JAR. Before Maven. and Maven is software. Declare you dependencies and let Maven take care of details like compilation and testing classpaths.2. in the background. if your project has ten web applications which all depend on version 1. and. Maven provides such a technology for project management. in doing so. it is the adoption of processes that allow you to take your software development to the next level. you would check in the 10-20 JAR files your project relies upon into a lib directory. the common pattern in most project was to store JAR files in a project's subdirectory. there is no need to store the various spring JAR files in your project. you don't have to jump through hoops trying to get it to work. if ever. Maven's Benefits A successful technology takes away a burden. Like the engine in your car or the processor in your laptop.
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.
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. it may be necessary to make a few more preparations for Maven to function correctly.mycompany.mycompany. so for now simply assume that the above settings will work. Create a <your-home-directory>/.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. Now you can perform the following basic check to ensure Maven is working correctly: mvn -version If Maven's version is displayed. ask your administrator if there if there is an internal Maven proxy.m2/settings. Better Builds With Maven 31 .com/maven2</url> <mirrorOf>central</mirrorOf> </mirror> </mirrors> </settings> In its optimal mode. Preparing to Use Maven In this chapter. it is assumed that you are a first time Maven user and have already set up Maven on your local system. then you will have to set up Maven to understand that.1.mycompany. Depending on where your machine is located.xml file with the following content.Getting Started with Maven 2. To do this.xml file with the following content: <settings> <proxies> <proxy> <active>true</active> <protocol>http</protocol> <host>proxy. Maven requires network access.com</id> <name>My Company's Maven Proxy</name> <url>http://maven. If you have not set up Maven yet. If there is an active Maven proxy running. then please refer to Maven's Download and Installation Instructions before continuing. create a <your-homedirectory>/. If you are behind a firewall.m2/settings.xml file. then note the URL and let Maven know you will be using a proxy. <mirrors> <mirror> <id>maven. then you should be all set to create your first Maven project. The settings.
An archetype is defined as an original pattern or model from which all other things of the same kind are made. To create the Quick Start Maven project. you will notice that a directory named my-app has been created for the new project.mycompany.0</modelVersion> <groupId>com. but if you would like more information about archetypes.xml. execute the following: C:\mvnbook> mvn archetype:create -DgroupId=com. you will use Maven's Archetype mechanism.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1. In Maven.1</version> <scope>test</scope> </dependency> </dependencies> </project> At the top level of every project is your pom.apache.xml file. Whenever you see a directory structure which contains a pom. which looks like the following: <project> <modelVersion>4.0.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. Better Builds With Maven 32 . This chapter will show you how the archetype mechanism works. which is combined with some user input to produce a fullyfunctional Maven project. Creating Your First Maven Project To create your first project.app \ -DartifactId=my-app You will notice a few things happened when you executed this command. an archetype is a template of a project.2. First.Getting Started with Maven 2.mycompany. and this directory contains your pom. After the archetype generation has completed you will notice that the following directory structure has been created.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven.xml file you know you are dealing with a Maven project. and it in fact adheres to Maven's standard directory layout discussed in Chapter 1. please refer to the Introduction to Archetypes.8.
you are ready to build your project. testing. In this first stage you have Java source files only. Now that you have a POM. and deploying the project (source files. documenting.Getting Started with Maven Figure 2-1: Directory structure after archetype generation The src directory contains all of the inputs required for building. the site. and some test sources. various descriptors such as assembly descriptors. and so on). but later in the chapter you will see how the standard directory layout is employed for other project content. some application sources. Better Builds With Maven 33 . configuration files.
in order to accomplish the desired task..plugins:maven-resources-plugin: checking for updates from central .apache..maven. ${basedir}. [INFO] [resources:resources] . [INFO] artifact org. Compiling Application Sources As mentioned in the introduction. Before you issue the command to compile the application sources. 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.Getting Started with Maven 2. in one fell swoop.. in a declarative way...maven..apache.plugins:maven-compiler-plugin: checking for updates from central . 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. Then. 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.3. [INFO] [compiler:compile] Compiling 1 source file to c:\mvnbook\my-app\target\classes [INFO]------------------------------------------------------------------[INFO] BUILD SUCCESSFUL [INFO]------------------------------------------------------------------[INFO] Total time: 3 minutes 54 seconds [INFO] Finished at: Fri Sep 23 15:48:34 GMT-05:00 2005 [INFO] Final Memory: 2M/6M [INFO]------------------------------------------------------------------- Now let's dissect what actually happened and see where Maven's four principles come into play with the execution of this seemingly simple command. The <my-app> directory is the base directory. you tell Maven what you need. Change into the <my-app> directory. for the my-app project. Better Builds With Maven 34 . at a very high level.
it took almost 4 minutes with a broadband connection). by default. Maven downloads plugins when they are needed. The same build logic encapsulated in the compiler plugin will be executed consistently across any number of projects. By following the standard Maven conventions you can get a lot done with very little effort! Better Builds With Maven 35 . Maven will download all the plugins and related dependencies it needs to fulfill the command. now you know how Maven finds application sources. The same holds true for the location of the compiled classes which. Instead. If you're a keen observer you'll notice that using the standard conventions makes the POM above very small. Although you now know that the compiler plugin was used to compile the application sources. of course. The next time you execute the same command again. or where your output should go. application sources are placed in src/main/java. along with its default configuration. Even the simplest of POMs knows the default location for application sources. but there is very little reason to do so. override this default location. how was Maven able to retrieve the compiler plugin? After all. what Maven uses to compile the application sources. it won't download anything new.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. you won't find the compiler plugin since it is not shipped with the Maven distribution. This default value (though not visible in the POM above) was. As you can see from the output. in fact. You can. which is specified by the standard directory layout. This means you don't have to state this location at all in any of your POMs. is target/classes. if you use the default location for application sources. inherited from the Super POM. the compiled classes were placed in target/classes. The standard compiler plugin. is the tool used to compile your application sources. and eliminates the requirement for you to explicitly tell Maven where any of your sources are. So. there is a form of mapping and it is called Maven's default build life cycle. because Maven already has what it needs. and how Maven invokes the compiler plugin. Therefore. The next question is. From a clean installation of Maven this can take quite a while (in the output above. how was Maven able to decide to use the compiler plugin. if you poke around the standard Maven installation. Maven will execute the command much more quickly. What actually compiled the application sources? This is where Maven's second principle of "reusable build logic" comes into play. in the first place? You might be guessing that there is some background process that maps a simple command to a particular plugin. The first time you execute this (or any other) command. By default. In fact.
..app.AppTest [surefire] Tests run: 1.maven. [INFO] [resources:resources] [INFO] [compiler:compile] [INFO] Nothing to compile . you probably have unit tests that you want to compile and execute as well (after all.plugins:maven-surefire-plugin: checking for updates from central . wink wink*). [INFO] [surefire:test] [INFO] Setting reports dir: C:\Test\Maven2\test\my-app\target/surefire-reports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running com. Compiling Test Sources and Running Unit Tests Now that you're successfully compiling your application's sources. simply tell Maven you want to test your sources. This implies that all prerequisite phases in the life cycle will be performed to ensure that testing will be successful. Failures: 0. Failures: 0. programmers always write and execute their own unit tests *nudge nudge. Time elapsed: 0 sec Results : [surefire] Tests run: 1. Again.Getting Started with Maven 2. 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. 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.apache.mycompany.4.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 .
remember that it isn't necessary to run this every time. Better Builds With Maven 37 . Maven compiles the main code (all these classes are up-to-date. since we haven't changed anything since we compiled last). • Before compiling and executing the tests. Now that you can compile the application sources. and execute the tests. • If you simply want to compile your test sources (but not execute the tests). compile the tests. as well as all the others defined before it. 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). mvn test will always run the compile and test-compile phases first. how to package your application.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.
Take a look in the the target directory and you will see the generated JAR file.0-SNAPSHOT\my-app-1.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 . 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. It can then be used by other projects as a dependency.jar [INFO] [install:install] [INFO] Installing c:\mvnbook\my-app\target\my-app-1. Failures: 0.0-SNAPSHOT.AppTest [surefire] Tests run: 1. This is how Maven knows to produce a JAR file from the above command (you'll read more about this later). Now.m2/repository is the default location of the repository. To install. you'll want to install the artifact (the JAR file) you've generated into your local repository.001 sec Results : [surefire] Tests run: 1.jar to <localrepository>\com\mycompany\app\my-app\1. Errors: 0 [INFO] [jar:jar] [INFO] Building jar: <dir>/my-app/target/my-app-1. Errors: 0.you will notice the packaging element is set to jar. Failures: 0. Time elapsed: 0.app.mycompany.0-SNAPSHOT.Getting Started with Maven 2. 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.5. The directory <your-homedirectory>/.
it will update the settings rather than starting fresh. 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.java **/Abstract*TestCase. and installing a typical Maven project. the following tests are excluded: • • **/Abstract*Test.java • Conversely. Of course. this covers the majority of tasks users perform. there is far more functionality available to you from Maven without requiring any additions to the 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. there are a great number of Maven plugins that work out of the box. and if you've noticed. building. alternatively you might like to generate an Eclipse descriptor: C:\mvnbook\my-app> mvn eclipse:eclipse Better Builds With Maven 39 . packaging.java • **/Test*. the following tests are included: **/*Test. for example: C:\mvnbook\my-app> mvn clean This will remove the target directory with the old build data before starting. So. this POM has enough information to generate a Web site for your project! Though you will typically want to customize your Maven site. as it currently stands. testing.java • **/*TestCase. In contrast. what other functionality can you leverage. everything done up to this point has been driven by an 18-line POM. if you're pressed for time and just need to create a basic Web site for your project. to get any more functionality out of an Ant build script. Or.java You have now completed the process for setting up. given Maven's re-usable build logic? With even the simplest POM. By default. This chapter will cover one in particular. In this case. so it is fresh. For projects that are built with Maven. 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. Without any work on your part. you must keep making error-prone additions. as it is one of the highly-prized features in Maven.
is the packaging of resources into a JAR file. In the example following. Handling Classpath Resources Another common use case which requires no changes to the POM shown previously.Getting Started with Maven 2. simply by placing those resources in a standard directory structure. Figure 2-2: Directory structure after adding the resources directory You can see in the preceding example that there is a META-INF directory with an application.properties file within that directory. That is where you place any resources you wish to package in the JAR. Maven again uses the standard directory layout. 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. you can package resources within JARs. If you unpacked the JAR that Maven created you would see the following: Better Builds With Maven 40 . starting at the base of the JAR. For this common task. This means that by adopting Maven's standard conventions.6. you need to add the directory src/main/resources.
as well as a pom. You will also notice some other files there like META-INF/MANIFEST. should the need arise.xml and pom. These come standard with the creation of a JAR in Maven. Operating on the POM file would require you to use Maven utilities. except place resources in the src/test/resources directory. Handling Test Classpath Resources To add resources to the classpath for your unit tests.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. One simple use might be to retrieve the version of your application. but the properties can be utilized using the standard Java APIs. follow the same pattern as you do for adding resources to the JAR. but Maven will generate one by default if you don't.1. You can create your own manifest if you choose.6.properties file is there in the META-INF directory.xml and pom. The pom.properties file. At this point you have a project directory structure that should look like the following: Better Builds With Maven 41 .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.MF. 2.
you could use a simple snippet of code like the following for access to the resource required for testing: [.xml: <project> Better Builds With Maven 42 .Getting Started with Maven Figure 2-4: Directory structure after adding test resources In a unit test.] // Retrieve resource InputStream is = getClass(). The property can be either one of the values defined in your pom. To have Maven filter resources when copying. a value defined in the user's settings.... To accomplish this in Maven.6.] 2. or a system property.xml. only. a property defined in an external properties file.. Filtering Classpath Resources Sometimes a resource file will need to contain a value that can be supplied at build time.getResourceAsStream( "/test. simply set filtering to true for the resource directory in your pom. put a reference to the property that will contain the value into your resource file using the syntax ${<property name>}. // Do something with the resource [.2.properties" ).xml.
To override the default value for filtering and set it to true.properties file. which weren't there before.properties application. when the built project is packaged.0. In addition.build.mycompany. this information had to be added to the pom. the property name uses the names of the XML elements that define the value.name=${project.xml.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven.version} refers to the version of the project.name} application.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.Getting Started with Maven <modelVersion>4.finalName} refers to the final name of the file created. To continue the example.name} refers to the name of the project. All of this information was previously provided as default values. any element in your POM is available when filtering resources. whose values will be supplied when the resource is filtered as follows: # application.0</modelVersion> <groupId>com.apache.xml. 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 . create an src/main/resources/application. So ${project. resources.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8. To reference a property defined in your pom.version} With that in place.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. and resource elements have been added. ${project. the POM has to explicitly state that the resources are located in the src/main/resources directory. and ${project. In fact.version=${project.
.properties application.properties.properties either): Better Builds With Maven 44 .properties application.value property in an external file.xml and you'd get the same effect (notice you don't need the references to src/main/filters/filter.properties</filter> </filters> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> [.0-SNAPSHOT To reference a property defined in an external file.Getting Started with Maven The application.value} The next execution of the mvn process-resources command will put the new property value into application.name} application. First.] <build> <filters> <filter>src/main/filters/filter. which will eventually go into the JAR looks like this: # application. all you need to do is add a reference to this external file in your pom.filter.name=Maven Quick Start Archetype application. As an alternative to defining the my.properties file as follows: # application.properties: # filter.filter.] Then.xml.version=1.version} message=${my.. you could have defined it in the properties section of your pom..name=${project.version=${project. create an external properties file and call it src/main/filters/filter.value=hello! Next. add a reference to this property in the application.xml file: [.properties my.properties file under target/classes.. add a reference to this new file in the pom.filter.
0</modelVersion> <groupId>com.0.line.filter.version} command.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. This is most often the case with binary resources.prop=${command. for example image files.home). either the system properties built into Java (like java.properties file will contain the values from the system properties.line. To continue the example. In addition you would add another resource entry.properties file to look like the following: # application.6. The build element would look like the following: Better Builds With Maven 45 .prop property on the command line).Getting Started with Maven <project> <modelVersion>4.app</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.value> </properties> </project> Filtering resources can also retrieve values from system properties.1</version> <scope>test</scope> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> <properties> <my.filter.properties java.3.value>hello</my.prop=hello again" 2. and an inclusion of your images directory. mvn process-resources "-Dcommand. but you do not want them filtered. with filtering disabled. then you would create one resource entry that handled the filtering of resources with an exclusion on the resources you wanted unfiltered. change the application.line. the application. Preventing Filtering of Binary Resources Sometimes there are classpath resources that you want included in your JAR.version or user. If you had a src/main/resources/images that you didn't want to be filtered.mycompany.apache.8.0-SNAPSHOT</version> <name>Maven Quick Start Archetype</name> <url>http://maven.version=${java.prop} Now. when you execute the following command (note the definition of the command. or properties defined on the command line using the standard Java -D parameter.line.
... To illustrate the similarity between plugins and dependencies.Getting Started with Maven <project> ... Better Builds With Maven 46 .maven. This plugin will be downloaded and installed automatically.7. to customize the build for a Maven project.5</source> <target>1. For example.0 sources. <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> ..5</target> </configuration> </plugin> </plugins> </build> .plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2. but in most cases these elements are not required. Using Maven Plugins As noted earlier in the chapter.0</version> <configuration> <source>1..and in some ways they are. the groupId and version elements have been shown..apache. in much the same way that a dependency would be handled. if it is not present on your local system. you must include additional Maven plugins. </project> 2. <build> <plugins> <plugin> <groupId>org. </project> You'll notice that all plugins in Maven 2 look very similar to a dependency. or configure parameters for the plugins already included in the build. you may want to configure the Java compiler to allow JDK 5. This is as simple as adding this following to your POM: <project> .
maven. If someone throws a Maven project at you. The chapter focused on Maven as a concrete build tool.codehaus. but you may want to specify the version of a plugin to ensure reproducibility. 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 mvn help:describe command.8. test. and packaging a project. In seventeen pages. You should also have some insight into how Maven handles dependencies and provides an avenue for customization using Maven plugins. plugin developers take care to ensure that new versions of plugins are backward compatible so you are usually OK with the latest release. you have gained access to every single project uses Maven. You can specify an additional groupId to search within your POM. and if you were just looking for a build tool.org/plugins/ and navigating to the plugin and goal you are using. compiling a project. If you do not specify a version then Maven will attempt to use the latest released version of the specified plugin. it laid a good foundation for the rest of this book. The next few chapters provide you with the tools to customize Maven's behavior and use Maven to manage interdependent software projects.maven. Better Builds With Maven 47 . the compiler plugin is already used as part of the build process and this just changes the configuration. you've seen how you can use Maven to build your project. This is often the most convenient way to use a plugin. 2. but if you find something has changed . you'll know how to exercise the basic features of Maven: creating a project.apache.apache. If you want to find out what the plugin's configuration options are. use the following command: mvn help:describe -DgroupId=org. and build it.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. you could safely stop reading this book now.you can lock down a specific version.apache. By learning how to build a Maven project.mojo groupId label. You've learned a new language and you've taken Maven for a test drive. then Maven will default to looking for the plugin with the org. If you want to see the options for the maven-compiler-plugin shown previously. The configuration element applies the given parameters to every goal from the compiler plugin. you would know enough to compile. read on. You might need to refer to the next chapter for more information about customizing your build to fit your project's unique needs. you should be up and running with Maven. testing a project. Summary After reading this chapter. If someone gave you a project using Maven tomorrow.Getting Started with Maven If you do not specify a groupId. or settings.xml. For the most part. In the above case.plugins or the org.
Berard Better Builds With Maven 48 . 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.3. .Edward V.
• Proficio API: The application programming interface for Proficio. each of which addresses one or more concerns. and can easily identify what a particular module does simply by looking at its name. you can see in the modules element all the modules that make up the Proficio application.2. Setting Up an Application Directory Structure In setting up the directory structure for Proficio. a necessary goal for every software development project. In doing so you will be guided through the specifics of setting up an application and managing that structure. Concerns are the primary motivation for organizing and decomposing software into smaller. more manageable and comprehensible parts. The guiding principle in determining how best to decompose your application is called the Separation of Concerns (SoC). The interfaces for the APIs of major components. The only real criterion to which to adhere is that your team has a single convention. goal.Creating Applications with Maven 3. and operate on the pieces of software that are relevant to a particular concept. Proficio has a very simple memory-based store and a simple XStream-based store. like the store. The application that you are going to create is called Proficio. In examining the top-level POM for Proficio. 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 . but you are free to name your modules in any fashion your team decides. and modular builds. The natural outcome of this practice. are also kept here. So. A module is a reference to another Maven project. task. Now you will delve in a little deeper. lets start by discussing the ideal directory structure for Proficio. are discrete and coherent components. coherent. which enables code reusability. or purpose. • Proficio Stores: The module which itself houses all the store modules. which is Latin for "help". using a real-world example. 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). These are default naming conventions that Maven uses. it is important to keep in mind that Maven emphasizes the practice of discrete. SoC refers to the ability to identify. Introduction In the second chapter you stepped though the basics of setting up a simple project. 3.1. As such. encapsulate. • Proficio Core: The implementation of the API. which really means a reference to another POM. • • Proficio CLI: The code which provides a command line interface to Proficio. and they it clearly understands that convention. which consists of a set of interfaces. you will see that the Proficio sample application is made up of several modules: Proficio Model: The data model for the Proficio application. In this chapter. which consists of all the classes that will be used by Proficio as a whole.
apache. 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.apache.Creating Applications with Maven <project> <modelVersion>4.0</modelVersion> <groupId>org. <modules> <module>proficio-model</module> <module>proficio-api</module> <module>proficio-core</module> <module>proficio-stores</module> </modules> .maven. Currently there is some variance on the Maven web site when referring to directory structures that contain more then one Maven project... 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 . but the Maven team is now trying to consistently refer to these setups as multimodule builds. For POMs that contain modules. It is recommended that you specify the application version in the top-level POM and use that version across all the modules that make up your application.0.org</url> .x these were commonly referred to as multi-project builds and some of this vestigial terminology carried over to the Maven 2.0-SNAPSHOT.proficio</groupId> <artifactId>proficio</artifactId> <packaging>pom</packaging> <version>1. </project> An important feature to note in the POM above is the value of the version element.x documentation. You should take note of the packaging element. which you can see is 1. 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. which has a value of pom... In Maven 1.0-SNAPSHOT</version> <name>Maven Proficio</name> <url>http://maven.
apache.0-SNAPSHOT</version> </parent> <modelVersion>4.0.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. Looking at the module names is how Maven steps into the right directory to process the POM located there. If you take a look at the POM for the proficio-stores module you will see a set of modules contained there: <project> <parent> <groupId>org. 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. but the interesting thing here is that we have a another project with a packaging type of pom.proficio</groupId> <artifactId>proficio</artifactId> <version>1. which is the proficio-stores module.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 .maven.
So. you will see that in the dependencies section there is a declaration for JUnit version 3. if you take a look at the POM for the proficio-core module you will see the following.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. note specifically there is no visible dependency declaration for JUnit: Better Builds With Maven 52 . 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: .. Using Project Inheritance One of the most powerful features in Maven is project inheritance. Let's examine a case where it makes sense to put a resource in the top-level POM.8.1</version> <scope>test</scope> </dependency> </dependencies> . by stating the dependency in the top-level POM once.maven. organizing your projects in groups according to concern. 3. which are all placed in one directory..proficio</groupId> <artifactId>proficio</artifactId> <version>1..apache. or state your common dependencies .8..1. In this case the assumption being made is that JUnit will be used for testing in all our child projects. state your deployment information. you never have to declare this dependency again.. Using project inheritance allows you to do things like state your organizational information. So. You can nest sets of projects like this to any level. If you look at the top-level POM for Proficio.3.enabling you to add resources where it makes sense in the hierarchy of your projects. Being the observant user.0-SNAPSHOT</version> </parent> . <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.... just as has been done with Proficio's multiple storage mechanisms. using our the top-level POM for the sample Proficio application.all in a single place. is that each one inherits the dependencies section of the top-level POM. in any of your child POMs. <parent> <groupId>org. 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 . </project> What specifically happens for each child POM. The dependency is stated as following: <project> .
. Better Builds With Maven 53 .1</version> <scope>test</scope> </dependency> .8.. take a look at the resulting POM you will see the JUnit version 3.maven...codehaus. But remember from Chapter 2 that the Super POM sits at the top of the inheritance hierarchy. 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.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. This command will show you the final result for a target POM. </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. <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.Creating Applications with Maven <project> <parent> <groupId>org.. <dependencies> .. After you move into the proficio-core module and run the command. </dependencies> ..1 dependency: <project> . So in this case.apache.8. which in turn inherits from the Super POM.proficio</groupId> <artifactId>proficio-api</artifactId> </dependency> <dependency> <groupId>org.maven..proficio</groupId> <artifactId>proficio</artifactId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.apache.0</modelVersion> <artifactId>proficio-core</artifactId> <packaging>jar</packaging> <name>Maven Proficio Core</name> <dependencies> <dependency> <groupId>org.0.
When you write applications which consist of multiple.codehaus.maven.proficio</groupId> <artifactId>proficio-core</artifactId> <version>${project.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1. <dependencyManagement> <dependencies> <dependency> <groupId>org. individual projects.. so that the final application works correctly.. When this happens it is critical that the same version of a given dependency is used for all your projects.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project..maven.apache. for example. as the results can be far from desirable.maven. In order to manage. across all of your projects are in alignment so that your testing accurately reflects what you will deploy as your final result.version} specification is the version specified by the top-level POM's version element. You want to make sure that all the versions. To illustrate how this mechanism works. Managing Dependencies When you are building applications you have many dependencies to manage and the number of dependencies only increases over time.version}</version> </dependency> <dependency> <groupId>org. which is the application version.Creating Applications with Maven 3. it is likely that some of those projects will share common dependencies. Better Builds With Maven 54 . You don't want. to end up with multiple versions of a dependency on the classpath when your application executes.version}</version> </dependency> <dependency> <groupId>org. or align.proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project.version}</version> </dependency> <dependency> <groupId>org. let's look at the dependency management section of the Proficio top-level POM: <project> . </project> Note that the ${project.4.apache. making dependency management difficult to say the least. versions of dependencies across several projects. you use the dependency management section in the top-level POM of an application.0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> . Maven's strategy for dealing with this problem is to combine the power of project inheritance with specific dependency management elements in the POM..apache. of all your dependencies.
. The dependencies element contained within the dependencyManagement element is used only to state the preference for a version and by itself does not affect a project's dependency graph.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.apache. The dependencyManagement declares a stated preference for the 1.version}) for proficio-model so that version is injected into the dependency above.maven. 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. whereas the top-level dependencies element does affect the dependency graph. If you take a look at the POM for the proficio-api module.0-SNAPSHOT (stated as ${project.. The dependencies stated in the dependencyManagement only come into play when a dependency is declared without a version.Creating Applications with Maven As you can see within the dependency management section we have several Proficio dependencies and a dependency for the Plexus IoC container. Better Builds With Maven 55 . to make it complete. you will see a single dependency declaration and that it does not specify a version: <project> . <dependencies> <dependency> <groupId>org.
A snapshot in Maven is an artifact which has been prepared using the most recent sources available..5.proficio</groupId> <artifactId>proficio-api</artifactId> <version>${project.0-alpha-9</version> </dependency> </dependencies> </dependencyManagement> .codehaus. it is usually the case that each of the modules are in flux. </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.apache.maven.proficio</groupId> <artifactId>proficio-model</artifactId> <version>${project.version}</version> </dependency> <dependency> <groupId>org. Your build system needs to be able to easily deal with this real-time flux.apache. Better Builds With Maven 56 . If you look at the top-level POM for Proficio you will see a snapshot version specified: <project> . and this is where Maven's concept of a snapshot comes into play. Snapshot dependencies are assumed to be changing..plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1.. By default Maven will look for snapshots on a daily basis. Your APIs might be undergoing some change or your implementations are undergoing change and are being fleshed out. so Maven will attempt to update them.0-SNAPSHOT</version> <dependencyManagement> <dependencies> <dependency> <groupId>org. When you specify a non-snapshot version of a dependency Maven will download that dependency once and never attempt to retrieve it again. Controlling how snapshots work will be explained in detail in Chapter 7. or you may be doing some refactoring.. <version>1.version}</version> </dependency> <dependency> <groupId>org.Creating Applications with Maven 3.maven. Using Snapshots While you are developing an application with multiple modules. but you can use the -U command line option to force the search for updates.
0-SNAPSHOT (selected for compile) plexus-utils:1. Removing the incorrect version requires identifying the source of the incorrect version by running Maven with the -X flag (for more information on how to do this. there are ways to manually resolve these conflicts as the end user of a dependency. However. to compile. and Proficio requires version 1. In this example. For example.0..1-alpha-2 (selected for compile) junit:3. you can remove the incorrect version from the tree.8.1 (not setting. the version selected is the one declared "nearest" to the top of the tree . local scope test wins) proficio-api:1.0-SNAPSHOT junit:3. In Maven 2. this has limitations: The version chosen may not have all the features required by the other dependency. then the result is undefined. • While further dependency management features are scheduled for the next release of Maven at the time of writing.0. it became possible to simplify your own POM by only including the dependencies you need directly. Resolving Dependency Conflicts and Using Version Ranges With the introduction of transitive dependencies in Maven 2.0-alpha-9 (selected for compile) plexus-utils:1. In this case.1 be used. However.that is.Creating Applications with Maven 3. or you can override both with the correct version.0-SNAPSHOT (selected for compile) proficio-model:1.6. To ensure this. see section 6. Maven must choose which version to provide. the output will contain something similar to: proficio-core:1.1 (selected for test) plexus-container-default:1.xml file as follows: Better Builds With Maven 57 .4 (selected for compile) classworlds:1. as the graph grows. To manually resolve conflicts. modify the plexus-container-default dependency in the proficio-core/pom.. and to allow Maven to calculate the full dependency graph. if you run mvn -X test on the proficio-core module.1 (selected for compile) Once the path to the version has been identified. you can exclude the dependency from the graph by adding an exclusion to the dependency that introduced it. A dependency in the POM being built will be used over anything else. and more importantly ways to avoid it as the author of a reusable library. • If multiple versions are selected at the same depth. it is inevitable that two or more artifacts will require different versions of a particular dependency.9 in Chapter 6). the least number of dependencies that were traversed to get this version. plexus-utils occurs twice.8.
if it were required for compilation. When a version is declared as 1.plexus</groupId> <artifactId>plexus-utils</artifactId> </exclusion> </exclusions> </dependency> . that will be used widely by others. This is extremely important if you are publishing a build.. so that the 1.1 version is used instead.1.codehaus.4 version of plexus-utils in the dependency graph. The reason for this is that it distorts the true dependency graph. However. as follows: . This is because in this situation. a WAR file). However.plexus</groupId> <artifactId>plexus-container-default</artifactId> <version>1. is to include it directly in the POM.regardless of whether another dependency introduces it. This ensures that Maven ignores the 1.0.. for stability it would always be declared in the current POM as a dependency .plexus</groupId> <artifactId>plexus-utils</artifactId> <version>1. <dependencies> <dependency> <groupId>org. not for compilation.. which will accumulate if this project is reused as a dependency itself. Maven has no knowledge about what versions will definitely work.1. The alternate way to ensure that a particular version of a dependency is used.. <dependency> <groupId>org. This is achieved using version ranges instead.1</version> <scope>runtime</scope> </dependency> </dependencies> . You'll notice here that the runtime scope is used.codehaus. 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. Neither of these solutions are ideal. Maven assumes that all versions are valid and uses the "nearest dependency" technique described previously to determine which version to use. the dependency is used only for packaging. you may require a feature that was introduced in plexus-utils version 1.Creating Applications with Maven ... so in the case of a conflict with another dependency.1.0-alpha-9</version> <exclusions> <exclusion> <groupId>org. 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.. as shown above for plexus-utils. this indicates that the preferred version of the dependency is 1. for a library or framework. In fact.codehaus. In this case.. but that other versions may be acceptable. the dependency should be specified as follows: Better Builds With Maven 58 .
codehaus.1. beta-1.2.0] [1. a version is broken down into five parts: the major. then the qualifier and finally a build number.Creating Applications with Maven <dependency> <groupId>org. Better Builds With Maven 59 . that is greater than or equal to 1. alpha-1. it is possible to make the dependency mechanism more reliable for your builds and to reduce the number of exception cases that will be required.0 Greater than or equal to 1. rc1). In a regular version.1. You can see how a version is partitioned by Maven in figure 3-18.104.22.168) [1. the build will fail.1).plexus</groupId> <artifactId>plexus-utils</artifactId> <version>[1.3 (inclusive) Greater than or equal to 1. the version that is used must fit the range given.1.5 Any version.0 Between 1. except 1. However. It is intended that the qualifier indicates a version prior to release (for example.0. If the nearest version does not match. will be retrieved from the repository.0. This means that the latest version. while the nearest dependency technique will still be used in the case of a conflict. Finally.) Less than or equal to 1. but less than 2. or there were no conflicts originally. If two ranges in a dependency graph do not intersect at all. Figure 3-3: Version parsing As you can see.2.1.(1.1. while the build number is an increment after release to indicate patched builds. you also need to avoid being too specific. minor and bug fix releases. and table 3-2 shows some of the values that can be used.1 By being more specific through the use of version ranges. Table 3-2: Examples of version ranges Range Meaning (. or only the build number. In the current version scheme. The notation used above is set notation.2 and 1.5.).)</version> </dependency> What this means is that.3] [1.) (. the version you are left with is [1. if none of them match. the snapshot (as shown above) is a special case where the qualifier and build number are both allowed. To understand how ranges work. it is necessary to understand how versions are compared. then the next nearest will be tested. you can provide only the qualifier. and so on.
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 . second .by minor version. Maven's default build life cycle will suffice for a great number of projects without any augmentation but. that is considered newer than if it doesn't.1.2-beta-1 exist.. third by bug fix version. <releases> <updatePolicy>interval:60</updatePolicy> </releases> </repository> 3. and finally. then 1. and the versions 1. If it will be configured for a particular repository. of course.Creating Applications with Maven With regard to ordering. typically. However. For example. Conversely. Whether you use snapshots until the final release.1 and 1.. In those case. the generate-sources phase. By default. Proficio has a requirement to generate Java sources from a model. If a qualifier exists. In some cases. Often this is not desired. by build number. the repository is checked once a day for updates to the versions of artifacts in use. which is actually Maven's default build life cycle. if the build number exists. the ranges do not differentiate. This will ensure that the beta versions are used in a range only if the project has declared the snapshot (or development) repository explicitly. you should deploy them to a snapshot repository as is discussed in Chapter 7 of this book.7. Maven accommodates this requirement by allowing the declaration of a plugin. the updatePolicy value is changed for releases.. which means the plugin is bound to a specific phase in the default life cycle. Plugins in Maven are created with a specific task in mind. through the use of a separate repository. the Modello plugin is used to generate the Java sources for Proficio's data model.if the major versions were equal . if you use the range [1. the elements are considered in sequence to determine which is greater .). So.first by major version. For example: . the two versions are compared entirely as strings. fourth by qualifier (using string comparison). so to avoid such a situation. the versions will not match this syntax.6..2-beta-1 will be selected. or forced from the command line using the -U option for a particular Maven execution. or release betas as milestones along the way. 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. all projects have different requirements and it is sometimes necessary to augment the life cycle to satisfy these requirements. Because all of these elements are considered part of the version. it means that the version is older than if the qualifier didn't. this can be configured perrepository to be on a more regular interval. A final note relates to how version updates are determined when a range is in use. you must structure your releases accordingly. This mechanism is identical to that of the snapshots that you learned in section 3. which binds itself to a standard phase in Maven's default life cycle. In Proficio. <repository> .
by specifying the goal in the executions element.codehaus. building with different JVMs. A plugin in Maven may have several goals.Creating Applications with Maven <project> <parent> <groupId>org.0-SNAPSHOT</version> </parent> <modelVersion>4.0. Profiles are specified using a subset of the elements available in the POM itself (plus one extra section).maven.modello</groupId> <artifactId>modello-maven-plugin</artifactId> <version>1. and can be activated in several ways.proficio</groupId> <artifactId>proficio</artifactId> <version>1. but sometimes you simply have to take into consideration variation across systems and this is why profiles were introduced in Maven.0</modelVersion> <artifactId>proficio-model</artifactId> <packaging>jar</packaging> <name>Proficio Model</name> <build> <plugins> <plugin> <groupId>org.0.apache. Typically you try to encapsulate as much as possible in the POM to ensure that builds are portable. testing with different databases. 3.0-alpha-5</version> <executions> <execution> <goals> <goal>java</goal> </goals> </execution> </executions> <configuration> <version>1. 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. Profiles modify the POM at build time. so you need to specify which goal in the plugin you wish to run. and are meant to be used in complementary sets to give equivalent-but-different parameters for a set of target environments (providing. testing.8. for example. but here you see an additional executions element.0</version> <packageWithVersion>false</packageWithVersion> <model>src/main/mdo/proficio. or referencing the local file system. and production environments). the path of the application server root in the development. Better Builds With Maven 61 .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.
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. This option takes an argument that contains a comma-delimited list of profile-ids..Creating Applications with Maven As such.m2/settings.xml) • A file in the the same directory as the POM. </settings> Better Builds With Maven 62 . called profiles. used properly. When this option is specified. For example: <settings> .. but used behind the scenes) modules reporting dependencyManagement distributionManagement A subset of the build element. You can define profiles in one of the following three places: The Maven settings file (typically <your -home-directory>/. each containing a profile-id.profile2 install Profiles can be activated in the Maven settings. For example: mvn -Pprofile1. profiles can easily lead to differing build results from different members of your team. via the activeProfiles section.xml • The POM itself • In any of the above three profile sites.. Note that you must have defined the profiles in your settings.. </profile> </profiles> <activeProfiles> <activeProfile>profile1</activeProfile> </activeProfiles> . you can still preserve build portability with profiles.. no profiles other than those specified in the option argument will be activated. • <profiles> <profile> <id>profile1</id> . However.. you can define the following elements: • • • • • • • • • repositories pluginRepositories dependencies plugins properties (not actually available in the main POM. This section takes a list of activeProfile elements.xml file as well.
<activation> <jdk>1. "1. "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".Creating Applications with Maven • Profiles can be triggered automatically based on the detected state of the build environment. "1. <profile> <id>profile1</id> .. you are going to use them to create tailored assemblies: an assembly of Proficio which uses the memory-based store and an assembly of Proficio which uses the XStream-based store...4</jdk> </activation> </profile> This activator will trigger the profile when the JDK's version starts with "1. Now that you are familiar with profiles..0_08". <activation> <property> <name>debug</name> </property> </activation> </profile> This will activate the profile when the system property "debug" is specified with any value.4. <profile> <id>profile1</id> .2_07". 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..4.4" (eg. or the value of a system property. the presence of a system property. These activators are specified via an activation section in the profile itself. Currently.. Better Builds With Maven 63 . this detection is limited to prefix-matching of the JDK version.4"). Here are some examples: <profile> <id>profile1</id> .
xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>xstream</name> </property> </activation> </profile> </profiles> </project> Better Builds With Maven 64 .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.Profile which creates an assembly using the memory based store --> <profile> <id>memory</id> <build> <plugins> <plugin> <artifactId>maven-assembly-plugin</artifactId> <configuration> <descriptors> <descriptor>src/main/assembly/assembly-store-memory. <!-..Creating Applications with Maven If you take a look at the POM for the proficio-cli module you will see the profile definitions: <project> .xml</descriptor> </descriptors> </configuration> </plugin> </plugins> </build> <activation> <property> <name>memory</name> </property> </activation> </profile> <!-.
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-1.0-SNAPSHOT. You will also notice that the profiles are activated using a system property. 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.0-SNAPSHOT.jar file. Better Builds With Maven 65 .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.
.. 3. SSH2 deployment. Deploying your Application Now that you have an application assembly. SFTP deployment..9.. Deploying with SSH2 To deploy to an SSH2 server you would use something like the following: <project> . which would typically be your top-level POM so that all child POMs can inherit this information.1. you'll want to share it with as many people as possible! So.yourcompany.. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scp://sshserver. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>file://${basedir}/target/deploy</url> </repository> </distributionManagement> . Deploying to the File System To deploy to the file system you would use something like the following: <project> . FTP deployment..9.. and external SSH deployment. </project> 3.. </project> Better Builds With Maven 66 .10.com/deploy</url> </repository> </distributionManagement> . In order to deploy you need to correctly configure your distributionManagement element in your POM.Creating Applications with Maven 3. Currently Maven supports several methods of deployment include simple file-based deployment. Here are some examples of how to configure your POM via the various deployment mechanisms. it is now time to deploy your application assembly.
but to use an external SSH command to deploy you must configure not only the distributionManagment element.11.. Deploying with an External SSH Now..apache.. so only the distributionManagement element is required.com/deploy</url> </repository> </distributionManagement> ..com/deploy</url> </repository> </distributionManagement> <build> <extensions> <extension> <groupId>org. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>scpexe://sshserver.maven.. </project> The build extension specifies the use of the Wagon external SSH provider.Creating Applications with Maven 3. Better Builds With Maven 67 . Wagon is the general purpose transport mechanism used throughout Maven. but also a build extension. <distributionManagement> <repository> <id>proficio-repository</id> <name>Proficio Repository</name> <url>sftp://ftpserver. Deploying with SFTP To deploy to an SFTP server you would use something like the following: <project> .11. </project> 3. <project> ..1.0-alpha-6</version> </extension> </extensions> </build> .wagon</groupId> <artifactId>wagon-ssh-external</artifactId> <version>1. which does the work of moving your files to the remote server.yourcompany..yourcompany.. the first three methods illustrated are included with 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:
Better Builds With Maven
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.
Better Builds With Maven
Creating Applications with Maven
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>
Better Builds With Maven
Creating Applications with Maven
This is a fairly standard site descriptor, but you should know about the specifics of each of the elements in the site descriptor: Table 3-3: Site descriptor
Site Descriptor Element Description
bannerLeft and bannerRight skin publishDate body/links body/head
These elements take a name, href and optional src element, which can be used for images. This element looks very much like a dependency (the same mechanism is used to retrieve the skin) and controls which skin is used for the site. The format of the publish date is that of the SimpleDateFormat class in Java. The link elements control the references that are displayed below the banner and take a simple name and href. The head element allows you to insert anything in the head element of generated pages. You may wish to add metadata, or script snippets for activating tools like Google Analytics. The menu elements control the list of menus and their respective menu items that are displayed in the navigation column of the site. You can have any number of menu items each containing any number of links. The inclusion of the ${reports} reference controls whether the project reports are displayed in the web site. You might exclude ${reports} reference for a site that consists purely of user documentation for example.
One of the most popular features of Maven are the standard reports that can be produced with little effort. If you simply include the ${reports} reference in your site descriptor you will, by default, have the standard project information reports generated and displayed automatically for you. The standard project information reports consist of the following:
• • • • • • •
Dependencies Report Mailing Lists Report Continous Integration Report Source Repository Report Issue Tracking Report Project Team Report License
Even though the standard reports are very useful, often you will want to customize the projects reports that are created and displayed in your web site. The reports created and displayed are controlled in the build/reports element in the POM. You may want to be more selective about the reports that you generate and to do so you need to list each report that you want to include as part of the site generation. You do so by configuring the plugin as follows:
Better Builds With Maven
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
Better Builds With Maven
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 .
Creating Applications with Maven Figure 3-6: The sample generated site If you have resources like images or PDFs that you want to be able to reference in your documents you can use the src/site/resources to store them and when the site is generated the content of src/site/resources will be copied to the top-level directory of the site. how to make small modifications to Maven's build life cycle. Better Builds With Maven 74 . Keeping in mind this simple rule you can add any resources you wish to your site. how to deploy your application. 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. 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. and using Maven in a collaborative environment.13. You should now have a grasp of how project inheritance works. and how to create a simple Web site for your application. how to manage your application's dependencies. augmenting your site to view quality metrics. 3. 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.
. WAR. Web Services) Setting up in-place Web development Deploying J2EE archives to a container Automating container start/stop Keep your face to the sun and you will never see the shadows. EAR.Helen Keller Better Builds With Maven 75 . Building J2EE Applications Building J2EE Applications This chapter covers: • • • • • Organizing the directory structure Building J2EE archives (EJB.4.
Through this example. and Web applications.2. As a consequence the Maven community has developed plugins to cover every aspect of building J2EE applications. and it's architecture is shown in Figure . EJBs. Introducing the DayTrader Application DayTrader is a real world application developed by IBM and then donated to the Apache Geronimo project. Figure 4-1: Architecture of the DayTrader application Better Builds With Maven 76 . Whether you are using the full J2EE stack with EJBs or only using Web applications with frameworks such as Spring or Hibernate. This chapter demonstrates how to use Maven on a real application to show how to address the complex issues related to automated builds. you'll learn how to automate configuration and deployment of J2EE application servers. The functional goal of the DayTrader application is to buy and sell stock.Building J2EE Applications 4. Introduction J2EE (or Java EE as it is now called) applications are everywhere. This chapter will take you through the journey of creating the build for a full-fledged J2EE application called DayTrader. 4. you'll learn how to build EARs. it's likely that you are using J2EE in some of your projects.4 application and as a test bed for running performance tests. 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.1. Web services. Its goal is to serve as both a functional example of a full-stack J2EE 1. As importantly.
Asynchronously the order that was placed on the queue is processed and the purchase completed. get a stock quote. 3. The Data layer consists of a database used for storing the business objects and the status of each purchase. 2. 4.Building J2EE Applications There are 4 layers in the architecture: • The Client layer offers 3 ways to access the application: using a browser. Holding. • • • A typical "buy stock" use case consists of the following steps that were shown in Figure : 1. The Quote Streamer is a Swing GUI application that monitors quote information about stocks in real-time as the price changes. and using the Quote Streamer. Account. and so on. The user is notified of the completed order on a subsequent request. cancel an order. Once this happens the Trade Broker MDB is notified 6. logout. It uses servlets and JSPs. A new "open" order is saved in the database using the CMP Entity Beans. and Message-Driven Beans (MDB) to send purchase orders and get quote changes. The creation of the "open" order is confirmed for the user. The Trade Session is a stateless session bean that offers the business services such as login. Better Builds With Maven 77 . and a JMS Server for interacting with the outside world. buy or sell a stock. The Trade Broker calls the Trade Session bean which in turn calls the CMP entity beans to mark the order as "completed". The Web layer offers a view of the application for both the Web client and the Web services client. This request is handled by the Trade Session bean.Quote and AccountProfile). using Web services. The order is then queued for processing in the JMS Message Server. It uses container-managed persistence (CMP) entity beans for storing the business objects (Order. The user gives a buy order (by using the Web client or the Web services client). 5. The EJB layer is where the business logic is.
Note that this is the minimal number of modules required. Figure 4-2 shows these modules in a flat directory structure. The next step is to give these modules names and map them to a directory structure. 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 Web services client application ear . However.3.Building J2EE Applications 4. On the other hand. it is important to split the modules when it is appropriate for flexibility. you may want to split the WAR module into 2 WAR modules: one for the browser client and one for the Web services client. It is flat because you're locating all the modules in the same directory. For example. For the DayTrader application the following names were chosen: • • • • • ejb . a WAR which will contain the Web application. It is possible to come up with more. Let's discuss the pros and cons of each layout. another JAR that will contain the Web services client application. if you needed to physically locate the WARs in separate servlet containers to distribute the load.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. a JAR that will contain the Quote Streamer client application. Best practices suggest to do this only when the need arises. If there isn't a strong need you may find that managing several modules can be more cumbersome than useful. Better Builds With Maven 78 . This EAR will be used to easily deploy the server code into a J2EE container.the module containing the Web application streamer . As a general rule. Organizing the DayTrader Directory Structure The first step to organizing the directory structure is deciding what build modules are required. The easy answer is to follow Maven's artifact guideline: one module = one main artifact. 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. it is better to find functional names for modules. For example.the module containing the EJBs web .the module containing the client side streamer application wsappclient . it is usually easier to choose names that represent a technology instead.
. not nested within each other.. This file also contains the list of modules that Maven will build when executed from this directory (see the Chapter 3.] <modules> <module>ejb</module> <module>web</module> <module>streamer</module> <module>wsappclient</module> <module>ear</module> </modules> [. Better Builds With Maven 79 .Building J2EE Applications Figure 4-2: Module names and a simple flat directory structure The top-level daytrader/pom. Creating Applications with Maven. and is the structure used in this chapter. Figure 4-3: Modules split according to a server-side vs client-side directory organization As before. Note that in this case the modules are still separate.xml file contains the POM elements that are shared between all of the modules.] This is the easiest and most flexible structure to use. each directory level containing several modules contains a pom.xml file containing the shared POM elements and the list of modules underneath. you might separate the client side modules from the server side modules in the way shown in Figure 4-3. for more details): [. However. For example. if you have many modules in the same directory you may consider finding commonalities between them and create subdirectories to partition them...
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. For example. you're going to create the Maven build for each module. In those cases using a nested directory structure should be avoided. For example. the three modules wouldn't be able to have different natures (Web application project. You'd need to consider the three modules as one project. EAR project). the ejb and web modules are nested in the ear module. Having this nested structure clearly shows how nested modules are linked to their parent. Figure 4-4: Nested directory structure for the EAR. 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. the nested strategy doesn't fit very well with the Assembler role as described in the J2EE specification. In this case. but by some client-side application.Building J2EE Applications The other alternative is to use a nested directory structure. • It doesn't allow flexible packaging. EJB and Web modules However. Better Builds With Maven 80 . starting with the EJB module. EJB project. the ejb or web modules might depend on a utility JAR and this JAR may be also required for some other EAR. Now that you have decided on the directory structure for the DayTrader application. even though the nested directory structure seems to work quite well here. This makes sense as the EAR artifact is composed of the EJB and WAR artifacts produced by the ejb and web modules. A flat layout is more neutral with regard to assembly and should thus be preferred. as shown in Figure 4-4. In addition. etc. Or the ejb module might be producing a client EJB JAR which is not used by the EAR. The Assembler has a pool of modules and its role is to package those modules for deployment.
the standard ejb-jar. Any container-specific deployment descriptor should also be placed in this directory. More specifically.Building J2EE Applications 4. Unit tests are tests that execute in isolation from the container. Better Builds With Maven 81 .4. • Runtime classpath resources in c. Building an EJB Project Let's create a build for the ejb module. • • Unit tests in src/test/java and classpath resources for the unit tests in src/test/resources.xml deployment descriptor is in src/main/resources/META-INF/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.xml. Tests that require the container to run are called integration tests and are covered at the end of this chapter.
apache.3</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.maven. you're extending a parent POM using the parent element.geronimo.apache.xml file.0</modelVersion> <parent> <groupId>org.geronimo.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1. This is because the DayTrader build is a multi-module build and you are gathering common POM elements in a parent daytrader/pom.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. Now run maven -N install in daytrader/ in order to install the parent POM in your local repository and make it available to all modules when you build them: Better Builds With Maven 82 .samples.xml file: <project> <modelVersion>4.0.apache. take a look at the content of this project's pom.specs</groupId> <artifactId>geronimo-j2ee_1.Building J2EE Applications Now.class</clientExclude> </clientExcludes> </configuration> </plugin> </plugins> </build> </project> As you can see.0.4_spec</artifactId> <version>1.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean.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.
.m2\repository\org\apache\geronimo\samples\daytrader\daytrader\1.. The Client will be used in a later examples when building the web module. Fortunately.xml to C:\[.class. this JAR is not redistributable and as such cannot be found on ibiblio. the Geronimo project has made the J2EE JAR available under an Apache license and this JAR can be found on ibiblio.xml contains a configuration to tell the Maven EJB plugin to generate a Client EJB JAR file when mvn install is called. Better Builds With Maven 83 .maven. You make this clear to Maven by using the provided scope. By default the EJB plugin does not generate the client JAR. the pom.class</clientExclude> </clientExcludes> </configuration> </plugin> The EJB plugin has a default set of files to exclude from the client EJB JAR: **/*Bean. You should note that you're using a provided scope instead of the default compile scope.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. • Lastly.0\daytrad er-1. **/*Session.]\. Even though this dependency is provided at runtime.pom The ejb/pom.Building J2EE Applications C:\dev\m2book\code\j2ee\daytrader>mvn -N install [INFO] Scanning for projects.plugins</groupId> <artifactId>maven-ejb-plugin</artifactId> <configuration> <generateClient>true</generateClient> <clientExcludes> <clientExclude>**/ejb/*Bean. [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.class. This is achieved by specifying a dependency element on the J2EE JAR. You could instead specify a dependency on Sun's J2EE JAR. The reason is that this dependency will already be present in the environment (being the J2EE application server) where your EJB will execute. it still needs to be listed in the POM so that the code can be compiled.class and **/package. 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.apache. so you must explicitly tell it to do so: <plugin> <groupId>org.. **/*CMP. this prevents the EAR module from including the J2EE JAR when it is packaged. However.html..0.
apache. 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.geronimo. Failures: 0.0\daytrader-ejb-1.m2\repository\org\apache\geronimo\samples\ daytrader\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. Time elapsed: 0.0-client.FinancialUtilsTest [surefire] Tests run: 1.jar [INFO] Building ejb client daytrader-ejb-1. [INFO] [compiler:testCompile] Compiling 1 source file to C:\dev\m2book\code\j2ee\daytrader\ejb\target\testclasses [INFO] [surefire:test] [INFO] Setting reports dir: C:\dev\m2book\code\j2ee\daytrader\ejb\target/surefirereports ------------------------------------------------------T E S T S ------------------------------------------------------[surefire] Running org.jar Better Builds With Maven 84 ... 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.0.jar [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.0 [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.0.jar to C:\[.. Errors: 0. Note that it's also possible to specify a list of files to include using clientInclude elements. Errors: 0 [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ejb\1..0\daytrader-ejb-1. You're now ready to execute the build.jar to C:\[. Relax and type mvn install: C:\dev\m2book\code\j2ee\daytrader\ejb>mvn install [INFO] Scanning for projects.. Failures: 0.daytrader. [INFO] ----------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [install] [INFO] ----------------------------------------------------------[INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources.]\..02 sec Results : [surefire] Tests run: 1.Building J2EE Applications In this example.samples.0.jar [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.0-client.0-client.class).class pattern and which need to be present in the generated client EJB JAR.]\.0-client [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ejb\ target\daytrader-ejb-1.
5.Building J2EE Applications Maven has created both the EJB JAR and the client EJB JAR and installed them in your local Maven repository. the EJB3 specification is still not final. 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. and the ejb-jar. the Remote and Local interfaces.org/plugins/maven-ejb-plugin/. 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. When writing EJBs it means you simply have to write your EJB implementation class and XDoclet will generate the Home interface. At the time of writing.apache. Using XDoclet is easy: by adding Javadoc annotations to your classes. you can run the XDoclet processor to generate those files for you. Early adopters of EJB3 may be interested to know how Maven supports EJB3. you can safely skip this section – you won't need it! Better Builds With Maven 85 . the container-specific deployment descriptors. There is a working prototype of an EJB3 Maven plugin. Stay tuned! 4.xml descriptor. Note that if you're an EJB3 user. Please refer to the EJB plugin documentation on http://maven.
apache.ejb.Building J2EE Applications Here's an extract of the TradeBean session EJB using Xdoclet: /** * Trade Session EJB manages all Trading services * * @ejb.transaction * type="RequiresNew" *[…] */ public void queueOrderOnePhase(Integer orderID) throws javax.interface-method * view-type="remote" * @ejb.jms. create a copy of the DayTrader ejb module called ejb-xdoclet. but you don't need the ejb-jar.geronimo.Trade" * […] */ public class TradeBean implements SessionBean { […] /** * Queue the Order identified by orderID to be processed in a * One Phase commit […] * * @ejb.TradeBean" * @ejb.geronimo.samples. Exception […] To demonstrate XDoclet. Figure 4-6: Directory structure for the DayTrader ejb module when using Xdoclet Better Builds With Maven 86 .interface * generate="remote" * remote-class= * "org.JMSException.apache.ejb.TradeHome" * @ejb.geronimo.daytrader.samples.daytrader. the project's directory structure is the same as in Figure 4-5. As you can see in Figure 4-6.samples.bean * display-name="TradeEJB" * name="TradeEJB" * view-type="remote" * impl-class-name= * "org.daytrader.apache.ejb.home * generate="remote" * remote-class= * "org.xml file anymore as it's going to be generated by Xdoclet.
xml that configures the plugin: <plugin> <groupId>org.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.build.directory}/generated-sources/xdoclet (you can configure this using the generatedSourcesDirectory configuration element).java"></include> <include name="**/*MDB.codehaus. In practice you can use any XDoclet task (or more generally any Ant task) within the tasks element.sourceDirectory}"> <include name="**/*Bean.java classes and remove all of the Home. Now you need to tell Maven to run XDoclet on your project. In addition.html). Better Builds With Maven 87 .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.Building J2EE Applications The other difference is that you only need to keep the *Bean. The plugin generates sources by default in ${project.build. in the tasks element you use the ejbdoclet Ant task provided by the XDoclet project (for reference documentation see http://xdoclet.directory}/generated-sources/xdoclet"> <fileset dir="${project.outputDirectory}/META-INF"/> </ejbdoclet> </tasks> </configuration> </execution> </executions> </plugin> The XDoclet plugin is configured within an execution element. this has to be run before the compilation phase occurs. This is achieved by using the Maven XDoclet plugin and binding it to the generate-sources life cycle phase. the XDoclet plugin will also trigger Maven to download the XDoclet libraries from Maven's remote repository and add them to the execution classpath. This is required by Maven to bind the xdoclet goal to a phase. Local and Remote interfaces as they'll also get generated.build. Finally.build. It also tells Maven that this directory contains sources that will need to be compiled when the compile phase executes.mojo</groupId> <artifactId>xdoclet-maven-plugin</artifactId> <executions> <execution> <phase>generate-sources</phase> <goals> <goal>xdoclet</goal> </goals> <configuration> <tasks> <ejbdoclet verbose="true" force="true" ejbSpec="2. Since XDoclet generates source files.1" destDir= "${project. Here's the portion of the pom.sourceforge.
ejb.samples.apache.XDocletMain start INFO: Running <localinterface/> Generating Local interface for 'org. 2006 16:53:51 xdoclet.org/Maven2+Plugin. It's based on a new architecture but the tag syntax is backwardcompatible in most cases. 2006 16:53:50 xdoclet. […] 10 janv. […] 10 janv.ejb. […] INFO: Running <remoteinterface/> Generating Remote interface for 'org.apache.geronimo.0 […] You might also want to try XDoclet2. However.geronimo.samples.TradeBean'.Building J2EE Applications Executing mvn install now automatically executes XDoclet and compiles the generated files: C:\dev\m2book\code\j2ee\daytrader\ejb-xdoclet>mvn install […] [INFO] [xdoclet:xdoclet {execution: default}] [INFO] Initializing DocletTasks!!! [INFO] Executing tasks 10 janv.geronimo. it should be noted that XDoclet2 is a work in progress and is not yet fully mature.AccountBean'. […] 10 janv.geronimo.XDocletMain start INFO: Running <localhomeinterface/> Generating Local Home interface for 'org.daytrader.XDocletMain start INFO: Running <homeinterface/> Generating Home interface for 'org.ejb.ejb.TradeBean'.apache.XDocletMain start INFO: Running <deploymentdescriptor/> Generating EJB deployment descriptor (ejb-jar.daytrader.daytrader.samples.apache. nor does it boast all the plugins that XDoclet1 has.AccountBean'.daytrader. 2006 16:53:50 xdoclet. […] [INFO] [ejb:ejb] [INFO] Building ejb daytrader-ejb-1. Better Builds With Maven 88 .xml). There's also a Maven 2 plugin for XDoclet2 at http://xdoclet.samples. 2006 16:53:51 xdoclet.codehaus.
net/ sourceforge/jboss/jboss-4.log</output> <log>${project. Deploying EJBs Now that you know how to build an EJB project. stopping.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> </plugin> </plugins> </build> If you want to debug Cargo's execution..org/Debugging for full details. In order to build this project you need to create a Profile where you define the ${installDir} property's value.xml file and add the following Cargo plugin configuration: <build> <plugins> [.directory}/jboss4x.] <plugin> <groupId>org.2 distribution from the specified URL and install it in ${installDir}. configuring them and deploying modules to them. the JBoss container will be used.6. Maven 2.directory}/cargo.log</log> [. For example: <container> <containerId>jboss4x</containerId> <output>${project.sourceforge.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <zipUrlInstaller> <url>http://internap. you can use the log element to specify a file where Cargo logs will go and you can also use the output element to specify a file where the container's output will be dumped. In this example.] See http://cargo. you will learn how to deploy it.build. Maven 1. Cargo is a framework for manipulating containers. It offers generic APIs (Java. Netbeans.codehaus.x (containerId element) and that you want Cargo to download the JBoss 4. The location where Cargo should install JBoss is a user-dependent choice and this is why the ${installDir} property was introduced.Building J2EE Applications 4. etc. in the Testing J2EE Applications section of this chapter. To do so you're going to use the Maven plugin for Cargo.. IntelliJ IDEA. Let's discover how you can automatically start a container and deploy your EJBs into it.build...2. Ant. Later. you will also learn how to test it automatically. Better Builds With Maven 89 . Edit the ejb/pom. you will need to have Maven start the container automatically.0. In the container element you tell the Cargo plugin that you want to use JBoss 4.dl.0.) for performing various actions on containers such as starting.codehaus. First.
and the EJB JAR has been deployed. then start JBoss and deploy the EJB JAR by running mvn cargo:start (or mvn package cargo:start to do it all at once): C:\dev\m2book\code\j2ee\daytrader\ejb>mvn cargo:start [INFO] Scanning for projects. Of course.. The Cargo plugin does all the work: it provides a default JBoss configuration (using port 8080 for example).xml file. Better Builds With Maven 90 .xml file. in a settings. the EJB JAR should first be created.2 started on port [8080] [INFO] Press Ctrl-C to stop the container. so run mvn package to generate it.2] [INFO] [talledLocalContainer] JBoss 4. or in a settings.2 starting. That's it! JBoss is running. in a profiles.2</home> That's all you need to have a working build and to deploy the EJB JAR into JBoss. In this case..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. Thus the best place is to create a profiles.0.xml file defines a profile named vmassol. It's also possible to tell Cargo that you already have JBoss installed locally..Building J2EE Applications As explained in Chapter 3. it detects that the Maven project is producing an EJB from the packaging element and it automatically deploys it when the container is started. For example: <home>c:/apps/jboss-4. [INFO] [talledLocalContainer] JBoss 4..xml file.0.0. Nor should the content be shared with other Maven projects at large. In that case replace the zipURLInstaller element with a home element. activated by default and in which the ${installDir} property points to c:/apps/cargo-installs.. you can define a profile in the POM.0. [INFO] Searching repository for plugin with prefix: 'cargo'.. [INFO] ----------------------------------------------------------------------[INFO] Building DayTrader :: EJBs [INFO] task-segment: [cargo:start] [INFO] ----------------------------------------------------------------------[INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4. as the content of the Profile is user-dependent you wouldn't want to define it in the POM.
codehaus.org/Maven2+plugin. deploying on a remote machine.Building J2EE Applications As you have told Cargo to download and install JBoss. let's focus on building the DayTrader web module. Subsequent calls will be fast as Cargo will not download JBoss again. Cargo has many other configuration options such as the possibility of using an existing container installation. (see Figure 4-7). Finally. 4. modifying various container parameters. WEB-INF configuration files. Building a Web Application Project Now. If the container was already started and you wanted to just deploy the EJB. JSPs. The layout is the same as for a JAR module (see the first two chapters of this book). the first time you execute cargo:start it will take some time. Check the documentation at http://cargo. except that there is an additional src/main/webapp directory for locating Web application resources such as HTML pages. to stop the container call mvn cargo:stop. etc. you would run the cargo:deploy goal.7. especially if you are on a slow connection. Figure 4-7: Directory structure for the DayTrader web module showing some Web application resources Better Builds With Maven 91 . and more.
0.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.0</version> </parent> <artifactId>daytrader-web</artifactId> <name>DayTrader :: Web Application</name> <packaging>war</packaging> <description>DayTrader Web</description> <dependencies> <dependency> <groupId>org. It's always cleaner to depend on the minimum set of required classes.samples.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.0</modelVersion> <parent> <groupId>org.geronimo. Therefore.apache.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1.xml. you need to add a dependency on the ejb module in web/pom.samples. This is because the servlets are a client of the EJBs.4_spec</artifactId> <version>1.apache. for example to prevent coupling. This is why you told the EJB plugin to generate a client JAR earlier on in ejb/pom.Building J2EE Applications As usual everything is specified in the pom.geronimo.samples. the servlets only need the EJB client JAR in their classpath to be able to call the EJBs. but it's not necessary and would increase the size of the WAR file.specs</groupId> <artifactId>geronimo-j2ee_1.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1. Therefore. Depending on the main EJB JAR would also work.xml: <dependency> <groupId>org. you specify the required dependencies.apache. If you add a dependency on a WAR.geronimo.0</version> <type>ejb-client</type> </dependency> Note that you're specifying a type of ejb-client and not ejb.xml file: <project> <modelVersion>4.apache. then the WAR you generate will be overlaid with the Better Builds With Maven 92 . The reason you are building this web module after the ejb module is because the web module's servlets call the EJBs.0</version> <type>ejb-client</type> </dependency> <dependency> <groupId>org.geronimo.
war [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. The configuration is very simple because the defaults from the WAR plugin are being used. as it reduces the size of the pom..0\daytrader-web-1.0. Otherwise it would have surfaced in the WEB-INF/lib directory of the generated WAR.. An alternative is to use the uberwar goal from the Cargo Maven Plugin (see http://cargo. only files not in the existing Web application will be added. it recursively adds your module's dependencies.. This is why we defined the J2EE JAR using a provided scope in the web module's pom.0. [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.codehaus. and files such as web. it's a good practice to use the default conventions as much as possible.. Maven 2 supports transitive dependencies. Again. However..war Better Builds With Maven 93 . Running mvn install generates the WAR and installs it in your local repository: C:\dev\m2book\code\j2ee\daytrader\web>mvn install [. As seen in the introduction.0.0 [INFO] Assembling webapp daytrader-web in C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1. allowing the aggregation of multiple WAR files.xml. As you know.]\.org/Merging+WAR+files). When it generates your WAR.. The final dependency listed is the J2EE JAR as your web module uses servlets and calls EJBs.m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-web\1. the Geronimo J2EE specifications JAR is used with a provided scope (as seen previously when building the EJB). unless their scope is test or provided.war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.war to C:\[.xml file and reduces maintenance.Building J2EE Applications content of that dependent WAR.] [INFO] [war:war] [INFO] Exploding webapp.xml won't be merged.0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.0.
warSourceIncludes/war All files are included SourceExcludes warName ${project. Specify where to find the web.Building J2EE Applications Table 4-1 lists some other parameters of the WAR plugin that you may wish to configure. Specify the files to include/exclude from the generated WAR. Better Builds With Maven 94 .build. Table 4-1: WAR plugin configuration properties Configuration property Default value Description warSourceDirectory webXml ${basedir}/src/main/webapp The web. see the reference documentation for the WAR plugin at http://maven.xml Location of Web application resources to include in the WAR.apache.finalName} For the full list.org/plugins/maven-war-plugin/.xml file.xml file found in ${warSourceDirectory}/WEBINF/web. Name of the generated WAR.
Improving Web Development Productivity If you're doing Web development you know how painful it is to have to package your code in a WAR and redeploy it every time you want to try out a change you made to your HTML. and it adds the compiled classes in target/classes to its execution classpath. adding this dependency to the plugin adds it to the classpath for Jetty. the project dependencies and the compiled classes and classpath resources in target/classes. 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. Let's try the Jetty6 plugin on the DayTrader web module.Building J2EE Applications 4.mortbay. the web. the src/main/webapp tree.xml file: […] <build> <plugins> <plugin> <groupId>org. JSP or servlet code.jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> <scanIntervalSeconds>10</scanIntervalSeconds> </configuration> <dependencies> <dependency> <groupId>org.apache. Thus any recompilation in your IDE will trigger a redeploy of your Web application in Jetty. the plugin reloads the Web application in Jetty.xml file. Fortunately. If any change is detected.specs</groupId> <artifactId>geronimo-j2ee_1. providing an extremely fast turnaround time for development. The plugin is configured by default to look for resource files in src/main/webapp. The plugin monitors the source tree for changes.xml file. including the pom. The Jetty6 plugin creates a custom Jetty 6 configuration that is wired to your source tree.4_spec</artifactId> <version>1.8. Add the following to the web/pom. Since the Web application earlier declared that the specification must be provided through the provided scope. You execute the Jetty6 plugin by typing mvn jetty6:run: Better Builds With Maven 95 . 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). There are two plugins that can alleviate this problem: the Cargo plugin and the Jetty6 plugin.0</version> <scope>provided</scope> </dependency> </dependencies> </plugin> […] The scanIntervalSeconds configuration property tells the plugin to monitor for changes every 10 seconds.geronimo. 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. Maven can help.
jsp URL as shown in Figure 4-8 to see the Web application running.log .log.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.SelectChannelConnector listening on 8080 with maxIdleTime 30000 0 [main] INFO org.Logging to org.log . Figure 4-8: DayTrader JSP registration page served by the Jetty6 plugin Better Builds With Maven 96 .xml. Maven pauses as Jetty is now started. [INFO] Finished setting up classpath [INFO] Started configuring web.nio.. resource base= C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Finished configuring web.slf4j.0. listening for changes. Open a browser with the http://localhost:8080/daytrader-web/register.impl...mortbay.Slf4jLog [INFO] Context path = /daytrader-web [INFO] Webapp directory = C:\dev\m2book\code\j2ee\daytrader\web\src\main\webapp [INFO] Setting up classpath ..xml file located at: C:\dev\m2book\code\j2ee\daytrader\ web\src\main\webapp\WEB-INF\web.SimpleLogger@1242b11 via org.mortbay.0.xml 681 [main] INFO org.mortbay. [INFO] No connectors configured.0:8080 [INFO] Starting scanner at interval of 10 seconds.jetty. using defaults: org. Your Web application has been deployed and the plugin is waiting.Started SelectChannelConnector @ 0.xml [INFO] Classes located at: C:\dev\m2book\code\j2ee\daytrader\ web\target\classes [INFO] tmp dir for webapp will be C:\dev\m2book\code\j2ee\daytrader\web\target\jetty-tmp [INFO] Starting Jetty Server . As you can see.mortbay.
In practice it's easier to deploy a full EAR as you'll see below. you would use: Better Builds With Maven 97 . but the EJBs and all the back end code has not been deployed. There are various configuration parameters available for the Jetty6 plugin such as the ability to define Connectors and Security realms.properties. Edit web/src/main/webapp/register. isn't it? What happened is that the Jetty6 plugin realized the page was changed and it redeployed the Web application automatically. The Jetty container automatically recompiled the JSP when the page was refreshed. search for "10000" and replace it with "90000" (a much better starting amount!): <TD colspan="2" align="right">$<B> </B><INPUT size="20" type="text" name="money" value='<%= money==null ? "90000" : money %>'></TD> Now simply refresh your browser (usually the F5 key) and the new value will appear as shown in Figure 4-9: Figure 4-9: Modified registration page automatically reflecting our source change That's nifty.Building J2EE Applications Note that the application will fail if you open a page that calls EJBs.jsp. The reason is that we have only deployed the Web application here. In order to make it work you'd need to have your EJB container started with the DayTrader code deployed in it. For example if you wanted to run Jetty on port 9090 with a user realm defined in etc/realm. Now let's try to modify the content of this JSP by changing the opening account balance.
xml file is modified.html.xml file will be applied first.SelectChannelConnector"> <port>9090</port> <maxIdleTime>60000</maxIdleTime> </connector> </connectors> <userRealms> <userRealm implementation= "org. The Jetty6 plugin also contains two goals that can be used in this situation: • etty6:run-war: The plugin first runs the package phase which generates the WAR file. WEB-INF/classes.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. 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.org/jetty6/mavenplugin/index.jetty.mortbay. that you have custom plugins that do all sorts of transformations to Web application resource files. Now imagine that you have an awfully complex Web application generation process.Building J2EE Applications <plugin> <groupId>org. The plugin then watches the following files: WEB-INF/lib. possibly generating some files. Better Builds With Maven 98 . Then it deploys the unpacked Web application located in target/ (whereas the jetty6:run-war goal deploys the WAR file).nio. 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.HashUserRealm"> <name>Test Realm</name> <config>etc/realm. • jetty6:run-exploded: The plugin runs the package phase as with the jetty6:run-war goal.jetty. and so on.security.xml. any change to those files results in a hot redeployment. It's also possible to pass in a jetty.mortbay. for example) or when the pom. By default the plugin uses the module's artifactId from the POM.xml configuration file using the jettyConfig configuration element.mortbay. The WAR plugin has an exploded goal which produces an expanded Web application in the target directory. Calling this goal ensures that the generated Web application is the correct one.jetty</groupId> <artifactId>maven-jetty6-plugin</artifactId> <configuration> […] <connectors> <connector implementation= "org. For a reference of all configuration options see the Jetty6 plugin documentation at http://jetty. WEB-INF/web. Fortunately there's a solution.xml and pom.mortbay. In that case anything in the jetty.
0 [INFO] Generating war C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1.Building J2EE Applications To demonstrate.0 [INFO] Assembling webapp daytrader-web in C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1.Started SelectChannelConnector @ 0.impl...log .mortbay.] [INFO] [war:war] [INFO] Exploding webapp.0.war [INFO] [jetty6:run-exploded] [INFO] Configuring Jetty for project: DayTrader :: Web Application [INFO] Starting Jetty Server . Restart completed. [INFO] Scan complete at Wed Feb 15 11:59:00 CET 2006 [INFO] Starting scanner at interval of 10 seconds..0..slf4j. Listeners completed. Stopping webapp .log..Logging to org..0:8080 [INFO] Scanning . execute mvn jetty6:run-exploded goal on the web module: C:\dev\m2book\code\j2ee\daytrader\web>mvn jetty6:run-exploded [.. Restarting webapp . No more excuses! Better Builds With Maven 99 . You're now ready for productive web development...mortbay.log . 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.....SimpleLogger@78bc3b via org.... 0 [main] INFO org.0. Reconfiguring webapp .0.Slf4jLog [INFO] Context path = /daytrader-web 2214 [main] INFO org.war [INFO] Building war: C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web1.. 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 . Scanning . [INFO] Copy webapp resources to C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1..
port>8280</cargo.codehaus. add the following profiles to the web/pom. This is very useful when you're developing an application and you want to verify it works on several containers.xml file and add the Cargo configuration: <plugin> <groupId>org.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. edit the web module's pom. This is very useful if you have containers already running your machine and you don't want to interfere with them.9.xml file. so now the focus will be on deploying a packaged WAR to your target container.port element has been introduced to show how to configure the containers to start on port 8280 instead of the default 8080 port.codehaus.org/Containers). Those properties will be defined in a Profile. Deploying Web Applications You have already seen how to deploy a Web application for in-place Web development in the previous section. A cargo. First. This example uses the Cargo Maven plugin to deploy to any container supported by Cargo (see http://cargo.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>${containerId}</containerId> <zipUrlInstaller> <url>${url}</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <configuration> <properties> <cargo.servlet.servlet. the containerId and url properties should be shared for all users of the build. As seen in the Deploying EJBs section the installDir property is user-dependent and should be defined in a profiles.xml file: Better Builds With Maven 100 . There are two differences though: • • Two new properties have been introduced (containerId and url) in order to make this build snippet generic.servlet. However. Thus.Building J2EE Applications 4.
0..0..] [INFO] [cargo:start] [INFO] [talledLocalContainer] Tomcat 5.zip</url> </properties> </profile> </profiles> </project> You have defined two profiles: one for JBoss and one for Tomcat and the JBoss profile is defined as active by default (using the activation element).0.net/sourceforge/jboss/jboss4.. You could add as many profiles as there are containers you want to execute your Web application on.0.dl. starts the JBoss container and deploys the WAR into it: C:\dev\m2book\code\j2ee\daytrader\web>mvn install cargo:start [.30/bin/ jakarta-tomcat-5.30.] </build> <profiles> <profile> <id>jboss4x</id> <activation> <activeByDefault>true</activeByDefault> </activation> <properties> <containerId>jboss4x</containerId> <url>http://ovh.Building J2EE Applications [.2 starting...0. [INFO] [talledLocalContainer] Tomcat 5.0.]\Temp\cargo\50866\webapps]..apache.sourceforge..2 started on port [8280] [INFO] Press Ctrl-C to stop the container. Better Builds With Maven 101 ..30 starting.0. [INFO] [CopyingLocalDeployer] Deploying [C:\dev\m2book\code\j2ee\daytrader\web\target\daytrader-web-1...] [INFO] [cargo:start] [INFO] [talledLocalContainer] Parsed JBoss version = [4..org/dist/jakarta/tomcat-5/v5...0...2] [INFO] [talledLocalContainer] JBoss 4.zip</url> </properties> </profile> <profile> <id>tomcat5x</id> <properties> <containerId>tomcat5x</containerId> <url>http://www.2. Executing mvn install cargo:start generates the WAR. [INFO] [talledLocalContainer] JBoss 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 [.war] to [C:\[.0.30 started on port [8280] [INFO] Press Ctrl-C to stop the container.
hostname> <cargo. • 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. At this stage you have learned how to build and deploy EJBs and WARs. Note that there was no need to specify a deployment URL as it is computed automatically by Cargo. Let's now discover how to build Web services modules. All the properties introduced need to be declared inside the POM for those shared with other users and in the profiles. you would need the following Cargo plugin configuration in web/pom.codehaus.username> <cargo.port> <cargo. However.remote.password> </properties> </configuration> </configuration> </plugin> When compared to the configuration for a local deployment above.remote.hostname>${remoteServer}</cargo.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>jboss4x</containerId> <type>remote</type> </container> <configuration> <type>runtime</type> <properties> <cargo. One solution is to have your container running on that integration platform and to perform a remote deployment of your WAR to it.remote.port>${remotePort}</cargo.org/Deploying+to+a+running+container.xml file) for those user-dependent.servlet. Better Builds With Maven 102 . the changes are: A remote container and configuration type to tell Cargo that the container is remote and not under Cargo's management.password>${remotePassword}</cargo.Building J2EE Applications This is useful for development and to test that your code deploys and works. To deploy the DayTrader's WAR to a running JBoss server on machine remoteserver and executing on port 80.servlet.username>${remoteUsername}</cargo.codehaus.xml: <plugin> <groupId>org.xml file (or the settings. • Check the Cargo reference documentation for all details on deployments at http://cargo. once this is verified you'll want a solution to deploy your WAR into an integration platform.remote.
For example. which is the default used by the Axis Tools plugin: Figure 4-10: Directory structure of the wsappclient module Better Builds With Maven 103 . and Maven's ability to integrate toolkits can make them easier to add to the build process. and this will be used from DayTrader's wsappclient module. Building a Web Services Client Project Web services are a part of many J2EE applications. As the name suggests. As you may notice. Figure 4-10 shows the directory structure of the wsappclient module.Building J2EE Applications 4.10. the Maven plugin called Axis Tools plugin takes WSDL files and generates the Java files needed to interact with the Web services it defines.org/axis/java/userguide.apache. Axis generates the following: Table 4-2: Axis generated classes WSDL clause Java class(es) generated For each entry in the type section For each port type For each binding For each service A Java class A holder if this type is used as an in-out/out parameter A Java interface A stub class A service interface A service implementation (the locator) For more details on the generation process. the WSDL files are in src/main/wsdl. the plugin uses the Axis framework (http://ws. see http://ws.html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL.org/axis/java/).apache.
it would fail. Better Builds With Maven 104 .. At this point f you were to execute the build.. This is because after the sources are generated.Building J2EE Applications The location of WSDL source can be customized using the sourceDirectory property.] In order to generate the Java source files from the TradeServices. and more importantly.] <plugin> <groupId>org.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.mojo</groupId> <artifactId>axistools-maven-plugin</artifactId> <configuration> <sourceDirectory> src/main/resources/META-INF/wsdl </sourceDirectory> </configuration> [.xml file must declare and configure the Axis Tools plugin: <project> [.] <build> <plugins> [. While you might expect the Axis Tools plugin to define this for you.wsdl file.. any tools that report on the POM will be able to recognize the dependency. For example: [...xml. 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. it allows users of your project to automatically get the dependency transitively. you will require a dependency on Axis and Axis JAXRPC in your pom....codehaus. the wsappclient/pom.] <plugin> <groupId>org.codehaus. Similarly.
4_spec</artifactId> <version>1. they are not present on ibiblio and you'll need to install them manually. Thus.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>org. Better Builds With Maven 105 .Building J2EE Applications As before. Run mvn install and Maven will fail and print the installation instructions. you need to add the J2EE specifications JAR to compile the project's Java sources.2</version> <scope>provided</scope> </dependency> <dependency> <groupId>axis</groupId> <artifactId>axis-jaxrpc</artifactId> <version>1.apache.geronimo.specs</groupId> <artifactId>geronimo-j2ee_1. Thus add the following two dependencies to your POM: <dependencies> <dependency> <groupId>axis</groupId> <artifactId>axis</artifactId> <version>1.0</version> <scope>provided</scope> </dependency> </dependencies> The Axis JAR depends on the Mail and Activation Sun JARs which cannot be redistributed by Maven.
] Note that the daytrader-wsappclient JAR now includes the class files compiled from the generated source files...codehaus.0.jar to C:\[.org/axistoolsmaven-plugin/.. Better Builds With Maven 106 . The generated WSDL file could then be injected into the Web Services client module to generate client-side Java files. But that's another story..m2\repository\org\apache\geronimo\samples\daytrader\ daytrader-wsappclient\1. [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.0.jar [.] [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. The Axis Tools plugin boasts several other goals including java2wsdl that is useful for generating the server-side WSDL file from handcrafted Java classes. in addition to the sources from the standard source directory...0\daytrader-wsappclient-1... [INFO] [jar:jar] [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1. The Axis Tools reference documentation can be found at http://mojo.jar [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\wsappclient\ target\daytrader-wsappclient-1.]\. [INFO] [compiler:testCompile] [INFO] No sources to compile [INFO] [surefire:test] [INFO] No tests to run.wsdl [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources.0.Building J2EE Applications Running the build with mvn install leads to: C:\dev\m2book\code\j2ee\daytrader\wsappclient>mvn install [.
. Building an EAR Project You have now built all the individual modules.0</modelVersion> <parent> <groupId>org.Building J2EE Applications 4.0</version> </parent> <artifactId>daytrader-ear</artifactId> <name>DayTrader :: Enterprise Application</name> <packaging>ear</packaging> <description>DayTrader EAR</description> Next.11.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.. Start by defining that this is an EAR project by using the packaging element: <project> <modelVersion>4.geronimo.xml file. The ear module's directory structure can't be any simpler. define all of the dependencies that need to be included in the generated EAR: Better Builds With Maven 107 .apache. It's time to package the server module artifacts (EJB and WAR) into an EAR for convenient deployment. Figure 4-11: Directory structure of the ear module As usual the magic happens in the pom. it solely consists of a pom.0.xml file (see Figure 4-11).samples.
ejb3.samples.samples.geronimo.samples. the description to use. jar. This includes the display name to use. war. and EJB modules.daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <version>1. ejb-client.0</version> </dependency> <dependency> <groupId>org.apache.daytrader</groupId> <artifactId>daytrader-web</artifactId> <version>1.geronimo.Building J2EE Applications <dependencies> <dependency> <groupId>org. sar and wsr.apache.apache.xml deployment descriptor file.samples.0</version> <type>ejb</type> </dependency> <dependency> <groupId>org.daytrader</groupId> <artifactId>daytrader-ejb</artifactId> <version>1.0</version> </dependency> </dependencies> Finally.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <version>1. par. and the J2EE version to use.0</version> <type>war</type> </dependency> <dependency> <groupId>org. It is also necessary to tell the EAR plugin which of the dependencies are Java modules. Better Builds With Maven 108 .apache. rar. the EAR plugin supports the following module types: ejb. At the time of writing. Web modules.geronimo. you need to configure the Maven EAR plugin by giving it the information it needs to automatically generate the application.geronimo.
daytrader</groupId> <artifactId>daytrader-wsappclient</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <webModule> <groupId>org.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <includeInApplicationXml>true</includeInApplicationXml> </javaModule> <javaModule> <groupId>org. Better Builds With Maven 109 . or those with a scope of test or provided.geronimo.Building J2EE Applications By default. You should also notice that you have to specify the includeInApplicationXml element in order to include the streamer and wsappclient libraries into the EAR.daytrader</groupId> <artifactId>daytrader-web</artifactId> <contextRoot>/daytrader</contextRoot> </webModule> </modules> </configuration> </plugin> </plugins> </build> </project> Here.maven. However.apache.samples. only EJB client JARs are included when specified in the Java modules list.geronimo.samples.geronimo.plugins</groupId> <artifactId>maven-ear-plugin</artifactId> <configuration> <displayName>Trade</displayName> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <version>1.apache.apache. it is often necessary to customize the inclusion of some dependencies such as shown in this example: <build> <plugins> <plugin> <groupId>org.apache. 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.4</version> <modules> <javaModule> <groupId>org.samples. all dependencies are included. with the exception of those that are optional. By default.xml file.
The streamer module's build is not described in this chapter because it's a standard build generating a JAR.Building J2EE Applications It is also possible to configure where the JARs' Java modules will be located inside the generated EAR. Better Builds With Maven 110 ...] </javaModule> [. 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. if you wanted to put the libraries inside a lib subdirectory of the EAR you would use the bundleDir element: <javaModule> <groupId>org.daytrader</groupId> <artifactId>daytrader-streamer</artifactId> <includeInApplicationXml>true</includeInApplicationXml> <bundleDir>lib</bundleDir> </javaModule> <javaModule> <groupId>org.apache.apache.] There are some other configuration elements available in the EAR plugin which you can find out by checking the reference documentation on http://maven. For example.geronimo..samples..org/plugins/maven-ear-plugin. Run mvn install in daytrader/streamer.] <defaultBundleDir>lib</defaultBundleDir> <modules> <javaModule> [..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: [.geronimo..apache.
0.Generating one [INFO] Building jar: C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1.0] to[daytrader-ejb-220.127.116.11.jar] [INFO] Copying artifact [ejb-client:org.samples.geronimo.daytrader: daytrader-ejb:1.MF .samples.jar] [INFO] Copying artifact [war:org.0] to [daytrader-web-1.0.jar] [INFO] Could not find manifest file: C:\dev\m2book\code\j2ee\daytrader\ear\src\main\application\ META-INF\MANIFEST.geronimo.ear Better Builds With Maven 111 .samples.geronimo.daytrader: daytrader-wsappclient:1.daytrader: daytrader-streamer:1.0] to [daytrader-ejb-1.samples.apache. [INFO] [ear:ear] [INFO] Copying artifact [jar:org..xml [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources..0] to [daytrader-streamer-1.0\daytrader-ear-1.ear [INFO] [install:install] [INFO] Installing C:\dev\m2book\code\j2ee\daytrader\ear\ target\daytrader-ear-1.geronimo.m2\repository\org\apache\geronimo\samples\ daytrader\daytrader-ear\1.apache.apache.samples.daytrader: daytrader-ejb:1.0.war] [INFO] Copying artifact [ejb:org.daytrader: daytrader-web:1.geronimo. run mvn install: C:\dev\m2book\code\j2ee\daytrader\ear>mvn install […] [INFO] [ear:generate-application-xml] [INFO] Generating application.apache.0-client.apache.ear to C:\[.jar] [INFO] Copying artifact [jar:org.0] to [daytrader-wsappclient-1.]\.Building J2EE Applications To generate the EAR.0.
0.0.com/xml/ns/j2ee http://java.jar</java> </module> <module> <java>daytrader-wsappclient-1.w3.4"> <description> DayTrader Stock Trading Performance Benchmark Sample </description> <display-name>Trade</display-name> <module> <java>daytrader-streamer-1.com/xml/ns/j2ee/application_1_4.0.0.xml to prove that it has everything you need: <?xml version="1.war</web-uri> <context-root>/daytrader</context-root> </web> </module> <module> <ejb>daytrader-ejb-1.sun. Better Builds With Maven 112 .0" encoding="UTF-8"?> <application xmlns="http://java.jar</ejb> </module> </application> This looks good. The next section will demonstrate how to deploy this EAR into a container.jar</java> </module> <module> <web> <web-uri>daytrader-web-1.sun.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.com/xml/ns/j2ee" xmlns:xsi="http://www.xsd" version="1.Building J2EE Applications You should review the generated application.sun.
12.xml configuration snippet: Better Builds With Maven 113 . Deploying a J2EE Application You have already learned how to deploy EJBs and WARs into a container individually. Deploying EARs follows the same principle. To get started. you'll deploy the DayTrader EAR into Geronimo. You would need the following pom.xml. You'll need to use the JDK 1. etc. as shown on Figure 4-2. it is recommended that you use an external plan file so that the deployment configuration is independent from the archives getting deployed. enabling the Geronimo plan to be modified to suit the deployment environment. In this example. Geronimo is somewhat special among J2EE containers in that deploying requires calling the Deployer tool with a deployment plan. 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. Like any other container. store the deployment plan in ear/src/main/deployment/geronimo/plan. The DayTrader application does not deploy correctly when using the JDK 5 or newer.Building J2EE Applications 4. Geronimo also supports having this deployment descriptor located within the J2EE archives you are deploying. A plan is an XML file containing configuration information such as how to map CMP entity beans to a specific database. However. how to map J2EE resources in the container.4 for this section and the following.
or when Cargo doesn't support the container you want to deploy into.0/ geronimo-tomcat-j2ee-1.mojo</groupId> <artifactId>exec-maven-plugin</artifactId> <configuration> <executable>java</executable> <arguments> <argument>-jar</argument> <argument>${geronimo. Modify the ear/pom.xml to configure the Exec plugin: <plugin> <groupId>org.directory}/${project.xm</plan> </properties> </deployable> </deployables> </deployer> </configuration> </plugin> However.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> <deployer> <deployables> <deployable> <properties> <plan>${basedir}/src/main/deployment/dayTrader-plan.org/dist/geronimo/1. in this section you'll learn how to use the Maven Exec plugin.codehaus. learning how to use the Exec plugin is useful in situations where you want to do something slightly different. This plugin can execute any process.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www. Even though it's recommended to use a specific plugin like the Cargo plugin.codehaus.finalName}.home}/bin/deployer.Building J2EE Applications <plugin> <groupId>org.build.jar</argument> <argument>--user</argument> <argument>system</argument> <argument>--password</argument> <argument>manager</argument> <argument>deploy</argument> <argument> ${project.build.apache.0.xml </argument> </arguments> </configuration> </plugin> Better Builds With Maven 114 . You'll use it to run the Geronimo Deployer tool to deploy your EAR into a running Geronimo container.ear </argument> <argument> ${basedir}/src/main/deployment/geronimo/plan.
jar [INFO] [INFO] `-> TradeDataSource [INFO] [INFO] `-> TradeJMS You can now access the DayTrader application by opening your browser to http://localhost:8080/daytrader/.war [INFO] [INFO] `-> daytrader-ejb-1.0-tomcat/bin/deployer.jar [INFO] [INFO] `-> daytrader-streamer-1. Better Builds With Maven 115 .0-SNAPSHOT.xml or settings..jar –user system –password manager deploy C:\dev\m2book\code\j2ee\daytrader\ear\target/daytrader-ear-1. the Exec plugin will transform the executable and arguments elements above in the following command line: java -jar c:/apps/geronimo-1.Building J2EE Applications You may have noticed that you're using a geronimo.0-SNAPSHOT.xml First.home> </properties> </profile> </profiles> At execution time.home property that has not been defined anywhere.] [INFO] [exec:exec] [INFO] Deployed Trade [INFO] [INFO] `-> daytrader-web-1. start your preinstalled version of Geronimo and run mvn exec:exec: C:\dev\m2book\code\j2ee\daytrader\ear>mvn exec:exec [. As you've seen in the EJB and WAR deployment sections above and in previous chapters it's possible to create properties that are defined either in a properties section of the POM or in a Profile.0-tomcat</geronimo. As the location where Geronimo is installed varies depending on the user.0-SNAPSHOT.0..ear C:\dev\m2book\code\j2ee\daytrader\ear/src/main/deployment/geronimo/plan.0-SNAPSHOT. put the following profile in a profiles.home>c:/apps/geronimo-1.jar [INFO] [INFO] `-> daytrader-wsappclient-1.xml file: <profiles> <profile> <id>vmassol</id> <properties> <geronimo.
so you can define a profile to build the functional-tests module only on demand.0-tomcat\bin>deploy undeploy Trade 4.xml file as follows: Better Builds With Maven 116 . Since Geronimo 1. 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.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.xml so that it's built along with the others. you should first stop it. Testing J2EE Applications In this last section you'll learn how to automate functional testing of the EAR built previously. Maven only supports integration and functional testing by creating a separate module. Functional tests can take a long time to execute.0 comes with the DayTrader application bundled. create a functional-tests module as shown in Figure 4-12. modify the daytrader/pom. by creating a new execution of the Exec plugin or run the following: C:\apps\geronimo-1.0-tomcat\bin>deploy stop geronimo/daytrader-derby-tomcat/1.0/car If you need to undeploy the DayTrader version that you've built above you'll use the "Trade" identifier instead: C:\apps\geronimo-1.13. To achieve this. For example. At the time of writing.
take a look in the functional-tests module itself. This means that running mvn install will not build the functional-tests module. see Chapter 7. Now.xml. • Better Builds With Maven 117 . • The Geronimo deployment Plan file is located in src/deployment/geronimo/plan.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. • Classpath resources required for the tests are put in src/it/resources (this particular example doesn't have any resources). Figure 4-1 shows how it is organized: Functional tests are put in src/it/java. but running mvn install-Pfunctional-test will.
the compiler and Surefire plugins are not triggered during the build life cycle of projects with a pom packaging. However. the packaging should be defined as pom. so these need to be configured in the functional-tests/pom.xml file: Better Builds With Maven 118 .Building J2EE Applications Figure 4-14: Directory structure for the functional-tests module As this module does not generate an artifact.
geronimo.0.0</modelVersion> <parent> <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.apache.daytrader</groupId> <artifactId>daytrader-ear</artifactId> <version>1.Building J2EE Applications <project> <modelVersion>4.daytrader</groupId> <artifactId>daytrader</artifactId> <version>1.apache.0-SNAPSHOT</version> <type>ear</type> <scope>provided</scope> </dependency> [.maven.] </dependencies> <build> <testSourceDirectory>src/it</testSourceDirectory> <plugins> <plugin> <groupId>org.maven..apache.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <executions> <execution> <phase>integration-test</phase> <goals> <goal>test</goal> </goals> </execution> </executions> </plugin> [.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <executions> <execution> <goals> <goal>testCompile</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.samples.geronimo.apache....] </plugins> </build> </project> Better Builds With Maven 119 .samples.
. you will usually utilize a real database in a known state. You're going to use the Cargo plugin to start Geronimo and deploy the EAR into it. As the Surefire plugin's test goal has been bound to the integration-test phase above.] <dependencies> [.sourceforge..cargo</groupId> <artifactId>cargo-ant</artifactId> <version>0. so DBUnit is not needed to perform any database operations.8</version> <scope>test</scope> </dependency> </dependencies> Better Builds With Maven 120 .cargo</groupId> <artifactId>cargo-core-uberjar</artifactId> <version>0. in the case of the DayTrader application. 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. 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. You may be asking how to start the container and deploy the DayTrader EAR into it. In addition. However. 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/.Building J2EE Applications As you can see there is also a dependency on the daytrader-ear module.] <dependency> <groupId>org.8</version> <scope>test</scope> </dependency> <dependency> <groupId>org.codehaus.xml file: <project> [. and it is started automatically by Geronimo. For integration and functional tests.codehaus. thus ensuring the proper order of execution.net/). Derby is the default database configured in the deployment plan. there's a DayTrader Web page that loads test data into the database. This is because the EAR artifact is needed to execute the functional tests..
apache.geronimo..codehaus.zip</url> <installDir>${installDir}</installDir> </zipUrlInstaller> </container> </configuration> <executions> <execution> <id>start-container</id> <phase>pre-integration-test</phase> <goals> <goal>start</goal> <goal>deploy</goal> </goals> <configuration> <deployer> <deployables> <deployable> <groupId>org. Better Builds With Maven 121 .0.Building J2EE Applications Then create an execution element to bind the Cargo plugin's start and deploy goals: <build> <plugins> [.daytrader</groupId> <artifactId>daytrader-ear</artifactId> <type>ear</type> <properties> <plan>${basedir}/src/deployment/geronimo/plan.xml</plan> </properties> <pingURL>http://localhost:8080/daytrader</pingURL> </deployable> </deployables> </deployer> </configuration> </execution> [. It is configured to deploy the EAR using the Geronimo Plan file.apache.] The deployer element is used to configure the Cargo plugin's deploy goal.org/dist/geronimo/1.cargo</groupId> <artifactId>cargo-maven2-plugin</artifactId> <configuration> <wait>false</wait> <container> <containerId>geronimo1x</containerId> <zipUrlInstaller> <url>http://www.] <plugin> <groupId>org.. a pingURL element is specified so that Cargo will ping the specified URL till it responds.. thus ensuring that the EAR is ready for servicing when the tests execute.. In addition.samples.0/ geronimo-tomcat-j2ee-1.
.8.sourceforge. as you're only using them for testing: <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. add an execution element to bind the Cargo plugin's stop goal to the post-integration-test phase: [. An alternative to using Cargo's Maven plugin is to use the Cargo Java API directly from your tests.6. Add the JUnit and HttpUnit dependencies.1</version> <scope>test</scope> </dependency> Better Builds With Maven 122 . 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.] <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.Building J2EE Applications Last.net/) to call a Web page from the DayTrader application and check that it's working. by wrapping it in a JUnit TestSetup class to start the container in setUp() and stop it in tearDown().1</version> <scope>test</scope> </dependency> <dependency> <groupId>httpunit</groupId> <artifactId>httpunit</artifactId> <version>1. with both defined using a test scope.
daytrader. deploying J2EE archives and implementing functional tests.httpunit. how to effectively set up Maven in a team. WebResponse response = wc. In the class.meterware. 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.14. public class FunctionalTest extends TestCase { public void testDisplayMainPage() throws Exception { WebConversation wc = new WebConversation()..] [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.apache. import com.Building J2EE Applications Next. Failures: 0.getTitle()). and more. Errors: 0. add a JUnit test class called src/it/java/org/apache/geronimo/samples/daytrader/FunctionalTest. response.samples. how to gather project health information from your builds.FunctionalTest [surefire] Tests run: 1.geronimo. Time elapsed: 0. WebRequest request = new GetMethodWebRequest( "http://localhost:8080/daytrader").samples. } } It's time to reap the benefits from your build. Change directory into functional-tests. type mvn install and relax: C:\dev\m2book\code\j2ee\daytrader\functional-tests>mvn install [.*..daytrader. the http://localhost:8080/daytrader URL is called to verify that the returned page has a title of "DayTrader": package org. In addition you've discovered how to automate starting and stopping containers.getResponse(request). Better Builds With Maven 123 .geronimo.apache. import junit.framework.531 sec [INFO] [cargo:stop {execution: stop-container}] 4.*. 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.java. assertEquals("DayTrader".
5. 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. and resources from a plugin Attaching an artifact to the project For a successful technology. for Nature cannot be fooled. . source directories. reality must take precedence over public relations.Richard Feynman Better Builds With Maven 124 .
Even if a project requires a special task to be performed. but also extending a project's build to incorporate new functionality. It executes an atomic build task that represents a single step in the build process. it is still likely that a plugin already exists to perform this task. it traverses the phases of the life cycle in order. Introduction As described in Chapter 2. Such supplemental plugins can be found at the Apache Maven project the loosely affiliated CodeHaus Mojo project. Correspondingly. Packaging these mojos inside a single plugin provides a consistent access mechanism for users. The actual functional tasks. the chapter will cover the tools available to simplify the life of the plugin developer. injecting runtime parameter information. 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 starts by describing fundamentals. it may be necessary to write a custom plugin to integrate these tasks into the build life cycle. Each mojo can leverage the rich infrastructure provided by Maven for loading projects.Developing Custom Maven Plugins 5. if your project requires tasks that have no corresponding plugin. For example. they are packaged together into a plugin.1. allowing shared configuration to be added to a single section of the POM. A mojo is the basic unit of work in the Maven application. the common theme for these tasks is the function of compiling code. Additionally. in order to perform the tasks necessary to build a project. When Maven executes a build. the build process for a project is comprised of set of mojos executing in a particular. This ordering is called the build life cycle. and organizing and running plugins. However. plugins provide a grouping mechanism for multiple mojos that serve similar functions within the build life cycle. it will discuss the various ways that a plugin can interact with the Maven build environment and explore some examples. executing all the associated mojos at each phase of the build. This makes Maven's plugin framework extremely important as a means of not only building a project. including a review of plugin terminology and the basic mechanics of the the Maven plugin framework. let's begin by reviewing the terminology used to describe a plugin and its role in the build. This chapter will focus on the task of writing custom plugins. 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. Just like Java packages. resolving project dependencies. called phases. and is defined as a set of task categories. A Review of Plugin Terminology Before delving into the details of how Maven plugins function and how they are written. From there. well-defined order. Maven is actually a platform that executes plugins within a build life cycle. In this case. When a number of mojos perform related tasks. 5. the maven-compiler-plugin incorporates two mojos: compile and testCompile. or work. of the build process are executed by the set of plugins associated with the phases of a project's build life-cycle. With most projects. and more. it enables these mojos to share common code more easily. refer to the Plugin Matrix.2. Finally. Recall that a mojo represents a single task in the build process. Better Builds With Maven 125 . such as integration with external tools and systems. This association of mojos to phases is called binding and is described in detail below. resolving dependencies. Maven's core APIs handle the "heavy lifting" associated with loading project definitions (POMs).
Using the life cycle. since they often perform tasks for the POM maintainer. before a mojo can execute. to ensure compatibility with other plugins. the ordered execution of Maven's life cycle gives coherence to the build process. so be sure to check the documentation for a mojo before you re-bind it. you will also need a good understanding of how plugins are structured and how they interact with their environment. These mojos are meant to be used by way of direct invocation.1. While Maven does in fact define three different lifecycles. will not have a life-cycle phase binding at all since they don't fall into any natural category within a typical build process. mojos have a natural phase binding which determines when a task should execute within the life cycle. 5.3.Developing Custom Maven Plugins Together with phase binding. Using Maven's parameter injection infrastructure. plus much more. Each execution can specify a separate phase binding for its declared set of mojos. The Plugin Framework Maven provides a rich framework for its plugins. or aid integration with external development tools. and as such. Most mojos fall into a few general categories. Bootstrapping into Plugin Development In addition to understanding Maven's plugin terminology. successive phases can make assumptions about what work has taken place in the previous phases. Indeed. in addition to determining its appropriate phase binding. you must understand the mechanics of life-cycle phase binding and parameter injection. Together. it may still require that certain activities have already been completed. Understanding this framework will enable you to extract the Maven build-state information that each mojo requires. it is important to provide the appropriate phase binding for your mojos. While mojos usually specify a default phase binding. they can be bound to any phase in the life cycle. a given mojo can even be bound to the life cycle multiple times during a single build. Better Builds With Maven 126 . In some cases. Maven also provides a well-defined procedure for building a project's sources into a distributable archive. Since phase bindings provide a grouping mechanism for mojos within the life cycle. dependency management. Think of these mojos as tangential to the the Maven build process. or even create the directory structure for a new project. However. As a plugin developer. As a result. a mojo can pick and choose what elements of the build state it requires in order to execute its task. Binding to a phase of the Maven life cycle allows a mojo to make assumptions based upon what has happened in the preceding phases. A discussion of all three build life cycles can be found in Appendix A. using the plugin executions section of the project's POM.3. the discussion in this chapter is restricted to the default life cycle. which is used for the majority of build activities (the other two life cycles deal with cleaning a project's work directory and generating a project web site). a mojo may be designed to work outside the context of the build life cycle. Such mojos may be meant to check out a project from version control. which correspond to the phases of the build life cycle. Therefore. including a well-defined build life cycle. sequencing the various build operations. and parameter resolution and injection. parameter injection and life-cycle binding form the cornerstone for all mojo development. 5.
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. consider a very basic Maven build: a project with source code that should be compiled and archived into a jar file for redistribution. This level of extensibility is part of what makes Maven so powerful. As a specific example of how plugins work together through the life cycle. Maven's plugin framework ensures that almost anything can be integrated into the build life cycle. Instead. then two additional mojos will be triggered to handle unit testing. at least two of the above mojos will be invoked. generation of the project's website. determining when not to execute. each of the resource-related mojos will discover this lack of non-code resources and simply opt out without modifying the build in any way. Better Builds With Maven 127 . none of the mojos from the maven-resources-plugin will be executed. Only those mojos with tasks to perform are executed during this build. did not execute. validation of project content. but a requirement of a well-designed mojo. Depending on the needs of a given project. The testCompile mojo from the maven-compiler-plugin will compile the test sources. and much more. First. These mojos were always present in the life-cycle definition. many more plugins can be used to augment the default life-cycle definition. then the test mojo from the maven-surefire-plugin will execute those compiled tests. Maven will execute a default life cycle for the 'jar' packaging. Indeed. the jar mojo from the maven-jarplugin will harvest these class files and archive them into a jar file. is often as important as the modifications made during execution itself. During this build process. but until now they had nothing to do and therefore. In good mojo design. 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. Since our hypothetical project has no "non-code" resources. This is not a feature of the framework. If this basic Maven project also includes source code for unit tests. the compile mojo from the maven-compiler-plugin will compile the source code into binary class files in the output directory. providing functions as varied as deployment into the repository system. Then.
the expression associated with a parameter is resolved against the current build state. The plugin descriptor Though you have learned about binding mojos to life-cycle phases and resolving parameter values using associated expressions. It contains information about the mojo's implementation class (or its path within the plugin jar). each declared mojo parameter includes information about the various expressions used to resolve its value. To gain access to the current build state. Using the correct parameter expressions. see Appendix A. the life-cycle phase to which the mojo should be bound. how do you instruct Maven to instantiate a given mojo in the first place? The answers to these questions lie in the plugin descriptor. the set of parameters the mojo declares. thereby avoiding traversal of the entire build-state object graph. That is to say. whether it is editable. This mojo would retrieve the list of source directories from the current build information using the following expression: ${project. For the complete plugin descriptor syntax. Within this descriptor. This information comes in two categories: • • Project information – which is derived from the project POM. how do you instruct Maven to inject those values into the mojo instance? Further. assuming the patch directory is specified as mojo configuration inside the POM. they require information about the state of the current build. a mojo that applies patches to the project source code will need to know where to find the project source and patch files. The descriptor is an XML file that informs Maven about the set of mojos that are contained within the plugin. The Maven plugin descriptor is a file that is embedded in the plugin jar archive.xml. under the path /META-INF/maven/plugin. using a language-appropriate mechanism. At runtime. and what methods Maven uses to extract mojo parameters from the build state. and once resolved. and consists of the user. Environment information – which is more static. whether it is required for the mojo's execution. and more. and the mechanism for injecting the parameter value into the mojo instance.compileSourceRoots} Then. a mojo can keep its dependency list to a bare minimum. For example.Developing Custom Maven Plugins Accessing build information In order for mojos to execute effectively. Maven allows mojos to specify parameters whose values are extracted from the build state using expressions.and machine-level Maven settings. until now you have not seen exactly how a life-cycle binding occurs. how do you associate mojo parameters with their expression counterparts. along with any system properties that were provided when Maven was launched. the expression to retrieve that information might look as follows: ${patchDirectory} For more information about which mojo expressions are built into Maven. Better Builds With Maven 128 . see Appendix A. and the resulting value is injected into the mojo. in addition to any programmatic modifications made by previous mojo executions.
Maven provides plugin tools to parse mojo metadata from a variety of formats. and orchestrates the process of extracting metadata from mojo implementations. Maven's development tools expose only relevant specifications in a format convenient for a given plugin's implementation language. Maven's plugindevelopment tools remove the burden of maintaining mojo metadata by hand. However. this flexibility comes at a price.Developing Custom Maven Plugins The plugin descriptor is very powerful in its ability to capture the wiring information for a wide variety of mojos. POM configurations. In short. adding any other plugin-level metadata through its own configuration (which can be modified in the plugin's POM).3.2. Writing a plugin descriptor by hand demands that plugin developers understand low-level details about the Maven plugin framework – details that the developer will not use. except when configuring the descriptor. 5. 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. Using Java. so it can be referenced from lifecycle mappings. Plugin Development Tools To simplify the creation of plugin descriptors. 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. to generate the plugin descriptor). the clean mojo in the maven-cleanplugin provides the following class-level javadoc annotation: /** * @goal clean */ public class CleanMojo extends AbstractMojo This annotation tells the plugin-development tools the mojo's name. one per supported mojo language). it uses a complex syntax. This metadata is embedded directly in the mojo's source code where possible. This is where Maven's plugin development tools come into play. By abstracting many of these details away from the plugin developer. For example. This framework generates both plugin documentation and the coveted plugin descriptor. and direct invocations (as from the command line). the format used to write a mojo's metadata is dependent upon the language in which the mojo is implemented. • Of course. The clean mojo also defines the following: Better Builds With Maven 129 . and its format is specific to the mojo's implementation language. To accommodate the extensive variability required from the plugin descriptor. it's a simple case of providing special javadoc annotations to identify the properties and parameters of the mojo. it consists of a framework library which is complemented by a set of provider libraries (generally. The maven-plugin-plugin – which uses the plugin extractor framework.
But consider what would happen if the default value you wanted to inject contained a parameter expression. Moreover. Since the plugin tools can also generate documentation about plugins based on these annotations. this value is resolved based on the POM and injected into this field. The second specifies that this parameter can also be configured from the command line as follows: -Dclean. the annotation identifies this field as a mojo parameter. If you choose to write mojos in another language. 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. Remember. it's impossible to initialize the Java field with the value you need. Here.build. default-value and expression. it's implicit when using the @parameter annotation. the underlying principles remain the same. rather than in the Java field initialization code. consider the following field annotation from the resources mojo in the maven-resources-plugin: /** * Directory containing the classes. The first specifies that this parameter's default value should be set to true. like Ant.verbose}" default=value="false" */ private boolean verbose.Developing Custom Maven Plugins /** * Be verbose in the debug log-level? * * @parameter expression="${clean. it might seem counter-intuitive to initialize the default value of a Java field using a javadoc annotation.verbose=true At first.File instance. see Appendix A. In this case. namely the java. which references the output directory for the current project. However. However. For a complete list of javadoc annotations available for specifying mojo metadata.io. * * @parameter default-value="${project. these annotations are specific to mojos written in Java. Better Builds With Maven 130 . it's a good idea to consistently specify the parameter's default value in the metadata. For instance. this parameter annotation also specifies two attributes. especially when you could just declare the field as follows: private boolean verbose = true. then the mechanism for specifying mojo metadata such as parameter definitions will be different. When the mojo is instantiated.outputDirectory}" */ private File classesDirectory.
Maven can accommodate mojos written in virtually any language. Since it provides easy reuse of third-party APIs from within your mojo. the examples in this chapter will focus on a relatively simple problem space: gathering and publishing information about a particular build. mojo mappings and parameters definitions are declared via an associated metadata file. For example. A Note on the Examples in this Chapter When learning how to interact with the different aspects of Maven from within a mojo. called mavenbuildinfo. you will need to work with an external project. To make Ant scripts reusable. due to the mitigation value of Ant-based mojos when converting a build to Maven. Ant. Therefore. This project can be found in the source code that accompanies this book. and Beanshell. Maven currently supports mojos written in Java.Developing Custom Maven Plugins Choose your mojo implementation language Through its flexible plugin descriptor format and invocation framework. 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. 5. In addition. individual mojos each mapped to separate scripts. Since Beanshell behaves in a similar way to standard Java. you risk confusing the issue at hand – namely. Whatever language you use. For many mojo developers. the specific snapshot versions of dependencies used in the build. when translating a project build from Ant to Maven (refer to Chapter 8 for more discussion about migrating from Ant to Maven). 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. or any combination thereof. In these cases. Such information might include details about the system environment. This relieves you of the burden associated with traversing a large object graph in your code. the particular feature of the mojo framework currently under discussion.3. Maven lets you select pieces of the build state to inject as mojo parameters. it is often simpler to wrap existing Ant build targets with Maven mojos and bind them to various phases in the life cycle. Maven can wrap an Ant build target and use it as if it were a mojo. You can install it using the following simple command: mvn install Better Builds With Maven 131 . Java is the language of choice. Otherwise. Simple javadoc annotations give the plugin processing plugin (the maven-plugin-plugin) the instructions required to generate a descriptor for your mojo. it also provides good alignment of skill sets when developing mojos from scratch. which is used to read and write build information metadata files. During the early phases of such a migration. This is especially important during migration. and minimizes the number of dependencies you will have on Maven's core APIs. Since Java is currently the easiest language for plugin development. and because many Maven-built projects are written in Java. To facilitate these examples. Plugin parameters can be injected via either field reflection or setter methods. it's important to keep the examples clean and relatively simple. in certain cases you may find it easier to use Ant scripts to perform build tasks. this technique also works well for Beanshell-based mojos. However. this chapter will also provide an example of basic plugin development using Ant.3. and so on.
and this dependency is injected by one of the aforementioned profiles. you will look at the development effort surrounding a sample project. Therefore. which allows the build to succeed in that environment. Once you have the plugin's project structure in place.mergere. since this plugin doesn't currently have an associated web site.4.4. it's helpful to use the archetype plugin to create a simple stub project. This information should capture relevant details about the environment used to build the Guinea Pig artifacts. called Guinea Pig.archetypes \ -DarchetypeArtifactId=maven-archetype-mojo \ -DarchetypeVersion=1. Here. Using the archetype plugin to generate a stub plugin project To jump-start the process of writing a new plugin. If you have a test dependency which contains a defect. consider a case where the POM contains a profile. To generate a stub plugin project for the buildinfo plugin. writing your custom mojo is simple. you will need to disseminate the build to the rest of the development team. this dependency is used only during testing. 5. you'll find a basic POM and a sample mojo.plugins \ -DartifactId=maven-buildinfo-plugin \ -DarchetypeGroupId=org. then the value of the triggering system property – and the profile it triggers – could reasonably determine whether the build succeeds or fails.apache. Inside.name is set to the value Linux (for more information on profiles. refer to Chapter 3). 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. Capturing this information is key. • Remove the url element. and has no impact on transitive dependencies for users of this project. • Better Builds With Maven 132 . the values of system properties used in the build are clearly very important. this profile adds a new dependency on a Linux-specific library. BuildInfo Example: Capturing Information with a Java Mojo To begin. if the system property os. a default profile injects a dependency on a windows-specific library. you will need to modify the POM as follows: Change the name element to Maven BuildInfo Plugin. This development effort will have the task of maintaining information about builds that are deployed to the development repository. For the purposes of this plugin.maven. Developing Your First Mojo For the purposes of this chapter. When triggered.1.mvnbook. When this profile is not triggered. for the purposes of debugging.0-alpha-4 This will create a project with the standard layout under a new subdirectory called mavenbuildinfo-plugin within the current working directory. For simplicity. since it can have a critical effect on the build process and the composition of the resulting Guinea Pig artifacts. which will be triggered by the value of a given system property – say. In addition to simply capturing build-time information. 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).Developing Custom Maven Plugins 5. simply execute the following: mvn archetype:create -DgroupId=com. which will be deployed to the Maven repository system.
i++ ) { String key = keys[i].split( ".getProperties().addSystemProperty( key.MISSING_INFO_PLACEHOLDER ). public void execute() throws MojoExecutionException { BuildInfo buildInfo = new BuildInfo().version}buildinfo. i < keys.java.Developing Custom Maven Plugins You will modify the POM again later.getProperty( key." ). since you will be creating your own mojo from scratch. The mojo You can handle this scenario using the following. String value = sysprops.artifactId}-${project. } try Better Builds With Maven 133 . value ). if ( systemProperties != null ) { String[] keys = systemProperties. * @parameter expression="${systemProperties}" */ private String systemProperties.xml" * @required */ private File outputFile. for ( int i = 0. * This is a comma-delimited list.. as you know more about your mojos' dependencies. fairly simple Java-based mojo: [. this simple version will suffice for now. /** * The location to write the buildinfo file.outputDirectory}/${project.] /** * Write environment information for the current build to file. BuildInfoConstants. Finally. * @parameter expression="${buildinfo. However. you should remove the sample mojo. Properties sysprops = System. It can be found in the plugin's project directory. * @goal extract * @phase package */ public class WriteBuildInfoMojo extends AbstractMojo { /** * Determines which system properties are added to the file.outputFile}" defaultvalue="${project. } buildInfo.build.length..trim(). under the following path: src/main/java/org/codehaus/mojo/MyMojo.
consider the systemProperties parameter: /** * @parameter expression="${buildinfo. } catch ( IOException e ) { throw new MojoExecutionException( "Error writing buildinfo XML file.getMessage(). Reason: " + e. In the class-level javadoc comment.user. tells the plugin tools to treat this class as a mojo named extract. } While the code for this mojo is fairly straightforward. In general. it makes sense to execute this mojo in the package phase.writeXml( buildInfo. you're collecting information from the environment with the intent of distributing it alongside the main project artifact in the repository. there are two special annotations: /** * @goal extract * @phase package */ The first annotation. you will use this name. Using the @parameter annotation by itself. 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. First. you may want to allow a user to specify which system properties to include in the build information file. Take another look: Better Builds With Maven 134 . it's worthwhile to take a closer look at the javadoc annotations.dir Finally. In this case. the complexity is justified. Therefore. which are used to specify the mojo's parameters. In this case. e ). Each offers a slightly different insight into parameter specification. This is where the expression attribute comes into play.systemProperties}" */ This is one of the simplest possible parameter specifications. However. with no attributes. the expression attribute allows you to specify a list of system properties on-the-fly.version. will allow this mojo field to be configured using the plugin configuration specified in the POM. The second annotation tells Maven where in the build life cycle this mojo should be executed. so it will be ready to attach to the project artifact. However.systemProperties=java. outputFile ). you can specify the name of this parameter when it's referenced from the command line. the outputFile parameter presents a slightly more complex example of parameter annotation. Using the expression attribute. as follows: localhost $ mvn buildinfo:java-write \ -Dbuildinfo. so they will be considered separately. When you invoke this mojo. you have several field-level javadoc comments.Developing Custom Maven Plugins { } } BuildInfoUtils. since you have more specific requirements for this parameter. Aside from the class-level comment. @goal.
which provides the parsing and formatting utilities for the build information file.mvnbook. you can see why the normal Java field initialization is not used. Better Builds With Maven 135 . note the packaging – specified as maven-plugin – which means that this plugin build will follow the maven-plugin life-cycle mapping.Developing Custom Maven Plugins /** * The location to write the buildinfo file. the build will fail with an error.mvnbook. In addition.build. If this parameter has no value when the mojo is configured. you want the mojo to use a certain value – calculated from the project's information – as a default value for this parameter.0</version> </dependency> <dependency> <groupId>com.outputFile}" defaultvalue="${project. Also. which simply adds plugin descriptor extraction and generation to the build process.0-SNAPSHOT</version> <packaging>maven-plugin</packaging> <dependencies> <dependency> <groupId>org. * * @parameter expression="${buildinfo.0. In this example. This mapping is a slightly modified version of the one used for the jar packaging. using several expressions to extract project information on-demand. the mojo cannot function unless it knows where to write the build information file. The plugin POM Once the mojo has been written. To ensure that this parameter has a value. you can construct an equally simple POM which will allow you to build the plugin. Note the dependency on the buildinfo project.mergere. as execution without an output file would be pointless.maven</groupId> <artifactId>maven-plugin-api</artifactId> <version>2.outputDirectory}/${project.apache. The default output path is constructed directly inside the annotation.artifactId}-${project.version}buildinfo.0</modelVersion> <groupId>com.0-SNAPSHOT</version> </dependency> </dependencies> </project> This POM declares the project's identity and its two dependencies.shared</groupId> <artifactId>buildinfo</artifactId> <version>1.xml" * * @required */ In this case. as follows: <project> <modelVersion>4.plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <version>1. the mojo uses the @required annotation.mergere.
mergere. which you can do by adding the configuration of the new plugin to the Guinea Pig POM. <plugins> <plugin> <groupId>com..Developing Custom Maven Plugins Binding to the life cycle Now that you have a method of capturing build-time environmental information.. </plugins> ... This involves modification of the standard jar lifecycle..name</systemProperty> </systemProperties> </configuration> <goals> <goal>extract</goal> </goals> </execution> </executions> </plugin> .plugins</groupId> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> <configuration> <systemProperties> <systemProperty>os.mvnbook.name system property. </build> The above binding will execute the extract mojo from your new maven-buildinfo-plugin during the package phase of the life cycle. so that every build triggers it. Better Builds With Maven 136 . The easiest way to guarantee this is to bind the extract mojo to the life cycle. as follows: <build> .. you need to ensure that every build captures this information. and capture the os.
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.] [buildinfo:extract {execution:extract}] ------------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------------- Under the target directory.Developing Custom Maven Plugins The output Now that you have a mojo and a POM. 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 .name> </systemProperties> </buildinfo> Formatting aside.. you should see output similar to the following: [. there should be a file named: guinea-pig-1.xml In the file..] [INFO] [INFO] [INFO] [INFO] [. Your mojo has captured the version of Java being used to execute the build..0" encoding="UTF-8"?><buildinfo> <systemProperties> <os..0-SNAPSHOT-buildinfo.name>Linux</os. the output of of the generated build information is clear enough. a property that can have profound effects on binary compatibility. you can build the plugin and try it out! First.
For now. therefore. which is associated to the build script using a naming convention. such a task could be handled using a Java-based mojo and the JavaMail API from Sun. given the amount of setup and code required. it might be enough to send a notification e-mail to the project development mailing list.build.outputFile}"> <to>${listAddr}</to> </mail> </target> </project> If you're familiar with Ant. you need to share it with others in your team when the resulting project artifact is deployed. From here. After writing the Ant target to send the notification e-mail. you just need to write a mojo definition to wire the new target into Maven's build process. The Ant target To leverage the output of the mojo from the previous example – the build information file – you can use that content as the body of the e-mail.Developing Custom Maven Plugins 5. To ensure these project properties are in place within the Ant Project instance. The corresponding metadata file will be called notify. it's simpler to use Ant.build. and should look similar to the following: <project> <target name="notify-target"> <mail from="maven@localhost" replyto="${listAddr}" subject="Build Info for Deployment of ${project.2.4. BuildInfo Example: Notifying Other Developers with an Ant Mojo Now that some important information has been captured.mojos. simply declare mojo parameters for them.xml and should appear as follows: Better Builds With Maven 138 . the build script was called notify. "deployment" is defined as injecting the project artifact into the Maven repository system.name}" mailhost="${mailHost}" mailport="${mailPort}" messagefile="${buildinfo. Your new mojo will be in a file called notify. and the dozens of well-tested. you'll notice that this mojo expects several project properties. Information like the to: address will have to be dynamic. However.xml.xml. It's important to remember that in the Maven world. metadata for an Ant mojo is stored in a separate file. so that other team members have access to it. mature tasks available for build script use (including one specifically for sending e-mails). In this example. and how. it should be extracted directly from the POM for the project we're building. The mojo metadata file Unlike the prior Java examples. Of course. it's a simple matter of specifying where the email should be sent.
artifactId}${project. the contents of this file may appear different than the metadata used in the Java mojo. upon closer examination.xml </defaultValue> <required>true</required> <readonly>false</readonly> </parameter> <parameter> <name>listAddr</name> <required>true</required> </parameter> <parameter> <name>project.name</name> <defaultValue>${project.build.outputFile</name> <defaultValue> ${project. ]]></description> <parameters> <parameter> <name>buildinfo.name}</defaultValue> <required>true</required> <readonly>true</readonly> </parameter> <parameter> <name>mailHost</name> <expression>${mailHost}</expression> <defaultValue>localhost</defaultValue> <required>false</required> </parameter> <parameter> <name>mailPort</name> <expression>${mailPort}</expression> <defaultValue>25</defaultValue> <required>false</required> </parameter> </parameters> </mojo> </mojos> </pluginMetadata> At first glance. Better Builds With Maven 139 .directory}/${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. you will see many similarities.version}-buildinfo.
The expression syntax used to extract information from the build state is exactly the same. the notification e-mails will be sent only when a new artifact becomes available in the remote repository. 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. notice that this mojo is bound to the deploy phase of the life cycle. parameters are injected as properties and references into the Ant Project instance. The maven-plugin-plugin is a perfect example.2). Maven still must resolve and inject each of these parameters into the mojo. default value. Instead. Better Builds With Maven 140 . in order to capture the parameter's type in the specification. Finally. but expressed in XML. to develop an Ant-based mojo. or through JavaBeans-style setXXX() methods. since you now have a good concept of the types of metadata used to describe a mojo. However. mojo-level metadata describes details such as phase binding and mojo name. and parameter flags such as required are still present. all of the mojo's parameter types are java. because you're going to be sending e-mails to the development mailing list.String (the default). Maven allows POM-specific injection of plugin-level dependencies in order to accommodate plugins that take a framework approach to providing their functionality.0 shipped without support for Ant-based mojos (support for Ant was added later in version 2. a more in-depth discussion of the metadata file for Ant mojos is available in Appendix A.lang. and more. The rule for parameter injection in Ant is as follows: if the parameter's type is java. In this example. you'd have to add a <type> element alongside the <name> element.or Beanshell-based mojos with no additional configuration. Also.Developing Custom Maven Plugins First of all. As with the Java example. the overall structure of this file should be familiar. metadata specify a list of parameters for the mojo. This allows developers to generate descriptors for Java. As with the Java example. you will have to add support for Ant mojo extraction to the maven-plugin-plugin. parameter injection takes place either through direct field assignment. otherwise. Fortunately. its value is injected as a project reference. the difference here is the mechanism used for this injection. each with its own information like name.lang. with its use of the MojoDescriptorExtractor interface from the maven-plugin-tools-api library. Modifying the plugin POM for Ant mojos Since Maven 2. When this mojo is executed. In Java. This is an important point in the case of this mojo. If one of the parameters were some other object type. expression.0. some special configuration is required to allow the maven-plugin-plugin to recognize Ant mojos. Any build that runs must be deployed for it to affect other development team members.String. In an Ant-based mojo however. then its value is injected as a property. The maven-plugin-plugin ships with the Java and Beanshell provider libraries which implement the above interface. so it's pointless to spam the mailing list with notification e-mails every time a jar is created for the project. by binding the mojo to the deploy phase of life cycle.
it requires a couple of new dependencies. quite simply.apache. the specifications of which should appear as follows: <dependencies> [.Developing Custom Maven Plugins To accomplish this. and it is always necessary for embedding Ant scripts as mojos in the Maven build process. The second new dependency is.. 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> [.] <build> <plugins> <plugin> <artifactId>maven-plugin-plugin</artifactId> <dependencies> <dependency> <groupId>org.2</version> </dependency> </dependencies> </plugin> </plugins> </build> [.5</version> </dependency> [. it will be quite difficult to execute an Ant-based plugin..0. If you don't have Ant in the plugin classpath. a dependency on the core Ant library (whose necessity should be obvious).apache.6.maven</groupId> <artifactId>maven-plugin-tools-ant</artifactId> <version>2..] </project> Additionally.. Better Builds With Maven 141 ...0.] <dependency> <groupId>org.] </dependencies> The first of these new dependencies is the mojo API wrapper for Ant build scripts.maven</groupId> <artifactId>maven-script-ant</artifactId> <version>2. since the plugin now contains an Ant-based mojo.2</version> </dependency> <dependency> <groupId>ant</groupId> <artifactId>ant</artifactId> <version>1...
.codehaus..Developing Custom Maven Plugins Binding the notify mojo to the life cycle Once the plugin descriptor is generated for the Ant mojo. which supplies the listAddr parameter value. Again... Better Builds With Maven 142 .] </execution> <execution> <id>notify</id> <goals> <goal>notify</goal> </goals> <configuration> <listAddr>dev@guineapig. Even its configuration is the same. In order to tell the notify mojo where to send this e-mail.] <plugins> <plugin> <artifactId>maven-buildinfo-plugin</artifactId> <executions> <execution> <id>extract</id> [.. you should add a configuration section to the new execution section. Instead. 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. execute the following command: > mvn deploy The build process executes the steps required to build and deploy a jar . notification happens in the deploy phase only..except in this case. it will also extract the relevant environmental details during the package phase. a new section for the notify mojo is created. and these two mojos should not execute in the same phase (as mentioned previously). Now.] </plugins> </build> The existing <execution> section – the one that binds the extract mojo to the build – is not modified. because non-deployed builds will have no effect on other team members.org</listAddr> </configuration> </execution> </executions> </plugin> [. and send them to the Guinea Pig development mailing list in the deploy phase. Adding a life-cycle binding for the new Ant mojo in the Guinea Pig POM should appear as follows: <build> [.
• Injecting the project dependency set As described above. Advanced Mojo Development The preceding examples showed how to declare basic mojo parameters. The following sections do not build on one another. it must tell Maven that it requires access to that set of artifacts. if you want to know how to develop plugins that manage dependencies. To enable a mojo to work with the set of artifacts that comprise the project's dependencies. the mojo must tell Maven that it requires the project dependency set.Set dependencies.artifacts}" * @required * @readonly */ private java.1.Developing Custom Maven Plugins 5. • Second. Maven makes it easy to inject a project's dependencies. Accessing Project Dependencies Many mojos perform tasks that require access to a project's dependencies. project source code and resources. this declaration has another annotation.util. The next examples cover more advanced topics relating to mojo development. the compile mojo in the maven-compiler-plugin must have a set of dependency paths in order to build the compilation classpath.</dependencies> </configuration> Better Builds With Maven 143 . only the following two changes are required: First. since the dependency resolution process is what populates the set of artifacts that make up the project's dependencies). However. then read on! 5. which might not be as familiar: @readonly. and artifact attachments. since it defines a parameter with a default value that is required to be present before the mojo can execute. This declaration should be familiar to you. namely it disables configuration via the POM under the following section: <configuration> <dependencies>. the mojo must tell Maven that it requires the project's dependencies be resolved (this second requirement is critical.5. However. As with all declarations. For example. and how to annotate the mojo with a name and a preferred phase binding. This annotation tells Maven not to allow the user to configure this parameter directly. and are not required for developing basic mojos.. if the mojo works with a project's dependencies. In addition. Fortunately. 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. 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..5.
so you configure this parameter by modifying that section directly. and if so. such as: -Ddependencies=[. if a mojo declares that it requires dependencies for the compile scope. If this parameter could be specified separately from the main dependencies section. Better Builds With Maven 144 . direct configuration could result in a dependency being present for compilation. Maven 2 addresses this problem by deferring dependency resolution until the project's dependencies are actually required. any dependencies specific to the test scope will remain unresolved. To gain access to the project's dependencies. users could easily break their builds – particularly if the mojo in question compiled project source code. However.Developing Custom Maven Plugins It also disables configuration via system properties. Consider the case where a developer wants to clean the project directory using Maven 1. Maven provides a mechanism that allows a mojo to specify whether it requires the project dependencies to be resolved. the build process doesn't incur the added overhead of resolving them. Maven 2. Returning to the example. it will force all of the dependencies to be resolved (test is the widest possible scope. it will have to tell Maven to resolve them. encapsulating all others). the @readonly annotation functions to force users to configure the POM.x term 'goal'). Therefore. Maven will resolve only the dependencies that satisfy the requested scope.x. If the project's dependencies aren't available. you may be wondering. In this case.0 uses the term 'mojo' as roughly equivalent to the Maven 1. at which scope. "How exactly can I configure this parameter?" The answer is that the mojos parameter value is derived from the dependencies section of the POM. Rather.. your mojo must declare that it needs them. if later in the build process. Requiring dependency resolution Having declared a parameter that injects the projects dependencies into the mojo. Maven 2 will not resolve project dependencies until a mojo requires it. Failure to do so will cause an empty set to be injected into the mojo's dependencies parameter. the mojo is missing one last important step. Even then. if your mojo needs to work with the project's dependencies. If a mojo doesn't need access to the dependency list. It's important to note that your mojo can require any valid dependency scope to be resolved prior to its execution. this is a direct result of the rigid dependency resolution design in Maven 1. If you've used Maven 1..] So. but being unavailable for testing.x. In other words. Maven encounters another mojo that declares a requirement for test-scoped dependencies. rather than configuring a specific plugin only. the clean process will fail – though not because the clean goal requires the project dependencies. you'll know that one of its major problems is that it always resolves all project dependencies before invoking the first goal in the build (for clarity.
This will result in the addition of a new section in the buildinfo file. so it can log the exact set of dependencies that were used to produce the project artifact.getVersion() ). In this case..setType( artifact. you will need to iterate through the set.setGroupId( artifact. if ( artifact. which enumerates all the dependencies used in the build.addResolvedDependency( rd )..setArtifactId( artifact.] */ Now.isEmpty() ) { for ( Iterator it = dependencies. rd. rd.Developing Custom Maven Plugins You can declare the requirement for the test-scoped project dependency set using the following classlevel annotation: /** * @requiresDependencyResolution test [. BuildInfo example: logging dependency versions Turning once again to the maven-buildinfo-plugin.getGroupId() ). ) { Artifact artifact = (Artifact) it.isOptional() ). adding the information for each individual dependency to your buildinfo object. it.getArtifactId() ).setResolvedVersion( artifact. For example.iterator().setScope( artifact.setClassifier( artifact. rd. the mojo should be ready to work with the dependency set. you will want to log the versions of the dependencies used during the build.next(). along with their versions – including those dependencies that are resolved transitively. Once you have access to the project dependency set.getClassifier() ). rd.setOptional( artifact. ResolvedDependency rd = new ResolvedDependency(). } Better Builds With Maven 145 .getType() ). rd. you'll add the dependency-set injection code discussed previously to the extract mojo in the maven-buildinfo-plugin. To that end. } } buildInfo. rd. one of the dependency libraries may have a newer snapshot version available. The code required is as follows: if ( dependencies != null && !dependencies. This is critical when the project depends on snapshot versions of other libraries. knowing the specific set of snapshots used to compile a project can lend insights into why other builds are breaking.getScope() ).hasNext().getClassifier() != null ) { rd.
it may be necessary to augment a project's code base with an additional source directory.4 environment.8.] <resolvedDependency> <groupId>com.0-alpha-SNAPSHOT. Therefore. particularly if the newest snapshot version is different. This is because snapshot time-stamping happens on deployment only.2. If this plugin adds resources like images. This dependency is part of the example development effort..5. the compile mojo will require access to it. it's possible that a plugin may be introduced into the build process when a profile is activated. The actual snapshot version used for this artifact in a previous build could yield tremendous insight into the reasons for a current build failure. with an additional section called resolvedDependencies that looks similar to the following: <resolvedDependencies> <resolvedDependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <resolvedVersion>3. Accessing Project Sources and Resources In certain cases. Once this new source directory is in place.] </resolvedDependencies> The first dependency listed here.8.0-alpha-SNAPSHOT in the POM. junit.guineapig</groupId> <artifactId>guinea-pig-api</artifactId> <resolvedVersion>1.. For instance. has a static version of 3.Developing Custom Maven Plugins When you re-build the plugin and re-run the Guinea Pig build. Better Builds With Maven 146 ..094434-1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>compile</scope> </resolvedDependency> [. and is still listed with the version 1. If you were using a snapshot version from the local repository which has not been deployed.1</resolvedVersion> <optional>false</optional> <type>jar</type> <scope>test</scope> </resolvedDependency> [.mvnbook.1. the resolvedVersion in the output above would be 1. 5. and other mojos may need to produce reports based on those same source directories. This won't add much insight for debuggers looking for changes from build to build. when a project is built in a JDK 1. but consider the next dependency: guinea-pigapi.. it can have dramatic effects on the resulting project artifact.0-20060210. 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.mergere. the extract mojo should produce the same buildinfo file. or new source code directories to the build.
it does improve the chances that your mojo will be compatible with other plugins bound to the same life cycle. or simply need to augment the basic project code base. as in the following example: project.addCompileSourceRoot( sourceDirectoryPath ). It requires access to the current MavenProject instance only. used to add new source directory to the build. unless declared otherwise. As in the prior project dependencies discussion. this parameter also adds the @readonly annotation. This can be very useful when plugins generate source code. Once the current project instance is available to the mojo. 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. and no other project contains current state information for this build. However. which tells Maven that it's OK to execute this mojo in the absence of a POM.build. The generally-accepted binding for this type of activity is in the generate-sources life-cycle phase.directory}/generated-sources/<plugin-prefix> While conforming with location standards like this is not required. the accepted default location for the generated source is in: ${project. which can be injected into a mojo using the following code: /** * Project instance. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project.Developing Custom Maven Plugins Adding a source directory to the build Although the POM supports only a single sourceDirectory entry.6. Maven's concept of a project can accommodate a whole list of directories. it's a simple matter of adding a new source root to it. Mojos that augment the source-root list need to ensure that they execute ahead of the compile phase. This declaration identifies the project field as a required mojo parameter that will inject the current MavenProject instance into the mojo for use. Chapter 3 of this book). any normal build will have a current project. when generating source code. mojos require a current project instance to be available. allowing plugins to add new source directories as they execute. The current project instance is a great example of this. Maven's project API bridges this gap. Better Builds With Maven 147 . Maven will fail the build if it doesn't have a current project instance and it encounters a mojo that requires one. instead. as in the case where the mavenarchetype-plugin is used to create a stub of a new project. This annotation tells Maven that users cannot modify this parameter. 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. So. It is possible that some builds won't have a current project. Further.
Component requirements are not available for configuration by users. the MavenProjectHelper is provided to standardize the process of augmenting the project instance. the mojo also needs access to the MavenProjectHelper component. Whatever the purpose of the mojo. Normally. The project helper component can be injected as follows: /** * project-helper instance. in some special cases. This component is part of the Maven application. To be clear. However. Right away. the Maven application itself is well-hidden from the mojo developer. This could be some sort of descriptor for binding the project artifact into an application framework. used to add new source directory to the build. used to make addition of resources * simpler. it does require a new type of parameter declaration: a requirement based on another component within the Maven application. so your mojo simply needs to ask for it. or it could be added to help identify some key attribute about the artifact to other developers. which will be packaged up in the same jar as the project classes. Just as the current project instance is required in order to add a new source root. the unadorned @component annotation – like the above code snippet – is adequate. This declaration will inject the current project instance into the mojo. as discussed previously. * @parameter default-value="${project}" * @required * @readonly */ private MavenProject project. to make it simpler to add resources to a project. the project is also required to achieve this. It provides methods for attaching artifacts and adding new resource definitions to the current project. as in the case of Maven itself. you should notice something very different about this parameter. and abstract the associated complexities away from the mojo developer. Maven components can make it much simpler to interact with the build process. in most cases. the process of adding a new resource directory to the current build is straightforward. For example. * @component */ private MavenProjectHelper helper. However. that it's not a parameter at all! In fact. Better Builds With Maven 148 . the project helper is not a build state.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. Namely. The project parameter is declared as follows: /** * Project instance. it is a utility. Component requirements are simple to declare. However. this is what Maven calls a component requirement (it's a dependency on an internal component of the running Maven application). which means it's always present.
Better Builds With Maven 149 . it will need to execute ahead of this phase. Resources are copied to the classes directory of the build during the process-resources phase. List includes = Collections. List excludes = null. it's important to understand where resources should be added during the build life cycle. as in the following example: /** * List of source roots containing non-test code. If your mojo is meant to add resources to the eventual project artifact. and exclusion patterns as local variables. Again. The prior example instantiates the resource's directory. excludes). Again. they have to modify the sourceDirectory element in the POM. Gaining access to the list of source root directories for a project is easy. if it's missing. Accessing the source-root list Just as some mojos add new source directories to the build. The classic example is the compile mojo in the maven-compiler-plugin. in order to perform some operation on the source code. adding a new resource couldn't be easier. however. instead. this parameter declaration states that Maven does not allow users to configure this parameter directly. and then call a utility method on the project helper. for the sake of brevity. these values would come from other mojo parameters.compileSourceRoots}" * @required * @readonly */ private List sourceRoots. conforming with these standards improves the compatibility of your plugin with other plugins in the build. Other examples include javadoc mojo in the maven-javadoc-plugin. Similar to the parameter declarations from previous sections. * @parameter default-value="${project. With these two objects at your disposal. and the jar mojo in the maven-source-plugin. In a typical case. The code should look similar to the following: String directory = "relative/path/to/some/directory". helper.addResource(project. the entire build will fail. Simply define the resources directory to add. as it is particularly useful to mojo developers. along with inclusion and exclusion patterns for resources within that directory. which may or may not be directly configurable. others must read the list of active source directories. directory. inclusion patterns. or else bind a mojo to the life-cycle phase that will add an additional source directory to the build. The most common place for such activities is in the generate-resources life-cycle phase.singletonList("**/*"). all you have to do is declare a single parameter to inject them. the MavenProjectHelper component is worth mentioning here. which actually compiles the source code contained in these root directories into classes in the project output directory. includes. The parameter is also required for this mojo to execute.Developing Custom Maven Plugins A complete discussion of Maven's architecture – and the components available – is beyond the scope of this chapter.
hasNext(). now. it could be critically important to track the list of source directories used in a particular build. source roots are expressed as absolute file-system paths. 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. 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. By the time the mojo gains access to them. Remember. binding to any phase later than compile should be acceptable.next(). You've already learned that mojos can modify the list of resources included in the project artifact. it's better to bind it to a later phase like package if capturing a complete picture of the project is important. This involves subtracting ${basedir} from the source-root paths. applying whatever processing is necessary. Returning to the buildinfo example. it can iterate through them.iterator(). as in the case of the extract mojo. in order to incorporate list of source directories to the buildinfo object. any reference to the path of the project directory in the local file system should be removed. } buildInfo. When you add this code to the extract mojo in the maven-buildinfo-plugin. then this profile would dramatically alter the resulting project artifact when activated. ) { String sourceRoot = (String) it. One thing to note about this code snippet is the makeRelative() method. for eventual debugging purposes.Developing Custom Maven Plugins Now that the mojo has access to the list of project source roots. which copies all non-code resources to the output directory for inclusion in the project artifact. you need to add the following code: for ( Iterator it = sourceRoots. In this case however. it. Therefore. Accessing the resource list Non-code resources complete the picture of the raw materials processed by a Maven build. it can be bound to any phase in the life cycle. let's learn about how a mojo can access the list of resources used in a build. If a certain profile injects a supplemental source directory into the build (most likely by way of a special mojo binding). Better Builds With Maven 150 . In order to make this information more generally applicable. the ${basedir} expression refers to the location of the project directory in the local file system. since compile is the phase where source files are converted into classes. However. To be clear. This is the mechanism used by the resources mojo in the maven-resources-plugin.addSourceRoot( makeRelative( sourceRoot ) ).
Developing Custom Maven Plugins
Much like the source-root list, the resources list is easy to inject as a mojo parameter. The parameter appears as follows:
/** * List of Resource objects for the current build, containing * directory, includes, and excludes. * @parameter default-value="${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 . 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.6. .
and then run mvn install from the proficio subdirectory to ensure everything is in place. if the bar is set too low. 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. In this chapter. if the build fails its checks? The Web site also provides a permanent record of a project's health. Maven has access to the information that makes up a project. For this reason. unzip the Code_Ch03. It is these characteristics that assist you in assessing the health of your project. and using a variety of tools. Because the POM is a declarative model of the project.zip for convenience as a starting point. Maven takes all of the information you need to know about your project and brings it together under the project Web site. But. This is important. and how well it adapts to change. It provides additional information to help determine the reasons for a failed build. When referring to health. and display that information in a single place. What Does Maven Have to do With Project Health? In the introduction. there will be too many failed builds. it was pointed out that Maven's application of patterns provides visibility and comprehensibility. Conversely. The next three sections demonstrate how to set up an effective project Web site. the project will meet only the lowest standard and go no further. why have a site. you'll learn how to use a number of these tools effectively. 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!). there are two aspects to consider: • • Code quality . and what the nature of that activity is. to get a build to pass. Project vitality . because if the bar is set too high. Better Builds With Maven 157 . how well it is tested. Maven can analyze.Assessing Project Health with Maven 6. The code that concluded Chapter 3 is also included in Code_Ch03. and whether the conditions for the checks are set correctly. To begin.determining how well the code works.1. relate.finding out whether there is any activity on the project. and learning more about the health of the project. new tools that can assess its health are easily integrated. Through the POM. This is unproductive as minor changes are prioritized over more important tasks. In this chapter. you will be revisiting the Proficio application that was developed in Chapter 3.zip file into C:\mvnbook or your selected working directory. which everyone can see at any time.
To start. issue tracker. unless you choose to disable them. On a new project.xml: Better Builds With Maven 158 . Adding Reports to the Project Web site This section builds on the information on project Web sites in Chapter 2 and Chapter 3. adding a new report is easy. and now shows how to integrate project health information. For newcomers to the project. These reports provide a variety of insights into the quality and vitality of the project. These reports are useful for sharing information with others. Project Reports.2. this menu doesn't appear as there are no reports included. you can add the Surefire report to the sample application. and so on. SCM. is the focus of the rest of this chapter. The second menu (shown opened in figure 6-1). The Project Info menu lists the standard reports Maven includes with your site by default. by including the following section in proficio/pom. For example. review the project Web site shown in figure 6-1. Figure 6-1: The reports generated by Maven You can see that the navigation on the left contains a number of reports.Assessing Project Health with Maven 6. having these standard reports means that those familiar with Maven Web sites will always know where to find the information they need. However. and to reference as links in your mailing lists.
<reporting> <plugins> < plugin> <groupId>org. and as a result.html. C:\mvnbook\proficio\proficio-core> mvn site This can now be found in the file target/site/surefire-report.. and is shown in figure 62... You can now run the following site task in the proficio-core directory to regenerate the site.apache.Assessing Project Health with Maven .plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> </plugin> </plugins> </reporting> . it will be inherited by all of the child modules. </project> This adds the report to the top level project..maven. Figure 6-2: The Surefire report Better Builds With Maven 159 .
apache.. For a quicker turn around.xml: .5</source> <target>1... Maven knows where the tests and test results are.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1. the report can be modified to only show test failures by adding the following configuration in pom. as seen in the previous section. Configuration of Reports Before stepping any further into using the project Web site.maven..apache. it is important to understand how the report configuration is handled in Maven. and due to using convention over configuration. the report shows the test results of the project... the defaults are sufficient to get started with a useful report. for example: . For example.xml. Configuration for a reporting plugin is very similar.3. <build> <plugins> <plugin> <groupId>org. the report can also be run individually using the following standalone goal: C:\mvnbook\proficio\proficio-core> mvn surefire-report:report That's all there is to generating the report! This is possible thanks to key concepts of Maven discussed in Chapter 2: through a declarative project model. however it is added to the reporting section of the POM.5</target> </configuration> </plugin> </plugins> </build> . Better Builds With Maven 160 . 6. <reporting> <plugins> <plugin> <groupId>org. while the configuration can be used to modify its appearance or behavior..Assessing Project Health with Maven As you may have noticed in the summary. The addition of the plugin element triggers the inclusion of the report in the Web site.. You might recall from Chapter 2 that a plugin is configured using the configuration element inside the plugin declaration in pom.plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <showSuccess>false</showSuccess> </configuration> </plugin> </plugins> </reporting> .
"Executions" such as this were introduced in Chapter 3. always place the configuration in the reporting section – unless one of the following is true: 1. they will all be included. Any plugin configuration declared in the reporting section is also applied to those declared in the build section. the reporting section: . the plugin would need to be configured in the build section instead of.directory}/surefire-reports </outputDirectory> </configuration> <executions> <execution> <phase>test</phase> <goals> <goal>report</goal> </goals> </execution> </executions> </plugin> </plugins> </build> .plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <configuration> <outputDirectory> ${project. The plugin is included in the build section to ensure that the configuration.maven. 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. even though it is not specific to the execution. consider if you wanted to create a copy of the HTML report in the directory target/surefirereports every time the build ran.build.apache. is used only during the build. When you configure a reporting plugin..Assessing Project Health with Maven If a plugin contains multiple reports. and not site generation. some reports apply to both the site. Fortunately. The reports will not be included in the site 2. However. However. this isn't the case – adding the configuration to the reporting section is sufficient. you might think that you'd need to configure the parameter in both sections. Plugins and their associated configuration that are declared in the build section are not used during site generation... or in addition to. To do this.. <build> <plugins> <plugin> <groupId>org. and the build. The configuration value is specific to the build stage Better Builds With Maven 161 . To continue with the Surefire report.
apache.. and a list of reports to include..build. Both of these cases can be achieved with the reportSets element.xml: . once for unit tests and once for a set of performance tests. you would include the following section in your pom. <reporting> <plugins> <plugin> <groupId>org. For example. by default all reports available in the plugin are executed once. there are cases where only some of the reports that the plugin produces will be required. and that you had had generated its XML results to target/surefire-reports/unit and target/surefire-reports/perf respectively.html. Each report set can contain configuration. Running mvn site with this addition will generate two Surefire reports: target/site/surefire-reportunit. which is the reporting equivalent of the executions element in the build section. 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.maven. and cases where a particular report will be run more than once. However.build..html and target/site/surefire-report-perf. Better Builds With Maven 162 .plugins</groupId> <artifactId>maven-surefire-report-plugin</artifactId> <reportSets> <reportSet> <id>unit</id> <configuration> <reportsDirectory> ${project.directory}/surefire-reports/perf </reportsDirectory> <outputName>surefire-report-perf</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> </reportSets> </plugin> </plugins> </reporting> . each time with a different configuration.directory}/surefire-reports/unit </reportsDirectory> <outputName>surefire-report-unit</outputName> </configuration> <reports> <report>report</report> </reports> </reportSet> <reportSet> <id>perf</id> <configuration> <reportsDirectory> ${project. To generate two HTML reports for these results..
as with executions. where much of the source code and Javadoc reference is of interest to the end user. • The open source reusable library. who isn't interested in the state of the source code.apache. This may be confusing for the first time visitor.Assessing Project Health with Maven However. 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. there's something subtly wrong with the project Web site. Separating Developer Reports From User Documentation After adding a report. add the following to the reporting section of the pom. <plugin> <groupId>org. outside of any report sets. • Better Builds With Maven 163 . they must be enumerated in this list. running mvn surefire-report:report will not use either of these configurations. Consider the following: The commercial product. which are targeted at an end user. depending on the project. This approach to balancing these competing requirements will be vary. It is also possible to include only a subset of the reports in a plugin.. The reports element in the report set is a required element.maven. If you want all of the reports in a plugin to be generated. On the entrance page there are usage instructions for Proficio..4. but quite separate to the end user documentation.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. but in the navigation there are reports about the health of the project. 6. For example.. where the end user documentation is on a completely different server than the developer information.. Maven will use only the configuration that is specified in the plugin element itself. • The open source graphical application.xml file: . When a report is executed individually. While the defaults are usually sufficient. this customization will allow you to configure reports in a way that is just as flexible as your build. to generate only the mailing list and license pages of the standard reports. where the developer information is available. The reports in this list are identified by the goal names that would be used if they were run from the command line. which are targeted at the developers.
It is important not to include documentation for features that don't exist in the last release. The best compromise between not updating between releases. each section of the site needs to be considered. It is also true of the project quality and vitality reports. and not introducing incorrect documentation. 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. This is true of the news and FAQs. The situation is different for end user documentation. Yes Yes No Yes Yes No No Yes No Yes No No In the table. You can maintain a stable branch. 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. While there are some exceptions. and a development branch where new features can be documented for when that version is released. Some standard reports. For libraries and frameworks. This is reference material (for example. However. Features that are available only in more recent releases should be marked to say when they were introduced. the Javadoc and other reference material are usually distributed for reference as well. that can be updated between releases without risk of including new features. This is documentation for the end user including usage instructions and guides. which are based on time and the current state of the project. as it is confusing for those reading the site who expect it to reflect the latest release. Table 6-1: Project Web site content types Content Description Updated Distributed Separated News. in some cases down to individual reports. The Separated column indicates whether the documentation can be a separate module or project. Sometimes these are included in the main bundle. source code references should be given a version and remain unchanged after being released. regardless of releases. This is typically true for the end user documentation.Assessing Project Health with Maven To determine the correct balance. The Distributed column in the table indicates whether that form of documentation is typically distributed with the project. is to branch the end user documentation in the same way as source code. which are continuously published and not generally of interest for a particular release. and sometimes they are available for download separately. the source code reference material and reports are usually generated from the modules that hold the source code and perform the build. Better Builds With Maven 164 . It refers to a particular version of the software. and the content's characteristics. Javadoc) that in a library or framework is useful to the end user. like mailing list information and the location of the issue tracker and SCM are updated also. For a single module library. These are the reports discussed in this chapter that display the current state of the project to the developers. but usually not distributed or displayed in an application. and to maintain only one set of documentation.
While these recommendations can help properly link or separate content according to how it will be used. which you can later add content to. or maybe totally independent.Assessing Project Health with Maven However. In the following example. This is done using the site archetype : C:\mvnbook\proficio> mvn archetype:create -DartifactId=user-guide \ -DgroupId=com. This avoids including inappropriate report information and navigation elements. In this case. The current structure of the project is shown in figure 6-3. It is important to note that none of these are restrictions placed on a project by Maven. you are free to place content wherever it best suits your project. the documentation and Web site should be kept in a separate module dedicated to generating a site.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple This archetype creates a very basic site in the user-guide subdirectory. a module is created since it is not related to the source code reference material. This separated documentation may be a module of the main project. In Proficio.mergere. You would make it a module when you wanted to distribute it with the rest of the project. you will learn how to separate the content and add an independent project for the news and information Web site. but make it an independent project when it forms the overall site with news and FAQs. Figure 6-3: The initial setup The first step is to create a module called user-guide for the end user documentation. the site currently contains end user documentation and a simple report. Better Builds With Maven 165 .mvnbook. and is not distributed with the project. The resulting structure is shown in figure 6-4. in most cases.
. is useful if you are maintaining multiple public versions. edit the top level pom. Adding the version to the development documentation.mergere. 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. First.com/mvnbook/proficio. Under the current structure.version} </url> </site> </distributionManagement> .. the development documentation would go to that location. and the user guide to http://library.com/www/library/mvnbook/proficio/reference/${project. In this example. <distributionManagement> <site> .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.xml file to change the site deployment url: . Previously. <url> scp://mergere..com/mvnbook/proficio/user-guide. whether to maintain history or to maintain a release and a development preview..mergere. Better Builds With Maven 166 .. the URL and deployment location were set to the root of the Web site: http://library.. while optional.
com/mvnbook/proficio/user-guide/ • http://library. you can create a new site using the archetype. C:\mvnbook> mvn archetype:create -DartifactId=proficio-site \ -DgroupId=com.proficio \ -DarchetypeArtifactId=maven-archetype-site-simple The resulting structure is shown in figure 6-5.mergere. Now that the content has moved. edit the user-guide/pom.mergere..mergere.xml as follows: Better Builds With Maven 167 .. This will include news and FAQs about the project that change regularly..0-SNAPSHOT/ • You will not be able to deploy the Web site to the location scp://mergere. This time. in the ch06-1 directory.xml file to set the site deployment url for the module: . <distributionManagement> <site> <id>mvnbook. As before. a top level site for the project is required.Assessing Project Health with Maven Next.com/www/library/mvnbook/proficio/user-guide and it is included here only for illustrative purposes.site</id> <url> scp://mergere.mvnbook.com/mvnbook/proficio/reference/1.com/www/library/mvnbook/proficio/user-guide </url> </site> </distributionManagement> . run it one directory above the proficio directory. There are now two sub-sites ready to be deployed: http://library.. 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.
Generating reference documentation is covered in section 6..xml that point to the other documentation as follows: ...apt file with a more interesting news page.Proficio project started Finally.0-SNAPSHOT/apidocs/" /> <item name="Developer Info" href="/reference/1.. <menu name="Documentation"> <item name="User's Guide" href="/user-guide/" /> </menu> <menu name="Reference"> <item name="API" href="/reference/1. so that link won't work even if the site is deployed.] <distributionManagement> <site> <id>mvnbook.. Note that you haven't produced the apidocs directory yet.] <url>http://library. like the following: ----Proficio ----Joe Blogs ----2 February 2006 ----Proficio Proficio is super. Better Builds With Maven 168 .6 of this chapter..com/mvnbook/proficio</url> [. You can now run mvn site in proficio-site to see how the separate site will look. you will then be able to navigate through the links and see how they relate.. The rest of this chapter will focus on using the developer section of the site effectively and how to build in related conditions to regularly monitor and improve the quality of your project.0-SNAPSHOT/" /> </menu> . * News * <16 Jan 2006> ..] Next. replace the src/site/apt/index. If you deploy both sites to a server using mvn site-deploy as you learned in Chapter 3.Assessing Project Health with Maven [..com/www/library/mvnbook/proficio</url> </site> </distributionManagement> [.mergere.website</id> <url>scp://mergere.. add some menus to src/site/site.
and look at the output to determine which reports to use. 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. For each report. Not useful if there are a lot of errors to be fixed – it will be slow and the result unhelpful. for more information. in addition to the generic reports such as those for dependencies and change tracking. In some instances. Report results and checks performed should be accurate and conclusive – every developer should know what they mean and how to address them. In particular. While future versions of Maven will aim to streamline this. and which checks to perform during the build. the performance of your build will be affected by this choice. is an important decision that will determine the effectiveness of your build reports.5. Yes Yes ✔ ✔ ✗ Better Builds With Maven 169 . While these aren't all the reports available for Maven. it is recommended that these checks be constrained to the continuous integration and release environments if they cause lengthy builds. Table 6-2: Report highlights Report Description Visual Check Notes ✔ ✔ ✔ ✔ ✗ Javadoc Produces an API reference from Javadoc. Table 6-2 covers the reports discussed in this chapter and reasons to use them.Assessing Project Health with Maven 6. Recommended to enhance readability of the code. Choosing Which Reports to Include Choosing which reports to include. such as Checkstyle Doesn't handle JDK 5. JXR Yes N/A Checkstyle Checks your source code against a standard descriptor for formatting issues. Produces a source cross reference for any Java code. Team Collaboration with Maven. See Chapter 7. You may notice that many of these tools are Java-centric. or you can walk through all of the examples one by one. and an applicable build check (for testing a certain condition and failing the build if it doesn't pass).0 features Use to enforce a standard code style. it is possible in the future that reports for other languages will be available. the guidelines should help you to determine whether you need to use other reports. the reports that utilize unit tests often have to re-run the tests with new parameters. there is also a note about whether it has an associated visual report (for project site inclusion). While this is certainly the case at present. 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.
Recommended for easier browsing of results. Show the results of unit tests visually. Check already performed by surefire:test. Some overlap with Checkstyle rules Can be used to identify lazy copy/pasted code that might be refactored into a shared method.Assessing Project Health with Maven Report Description Visual Check Notes ✔ ✔ PMD Checks your source code against known rules for code smells. Part of PMD. Avoids issues when one piece of code is fixed/updated and the other forgotten Useful for tracking TODO items Very simple. convenient set up Can be implemented using Checkstyle rules instead. Doesn't identify all missing or inadequate tests. Should be used for keeping teams up to date on internal projects also. checks for duplicate source code blocks that indicates it was copy/pasted. Yes Yes Should be used to improve readability and identify simple and common bugs. Recommended for teams with a focus on tests Can help identify untested or even unused code. CPD Yes No ✔ ✔ Tag List Yes No ✔ ✔ ✔ ✔ ✔ ✗ Cobertura Yes Yes Surefire Report Yes Yes ✔ ✔ ✔ Dependency Examine the state of Convergence dependencies in a multiple module build Clirr Compare two versions of a JAR for binary compatibility Yes No ✔ ✔ Yes Yes ✔ ✔ Changes Produce release notes and road maps from issue tracking systems Yes N/A ✔ ✔ Better Builds With Maven 170 . Recommended for all publicly released projects. Recommended for multiple module builds where consistent versions are important. Simple report on outstanding tasks or other markers in source code Analyze code statement coverage during unit tests or other code execution. so additional tools may be required. 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. Can help find snapshots prior to release. Can also show any tests that are long running and slowing the build.
Those familiar with Javadoc will recognize the framed navigation layout. and.Assessing Project Health with Maven 6. by running the following command: C:\mvnbook\proficio\proficio-core> mvn jxr:jxr You should now see a target/site/jxr. Creating Reference Material Source code reference materials are usually the first reports configured for a new project. however the content pane is now replaced with a syntax-highlighted. crossreferenced Java source file for the selected class. The hyper links in the content pane can be used to navigate to other classes and interfaces within the cross reference. as well as to the developer of the project itself. Figure 6-6: An example source code cross reference Figure 6-6 shows an example of the cross reference.6. and one for the unit tests. because it is often of interest to the end user of a library or framework. The two reports this section illustrates are: • • JXR – the Java source cross reference. Javadoc – the Java documentation tool You can get started with JXR on the example project very quickly. This page links to the two sets of cross references: one for the main source tree. Better Builds With Maven 171 .html created.
the Javadoc report is quite configurable. <reporting> <plugins> <plugin> <groupId>org.apache.apache.. Using Javadoc is very similar to the JXR report and most other reports in Maven.org/plugins/maven-jxr-plugin/.maven.. Including JXR as a permanent fixture of the site for the project is simple. In most cases. the links can be used to quickly find the source belonging to a particular exception. <plugin> <groupId>org. browsing source code is too cumbersome for the developer if they only want to know about how the API works. 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. you should include it in proficio/pom. A Javadoc report is only as good as your Javadoc! Make sure you document the methods you intend to display in the report.xml: . however if you'd like a list of available configuration options. Unlike JXR. Again.plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> </plugin> .. and if possible use Checkstyle to ensure they are documented. in target/site/apidocs. with most of the command line options of the Javadoc tool available...plugins</groupId> <artifactId>maven-jxr-plugin</artifactId> </plugin> . and can be done by adding the following to proficio/pom. However. The end result is the familiar Javadoc output. see the plugin reference at http://maven.. so an equally important piece of reference material is the Javadoc report. if you don't have the project open in your IDE. Or.xml as a site report to ensure it is run every time the site is regenerated: . Better Builds With Maven 172 .. Now that you have a source cross reference.. </plugins> </reporting> . many of the other reports demonstrated in this chapter will be able to link to the actual code to highlight an issue. the default JXR configuration is sufficient.apache.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...maven. 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.
Edit the configuration of the existing Javadoc plugin in proficio/pom.org/ref/1. but conversely to have the Javadoc closely related.. this is not sufficient. but this would still limit the available classes in the navigation as you hop from module to module.String and java. Better Builds With Maven 173 . the following configuration..4 API documentation and the Plexus container API documentation used by Proficio: . Setting up Javadoc has been very convenient. If you regenerate the site in proficio-core with mvn site again.plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> <configuration> <links> <link>http://java. <plugin> <groupId>org..com/j2se/1.lang. this simple change will produce an aggregated Javadoc and ignore the Javadoc report in the individual modules..sun. this will link to an external Javadoc reference at a given URL. the Javadoc plugin provides a way to produce a single set of API documentation for the entire project. of course!).maven.html.. Try running mvn clean javadoc:javadoc in the proficio directory to produce the aggregated Javadoc in target/site/apidocs/index.Object.. the next section will allow you to start monitoring and improving its health. you'll see that all references to the standard JDK classes such as java.apache.. Since it is preferred to have discreet functional pieces separated into distinct modules. will link both the JDK 1.xml.codehaus.. as well as any references to classes in Plexus. but it results in a separate set of API documentation for each library in a multi-module build. </configuration> .Assessing Project Health with Maven One useful option to configure is links. this setting is always ignored by the javadoc:jar goal. are linked to API documentation on the Sun website. ensuring that the deployed Javadoc corresponds directly to the artifact with which it is deployed for use in an IDE. This setting must go into the reporting section so that it is used for both reports and if the command is executed separately. Now that the sample application has a complete reference for the source code.lang. When built from the top level project..xml by adding the following line: . One option would be to introduce links to the other modules (automatically generated by Maven based on dependencies. Instead. In the online mode. when added to proficio/pom. However.4.2/docs/api</link> <link>http://plexus.0-alpha-9/apidocs</link> </links> </configuration> </plugin> . <configuration> <aggregate>true</aggregate> .. For example.
sf. 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. the line numbers in the report are linked to the actual source code so you can browse the issues. some source files are identified as having problems that could be addressed. this is important for both the efficiency of other team members and also to increase the overall level of code comprehension. Figure 6-7 shows the output of a PMD report on proficio-core.sf.Assessing Project Health with Maven 6. since the JXR report was included earlier. Also.net/) • Checkstyle (http://checkstyle. and violations of a coding standard. such as unused methods and variables.7. copy-and-pasted code. The result can help identify bugs. which is obtained by running mvn pmd:pmd. Better Builds With Maven 174 . and this section will look at three: PMD (http://pmd. Figure 6-7: An example PMD report As you can see.net/) • Tag List • PMD takes a set of either predefined or user-defined rule sets and evaluates the rules across your Java source code. which 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.
plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>/rulesets/basic. methods.maven.xml"> <exclude name="UnusedPrivateField" /> </rule> </ruleset> To use this rule set. The "unused code" rule set will locate unused private fields. change the configuration by overriding it in the proficio-core/pom. you can choose to create a custom rule set. For example. if you configure these. unused code.xml</ruleset> <ruleset>/rulesets/unusedcode. Or. and imports rule sets. adding: Better Builds With Maven 175 . However.maven. but not others.0"?> <ruleset name="custom"> <description> Default rules. In either case.xml</ruleset> <ruleset>/rulesets/finalizers.. but exclude the "unused private field" rule. The default PMD report includes the basic.. by passing the rulesets configuration to the plugin. you must configure all of them – including the defaults explicitly.xml" /> <rule ref="/rulesets/unusedcode. no unused private field warning </description> <rule ref="/rulesets/basic.xml</ruleset> </rulesets> </configuration> </plugin> . and the finalizer rule sets.. with the following content: <?xml version="1.xml</ruleset> <ruleset>/rulesets/imports.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. The "basic" rule set includes checks on empty blocks. variables and parameters. add the following to the plugin configuration you declared earlier: .xml file.xml file: ..apache.. <plugin> <groupId>org. create a file in the proficio-core directory of the sample application called src/main/pmd/custom.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> </plugin> . to include the default rules.apache.. For example. To try this.. unnecessary statements and possible bugs – such as incorrect loop variables.xml. The "imports" rule set will detect duplicate. redundant or unused import declarations. you may use the same rule sets in a number of projects. You may find that you like some rules in a rule set.xml" /> <rule ref="/rulesets/imports.. you could create a rule set with all the default rules. <plugin> <groupId>org. Adding new rule sets is easy.
For PMD. One important question is how to select appropriate rules.html. select the rules that apply to your own project. and add more as needed.apache. For more examples on customizing the rule sets. unusedcode.. you need to make sure it stays that way. and imports are useful in most scenarios and easily fixed.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <configuration> <rulesets> <ruleset>${basedir}/src/main/pmd/custom. [INFO] --------------------------------------------------------------------------- Better Builds With Maven 176 . basic..net/howtomakearuleset. 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. try the following guidelines from the Web site at http://pmd. Try this now by running mvn pmd:check on proficio-core.Assessing Project Health with Maven .sf. <reporting> <plugins> <plugin> <groupId>org.net/bestpractices. Start small. see the instructions on the PMD Web site at http://pmd.xml</ruleset> </rulesets> </configuration> </plugin> </plugins> </reporting> .html: • • Pick the rules that are right for you. If you've done all the work to select the right rules and are correcting all the issues being discovered. There is no point having hundreds of violations you won't fix.maven.sf.. From this starting.. It is also possible to write your own rules if you find that existing ones do not cover recurring problems in your source code.
</plugins> </build> You may have noticed that there is no configuration here. the pmd:check goal is run in the verify phase.java file by adding a //NOPMD comment to the unused variables and method: .. 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. To correct this. You will see that the build fails. the build will succeed. For that reason.Assessing Project Health with Maven Before correcting these errors.plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> . try running mvn verify in the proficio-core directory.. 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. To do so. adding the check to a profile. add the following section to the proficio/pom. // Trigger PMD and checkstyle int i. While this check is very useful.apache. fix the errors in the src/main/java/com/mergere/mvnbook/proficio/DefaultProficio.. but mandatory in an integration environment. which is executed only in an appropriate environment. If you run mvn verify again..... you should include the check in the build.. but recall from Configuring Reports and Checks section of this chapter that the reporting configuration is applied to the build as well.maven. Better Builds With Maven 177 . so that it is regularly tested. private void testMethod() // NOPMD { } . it can be slow and obtrusive during general development. If you need to run checks earlier...xml file: <build> <plugins> <plugin> <groupId>org. int j. By default. // NOPMD . // NOPMD . which occurs after the packaging phase. This is done by binding the goal to the build life cycle.
Assessing Project Health with Maven While the PMD report allows you to run a number of different rules. or to enforce a check will depend on the environment in which you are working. Figure 6-8: An example CPD report In a similar way to the main check.au/products/simian/). there is one that is in a separate report.com. Whether to use the report only. Simian can also be used through Checkstyle and has a larger variety of configuration options for detecting duplicate source code. such as Checkstyle. rather than identifying a possible factoring of the source code. or copy/paste detection report. the CPD report contains only one variable to configure: minimumTokenCount. This is the CPD. pmd:cpd-check can be used to enforce a failure if duplicate source code is found.This report is included by default when you enable the PMD plugin in your reporting section. and it includes a list of duplicate code fragments discovered across your entire source base. and a commercial product called Simian (http://www. However. which defaults to 100. There are other alternatives for copy and paste detection.redhillconsulting. With this setting you can fine tune the size of the copies detected. and will appear as "CPD report" in the Project Reports menu. This may not give you enough control to effectively set a rule for the source code. Better Builds With Maven 178 . An example report is shown in figure 6-8. resulting in developers attempting to avoid detection by making only slight modifications.
sf. Figure 6-9 shows the Checkstyle report obtained by running mvn checkstyle:checkstyle from the proficio-core directory. Some of the extra summary information for overall number of errors and the list of checks used has been trimmed from this display. similar to PMD. and rely on other tools for detecting other problems. warnings or errors are listed in a summary. • Use it to check code formatting and selected other problems. and then the errors are shown. you may choose to use it in one of the following ways: Use it to check code formatting only. Figure 6-9: An example Checkstyle report You'll see that each file with notices. Better Builds With Maven 179 . If you need to learn more about the available modules in Checkstyle. but has more recently added checks for other code issues. Depending on your environment. refer to the list on the Web site at http://checkstyle. It was originally designed to address issues of format and style. but Proficio is using the Maven team's code style. That's a lot of errors! By default. • Use it to check code formatting and to detect other problems exclusively • This section focuses on the first usage scenario. with a link to the corresponding source line – if the JXR report was enabled. in many ways. the rules used are those of the Sun Java coding conventions.Assessing Project Health with Maven Checkstyle is a tool that is.net/availablechecks. and still rely on other tools for greater coverage.html.
or a resource within a special dependency also.apache. Before completing this section it is worth mentioning the Tag List plugin. Table 6-3: Built-in Checkstyle configurations Configuration config/sun_checks.apache.html. The configLocation parameter can be set to a file within your build. a URL..apache.0. Better Builds With Maven 180 . While this chapter will not go into an example of how to do this. The Checkstyle plugin itself has a large number of configuration options that allow you to customize the appearance of the report.com/docs/codeconv/ http://maven. or would like to use the additional checks introduced in Checkstyle 3.0 and above.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. you will need to create a Checkstyle configuration. then it is likely to be more readable and easily learned by people joining your project. so to include the report in the site and configure it to use the Maven style. this will identify the tags TODO and @todo in the comments of your source code.net/config.html. filter the results.org/plugins/maven-checkstyle-plugin/tips.org/guides/development/guidem2-development. The built-in Sun and Maven standards are quite different.maven. the Checkstyle documentation provides an excellent reference at http://checkstyle. These checks are for backwards compatibility only.org/turbine/common/codestandards. known as "Task List" in Maven 1.xml</configLocation> </configuration> </plugin> Table 6-3 shows the configurations that are built into the Checkstyle plugin. However. It is a good idea to reuse an existing Checkstyle configuration for your project if possible – if the style you use is common.sun. It is also possible to share a Checkstyle configuration among multiple projects. and to parameterize the Checkstyle configuration for creating a baseline organizational standard that can be customized by individual projects.xml config/avalon_checks. and typically. This report. <plugin> <groupId>org.xml config/maven_checks.xml: .html#Maven%20Code%20Style http://jakarta.apache.xml config/turbine_checks. By default.sf.plugins</groupId> <artifactId>maven-checkstyle-plugin</artifactId> <configuration> <configLocation>config/maven_checks. one or the other will be suitable for most people.html No longer online – the Avalon project has closed.Assessing Project Health with Maven This style is also bundled with the Checkstyle plugin. as explained at http://maven. will look through your source code for known tags and provide a report on those it finds. if you have developed a standard that differs from these.. add the following to the reporting section of proficio/pom.
<plugin> <groupId>org. based on the theory that you shouldn't even try to use something before it has been tested.codehaus. and Tag List are just three of the many tools available for assessing the health of your project's source code. or as part of the site). using this report on a regular basis can be very helpful in spotting any holes in the test plan. PMD.codehaus. you saw that tests are run before the packaging of the library or application for distribution. 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. JavaNCSS and JDepend.8. it is easy to add a report to the Web site that shows the results of the tests that have been run. such as FindBugs. @todo.xml: . In the build life cycle defined in Chapter 2. or XXX in your source code.. Failing the build is still recommended – but the report allows you to provide a better visual representation of the results. As you learned in section 6.. This configuration will locate any instances of TODO. Some other similar tools. Better Builds With Maven 181 .Assessing Project Health with Maven To try this plugin..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. 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. for assessing coverage. Another critical technique is to determine how much of your source code is covered by the test execution.html.mojo</groupId> <artifactId>taglist-maven-plugin</artifactId> <configuration> <tags> <tag>TODO</tag> <tag>@todo</tag> <tag>FIXME</tag> <tag>XXX</tag> </tags> </configuration> </plugin> . add the following to the reporting section of proficio/pom. In addition to that.. Setting Up the Project Web Site. have beta versions of plugins available from the http://mojo. Cobertura (http://cobertura. 6. It is actually possible to achieve this using Checkstyle or PMD rules. While you are writing your tests.net) is the open source tool best integrated with Maven. Figure 6-10 shows the output that you can view in target/site/cobertura/index. Checkstyle. FIXME. the report (run either on its own. There are additional testing stages that can occur after the packaging step to verify that the assembled package works under other circumstances. and more plugins are being added every day. will ignore these failures when generated to show the current test state. At the time of writing.org/ project at the time of this writing. Knowing whether your tests pass is an obvious and important assessment of their health. While the default Surefire configuration fails the build if the tests fail.sf. To see what Cobertura is able to report. run mvn cobertura:cobertura in the proficio-core directory of the sample application.
you'll notice the following markings: • • • Unmarked lines are those that do not have any executable code associated with them. comments and white space. Lines in red are statements that were not executed (if the count is 0). This includes method and class declarations. in the familiar Javadoc style framed layout. Unmarked lines with a green number in the second column are those that have been completely covered by the test execution. and a line-by-line coverage analysis of each source file. or for which all possible branches were not executed. For a source file.Assessing Project Health with Maven The report contains both an overall summary. Figure 6-10: An example Cobertura report Better Builds With Maven 182 . For example. a branch is an if statement that can behave differently depending on whether the condition is true or false. Each line with an executable statement has a number in the second column that indicates during the test run how many times a particular statement was run.
ser. <build> <plugins> <plugin> <groupId>org.. If this is a metric of interest.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> <executions> <execution> <id>clean</id> <goals> <goal>clean</goal> </goals> </execution> </executions> </plugin> </plugins> </build> . The Cobertura report doesn't have any notable configuration. If you now run mvn site under proficio-core.. which measures the number of branches that occur in a particular method.Assessing Project Health with Maven The complexity indicated in the top right is the cyclomatic complexity of the methods in the class. 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.ser file is deleted. Better Builds With Maven 183 . Add the following to the reporting section of proficio/pom. High numbers (for example. you'll see that the cobertura.xml: .html. add the following to the build section of proficio/pom. While not required. over 10).. you might consider having PMD monitor it.. so including it in the site is simple.codehaus. If you now run mvn clean in proficio-core. the report will be generated in target/site/cobertura/index. Due to a hard-coded path in Cobertura. there is another useful setting to add to the build section....mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> </plugin> . might indicate a method should be re-factored into simpler pieces. as well as the target directory. To ensure that this happens.codehaus.. <plugin> <groupId>org.xml: . as it can be hard to visualize and test the large number of alternate code paths. the database used is stored in the project directory as cobertura. and is not cleaned with the rest of the project.
. as in the Proficio example. This is because Cobertura needs to instrument your class files. you would add unit tests for the functions that are missing tests. looking through the report. 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.. If you run mvn verify again.. You'll notice that your tests are run twice.xml: .Assessing Project Health with Maven To configure this goal for Proficio. Note that the configuration element is outside of the executions. Better Builds With Maven 184 . The rules that are being used in this configuration are 100% overall line coverage rate. and decide to reduce the overall average required.. and the tests are re-run using those class files instead of the normal ones (however. the check passes. and 100% branch coverage rate. <configuration> <check> <totalLineRate>80</totalLineRate> . these are instrumented in a separate directory... <configuration> <check> <totalLineRate>100</totalLineRate> <totalBranchRate>100</totalBranchRate> </check> </configuration> <executions> . the check will be performed. You can do this for Proficio to have the tests pass by changing the setting in proficio/pom. you may decide that only some exceptional cases are untested.. If you now run mvn verify under proficio-core. add a configuration and another execution to the build plugin definition you added above when cleaning the Cobertura database: . This wouldn't be the case if it were associated with the life-cycle bound check execution. so are not packaged in your application). the configuration will be applied. <execution> <id>check</id> <goals> <goal>check</goal> </goals> </execution> </executions> . However.. This ensures that if you run mvn cobertura:check from the command line. Normally... You would have seen in the previous examples that there were some lines not covered. so running the check fails.
see the Clover plugin reference on the Maven Web site at http://maven. and setting the total rate higher than both. The best known commercial offering is Clover. such as handling checked exceptions that are unexpected in a properly configured system and difficult to test. involve the whole development team in the decision. or as the average across each package. exceptional cases – and that's certainly not something you want! The settings above are requirements for averages across the entire source tree. In both cases. For more information. Cobertura is not the only solution available for assessing test coverage. Choosing appropriate settings is the most difficult part of configuring any of the reporting metrics in Maven. 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. Choose to reduce coverage requirements on particular classes or packages rather than lowering them globally. only allowing a small number of lines to be untested. which is very well integrated with Maven as well. Consider setting any package rates higher than the per-class rate. Remain flexible – consider changes over time rather than hard and fast rules. If you have another tool that can operate under the Surefire framework. It is just as important to allow these exceptions. To conclude this section on testing. It is also possible to set requirements on individual packages or classes using the regexes parameter. Don't set it too low. it is possible for you to write a provider to use the new tool.apache. Surefire supports tests written with TestNG. It also won't tell you whether the results of untested input values produce the correct results.sf. these reports work unmodified with those test types. there is more to assessing the health of tests than success and coverage. the easiest way to increase coverage is to remove code that handles untested. Set some known guidelines for what type of code can remain untested. using lineRate and branchRate.Assessing Project Health with Maven These settings remain quite demanding though. refer to the Cobertura plugin configuration reference at http://mojo.org/plugins/maven-clover-plugin/. as it is to require that the other code be tested.codehaus. It behaves very similarly to Cobertura. although not yet integrated with Maven directly.org/cobertura-maven-plugin. Of course. using packageLineRate and packageBranchRate. This will allow for some constructs to remain untested. and get integration with these other tools for free. so that they understand and agree with the choice. These reports won't tell you if all the features have been implemented – this requires functional or acceptance testing. 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. as it will become a minimum benchmark to attain and rarely more. Better Builds With Maven 185 . as it will discourage writing code to handle exceptional cases that aren't being tested. Some helpful hints for determining the right code coverage settings are: • • • • • • Like all metrics. Tools like Jester (http://jester. You may want to enforce this for each file individually as well. and you can evaluate it for 30 days when used in conjunction with Maven.net). For example. may be of assistance there. Don't set it too high. and at the time of writing experimental JUnit 4. Remember. For more information.0 support is also available.
Assessing Project Health with Maven 6. but any projects that depend on your project. used well it is a significant time saver. run mvn site in the proficio-core directory. but does introduce a drawback: poor dependency maintenance or poor scope and version selection affects not only your own project. the full graph of a project's dependencies can quickly balloon in size and start to introduce conflicts.9. Maven 2. where the dependencies of dependencies are included in a build. and a number of other features such as scoping and version selection. Monitoring and Improving the Health of Your Dependencies Many people use Maven primarily as a dependency manager. This brought much more power to Maven's dependency mechanism. The result is shown in figure 6-11. While this is only one of Maven's features. Left unchecked. The first step to effectively maintaining your dependencies is to review the standard report included with the Maven site.0 introduced transitive dependencies. If you haven't done so already.html. and browse to the file generated in target/site/dependencies. Figure 6-11: An example dependency report Better Builds With Maven 186 .
local scope test wins) proficio-api:1. and must be updated before the project can be released.0. This report is also a standard report. proficio-model is introduced by proficio-api. and is shown in figure 6-12. For example.1 (not setting scope to: compile. this requires running your build with debug turned on. Currently. This will output the dependency tree as it is calculated. which indicates dependencies that are in development. A dependency graphing plugin that will render a graphical representation of the information. such as mvn -X package.0-alpha-9 (selected for compile) plexus-utils:1. 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. Whether there are outstanding SNAPSHOT dependencies in the build. for example. as well as comments about what versions and scopes are selected. To see the report for the Proficio project. and that plexus-container-default attempts to introduce junit as a compile dependency. or an incorrect scope – and choose to investigate its inclusion. an incorrect version. This can be quite difficult to read.0-SNAPSHOT (selected for compile) Here you can see that. 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.1 (selected for test) plexus-container-default:1. It's here that you might see something that you didn't expect – an extra dependency. and why.8.0-SNAPSHOT (selected for compile) proficio-model:1. run mvn site from the base proficio directory. Another report that is available is the "Dependency Convergence Report".4 (selected for compile) classworlds:1. but more importantly in the second section it will list all of the transitive dependencies included through those dependencies. This helps ensure your build is consistent and reduces the probability of introducing an accidental incompatibility. The file target/site/dependencyconvergence. The report shows all of the dependencies included in all of the modules within the project. but appears in a multi-module build only. • Better Builds With Maven 187 . here is the resolution process of the dependencies of proficio-core (some fields have been omitted for brevity): proficio-core:1. using indentation to indicate which dependencies introduce other dependencies.0-SNAPSHOT junit:3. but that it is overridden by the test scoped dependency in proficio-core.Assessing Project Health with Maven This report shows detailed information about your direct dependencies.8.1-alpha-2 (selected for compile) junit:3.
Better Builds With Maven 188 . or runtime if it is needed to bundle with or run the application but not for compiling your source code). rather than using the latest available. You can control what version is actually used by declaring the dependency version in a project that packages or runs the application. 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. 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. To improve your project's health and the ability to reuse it as a dependency itself. Use a range of supported dependency versions. However.
Catching these before a release can eliminate problems that are quite difficult to resolve once the code is "in the wild". Two that are in progress were listed above. specification dependencies that let you depend on an API and manage the implementation at runtime. and more. This is particularly the case for dependencies that are optional and unused by your project. 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. there is no verification that a library is binary-compatible – incompatibility will be discovered only when there's a failure. but it is often tedious and error prone. and the information released with it. An important tool in determining whether a project is ready to be released is Clirr (http://clirr. this section will focus on improving the quality of the code released. 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. but then expected to continue working as they always have.sf. 6. While the next chapter will go into more detail about how Maven can help automate that task and make it more reliable. Libraries will often be substituted by newer versions to obtain new features or bug fixes. An example Clirr report is shown in figure 6-13. Clirr detects whether the current version of a library has introduced any binary incompatibilities with the previous release.Assessing Project Health with Maven • Add exclusions to dependencies to remove poorly defined dependencies from the tree.net/). Because existing libraries are not recompiled every time a version is changed. Monitoring and Improving the Health of Your Releases Releasing a project is one of the most important procedures you will perform. Given the importance of this task. more tools are needed in Maven. Better Builds With Maven 189 .10.
. Different modules may use different versions.. [clirr:clirr] Comparing to version: 0.9 ------------------------------------------------------------BUILD SUCCESSFUL ------------------------------------------------------------- This version is determined by looking for the newest release in repository.. the answer here is clearly – yes. This is particularly true in a Maven-based environment. by setting the minSeverity parameter. that is before the current development version. [INFO] [INFO] [INFO] [INFO] [INFO] . By default. To see this in action. If you run mvn site in proficio-api.9 of proficio-api against which to compare (and that it is downloaded if you don't have it already): . the Clirr report shows only errors and warnings.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... add the following to the reporting section of proficio-api/pom. you can configure the plugin to show all informational messages. or a quick patch may need to be made and a new version deployed into an existing application. As a project grows. the interactions between the project's own components will start behaving as if they were externally-linked.xml: . where the dependency mechanism is based on the assumption of binary compatibility between versions. For example. even if they are binary compatible.8 release.html. the report will be generated in target/site/clirrreport. While methods of marking incompatibility are planned for future versions. You can change the version used with the comparisonVersion parameter. to compare the current code to the 0.codehaus. back to the first release. <reporting> <plugins> <plugin> <groupId>org.. You can obtain the same result by running the report on its own using mvn clirr:clirr.8 Better Builds With Maven 190 . run the following command: mvn clirr:clirr -DcomparisonVersion=0. This gives you an overview of all the changes since the last release. Maven currently works best if any version of an artifact is backwards compatible..mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <minSeverity>info</minSeverity> </configuration> </plugin> </plugins> </reporting> . If you run either of these commands. However. you'll notice that Maven reports that it is using version 0..
it is important to agree up front.xml file. however you can see the original sources by extracting the Codeh_Ch06-2.Assessing Project Health with Maven These versions of proficio-api are retrieved from the repository. The Clirr plugin is also capable of automatically checking for introduced incompatibilities through the clirr:check goal. and to check them automatically..0 would be more stable in the long run. However. and it can assist in making your own project more stable. add the following to the build section: . </plugins> </build> . The longer poor choices remain. on the acceptable incompatibilities. Like all of the quality metrics. if the team is prepared to do so.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <executions> <execution> <goals> <goal>check</goal> </goals> </execution> </executions> </plugin> . To add the check to the proficio-api/pom.codehaus. there is nothing in Java preventing them from being used elsewhere. Even if they are designed only for use inside the project. If it is the only one that the development team will worry about breaking.. to discuss and document the practices that will be used. delegating the code. it is almost always preferable to deprecate an old API and add a new one. so that fewer people are affected.. It is best to make changes earlier in the development cycle.. it is a good idea to monitor as many components as possible. This is the most important one to check. 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.. rather than removing or changing the original API and breaking binary compatibility. You'll notice there are a more errors in the report. In this instance. you are monitoring the proficio-api component for binary compatibility changes only. since this early development version had a different API.. <build> <plugins> <plugin> <groupId>org. Better Builds With Maven 191 . Once a version has been released that is intended to remain binary-compatible going forward. as it will be used as the interface into the implementation by other applications.zip file. the harder they are to change as adoption increases. and later was redesigned to make sure that version 1.
<plugin> <groupId>org.Assessing Project Health with Maven If you now run mvn verify. which is available at http://mojo. and then act accordingly. With this simple setup. However.0 version. you can choose to exclude that from the report by adding the following configuration to the plugin: . and ignored in the same way that PMD does. as well as strategies for evolving an API without breaking it.. While the topic of designing a strong public API and maintaining binary compatibility is beyond the scope of this book. not just the one acceptable failure.org/jdiff-maven-plugin.9 preview release and the final 1.codehaus. A limitation of this feature is that it will eliminate a class entirely. This can be useful in getting a greater level of detail than Clirr on specific class changes. the following articles and books can be recommended: • • Evolving Java-based APIs contains a description of the problem of maintaining binary compatibility. so the report still lists the incompatibility. A similar tool to Clirr that can be used for analyzing changes between releases is JDiff. Note that in this instance.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <excludes> <exclude>**/Proficio</exclude> </excludes> </configuration> . Better Builds With Maven 192 .9 release. it will not pinpoint potential problems for you. Built as a Javadoc doclet. you can create a very useful mechanism for identifying potential release disasters much earlier in the development process. and particularly so if you are designing a public API. This allows the results to be collected over time to form documentation about known incompatibilities for applications using the library.. Since this was an acceptable incompatibility due to the preview nature of the 0. It has a functional Maven 2 plugin. </plugin> This will prevent failures in the Proficio class from breaking the build in the future. and so is most useful for browsing.. Hopefully a future version of Clirr will allow acceptable incompatibilities to be documented in the source code.codehaus.. taking two source trees and comparing the differences in method signatures and Javadoc annotations. Effective Java describes a number of practical rules that are generally helpful to writing code in Java. it is listed only in the build configuration. it takes a very different approach. you will see that the build fails due to the binary incompatibility introduced between the 0.
Some of the reports linked to one another. and will be used as the basis for the next chapter. and as the report set stabilizes – summary reports will start to appear.12. it requires a shift from a focus on time and deadlines. this focus and automated monitoring will have the natural effect of improving productivity and reducing time of delivery again.zip source archive. and have not yet been implemented for Maven 2. then. Better Builds With Maven 193 . regularly scheduled.Assessing Project Health with Maven 6. These are all important features to have to get an overall view of the health of a project. none of the reports presented how the information changes over time other than the release announcements. 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. Finally. In the absence of these reports. Best of all. to a focus on quality. The purpose. The next chapter examines team development and collaboration. While some attempts were made to address this in Maven 1. the Dashboard plugin). enforcing good. so that they feel that they are achievable. it is important that your project information not remain passive. It is important that developers are involved in the decision making process regarding build constraints. However. and few of the reports aggregated information across a multiple module build. 6. as there is a constant background monitor that ensures the health of the project is being maintained.0. along with techniques to ensure that the build checks are now automated. each in discrete reports. the model remains flexible enough to make it easy to extend and customize the information published on your project web site. a large amount of information was presented about a project. of the visual display is to aid in deriving the appropriate constraints to use. Viewing Overall Project Health In the previous sections of this chapter. it should be noted that the Maven reporting API was written with these requirements in mind specifically. In some cases.11. However. but none related information from another report to itself. Once established.xml). individual checks that fail the build when they're not met. will reduce the need to gather information from various sources about the health of the project. How well this works in your own projects will depend on the development culture of your team. Summary The power of Maven's declarative project model is that with a very simple setup (often only 4 lines in pom. and run in the appropriate environment. Most Maven plugins allow you to integrate rules into the build that check certain constraints on that piece information once it is well understood. they did not address all of these requirements. and incorporates the concepts learned in this chapter. The additions and changes to Proficio made in this chapter can be found in the Code_Ch06-1.0 (for example.
Tom Clancy Better Builds With Maven 194 .7. 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. .
An organizational and technology-based framework. and asynchronous engineering. However. These tools aid the team to organize. it does encompass a set of practices and tools that enable effective team communication and collaboration. project information can still be misplaced. Using the model of a community. iterative cycles.1. As each member retains project information that isn't shared or commonly accessible. widely-distributed teams. CoRE enables globally distributed development teams to cohesively contribute to high-quality software. A Community-oriented Real-time Engineering (CoRE) process excels with this information challenge. Better Builds With Maven 195 . or forgotten. resulting in shortened development cycles. although a distributed team has a higher communication overhead than a team working in a single location. While it's essential that team members receive all of the project information required to be productive. As teams continue to grow. further contributing to the problem. This value is delivered to development teams by supporting project transparency. component-based projects despite large. repeating errors previously solved or duplicating efforts already made. This problem is particularly relevant to those working as part of a team that is distributed across different physical locations and timezones. CoRE is based on accumulated learnings from open source projects that have achieved successful. The Issues Facing Teams Software development as part of a team. Even though teams may be widely distributed. in rapid. While Maven is not tied directly to the CoRE framework.Team Collaboration with Maven 7. 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. faces a number of challenges to the success of the effort. will inevitably have to spend time obtaining this localized information. real-time stakeholder participation. However. whether it is 2 people or 200 people. one of the biggest challenges relates to the sharing and management of development information. and dealing with differences in opinions. but also to incorporate feedback. 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. The CoRE approach to development also means that new team members are able to become productive quickly. Many of these challenges are out of any given technology's control – for instance finding the right people for the team. rapid development. visualize. web-based communication channels and web-based project management tools. misinterpreted. This problem gets exponentially larger as the size of the team increases. and that existing team members become more productive and effective. 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. every other member (and particularly new members). 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. CoRE emphasizes the relationship between project information and project members. working on complex. Even when it is not localized. which is enabled by the accessibility of consistently structured and organized information such as centralized code repositories. and document for reuse the artifacts that result from a software project.
you learned how to create your own settings.xml file.xml file contains a number of settings that are user-specific. through the practice of continuous integration. Maven can gather and share the knowledge about the health of a project. and other discrete settings such as user names and passwords. varying operating systems. and to user-specific profiles. <maven home>/conf/settings. it's a good idea to leverage Maven's two different settings files to separately manage shared and user-specific settings. Without it. In Maven. 7. In a shared development environment. This file can be stored in the conf directory of your Maven installation. multiple JDK versions. such as different installation locations for software. while an individual developer's settings are stored in their home directory. Additionally. Common configuration settings are included in the installation directory. such as proxy settings. while still allowing for this natural variability. In Chapter 2. but also several that are typically common across users in a shared environment. the set up process for a new developer can be slow. because the environment will tend to evolve inconsistently once started that way. and the use of archetypes to ensure consistency in the creation of new projects. While one of Maven's objectives is to provide suitable conventions to reduce the introduction of inconsistencies in the build environment. error-prone and full of omissions.xml: Better Builds With Maven 196 . How to Setup a Consistent Developer Environment Consistency is important when establishing a shared development environment. there are unavoidable variables that remain. demonstrating how Maven provides teams with real-time information on the builds and health of a project.Team Collaboration with Maven As described in Chapter 6.m2 subdirectory of your home directory (settings in this location take precedence over those in the Maven installation directory). To maintain build consistency. The following is an example configuration file that you might use in the installation directory. This chapter also looks at the adoption and use of a consistent development environment.2. In this chapter. the key is to minimize the configuration required by each individual developer. The settings. these variables relate to the user and installation settings files. it will be the source of timeconsuming development problems in the future. or in the . and to effectively define and declare them. this is taken a step further.
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.mycompany.plugins</pluginGroup> </pluginGroups> </settings> Better Builds With Maven 197 .mycompany.mycompany.com/internal/</url> </repository> </repositories> <pluginRepositories> <pluginRepository> <id>internal</id> <name>Internal Plugin Repository</name> <url>http://repo.username}</username> <filePermissions>664</filePermissions> <directoryPermissions>775</directoryPermissions> </server> </servers> <profiles> <profile> <repositories> <repository> <id>internal</id> <name>Internal Repository</name> <url>http://repo.com/internal/</url> </pluginRepository> </pluginRepositories> </profile> </profiles> <activeProfiles> <activeProfile>property-overrides</activeProfile> <activeProfile>default-repositories</activeProfile> </activeProfiles> <pluginGroups> <pluginGroup>com.
${user.3 of this chapter for more information on creating a mirror of the central repository within your own organization. property-overrides is also enabled by default. it would usually be set consistently across the organization or department. In Maven. such as ${website. These repositories are independent of the central repository in this configuration. issues with inconsistently-defined identifiers and permissions are avoided. the local repository is defined as the repository of single user. you can easily add and consistently roll out any new server and repository settings. The server settings will typically be common among a set of developers. While you may define a standard location that differs from Maven's default (for example. without having to worry about integrating local changes made by individual developers. at a single physical location. which are run from the command line and not defined in the POM.username>myuser</website. By placing the common configuration in the shared settings. See section 7. Using the basic template. across users.Team Collaboration with Maven There are a number of reasons to include these settings in a shared configuration: • • • • • • If a proxy server is allowed. The profile defines those common. internal repositories that contain a given organization's or department's released artifacts.username> </properties> </profile> </profiles> </settings> To confirm that the settings are installed correctly.3 for more information on setting up an internal repository. Another profile. This profile will be defined in the user's settings file to set the properties used in the shared file. with only specific properties such as the user name defined in the user's settings. which is typically one that has been set up within your own organization or department. The plugin groups are necessary only if an organization has plugins.home}/maven-repo). it is important that you do not configure this setting in a way that shares a local repository. The active profiles listed enable the profile defined previously in every environment.username}. The mirror element can be used to specify a mirror of a repository that is closer to you. See section 7. The user-specific configuration is also much simpler as shown below: <settings> <profiles> <profile> <id>property-overrides</id> <properties> <website. The previous example forms a basic template that is a good starting point for the settings file in the Maven installation. you can view the merged result by using the following help plugin command: C:\mvnbook> mvn help:effective-settings Better Builds With Maven 198 . You'll notice that the local repository is omitted in the prior example.
and run: C:\mvnbook\repository> java -jar jetty-5. A new release will be required each time the configuration is changed. the most popular is HTTP. or other source control management (SCM) system. it is possible to maintain multiple Maven installations. Change to that directory.1.1.3. The following are a few methods to achieve this: • • • • Rebuild the Maven release distribution to include the shared configuration file and distribute it internally. Now that each individual developer on the team has a consistent set up that can be customized as needed. While any of the available transport protocols can be used.10-bundle. If necessary. however it applies to all projects that are built in the developer's environment. If this infrastructure is available. so that multiple developers and teams can collaborate effectively. located in the project directory. since not everyone can deploy to the central Maven repository. • Adjusting the path or creating symbolic links (or shortcuts) to the desired Maven executable. Jetty. see Chapter 2. You can use an existing HTTP server for this. organization's will typically want to set up what is referred to as an internal repository. in this example C:\mvnbook\repository will be used. just as any other external repository would be. To set up Jetty. by one of the following methods: Using the M2_HOME environment variable to force the use of a particular installation. doing so will prevent Maven from being available off-line. download the Jetty 5. easily updated. Check the Maven installation into CVS.jar 8081 Better Builds With Maven 199 . For more information on profiles. Use an existing desktop management solution. • Configuring the settings. but requires a manual procedure. and when possible.xml file covers the majority of use cases for individual developer customization. or create a new server using Apache HTTPd. To set up your organization's internal repository using Jetty. In some circumstances however. each execution will immediately be up-to-date. To publish releases for use across different environments within their network. see Chapter 3. or any number of other servers. create a new directory in which to store the files. or if there are network problems. However. developers must use profiles in the profiles. 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. Place the Maven installation on a read-only shared or network drive from which each developer runs the application. Subversion.Team Collaboration with Maven Separating the shared settings from the user-specific settings is helpful. To do this. For an explanation of the different types of repositories. Apache Tomcat. Creating a Shared Repository Most organizations will need to set up one or more shared repositories. the next step is to establish a repository to and from which artifacts can be published and dependencies downloaded. Setting up an internal repository is simple. Each developer can check out the installation into their own machines and run it from there.10 server bundle from the book's Web site and copy it to the repository directory. but it is also important to ensure that that the shared settings are easily and reliably installed with Maven. 7. While it can be stored anywhere you have permissions.xml file. This internal repository is still treated as a remote repository in Maven. or other custom solution. if M2_HOME is not set.
It is deployed to your Jetty server (or any other servlet container) and provides remote repository proxies. Use rsync to take a copy of the central repository and regularly update it.2. The server is set up on your own workstation for simplicity in this example. Your repository is now set up. To populate the repository you just created. You can create a separate repository under the same server. configured securely and monitored to ensure it remains running at all times. However. For the first repository. it is common in many organizations as it eliminates the requirement for Internet access or proxy configuration. searching. create a subdirectory called internal that will be available at http://localhost:8081/internal/. 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. separate repositories. the size of the Maven repository was 5.apache. For more information. it provides faster performance (as most downloads to individual developers come from within their own network). In addition. but rather than set up multiple web servers. This chapter will assume the repositories are running from http://localhost:8081/ and that artifacts are deployed to the repositories using the file system. and gives full control over the set of artifacts with which your software is built. you will want to set up or use an existing HTTP server that is in a shared. Better Builds With Maven 200 . sftp and more. While this isn't required. and reporting. The repository manager can be downloaded from http://maven. scp.Team Collaboration with Maven You can now navigate to http://localhost:8081/ and find that there is a web server running displaying that directory. it is possible to user a repository on another server with any combination of supported protocols including http. This creates an empty repository. 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. Later in this chapter you will learn that there are good reasons to run multiple.org/repositorymanager/. However. • The Maven Repository Manager (MRM) is a new addition to the Maven build platform that is designed to administer your internal repository. refer to Chapter 3. you can store the repositories on this single server. accessible location. The setting for using this was shown in the mirror element of the settings file in section 7. as well as friendly repository browsing. and keep a copy in your internal repository for others on your team to reuse. This will download anything that is not already present. by avoiding any reliance on Maven's relatively open central repository.8G. using the following command: C:\mvnbook\repository> mkdir central This repository will be available at http://localhost:8081/central/. and is all that is needed to get started. ftp. At the time of writing.
The next section discusses how to set up an "organization POM". 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. 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.2.Team Collaboration with Maven When using this repository for your projects. You would use it as a mirror if it is intended to be a copy of the central repository exclusively. that declares shared settings within an organization and its departments. Repositories such as the one above are configured in the POM usually. or had it in their source code check out. there is a problem – when a POM inherits from another POM that is not in the central repository. it must retrieve the parent from the repository. Usually. If you have multiple repositories. you should override the central repository. there are two choices: use it as a mirror. or hierarchy. you must define a repository in a settings file and/or POM that uses the identifier central. It is still important to declare the repositories that will be used in the top-most POM itself. this must be defined as both a regular repository and a plugin repository to ensure all access is consistent. and as a result. On the other hand. for a situation where a developer might not have configured their settings and instead manually installed the POM. to configure the repository from the project level instead of in each user's settings (with one exception that will be discussed next). This makes it impossible to define the repository in the parent. if you want to prevent access to the central repository for greater control. unless you have mirrored the central repository using one the techniques discussed previously. or have it override the central repository. it is necessary to declare only those that contain an inherited POM. Better Builds With Maven 201 .2. as shown in section 7.xml file. or to include your own artifacts in the same repository. Not only is this very inconvenient. However. otherwise Maven will fail to download any dependencies that are not in your local repository. it would need to be declared in every POM. or the original central repository directly without consequence to the outcome of the build. so that a project can add repositories itself for dependencies located out of those repositories configured initially. and if it's acceptable to have developers configure this in their settings as demonstrated in section 7. To override the central repository with your internal repository. Developers may choose to use a different mirror.
apache. the easiest way to version a POM is through sequential numbering. project inheritance can be used to assist in ensuring project consistency. consider the Maven project itself. its departments. </modules> </project> If you were to review the entire POM. Better Builds With Maven 202 . Maven SCM. so it's possible to have one or more parents that define elements common to several projects... and then the teams within those departments.0.maven</groupId> <artifactId>maven-parent</artifactId> <version>1</version> </parent> <groupId>org. the current project – Maven 2 now retrieves parent projects from the repository. which is shared across all Maven projects through inheritance. Creating an Organization POM As previously mentioned in this chapter. By declaring shared elements in a common parent POM. from section 7. you'd find that there is very little deployment or repositoryrelated information.. It is a part of the Apache Software Foundation. as this is consistent information.Team Collaboration with Maven 7.scm</groupId> <artifactId>maven-scm</artifactId> <url>http://maven.org/maven-scm/</url> .apache. Maven Continuum. This project structure can be related to a company structure. consider the POM for Maven SCM: <project> <modelVersion>4.apache. As an example.maven. depending on the information that needs to be shared.xml file in the shared installation (or in each developer's home directory). and is a project that. As a result. consistency is important when setting up your build infrastructure. Any number of levels (parents) can be used. that if your inherited projects reside in an internal repository. <modules> <module>maven-scm-api</module> <module>maven-scm-providers</module> . itself. To continue the Maven example.0 – that is. Future versions of Maven plan to automate the numbering of these types of parent projects to make this easier. there are three levels to consider when working with any individual module that makes up the Maven project. wherein there's the organization.3. While project inheritance was limited by the extent of a developer's checkout in Maven 1. Since the version of the POM usually bears no resemblance to the software. or the organization as a whole. has a number of sub-projects (Maven.0</modelVersion> <parent> <groupId>org. It is important to recall. then that repository will need to be added to the settings.. You may have noticed the unusual version declaration for the parent project. etc. These parents (levels) may be used to define departments.).4.
..Team Collaboration with Maven If you look at the Maven project's parent POM.apache. </mailingList> </mailingLists> <developers> <developer> .maven</groupId> <artifactId>maven-parent</artifactId> <version>5</version> <url>http://maven.org/</url> .org</post> .apache</groupId> <artifactId>apache</artifactId> <version>1</version> </parent> <groupId>org.apache....0</modelVersion> <parent> <groupId>org. </developer> </developers> </project> Better Builds With Maven 203 .0.apache.. you'd see it looks like the following: <project> <modelVersion>4. <mailingLists> <mailingList> <name>Maven Announcements List</name> <post>announce@maven.
where they can be checked out. you can retain the historical versions in the repository if it is backed up (in the future. </repository> <snapshotRepository> . An issue that can arise... In fact. when working with this type of hierarchy. is regarding the storage location of the source POM files. For this reason. the Maven Repository Manager will allow POM updates from a web interface). and deployed with their new version as appropriate.apache. there is no best practice requirement to even store these files in your source control management system. These parent POM files are likely to be updated on a different. it is best to store the parent POM files in a separate area of the source control tree.0</modelVersion> <groupId>org.org/</url> </organization> <url>http://www.Team Collaboration with Maven The Maven parent POM includes shared elements. and the deployment locations. </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..org/</url> .snapshots</id> <name>Apache Snapshot Repository</name> <url>http://svn. <distributionManagement> <repository> .. and less frequent schedule than the projects themselves. most of the elements are inherited from the organization-wide parent project.apache.. 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. Again.apache</groupId> <artifactId>apache</artifactId> <version>1</version> <organization> <name>Apache Software Foundation</name> <url>http://www.0.6). such as the announcements mailing list and the list of developers that work across the whole project.org/maven-snapshot-repository</url> <releases> <enabled>false</enabled> </releases> </repository> </repositories> .. <repositories> <repository> <id>apache..apache. in this case the Apache Software Foundation: <project> <modelVersion>4. Better Builds With Maven 204 . modified..
0. More than just nightly builds. The first screen to appear will be the one-time setup page shown in figure 7-1. continuous integration enables automated builds of your project on a regular interval. continuous integration can enable a better development culture where team members can make smaller. You can verify the installation by viewing the web site at http://localhost:8080/continuum/.3> bin\win32\run There are scripts for most major platforms. and learn how to use Continuum to build this project on a regular basis. Continuous Integration with Continuum If you are not already familiar with it.tigris. however. First. This is very simple – once you have downloaded it and unpacked it. In this chapter. some additional steps are required. you will need to install Continuum. press Ctrl-C in the window that is running Continuum). The examples also assumes you have Subversion installed.3. and the company information for altering the logo in the top left of the screen. you will pick up the Proficio example from earlier in the book. As of Continuum 1. you can run it using the following command: C:\mvnbook\continuum-1. For most installations this is all the configuration that's required. 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 . The examples discussed are based on Continuum 1. continuous integration is a key element of effective collaboration. these additional configuration requirements can be set only after the previous step has been completed. however newer versions should be similar. if you are running Continuum on your desktop and want to try the examples in this section.0.3. iterative changes that can more easily support concurrent development processes. as well as the generic bin/plexus.org/. Continuum is Maven's continuous integration and build server. rather than close to a release.0.sh for use on other Unix-based platforms. and you must stop the server to make the changes (to stop the server. As such. ensuring that conflicts are detected earlier in a project's release life cycle. which you can obtain for your operating system from http://subversion.Team Collaboration with Maven 7.5.
.org/continuum/guides/mini/guide-configuration.xml and uncomment the following line: . refer to http://maven.. since paths can be entered from the web interface.codehaus.apache.formica. you can start Continuum again.UrlValidator </implementation> <configuration> <allowedSchemes> ..validation. To have Continuum send you e-mail notifications. To enable this setting. you will also need an SMTP server to which to send the messages. For instructions. The default is to use localhost:25.. this is disabled as a security measure. POM files will be read from the local hard disk where the server is running.plexus. By default. <implementation> org. If you do not have this set up on your machine. edit apps/continuum/conf/application.. edit the file above to change the smtp-host setting. Better Builds With Maven 206 . <allowedScheme>file</allowedScheme> </allowedSchemes> </configuration> .Team Collaboration with Maven Figure 7-1: The Continuum setup screen In the following examples.. After these steps are completed.html.
You can then check out Proficio from that location..xml to correct the e-mail address to which notifications will be sent. Better Builds With Maven 207 .Team Collaboration with Maven The next step is to set up the Subversion repository for the examples.. <scm> <connection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </connection> <developerConnection> scm:svn:file://localhost/c:/mvnbook/svn/proficio/trunk </developerConnection> </scm> . <distributionManagement> <site> <id>website</id> <url> file://localhost/c:/mvnbook/repository/sites/proficio /reference/${project.. This requires obtaining the Code_Ch07... Edit proficio/pom. and edit the location of the Subversion repository.. by uncommenting and modifying the following lines: . <ciManagement> <system>continuum</system> <url>http://localhost:8080/continuum <notifiers> <notifier> <type>mail</type> <configuration> <address>youremail@yourdomain.. since not all of the required details were known at the time of its creation. for example if it was unzipped in C:\mvnbook\svn: C:\mvnbook> svn co file://localhost/C:/mvnbook/svn/proficio/trunk \ proficio The POM in this repository is not completely configured yet. The ciManagement section can be used to configure a project for easier integration with Continuum..zip archive and unpacking it in your environment.version} </url> </site> </distributionManagement> .com</address> </configuration> </notifier> </notifiers> </ciManagement> .
If you haven't done so already. The result is shown in figure 7-3. or a Subversion HTTP server. you can now select Maven 2. refer to section 7. or upload from your local drive. You have two options: you can provide the URL for a POM. While uploading is a convenient way to configure from your existing check out. you must either log in with the administrator account you created during installation. If you return to the http://localhost:8080/continuum/ location that was set up previously.xml You should build all these modules to ensure everything is in order. Once these settings have been edited to reflect your setup. under the Continuum logo. This assumes that you are still running the repository Web server on localhost:8081. After submitting the URL. Initially.0. Continuum will return to the project summary page. the builds will be marked as New and their checkouts will be queued.3 this does not work when the POM contains modules. When you set up your own system later. a ViewCVS installation. enter the file:// URL as shown.Team Collaboration with Maven The distributionManagement setting will be used in a later example to deploy the site from your continuous integration environment. from the directory C:\mvnbook\repository. you will enter either a HTTP URL to a POM in the repository.3 for information on how to set this up. commit the file with the following command: C:\mvnbook\proficio> svn ci -m 'my settings' pom. as in the Proficio example. in Continuum 1. The login link is at the top-left of the screen. with the following command: C:\mvnbook\proficio> mvn install You are now ready to start using Continuum. Once you have logged in. or perform other tasks. Better Builds With Maven 208 .0+ Project from the Add Project menu. Figure 7-2: Add project screen shot This is all that is required to add a Maven 2 project to Continuum. Before you can add a project to the list. Instead. you will see an empty project list. or with another account you have since created with appropriate permissions. This will present the screen shown in figure 7-2. and each of the modules will be added to the list of projects.
remove the interface keyword: [.. for example. The build in Continuum will return to the successful state. If you want to put this to the test. 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). For example. The Build History link can be used to identify the failed build and to obtain a full output log. restore the file above to its previous state and commit it again. check the file in: C:\mvnbook\proficio\proficio-api> svn ci -m 'introduce error' \ src/main/java/com/mergere/mvnbook/proficio/Proficio.. press Build Now on the Continuum web interface next to the Proficio API module. and then fail. go to your earlier checkout and introduce an error into Proficio. This chapter will not discuss all of the features available in Continuum. In addition.java Finally. you should receive an e-mail at the address you configured earlier. but you may wish to go ahead and try them. Jabber.java..Team Collaboration with Maven Figure 7-3: Summary page after projects have built Continuum will now build the project hourly. the build will show an "In progress" status. MSN and Google Talk are all supported.] public Proficio [.] Now. To avoid receiving this error every hour. you might want to set up a notification to your favorite instant messenger – IRC. First. Better Builds With Maven 209 .
For these reports to be of value. Fix builds as soon as possible. there are a few tips for getting the most out of the system: • Commit early. it is recommend that a separate. before the developer moves on or loses focus. While this seems obvious. If the application is a web application. for example. separate from QA and production releases. if the source control repository supports post-commit hooks. This can be helpful for non-developers who need visibility into the state of the application. While rapid. This will make it much easier to detect the source of an error when the build does break. If multiple branches are in development. commit often. Continuous integration is most beneficial when tests are validating that the code is working as it always has. but rather keeping changes small and well tested. but regular schedule is established for site generation. operating system and other variables. it is important that it can be isolated to the change that caused it. Continuous integration will be pointless if developers repetitively ignore or delete broken build notifications. • • • • • • • In addition to the above best practices. you learned how to create an effective site containing project information and reports about the project's health and vitality.Team Collaboration with Maven Regardless of which continuous integration server you use. In Chapter 6. iterative builds are helpful in some situations. or local settings. Continuum currently defaults to doing a clean build. When a failure occurs in the continuous integration environment. Continuum can be configured to trigger a build whenever a commit occurs. and a future version will allow developers to request a fresh checkout. it is beneficial to test against all different versions of the JDK. Run clean builds. run a servlet container to which the application can be deployed from the continuous integration environment. Run a copy of the application continuously. and your team will become desensitized to the notifications in the future. it is also important that failures don't occur due to old build state. Run comprehensive tests. but it is best to detect a failure as soon as possible. Though it would be overkill to regenerate the site on ever commit. In addition. Continuum has preliminary support for system profiles and distributed testing. Avoid customizing the JDK. enhancements that are planned for future versions. This doesn't mean committing incomplete code. Consider a regular. the continuous integration environment should be set up for all of the active branches. and profile usage. if it isn't something already in use in other development. test and production environments. and independent of the environment being used. based on selected schedules. periodically. they need to be kept up-todate. This is another way continuous integration can help with project collaboration and communication. This will be constrained by the length of the build and the available resources on the build machine. Build all of a project's active branches. Better Builds With Maven 210 . clean build. This also means that builds should be fast – long integration and performance tests should be reserved for periodic builds. there are two additional topics that deserve special attention: automated updates to the developer web site. Continuous integration is most effective when developers commit regularly. not just that the project still compiles after one or more changes occur. Establish a stable environment. it is often ignored. Run builds as often as possible.
there is no way to make bulk changes to build definitions. It is not typically needed if using Subversion. which will be configured to run every hour during business hours (8am – 4pm weekdays). Click the Add button to add a new schedule. and select the top-most project. The project information shows just one build on the default schedule that installs the parent POM. only the default schedule is available. and add the same build definition to all of the modules. Next. from the Administration menu on the left-hand side. as well – if this is a concern..Team Collaboration with Maven Verify that you are still logged into your Continuum instance. 9:00:00. The appropriate configuration is shown in figure 7-4. but does not recurse into the modules (the -N or --non-recursive argument). The example above runs at 8:00:00..com/quartz/api/org/quartz/CronTrigger. Once you add this schedule. 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. In addition to building the sites for each module.html. In Continuum 1.. select Schedules. The downside to this approach is that Continuum will build any unchanged modules. You will see that currently.0. 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. Maven Proficio.opensymphony. use the non-recursive mode instead. so you will need to add the definition to each module individually. return to the project list.3. 16:00:00 from Monday to Friday.. it can aggregate changes into the top-level site as required. Better Builds With Maven 211 . since commits are not atomic and a developer might be committing midway through a update. This is useful when using CVS. The "quiet period" is a setting that delays the build if there has been a commit in the defined number of seconds prior.
Better Builds With Maven 212 . Click this for the site generation build definition. to ensure these checks are run.Team Collaboration with Maven In this example you will add a new build definition to run the site deployment for the entirety of the multi-module build. Any of these test goals should be listed after the site-deploy goal. The arguments provided are --batch-mode. The --non-recursive option is omitted. and -DenableCiProfile=true. Figure 7-5: Adding a build definition for site deployment The goals to run are clean and site-deploy. To add a new build definition. since most reports continue under failure conditions. verify or integrationtest goal to the list of goals. which means that Build Now from the project summary page will not trigger this build. However. and that it is not the default build definition. The meaning of this system property will be explained shortly. on the business hours schedule. 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. You can see also that the schedule is set to use the site generation schedule created earlier. The Add Build Definition screen is shown in figure 7-5. which will be visible from http://localhost:8081/sites/proficio/. you can add the test. which is essential for all builds to ensure they don't block for user input. The site will be deployed to the file system location you specified in the POM. However. so that if the build fails because of a failed check. the generated site can be used as reference for what caused the failure. and view the generated site from http://localhost:8081/sites/proficio/. when you first set up the Subversion repository earlier in this chapter. It is rare that the site build will fail. if you want to fail the build based on these checks as well. click the Add button below the default build definition. which sets the given system property.
<activeProfile>ciProfile</activeProfile> </activeProfiles> .xml file in your Subversion checkout to that used in Chapter 6.. If you haven't previously encountered profiles.m2/settings. please refer to Chapter 3.. if you run mvn -DenableCiProfile=true verify. In Chapter 6.xml file in <maven home>/conf/settings. it reads the ${user. If you compare the example proficio/pom. The first is to adjust the default build definition for each module. they will be. To enable this profile by default from these settings.. As you saw before. which can be a discouragement to using them. However..Team Collaboration with Maven In the previous example. for all projects in Continuum. As Maven 2 is still executed as normal. these checks delayed the build for all developers..plugins</groupId> <artifactId>maven-pmd-plugin</artifactId> <executions> . a number of plugins were set up to fail the build if certain project health checks failed. the profile is enabled only when the enableCiProfile system property is set to true. none of the checks added in the previous chapter are executed.. a system property called enableCiProfile was set to true.. you'll see that these checks have now been moved to a profile. <activeProfiles> . at least in the version of Continuum current at the time of writing. . such as the percentage of code covered in the unit tests dropping below a certain value. There are two ways to ensure that all of the builds added in Continuum use this profile. Better Builds With Maven 213 . as well as the settings in the Maven installation.. by going to the module information page.. it is necessary to do this for each module individually. Profiles are a means for selectively enabling portions of the build.apache. However.maven. You'll find that when you run the build from the command line (as was done in Continuum originally).xml file for the user under which it is running.home}/.xml: . The other alternative is to set this profile globally. In this particular case. 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. add the following configuration to the settings..
3.xml: Better Builds With Maven 214 . it may be necessary to schedule them separately for each module. 7. In Maven. For example. The guidelines discussed in this chapter will help point your team in the right direction. but the timing and configuration can be changed depending upon your circumstances. as discussed previously. which can be error-prone. Considering that example. So far in this book. which are not changed. the build involves checking out all of the dependent projects and building them yourself. The generated artifacts of the snapshot are stored in the local repository. the verify goal may need to be added to the site deployment build definition. such as the internal repository set up in section 7. Instead. in an environment where a number of modules are undergoing concurrent development. using binary snapshots that have been built and tested already. in some cases. and how to enable this within your continuous integration environment. Projects in Maven stay in the snapshot state until they are released. While building all of the modules from source can work well and is handled by Maven inherently.8 of this chapter. you will learn about using snapshots more effectively in a team environment. which is discussed in section 7. these artifacts will be updated frequently. it can lead to a number of problems: • • • • It relies on manual updates from developers. and in contrast to regular dependencies. this is achieved by regularly deploying snapshots to a shared repository. if the additional checks take too much time for frequent continuous integration builds.6. Additionally. Team Dependency Management Using Snapshots Chapter 3 of this book discussed how to manage your dependencies in a multi-module build. you must build all of the modules simultaneously from a master build. the team dynamic makes it critical. In this section. 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. is preferred. 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. building from source doesn't fit well with an environment that promotes continuous integration. rather than the property used to enable it. Snapshots were designed to be used in a team environment as a means for sharing development versions of artifacts that have already been built.Team Collaboration with Maven In this case the identifier of the profile itself. snapshots have been used to refer to the development version of an individual module. indicates that the profile is always active when these settings are read. Usually. where projects are closely related. you'll see that the repository was defined in proficio/pom. and while dependency management is fundamental to any Maven build.
Team Collaboration with Maven . </distributionManagement> Now. similar to the example below (note that this output has been abbreviated): .131114-1.. Better Builds With Maven 215 . the time stamp would change and the build number would increment to 2. build proficio-core with the following command: C:\mvnbook\proficio\proficio-core> mvn -U install During the build. <distributionManagement> <repository> <id>internal</id> <url>file://localhost/c:/mvnbook/repository/internal</url> </repository> .131114-1. proficio-api:1.. <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> </repository> </repositories> . the version used is the time that it was deployed (in the UTC timezone) and the build number. If you were to deploy again.. This technique allows you to continue using the latest version by declaring a dependency on 1.. To add the internal repository to the list of repositories used by Proficio regardless of settings.xml: ... or to lock down a stable version by declaring the dependency version to be the specific equivalent such as 1. you may also want to add this as a pluginRepository element as well.0-SNAPSHOT: checking for updates from internal . to see the updated version downloaded. Now..0SNAPSHOT. the Proficio project itself is not looking in the internal repository for dependencies. add the following to proficio/pom. The filename that is used is similar to proficio-api-1. In this case. but rather relying on the other modules to be built first.0-20060211...jar. you will see that some of the dependencies are checked for updates. 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. While this is not usually the case.0-20060211.. locking the version in this way may be important if there are recent changes to the repository that need to be ignored temporarily. though it may have been configured as part of your settings files.. Currently.. If you are developing plugins.
by default. to check for an update the first time that particular dependency is used after midnight local time. In this example. This causes many plugins to be checked for updates. and then deploy the snapshot to share with the other team members. always. deployed with uncommitted code. assuming that the other developers have remembered to follow the process. so let's go ahead and do it now. However. as well as updating any version ranges. If there is a repository configured to which to deploy them. How you implement this will depend on the continuous integration server that you use.. add the following configuration to the repository configuration you defined above in proficio/pom. this introduces a risk that the snapshot will not be deployed at all. To see this. as well.. The settings that can be used for the update policy are never. Better Builds With Maven 216 . Several of the problems mentioned earlier still exist – so at this point. you were not asked to apply this setting. You can always force the update using the -U command. but you can also change the interval by changing the repository configuration. To deploy from your server. or deployed without all the updates from the SCM. If it were omitted.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. this feature is enabled by default in a build definition. you must ensure that the distributionManagement section of the POM is correctly configured. it updates both releases and snapshots.xml: . Continuum can be configured to deploy its builds to a Maven snapshot repository automatically. and interval:minutes. This is because the default policy is to update snapshots daily – that is. no update would be performed. all that is being saved is some time. However. without having to manually intervene. A much better way to use snapshots is to automate their creation. In section 6. However. it makes sense to have it build snapshots.. making it out-of-date. daily (the default)..5 of this chapter. and without slowing down the build by checking on every access (as would be the case if the policy were set to always). Log in as an administrator and go to the following Configuration screen. Since the continuous integration server regularly rebuilds the code from a known state. <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> . Whenever you use the -U argument. shown in figure 7-6. This technique can ensure that developers get regular updates. <repository> . It is possible to establish a policy where developers do an update from the source control management (SCM) system before committing. the updates will still occur only as frequently as new versions are deployed to the repository. as you saw earlier.. any snapshot dependencies will be checked once an hour to determine if there are updates in the remote repository..
This relies on your internal repository and Continuum server being in the same location. To try this feature. Once the build completes.Team Collaboration with Maven Figure 7-6: Continuum configuration In Deployment Repository field. Better Builds With Maven 217 . or build from source. 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. Better yet. with an updated time stamp and build number. you can either lock a dependency to a particular build. but still keep a full archive of releases. If this is not the case. With this setup. you can avoid all of the problems discussed previously. you can enter a full repository URL such as scp://repositoryhost/www/repository/internal. while you get regular updates from published binary dependencies. when necessary. follow the Show Projects link. and click Build Now on the Proficio API project. This can be useful if you need to clean up snapshots on a regular interval. 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.
.. you can make the snapshot update process more efficient by not checking the repository that has only releases for updates. when it doesn't.. this separation is achieved by adding an additional repository to the distributionManagement section of your POM.snapshots</id> <url>file://localhost/www/repository/snapshots</url> </snapshotRepository> </distributionManagement> ... <snapshotRepository> <id>internal. Given this configuration. The replacement repository declarations in your POM would look like this: .. <distributionManagement> .Team Collaboration with Maven If you are using the regular deployment mechanism (instead of using Continuum).. <repositories> <repository> <id>internal</id> <url>http://localhost:8081/internal</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> <repository> <id>internal. you would add the following: .snapshots</id> <url>http://localhost:8081/snapshots</url> <snapshots> <updatePolicy>interval:60</updatePolicy> </snapshots> </repository> </repositories> . if you had a snapshot-only repository in /www/repository/snapshots. Better Builds With Maven 218 .. This will deploy to that repository whenever the version contains SNAPSHOT... and deploy to the regular repository you listed earlier. For example.
mergere. As you saw in this chapter. While this is convenient. To get started with the archetype. and the other. Creating a Standard Project Archetype Throughout this book. you have seen the archetypes that were introduced in Chapter 2 used to quickly lay down a project structure. either in adding or removing content from that generated by the archetypes. Figure 7-7: Archetype directory layout Better Builds With Maven 219 . there is always some additional configuration required. Writing an archetype is quite like writing your own project. run the following command: C:\mvnbook\proficio> mvn archetype:create \ -DgroupId=com. you can create one or more of your own archetypes. To avoid this. 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. Beyond the convenience of laying out a project structure instantly. and replacing the specific values with parameters. by hand.Team Collaboration with Maven 7.7.mvnbook \ -DartifactId=proficio-archetype \ -DarchetypeArtifactId=maven-archetype-archetype The layout of the resulting archetype is shown in figure 7-7. the requirement of achieving consistency is a key issue facing teams. using an archetype. in a way that is consistent with other projects in your environment.
0</modelVersion> <groupId>$groupId</groupId> <artifactId>$artifactId</artifactId> <version>$version</version> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. For this example.apache.1</version> <scope>test</scope> </dependency> </dependencies> </project> As you can see.8. The archetype descriptor describes how to construct a new project from the archetype-resources provided. but it is also possible to specify files for resources.xml at the top level.Team Collaboration with Maven If you look at pom.xsd"> <modelVersion>4. so everything else is contained under src/main/resources.0. There are two pieces of information required: the archetype descriptor in META-INF/maven/archetype.org/POM/4. These files will be used to generate the template files when the archetype is run.w3. you'll see that the archetype is just a normal JAR project – there is no special build configuration required.0 http://maven. and siteResources. The example descriptor looks like the following: <archetype> <id>proficio-archetype</id> <sources> <source>src/main/java/App. The JAR that is built is composed only of resources. testResources. you need to populate the template with the content that you'd like to have applied consistently to new projects. From here.org/POM/4.apache. the groupId.0.0" xmlns:xsi="http://www. The example above shows the sources and test sources.java</source> </testSources> </archetype> Each tag is a list of files to process and generate in the created project.xml file looks like the following: <project xmlns="http://maven.java</source> </sources> <testSources> <source>src/test/java/AppTest.org/maven-v4_0_0. artifactId and version elements are variables that will be substituted with the values provided by the developer running archetype:create. For more information on creating an archetype.0.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven. the pom.xml.apache. and the template project in archetype-resources. The files within the archetype-resources section are Velocity templates. Better Builds With Maven 220 . refer to the documentation on the Maven web site.
Maven will build. once a release has been made. However. it happens at the end of a long period of development when all everyone on the team wants to do is get it out there. Better Builds With Maven 221 . Worse. and creating tags (or equivalent for your SCM). Releasing a project is explained in section 7.mvnbook \ -DartifactId=proficio-example \ -DarchetypeGroupId=com. if omitted. The perform step could potentially be run multiple times to rebuild a release from a clean checkout of the tagged version. To do so. Maven provides a release plugin that provides the basic functions of a standard release process. updating the source control management system to check and commit release related changes. and does all of the project and source control manipulation that results in a tagged version.mergere. the content of the files will be populated with the values that you provided on the command line. such as deployment to the remote repository.9 of this chapter. and to perform standard tasks. now however. it is usually difficult or impossible to correct mistakes other than to make another. Continuing from the example in section 7. new release. Cutting a Release Releasing software is difficult. allowing them to be highly automated. The release plugin takes care of a number of manual steps in updating the project POM. 7.mergere. Finally. install and deploy it like any other JAR. since the archetype has not yet been released. releases should be consistent every time they are built.Team Collaboration with Maven Once you have completed the content in the archetype. so you can run the following command: C:\mvnbook\proficio\proficio-archetype> mvn deploy The archetype is now ready to be used. the required version would not be known (or if this was later development. The prepare step is run once for a release. Once the definition for a release has been set by a team.3 of this chapter. full of manual steps that need to be completed in a particular order. The release plugin operates in two steps: prepare and perform. It will look very similar to the content of the archetype-resources directory you created earlier. the archetypeVersion argument is not required at this point.0-SNAPSHOT Normally. you will use the "internal" repository. it has the correct deployment settings already.mvnbook \ -DarchetypeArtifactId=proficio-archetype \ -DarchetypeVersion=1. It is usually tedious and error prone. which often leads to omissions or short cuts. go to an empty directory and run the following command: C:\mvnbook> mvn archetype:create -DgroupId=com. a previous release would be used instead).8. You now have the template project laid out in the proficio-example directory. Since the archetype inherits the Proficio parent.
2. even if the plugin is not declared in the POM. To review the steps taken in this release process: Check for correct version of the plugin and POM (for example. the Proficio example will be revisited. or obtained from the development repository of the Maven project) that is implied through the build life cycle. Modify all POM files in the build. and released as 1. This is because the prepare step is attempting to guarantee that the build will be reproducible in the future. you may encounter a plugin snapshot. other modules). As the command runs. 7. You can continue using the code that you have been working on in the previous sections. The prepare step ensures that there are no snapshots in the build. you will be prompted for values. or part of the project. as they will be committed to the tag Run mvn clean integration-test to verify that the project will successfully build Describe other preparation goals (none are configured by default. This is because you are using a locally installed snapshot of a plugin (either built yourself. 4. However. and setting the version to the latest release (But only after verifying that your project builds correctly with that version!).Team Collaboration with Maven To demonstrate how the release plugin works. not ready to be used as a part of a release. In this project. Describe the SCM commit and tag operations 9. 5. if you are using a dependency that is a snapshot. other than those that will be released as part of the process (that is. Better Builds With Maven 222 . 3. 6. In some cases. or creating and committing an announcement file) 8.0. an error will appear. Accept the defaults in this instance (note that running Maven in "batch mode" avoids these prompts and will accept all of the defaults). run the following command: c:\mvnbook\proficio> mvn release:prepare -DdryRun=true This simulates a normal release preparation. as they will be committed for the next development iteration 10. and snapshots are a transient 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. This can be corrected by adding the plugin definition to your POM. without making any modifications to your project. all of the dependencies being used are releases. 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. You'll notice that each of the modules in the project is considered. Describe the SCM commit operation 1. but this might include updating the metadata in your issue tracker.
recall that in section 7. In this POM. For that reason. this file will be release-pom. However.tag file written out to each module directory.. or that different profiles will be applied.apache. when a build is run from this tag to ensure it matches the same circumstances as the release build.next respectively in each module directory. any active profiles are explicitly activated..xml. When the final run is executed. To include these checks as part of the release process. a number of changes are made: • • • the explicit version of plugins and dependencies that were used are added any settings from settings..5.xml You may have expected that inheritance would have been resolved by incorporating any parent elements that are used. there is also a release-pom. including profiles from settings.xml.xml. Also. or that expressions would have been resolved. and is set based on the values for which you were prompted during the release process.. 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.xml and profiles. To do so.] <plugin> <groupId>org.tag and pom. Having run through this process you may have noticed that only the unit and integration tests were run as part of the test build.plugins</groupId> <artifactId>maven-release-plugin</artifactId> <configuration> <prepareVerifyArgs>-DenableCiProfile=true</prepareVerifyArgs> </configuration> </plugin> [. This is not the case however.xml. these changes are not enough to guarantee a reproducible build – it is still possible that the plugin versions will vary. to verify they are correct.xml (both per-user and per-installation) are incorporated into the POM. that resulting version ranges will be different.xml in the same directory as pom. use the following plugin configuration: [. This is used by Maven.] Better Builds With Maven 223 . instead of the normal POM. This contains a resolved version of the POM that Maven will use to build from if it exists. you created a profile to enable those checks conditionally.maven. The SCM information is also updated in the tag POM to reflect where it will reside once it is tagged. and this is reverted in the next POM. you need to enable this profile during the verification step.Team Collaboration with Maven You might like to review the POM files that are created for steps 4 and 6. You'll notice that the version is updated in both of these files. named pom. as these can be established from the other settings already populated in the POM in a reproducible fashion.
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:
Better Builds With Maven 225
Team Collaboration with Maven
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
For Spring.).5 compatible source code and JUnit Better Builds With Maven 229 . Optional dependencies are indicated by dotted lines. etc. resulting in JARs that contain both 1.4 compatible source code and JUnit tests respectively tiger/src and tiger/test: contain additional JDK 1. using inclusions and exclusions that are based on the Java packages of each class.4 and 1. properties files. the Ant script compiles each of these different source directories and then creates a JAR for each module.Migrating to Maven Figure 8-1: Dependency relationship between Spring modules In figure 8-1. These modules are built with an Ant script from the following source directories: • • tests • mock: contains the source code for the spring-mock module • aspectj/src and aspectj/test: contain the source code for the spring-aspects module Each of the source directories also include classpath resources (XML files. you can see graphically the dependencies between the modules. src and test: contain JDK 1. and each produces a JAR. TLD files. Each of these modules corresponds.5 classes. The src and tiger/src directories are compiled to the same destination as the test and tiger/test directories. more or less. with the Java package structure.
you will create a subdirectory called 'm2' to keep all the necessary Maven changes clearly separated from the current build system.Migrating to Maven 8. Inside the 'm2' directory. that means you will need to have a Maven project (a POM) for each of the modules listed above. the rule of thumb to use is to produce one artifact (JAR. you will need to create a directory for each of Spring's modules.2.) per Maven project file. To start. etc. WAR. In the Spring example. Where to Begin? With Maven. Figure 8-2: A sample spring module directory Better Builds With Maven 230 .
springframework • artifactId: the setting specifies the name of this module (for example. each module will inherit the following values (settings) from the parent POM.m2book..org</url> <organization> <name>The Spring Framework Project</name> </organization> groupId: this setting indicates your area of influence. company. • packaging: the jar. For example. project.8. For this example. you will need to create a parent POM. Recall from previous chapters that during the release process. 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. primary used for documentation purposes.springframework. which will be used for testing in every module.0-m1-SNAPSHOT</version> <name>Spring parent</name> <packaging>pom</packaging> <description>Spring Framework</description> <inceptionYear>2002</inceptionYear> <url>http://www.Migrating to Maven In the m2 directory. thereby eliminating the requirement to specify the dependency repeatedly across multiple modules. and In this parent POM we can also add dependencies such as JUnit. in order to tag the release in your SCM.1</version> <scope>test</scope> </dependency> </dependencies> As explained previously. non-snapshot version for a short period of time. the version you are developing in order to release.migrating. You will use the parent POM to store the common configuration settings that apply to all of the modules. department. war. <groupId>com. Let's begin with these directories. spring-parent) • version: this setting should always represent the next release version number appended with . respectively. in Spring. the Spring team would use org.mergere.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2. Maven will convert to the definitive. Better Builds With Maven 231 . etc. <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3. • it should mimic standard package naming conventions to avoid duplicate values. however.mergere.SNAPSHOT – that is. as it is our 'unofficial' example version of Spring. the main source and test directories are src and test. you will use com.m2book.
For now. you can retrieve some of the configuration parameters for the compiler.3</source> <target>1.3" debug="${debug}" deprecation="false" optimize="false" failonerror="true"> <src path="${src.. deprecation and optimize (false).plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1. and failonerror (true) values. To specify the required debug function in Maven.debug=false to the mvn command (by default this is set to true)./src</sourceDirectory> <testSourceDirectory>.maven. in the buildmain target..3</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 232 .classes. At this point.src}"/> <classpath refid="all-libs"/> </javac> As you can see these include the source and target compatibility (1.3" target="1./.Include Commons Attributes generated Java sources --> <src path="${commons.dir}"/> <!-.. <javac destdir="${target. your build section will look like this: <build> <sourceDirectory>. These last three properties use Maven's default values.attributes. Recall from Chapter 2. so there is no need for you to add the configuration parameters. as you will learn about that later in this chapter. For the debug attribute.compiler.dir}" source="1.. you will need to append -Dmaven. Spring's Ant script uses a parameter.Migrating to Maven Using the following code snippet from Spring's Ant build script.3)./test</testSourceDirectory> <plugins> <plugin> <groupId>org. that Maven automatically manages the classpath from its list of dependencies. you don't have to worry about the commons-attributes generated sources mentioned in the snippet.apache.tempdir./.
includes and test.testclasses.dir}"/> <classpath location="${target. by default.mockclasses. • Better Builds With Maven 233 . You will not need any printsummary.classes. The nested element jvmarg is mapped to the configuration parameter argLine As previously noted. You will need to specify the value of the properties test.Need files loaded as resources --> <classpath location="${test. Maven uses the default value from the compiler plugin.Must go first to ensure any jndi.headless=true -XX:MaxPermSize=128m -Xmx128m"/> <!-.properties files etc take precedence --> <classpath location="${target. From the tests target in the Ant script: <junit forkmode="perBatch" printsummary="yes" haltonfailure="yes" haltonerror="yes"> <jvmarg line="-Djava. classpath is automatically managed by Maven from the list of dependencies. since the concept of a batch for testing does not exist.dir}"> <fileset dir="${target.excludes from the nested fileset. by default.Migrating to Maven The other configuration that will be shared is related to the JUnit tests. haltonfailure and haltonerror settings.dir}"/> <classpath refid="all-libs"/> <formatter type="plain" usefile="false"/> <formatter type="xml"/> <batchtest fork="yes" todir="${reports. and this doesn't need to be changed.properties file loaded from the Ant script (refer to the code snippet below for details).awt. formatter elements are not required as Maven generates both plain text and xml reports.includes}" excludes="${test.dir}" includes="${test. so you will not need to locate the test classes directory (dir). Maven sets the reports destination directory (todir) to target/surefire-reports. as Maven prints the test summary and stops for any test error or failure.excludes}"/> </batchtest> </junit> You can extract some configuration information from the previous code: • • • • • • • forkMode="perBatch" matches with Maven's forkMode parameter with a value of once.dir}"/> <classpath location="${target.testclasses.dir}"/> <!-. this value is read from the project.
1 # being compiled with target JDK 1. Spring's Ant build script also makes use of the commons-attributes compiler in its compileattr and compiletestattr targets. 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. mandatory when building in 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.excludes=**/Abstract* org/springframework/orm/hibernate3/** The includes and excludes referenced above.4. It makes tests run using the standard classloader delegation instead of the default Maven isolated classloader. translate directly into the include/exclude elements of the POM's plugin configuration. test.headless=true -XX:MaxPermSize=128m -Xmx128m </argLine> <includes> <include>**/*Tests.awt.maven. When building only on Java 5 you could remove that option and the XML parser (Xerces) and APIs (xml-apis) dependencies.3.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <forkMode>once</forkMode> <childDelegation>false</childDelegation> <argLine> -Djava. due to Hibernate 3.excludes=**/Abstract* #test.Migrating to Maven # Wildcards to be matched by JUnit tests. which are processed prior to the compilation.and generates sources from them that have to be compiled with the normal Java compiler.4 to run you do not need to exclude hibernate3 tests.5 . Better Builds With Maven 234 .apache.class # # Wildcards to exclude among JUnit tests. # Second exclude needs to be used for JDK 1.includes=**/*Tests. Since Maven requires JDK 1. # Convention is that our JUnit test classes have XXXTests-style names. The commons-attributes compiler processes javadoc style annotations – it was created before Java supported annotations in the core language on JDK 1.4. <plugin> <groupId>org. test.
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.mojo</groupId> <artifactId>commons-attributes-maven-plugin</artifactId> <executions> <execution> <configuration> <includes> <include>**/metadata/*. --> <attribute-compiler destdir="${commons.tempdir. to support indexing.dir}" includes="**/metadata/*.servlet.handler.src}"> <!-Only the PathMap attribute in the org.web. Better Builds With Maven 235 .attributes.tempdir.codehaus. --> <fileset dir="${src.Compile to a temp directory: Commons Attributes will place Java Source here.dir}" includes="org/springframework/aop/**/*.attributes.springframework.java</include> </includes> <testIncludes> <include>org/springframework/aop/**/*.test}"> <fileset dir="${test. this same function can be accomplished by adding the commons-attributes plugin to the build section in the POM.java"/> <fileset dir="${test.Migrating to Maven From compileattr: <!-. so you will only need to add the inclusions for the main source and test source compilation.metadata package currently needs to be shipped with an attribute. --> <attribute-compiler destdir="${commons.java"/> </attribute-compiler> In Maven. Maven handles the source and destination directories automatically.dir}" includes="org/springframework/jmx/**/*. <plugin> <groupId>org.java"/> </attribute-compiler> From compiletestattr: <!-.Compile to a temp directory: Commons Attributes will place Java Source here.java</include> <include>org/springframework/jmx/**/*.
As you saw before.migrating</groupId> <artifactId>spring-parent</artifactId> <version>2. since the sources and resources are in the same directory in the current Spring build. you will start to compile the main Spring source. etc. 8. you will need to exclude the *. which centralizes and maintains information common to the project. as those values are inherited from parent POM. where spring-core JAR is created: <jar jarfile="${dist. However.java files from the resources. This module is the best to begin with because all of the other modules depend on it. and organization name to the values in the POM. In each subdirectory. Better Builds With Maven 236 . Creating POM files Now that you have the basic configuration shared by all modules (project information.jar"> <fileset dir="${target.dir}"> <include name="org/springframework/core/**"/> <include name="org/springframework/util/**"/> </fileset> <manifest> <attribute name="Implementation-Title" value="${spring-title}"/> <attribute name="Implementation-Version" value="${spring-version}"/> <attribute name="Spring-Version" value="${spring-version}"/> </manifest> </jar> From the previous code snippet. <parent> <groupId>com.mergere.m2book. you will need to add a resources element in the build section.). you can determine which classes are included in the JAR and what attributes are written into the JAR's manifest. version. you need to create the POM files for each of Spring's modules. Compiling In this section. To begin. setting the files you want to include (by default Maven will pick everything from the resource directory). For the resources. While manifest entries can also be customized with additional configuration to the JAR plugin. The following is the POM for the spring-core module.dir}/modules/spring-core. or they will get included in the JAR.0-m1-SNAPSHOT</version> </parent> <artifactId>spring-core</artifactId> <name>Spring core</name> Again. Maven will automatically set manifest attributes such as name.classes. you will need to create a POM that extends the parent POM. JUnit test configuration. you will need to tell Maven to pick the correct classes and resources from the core and util packages. tests will be dealt with later in the chapter.3. you won't need to specify the version or groupId elements of the current module. review the following code snippet from Spring's Ant script.Migrating to Maven 8. description. in this case the defaults are sufficient. compiler configuration.4.
Migrating to Maven For the classes./src</directory> <includes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*. <build> <resources> <resource> <directory>. Maven will by default compile everything from the source directory..maven.apache. because as with resources.. 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 .java</exclude> </excludes> </resource> </resources> <plugins> <plugin> <groupId>org. which is inherited from the parent POM./.
commons.ibiblio.java:[30.34] package org.apache. From the previous output.logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\. You will see a long list of compilation failures. it's usually the JAR name without a version (in this case commonslogging)..logging does not exist C:\dev\m2book\code\migrating\spring\m2\springcore\.. beginning with the following: [INFO] -----------------------------------------------------------------------[ERROR] BUILD FAILURE [INFO] -----------------------------------------------------------------------[INFO] Compilation failure C:\dev\m2book\code\migrating\spring\m2\springcore\.apache. changing dots to slashes.core.io. the convention is to use a groupId that mirrors the package name. In the case of commons-logging.24] cannot find symbol symbol : class Log location: class org.springframework. and then choose from the search results.Migrating to Maven To compile your Spring build.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver.apache...\. For example. commons-logging groupId would become org.commons.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver.\.java:[19.\. As an alternative. Regarding the artifactId. you need to check the central repository at ibiblio. the actual groupId is commons-logging. located in the org/apache/commons/logging directory in the repository.\src\org\springframework\util\xml\SimpleSaxErrorHandler. But. you can search the repository using Google.org/maven2 commons logging.support. for historical reasons some groupId values don't follow this convention and use only the name of the project.. artifactId and version should we use? For the groupId and artifactId.logging does not exist These are typical compiler messages. Specify site:www. If you check the repository.34] package org. what groupid. you now know that you need the Apache Commons Logging library (commons-logging) to be added to the dependencies section in the POM.commons. the option that is closest to what is required by your project.java:[107.logging.java:[31.. you will find all the available versions of commons-logging under http://www.org/maven2/commons-logging/commons-logging/.ibiblio. However.\src\org\springframework\core\io\support\PathMatchingResourcePatternResol ver. Better Builds With Maven 238 .commons.34] package org. Typically..apache.\.PathMatchingResourcePatternResolver C:\dev\m2book\code\migrating\spring\m2\springcore\. caused by the required classes not being on the classpath. you can now run mvn compile..
<dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. to make explicit the dependencies and interrelationships of your projects. during the process of migrating Spring to Maven. 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. although you could simply follow the same behavior used in Ant (by adding all the dependencies in the parent POM so that. When needed.org/maven2 to the query.jar.1.ibiblio.1/hibernate-3. is under development (refer to the Maven Repository Manager project for details).hibernate) An easier way to search for dependencies. we discovered that the commons-beanutils version stated in the documentation is wrong and that some required dependencies are missing from the documentation.1). with the slashes changed to dots (org. component-oriented. you could search with: site:www.0.txt in the lib directory of the Spring source.ibiblio. You can use this as a reference to determine the versions of each of the dependencies.org/maven2 78d5c38f1415efc64f7498f828d8069a • The search will return: www.ibiblio. using a web interface. for the hibernate3. modular projects that are easier to maintain in the long term. Better Builds With Maven 239 .MF • For advanced users. you have to be careful as the documentation may contain mistakes and/or inaccuracies. For instance. through inheritance.org/maven2/org/hibernate/hibernate/3.md5 You can see that the last directory is the version (3. all sub-modules would use the same dependencies).4</version> </dependency> </dependencies> Usually you will convert your own project. Doing so will result in cleaner. and then search in Google prepending site:www. While adding dependencies can be the most painful part of migrating to Maven. you will find that there is documentation for all of Spring's dependencies in readme. For example. explicit dependency management is one of the biggest benefits of Maven once you have invested the effort upfront. we strongly encourage and recommend that you invest the time at the outset of your migration. So.jar provided with Spring under lib/hibernate.Migrating to Maven With regard the version. so you will have first hand knowledge about the dependencies and versions used. search the ibiblio repository through Google by calculating the MD5 checksum of the JAR file with a program such as md5sum. the previous directory is the artifactId (hibernate) and the other directories compose the groupId.
you will need to add the log4j. Using the optional tag does not affect the current project. you may decide to use another log implementation. This is because in other projects.1.this time all of the sources for spring-core will compile. 8. In addition.java</exclude> </excludes> </testResource> </testResources> Better Builds With Maven 240 . with the exception of changing the location from which the element name and directory are pulled. <dependency> <groupId>commons-collections</groupId> <artifactId>commons-collections</artifactId> <version>3. you will repeat the previous procedure for the main classes. setting which test resources to use.9</version> <optional>true</optional> </dependency> Notice that log4j is marked as optional.properties file required for logging configuration. you will notice that you also need Apache Commons Collections (aka commons-collections) and log4j. Now. run mvn compile again . Compiling Tests Setting the test resources is identical to setting the main resources. 8. For the first step.5. we will cover how to run the tests. and it is just for the convenience of the users. and setting the JUnit test sources to compile. Testing Now you're ready to compile and run the tests.1</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1./. After compiling the tests. Optional dependencies are not included transitively..2.Migrating to Maven Running again mvn compile and repeating the process previously outlined for commons-logging.properties</include> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </includes> <excludes> <exclude>**/*./test</directory> <includes> <include>log4j.5.. so log4j will not be included in other projects that depend on this. <testResources> <testResource> <directory>.
depend on classes from spring-core. the key here is to understand that some of the test classes are not actually unit tests for springcore.springframework.java</exclude> <exclude>org/springframework/core/io/ResourceTests. <testExcludes> <exclude>org/springframework/util/comparator/ComparatorTests. if you try to compile the test classes by running mvn test-compile. spring-web and spring-beans modules.springframework. but rather require other modules to be present. if spring-core depends on spring-beans and springbeans depends on spring-core.mock.java</exclude> </testExcludes> Now.beans packages are missing. Inside the mavencompiler-plugin configuration. as this is not needed for the main sources. but if you try to compile those other modules.4</version> <scope>test</scope> </dependency> The scope is set to test.Migrating to Maven Setting the test sources for compilation follows the same procedure. as before. In other words.springframework.java</exclude> <exclude>org/springframework/util/ObjectUtilsTests. when you run mvn test-compile. If you run mvn test-compile again you will have a successful build. you will see the following error: package javax. add the testExcludes element to the compiler configuration as follows. It may appear initially that spring-core depends on spring-mock. in order to compile the tests: <dependency> <groupId>javax. we cannot add a dependency from spring-core without creating a circular dependency. org. Better Builds With Maven 241 .java</exclude> <exclude>org/springframework/util/ClassUtilsTests. but this time there is a special case where the compiler complains because some of the classes from the org.java</exclude> <exclude>org/springframework/util/ReflectionUtilsTests. it makes sense to exclude all the test classes that reference other modules from this one and include them elsewhere. as all the test classes compile correctly now. So. <testIncludes> <include>org/springframework/core/**</include> <include>org/springframework/util/**</include> </testIncludes> Now. Therefore.web and org. which one do we build first? Impossible to know. you will see that their main classes. as well. you will need to add the testIncludes element.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.servlet does not exist This means that the following dependency must be added to the POM.java</exclude> <exclude>org/springframework/util/SerializationTestUtils. you will get compilation errors. As a result. not tests. To exclude test classes in Maven.
springframework. Failures: 1. compile tests. etc.io. [INFO] ------------------------------------------------------------------------ Upon closer examination of the report output. run tests.support. you will get the following error report: Results : [surefire] Tests run: 113.PathMatchingResourcePatternResolverTests [surefire] Tests run: 5.io. To debug the problem.support. 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.5. Errors: 1.PathMatchingResourcePatternResolverT ests.core. you will find the following: [surefire] Running org.015 sec <<<<<<<< FAILURE !! This output means that this test has logged a JUnit failure and error.) Better Builds With Maven 242 . compile.txt.io.0</version> <scope>test</scope> </dependency> Now run mvn test again.2. is to run mvn install to make the resulting JAR available to other projects in your local Maven repository. simply requires running mvn test.core. The first section starts with java. Failures: 1. when you run this command.aopalliance package is inside the aopallience JAR.Migrating to Maven 8. Time elapsed: 0. Within this file. for the test class that is failing org. you will need to check the test logs under target/surefire-reports. The org. This command can be used instead most of the time. there is a section for each failed test called stacktrace. as it will process all of the previous phases of the build life cycle (generate sources. However. Errors: 1 [INFO] -----------------------------------------------------------------------[ERROR] BUILD ERROR [INFO] -----------------------------------------------------------------------[INFO] There are test failures. so to resolve the problem add the following to your POM <dependency> <groupId>aopalliance</groupId> <artifactId>aopalliance</artifactId> <version>1. Running Tests Running the tests in Maven.springframework. This indicates that there is something missing in the classpath that is required to run the tests.FileNotFoundException: class path resource [org/aopalliance/] cannot be resolved to URL because it does not exist.
If you follow the order of the modules described at the beginning of the chapter you will be fine. Avoiding Duplication As soon as you begin migrating the second module. each of the modules will be able to inherit the required Surefire configuration. otherwise you will find that the main classes from some of the modules reference classes from modules that have not yet been built. move these configuration settings to the parent POM instead. you can refer to spring-core from spring-beans with the following.version}</version> </dependency> Better Builds With Maven 243 . you will find that you are repeating yourself. Other Modules Now that you have one module working it is time to move on to the other modules.6.6. In the same way. To avoid duplication.1.0. since they have the same groupId and version: <dependency> <groupId>${project. 8.groupId}: groupId of the current POM being built For example. and remove the versions from the individual modules (see Chapter 3 for more information). See figure 8-1 to get the overall picture of the interdependencies between the Spring modules. instead of repeatedly adding the same dependency version information to each module.groupId}</groupId> <artifactId>spring-core</artifactId> <version>${project. Using the parent POM to centralize this information makes it possible to upgrade a dependency version across all sub-projects from a single location. you will be adding the Surefire plugin configuration settings repeatedly for each module that you convert.4</version> </dependency> </dependencyManagement> The following are some variables that may also be helpful to reduce duplication: • • ${project. use the parent POM's dependencyManagement section to specify this information once.version}: version of the current POM being built ${project. <dependencyManagement> <dependencies> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1. That way.Migrating to Maven 8. For instance.
users will know that if they depend on the module composed of Java 5 classes. by specifying the test-jar type. you will need to create a new spring-beans-tiger module. To eliminate this problem. you can split Spring's mock classes into spring-context-mock.6. Generally with Maven.groupId}</groupId> <artifactId>spring-beans</artifactId> <version>${project.3 or 1. that a JAR that contains the test classes is also installed in the repository: <plugin> <groupId>org. there is a procedure you can use.5 sources be added? To do this with Maven.3 and some compiled for Java 5 in the same JAR.3. you can use it as a dependency for other components.3 compatibility. Although it is typically not recommended.Migrating to Maven 8. 8.maven.2. any users. this can cause previously-described cyclic dependencies problem. Better Builds With Maven 244 . Referring to Test Classes from Other Modules If you have tests from one component that refer to tests from other modules. with only those classes related to spring-context module. how can the Java 1. it's easier to deal with small modules.apache. However. be sure to put that JAR in the test scope as follows: <dependency> <groupId>${project. Building Java 5 Classes Some of Spring's modules include Java 5 classes from the tiger folder.6. By splitting them into different modules. would experience runtime errors. they will need to run them under Java 5.4. First. Consider that if you include some classes compiled for Java 1. with only those classes related to spring-web. So. As the compiler plugin was earlier configured to compile with Java 1. in this case it is necessary to avoid refactoring the test source code. and spring-web-mock. make sure that when you run mvn install. attempting to use one of the Java 5 classes under Java 1.version}</version> <type>test-jar</type> <scope>test</scope> </dependency> A final note on referring to test classes from other modules: if you have all of Spring's mock classes inside the same module. you 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.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <executions> <execution> <goals> <goal>test-jar</goal> </goals> </execution> </executions> </plugin> Once that JAR is installed. particularly in light of transitive dependencies.
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. 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 . the Java 5 modules will share a common configuration for the compiler.
with all modules In the tiger POM.. as well as build sections with source folders and compiler options: <modules> <module>spring-beans-tiger</module> <module>spring-aop-tiger</module> <module>spring-dao-tiger</module> <module>spring-jdbc-tiger</module> <module>spring-support-tiger</module> <module>spring-hibernate3-tiger</module> <module>spring-aspects</module> </modules> <build> <sourceDirectory>./..plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1./. you will need to add a module entry for each of the directories.maven..../tiger/src</sourceDirectory> <testSourceDirectory>.apache.5</source> <target>1.Migrating to Maven Figure 8-5: Dependency relationship././.5</target> </configuration> </plugin> </plugins> </build> Better Builds With Maven 246 ../tiger/test</testSourceDirectory> <plugins> <plugin> <groupId>org.
<profiles> <profile> <id>jdk1. Using Ant Tasks From Inside Maven In certain migration cases. you need to use the Ant task in the spring-remoting module to use the RMI compiler.5</id> <activation> <jdk>1.5 JDK. In this case.springframework.dir}" classname="org.Migrating to Maven In the parent POM.springframework.rmi.remoting.6. but to still be able to build the other modules when using Java 1. For example. you just need a new module entry for the tiger folder. From Ant.classes.RmiInvocationWrapper"/> <rmic base="${target. Maven can call Ant tasks directly from a POM using the maven-antrun-plugin. this is: <rmic base="${target.remoting. you may find that Maven does not have a plugin for a particular task or an Ant target is so small that it may not be worth creating a new plugin. with the Spring migration.4.classes.5</jdk> </activation> <modules> <module>tiger</module> </modules> </profile> </profiles> 8.RmiInvocationWrapper" iiop="true"> <classpath refid="all-libs"/> </rmic> Better Builds With Maven 247 .4 you will add that module in a profile that will be triggered only when using 1.rmi.dir}" classname="org.
springframework.RmiInvocationWrapper"/> <rmic base="${project.directory} and maven.compile.classpath. In this case.RmiInvocationWrapper" iiop="true"> <classpath refid="maven.home}/. such as ${project.rmi.build. which is bundled with the JDK.springframework. which is a classpath reference constructed from all of the dependencies in the compile scope or lower.jar</systemPath> </dependency> </dependencies> </plugin> As shown in the code snippet above. will take the compiled classes and generate the rmi skeleton.apache. There are also references for anything that was added to the plugin's dependencies section./lib/tools.directory}/classes" classname="org.build.build. stub and tie classes from them. So. Better Builds With Maven 248 .classpath"/> </rmic> </tasks> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> <dependencies> <dependency> <groupId>com.compile. such as the reference to the tools. the rmic task.sun</groupId> <artifactId>tools</artifactId> <scope>system</scope> <version>1.rmi. there are some references available already.maven. add: <plugin> <groupId>org.jar above.remoting. the most appropriate phase in which to run this Ant task is in the processclasses phase.4</version> <systemPath>${java.remoting.directory}/classes" classname="org.Migrating to Maven To include this in Maven build. and required by the RMI task..plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <executions> <execution> <phase>process-classes</phase> <configuration> <tasks> <echo>Running rmic</echo> <rmic base="${project. To complete the configuration. you will need to determine when Maven should run the Ant task. which applies to that plugin only.
such as spring-aspects. These issues were shared with the Spring developer community and are listed below: • • Moving one test class. Some Special Cases In addition to the procedures outlined previously for migrating Spring to Maven. NamespaceHandlerUtilsTests. special cases that must be handled. 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. For example. there are two additional. mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging> For instance. as these test cases will not work in both Maven and Ant. Sun's Activation Framework and JavaMail are not redistributable from the repository due to constraints in their licenses.Migrating to Maven 8. 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. Using classpath resources is recommended over using file system resources. These can be viewed in the example code.apache. see http://maven.mail -DartifactId=mail -Dversion=1. 8. For more information on dealing with this issue. to install JavaMail: mvn install:install-file -Dfile=mail. There is some additional configuration required for some modules. Better Builds With Maven 249 .jar -DgroupId=javax. which uses AspectJ for weaving the classes. from test directory to tiger/test directory – as it depends on a tiger class Fixing toplink tests that don't compile against the oracle toplink jar (Spring developers use a different version than the official one from Oracle) In this example it is necessary to comment out two unit tests.6. You can then install them in your local repository with the following command.6.org/guides/mini/guide-coping-with-sun-jars.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.5.6. which used relative paths in Log4JConfigurerTests class.3.html.
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
compiling source code. addPluginArtifact Metadata updateRegistry maven-plugin-plugin Integrate current plugin information with plugin search metadata. maven-plugin artifacts are in fact jar files. to install reflect the new plugin installed in the local repository. testing. to extract and format the metadata for the mojos within. 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. Better Builds With Maven 255 . packaging. the maven-plugin packaging also introduces a few new mojo bindings. and metadata references to latest plugin version. Indeed. However. if one exists. maven-plugin-plugin Update the plugin registry. As such. for example).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. they undergo the same basic processes of marshaling non-source-code resources. and generate a plugin descriptor. and the rest.
Appendix A: Resources for Plugin Developers A. along with a summary of the default bindings. Default life-cycle bindings Below are the clean life-cycle bindings for the jar packaging.2. Below is a listing of the phases in the clean life cycle. Maven provides a set of default mojo bindings for this life cycle. clean – remove all files that were generated during another build process 3. along with any additional directories configured in the POM.1. effective for all POM packagings. you will find a short description of what that mojo does. which perform the most common tasks involved in cleaning a project. Alongside each. the state of the project before it was built. post-clean – finalize the cleaning process. Better Builds With Maven 256 . 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. pre-clean – execute any setup or initialization procedures to prepare the project for cleaning 2. Life-cycle phases The clean life-cycle phase contains the following phases: 1. The clean Life Cycle This life cycle is executed in order to restore a project back to some baseline state – usually.
site – run all associated project reports. site-deploy deploy Better Builds With Maven 257 . The site Life Cycle This life cycle is executed in order to generate a web site for your project. along with a summary of the default bindings.1. and even deploy the resulting web site to your server. post-site – execute any actions required to finalize the site generation process. you will find a short description of what that mojo does.3. 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. Maven provides a set of default mojo bindings for this life cycle. Default Life Cycle Bindings Below are the site life-cycle bindings for the jar packaging. 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. It will run any reports that are associated with your project. site-deploy – use the distributionManagement configuration in the project's POM to deploy the generated web site files to the web server. and render documentation into HTML 3. Deploy the generated web site to the web server path specified in the POM distribution Management section. Life-cycle phases The site life cycle contains the following phases: 1. Below is a listing of the phases in the site life cycle. which perform the most common tasks involved in generating the web site for a project. and render documentation source files into HTML.Appendix A: Resources for Plugin Developers A. effective for all POM packagings. Alongside each. render your documentation source files into HTML.
maven. This contains avenSession methods for accessing information about how Maven was called.util.ma List of reports to be generated when the site ven.List<org.Appendix A: Resources for Plugin Developers A.project.apache.apache. which act as a shorthand for referencing commonly used build state objects. Mojo Parameter Expressions Mojo parameter values are resolved by way of parameter expressions when a mojo is initialized. and extract only the information it requires.M The current build session. It will summarize the root objects of the build state which are available for mojo expressions.project. in addition to providing a mechanism for looking up Maven components on-demand.apache. java.apache. mojo developers should have everything they need to extract the build state they require.MavenReport> life cycle executes. They are summarized below: Table A-5: Primitive expressions supported by Maven's plugin parameter Expression Type Description ${localRepository} ${session} org.execution. org. Simple Expressions Maven's plugin parameter injector supports several primitive expressions.Mav This is a cloned instance of the project enProject instance currently being built. This reduces the complexity of the code contained in the mojo.maven.artifact.List<org. Using the discussion below.re This is a reference to the local repository pository.reporting. it will describe the algorithm used to resolve complex parameter expressions.2. along with the published Maven API documentation. Better Builds With Maven 258 . and often eliminates dependencies on Maven itself beyond the plugin API. ${reactorProjects} ${reports} ${executedProject} java.ma List of project instances which will be ven. It is used for bridging results from forked life cycles back to the main line of execution.ArtifactRepository used to cache artifacts during a Maven build. A.1. org.maven.MavenProject> processed as part of the current build.apache. These expressions allow a mojo to traverse complex build state.2. This section discusses the expression language used by Maven to inject build state and plugin configuration into mojos.util. Finally.
Better Builds With Maven 259 . Maven supports more complex expressions that traverse the object graph starting at some root object that contains build state.settings. The valid root objects for plugin parameter expressions are summarized below: Table A-6: A summary of the valid root objects for plugin parameter expressions Expression Root Type Description ${basedir} ${project} ${settings} java.Maven Project instance which is currently being built.Appendix A: Resources for Plugin Developers A.apache.PluginDescriptor including its dependency artifacts. Project org.project.File The current project's root directory. ${plugin} org.2.descri The descriptor instance for the current plugin.xml in the user's home directory.apache. merged from ings conf/settings. org.2.xml in the maven application directory and from .plugin. Complex Expression Roots In addition to the simple expressions above. ptor.m2/settings. unless specified otherwise.maven.apache.maven.maven.io.Sett The Maven settings.
The description element of the plugin's POM. The resulting value then becomes the new 'root' object for the next round of traversal. If the value is still empty. the next expression part is used as a basis for reflectively traversing that object' state. it will be resolved as the parameter value at this point.and Ant-specific mojo source files. if there is one. if the expression matches one of the primitive expressions (mentioned above) exactly. This includes properties specified on the command line using the -D commandline option. Otherwise. No advanced navigation can take place using is such expressions. During this process. an ancestor POM. and must correspond to one of the roots mentioned above.2. then the value mapped to that expression is returned. The Expression Resolution Algorithm Plugin parameter expressions are resolved using a straightforward algorithm. If at this point Maven still has not been able to resolve a value for the parameter expression. Its syntax has been annotated to provide descriptions of the elements. or an active profile. First. the expression is split at each '. The POM properties. much like a primitive expression would. array index references. rendering an array of navigational directions. the value that was resolved last will be returned as the expression's value. If the parameter is still empty after these two lookups. then the string literal of the expression itself is used as the resolved value. this reflective lookup process is aborted.2. Maven plugin parameter expressions do not support collection lookups. it will attempt to find a value in one of two remaining places. When there are no more expression parts. This root object is retrieved from the running application using a hard-wired mapping. If at some point the referenced object doesn't contain a property that matches the next expression part. |-> Better Builds With Maven 260 . From there. or method invocations that don't conform to standard JavaBean naming conventions.' character. If a user has specified a property mapping this expression to a specific value in the current POM. The first is the root object. Currently.Appendix A: Resources for Plugin Developers A. It includes summaries of the essential plugin descriptor. successive expression parts will extract values from deeper and deeper inside the build state.These are the identity elements (groupId/artifactId/version) | from the plugin POM. following standard JavaBeans naming conventions. Repeating this. Maven will consult the current system properties. resolved in this order: 1. an expression part named 'child' translates into a call to the getChild() method on that object. <plugin> <!-. The system properties. --> <description>Sample Maven Plugin</description> <!-. as well the metadata formats which are translated into plugin descriptors from Java. Plugin descriptor syntax The following is a sample plugin descriptor. 2. Plugin metadata Below is a review of the mechanisms used to specify metadata for plugins.
| and specifies a custom life-cycle overlay that should be added to the | cloned life cycle before the specified phase is executed. via the | command line. |-> <goalPrefix>myplugin</goalPrefix> <!-. |-> <phase>compile</phase> <!-.The name of the mojo.maven. |-> <goal>do-something</goal> <!-. | This is useful when the user will be invoking this mojo directly from | the command line.0-SNAPSHOT</version> <!-. It is a good idea to provide this.</description> <!-. but the mojo itself has certain life-cycle | prerequisites.This is a list of the mojos contained within this plugin. | this name allows the user to invoke this mojo from the command line | using 'myplugin:do-something'. | This allows the user to specify that this mojo be executed (via the | <execution> section of the plugin configuration in the POM).Description of what this mojo does. unless the user specifies | <inherit>false</inherit>. For | instance. to give users a hint | at where this task should run. --> <description>Do something cool. without | also having to specify which phase is appropriate for the mojo's | execution.Which phase of the life cycle this mojo will bind to by default.This is optionally used in conjunction with the executePhase element. |-> <executePhase>process-resources</executePhase> <!-. |-> <inheritedByDefault>true</inheritedByDefault> <!-.apache. |-> Better Builds With Maven 261 . Combined with the 'goalPrefix' element above. this plugin could be referred to from the command line using | the 'myplugin:' prefix.This tells Maven to create a clone of the current project and | life cycle. |-> <executeLifecycle>myLifecycle</executeLifecycle> <!-.Tells Maven that this mojo can ONLY be invoked directly.This element provides the shorthand reference for this plugin. --> <mojos> <mojo> <!-.Ensure that this other mojo within the same plugin executes before | this one.plugins</groupId> <artifactId>maven-myplugin-plugin</artifactId> <version>2.Tells Maven that the this plugin's configuration should be inherted from | a parent POM by default. It's restricted to this plugin to avoid creating inter-plugin | dependencies. then execute that life cycle up to the specified phase. |-> <executeGoal>do-something-first</executeGoal> <!-. This is | useful to inject specialized behavior in cases where the main life | cycle should remain unchanged.Appendix A: Resources for Plugin Developers <groupId>org.
If the mojo is not marked as an | aggregator. Better Builds With Maven 262 . it will only | execute once. | It will be used as a backup for retrieving the parameter value.maven.The parameter's name.io. This flag controls whether the mojo requires | Maven to be online.This is a list of the parameters used by this mojo.The Java type for this parameter. |-> <requiresReports>false</requiresReports> <!-. If a mojo is marked as an aggregator. |-> <requiresProject>true</requiresProject> <!-.SiteDeployMojo</implementation> <!-.site. such mojos will | cause the build to fail. |-> <aggregator>false</aggregator> <!-. |-> <name>inputDirectory</name> <!-.The implementation language for this mojo.Tells Maven that the this plugin's configuration should be inherted | from a parent POM by default. |-> <alias>outputDirectory</alias> <!-.The class or script path (within the plugin's jar) for this mojo's | implementation. |-> <inheritedByDefault>true</inheritedByDefault> <!-.Whether this parameter is required to have a value. |-> <implementation>org. this will often reflect the | parameter field name in the mojo class. --> <type>java.File</type> <!-. --> <language>java</language> <!-. |-> <requiresOnline>false</requiresOnline> <!-.Some mojos cannot execute if they don't have access to a network | connection.Tells Maven that a valid list of reports for the current project are | required before this plugin can execute. the | mojo (and the build) will fail when this parameter doesn't have a | value.plugins. If true. unless the user specifies | <inherit>false</inherit>. In Java mojos. If Maven is operating in offline mode. it will be executed once for each project instance in the | current build. --> <parameters> <parameter> <!-.apache.Determines how Maven will execute this mojo in the context of a | multimodule build.Appendix A: Resources for Plugin Developers <requiresDirectInvocation>false</requiresDirectInvocation> <!-. regardless of the number of project instances in the | current build. Mojos that are marked as aggregators should use the | ${reactorProjects} expression to retrieve a list of the project | instances in the current build.Tells Maven that a valid project instance must be present for this | mojo to execute.This is an optional alternate parameter name for this parameter.
WagonManager</role> <!-.</description> </parameter> </parameters> <!-.Inject the component instance into the "wagonManager" field of | this mojo. the requirement specification tells | Maven which mojo-field should receive the component instance.File">${project.manager.Use a component of type: org.reporting. this parameter is named "inputDirectory".Description for this parameter. |-> <description>This parameter does something important.maven. |-> <requirements> <requirement> <!-. Each parameter must | have an entry here that describes the parameter name. Components are specified by their interface class name (role). |-> <inputDirectory implementation="java.WagonManager |-> <role>org.Appendix A: Resources for Plugin Developers |-> <required>true</required> <!-. as in the case of the list of project dependencies. specified in the javadoc comment | for the parameter field in Java mojo implementations. parameter type. | | The general form is: | <param-name implementation="param-type">param-expr</param-name> | |-> <configuration> <!-. |-> <editable>true</editable> <!-.This is the operational specification of this mojo's parameters.manager. either via command-line or POM configuration. If set to | false.outputDirectory}.For example. The expression used to extract the | parameter value is ${project.apache. |-> <field-name>wagonManager</field-name> </requirement> </requirements> </mojo> </mojos> </plugin> Better Builds With Maven 263 .outputDirectory}</inputDirectory> </configuration> <!-. | along with an optional classifier for the specific component instance | to be used (role-hint).artifact.maven. and it | expects a type of java. as | compared to the descriptive specification above.io.reporting.io.apache.File.This is the list of non-parameter component references used by this | mojo.Whether this parameter's value can be directly specified by the | user. this parameter must be configured via some other section of | the POM. | and the primary expression used to extract the parameter's value. Finally.artifact.
phase. Classlevel annotations correspond to mojo-level metadata elements. 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 . Java Mojo Metadata: Supported Javadoc Annotations The Javadoc annotations used to supply metadata about a particular mojo come in two types.4. life cycle name. Table A-7: A summary of class-level javadoc annotations Descriptor Element Javadoc Annotation Values Required? aggregator description executePhase. 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. and field-level annotations correspond to parameter-level metadata elements.2.Appendix A: Resources for Plugin Developers A. Class-level annotations The table below summarizes the class-level javadoc annotations which translate into specific elements of the mojo section in the plugin descriptor. Alphanumeric. executeLifecycle.
<pluginMetadata> <!-. |-> <requiresDependencyResolution>compile</requiresDependencyResolution> <!-.The default life-cycle phase binding for this mojo --> <phase>compile</phase> <!-. corresponding to the ability to map | multiple mojos into a single build script. Ant Metadata Syntax The following is a sample Ant-based mojo metadata file. NOTE: | multiple mojos are allowed here.2.The dependency scope required for this mojo. Table A-8: Field-level annotations Descriptor Element Javadoc Annotation Values Required? alias.Appendix A: Resources for Plugin Developers Field-level annotations The table below summarizes the field-level annotations which supply metadata about mojo parameters.The name for this mojo --> <goal>myGoal</goal> <!-.Whether this mojo requires access to project reports --> <requiresReports>true</requiresReports> Better Builds With Maven 265 .5. Its syntax has been annotated to provide descriptions of the elements. These metadata translate into elements within the parameter. |-> <mojos> <mojo> <!-.Whether this mojo requires a current project instance --> <requiresProject>true</requiresProject> <!-. Maven will resolve | the dependencies in this scope before this mojo executes. and Yes No No No No (recommended) No Requirements section required editable description deprecated usually left blank None None Anything Alternative parameter A. configuration. parameterconfiguration section @parameter expression="${expr}" alias="alias" default-value="val" @component roleHint="someHint" @required @readonly N/A (field comment) @deprecated Anything roleHint is optional. and requirements sections of a mojo's specification in the plugin descriptor.Contains the list of mojos described by this metadata file.
Another mojo within this plugin to execute before this mojo | executes. --> <name>nom</name> <!-.A named overlay to augment the cloned life cycle for this fork | only |-> <lifecycle>mine</lifecycle> <!-.List of non-parameter application components used in this mojo --> <components> <component> <!-. |-> <execute> <!-.The list of parameters this mojo uses --> <parameters> <parameter> <!-.Whether this mojo requires Maven to execute in online mode --> <requiresOnline>true</requiresOnline> <!-.This is an optional classifier for which instance of a particular | component type should be used. |-> <inheritByDefault>true</inheritByDefault> <!-.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.The phase of the forked life cycle to execute --> <phase>initialize</phase> <!-.ArtifactResolver</role> <!-. |-> <goal>goal</goal> </execute> <!-.Whether this mojo must be invoked directly from the command | line.resolver.The parameter name.Whether the configuration for this mojo should be inherited | from parent to child POMs by default.artifact. |-> <property>prop</property> <!-.This is the type for the component to be injected.Whether this mojo operates as an aggregator --> <aggregator>true</aggregator> <!-.maven.Appendix A: Resources for Plugin Developers <!-. |-> <requiresDirectInvocation>true</requiresDirectInvocation> <!-. --> <role>org. |-> <hint>custom</hint> </component> </components> <!-.apache.Whether this parameter is required for mojo execution --> <required>true</required> Better Builds With Maven 266 .
An alternative configuration name for this parameter --> <alias>otherProp</alias> <!-. </description> <!-. this element will provide advice for an | alternative parameter to use instead.When this is specified. |-> <deprecated>Use something else</deprecated> </parameter> </parameters> <!-. it provides advice on which alternative mojo | to use.artifactId}</defaultValue> <!-.project.The default value provided when the expression won't resolve --> <defaultValue>${project.The expression used to extract this parameter's value --> <expression>${my.property}</expression> <!-.The Java type of this mojo parameter --> <type>org. |-> <deprecated>Use another mojo</deprecated> </mojo> </mojos> </pluginMetadata> Better Builds With Maven 267 .maven.apache.MavenProject</type> <!-.Whether the user can edit this parameter directly in the POM | configuration or the command line |-> <readonly>true</readonly> <!-.The description of this parameter --> <description>Test parameter</description> <!-.The description of what the mojo is meant to accomplish --> <description> This is a test.If this is specified.Appendix A: Resources for Plugin Developers <!-.
Spock: I find that remark insulting.Star Trek Better Builds With Maven 268 .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. .
A license file is encouraged for easy identification by users and is optional. Directory for all generated output. Standard location for resource filters. For example. This would include compiled classes. Standard location for assembly descriptors.txt README. Standard location for test sources. A simple note which might help first time users and is optional. may generate some sources from a JavaCC grammar. Standard location for test resource filters.1. generated sources that may be compiled. Standard location for test resources. 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. which is always at the top-level of a project.xml LICENSE. the generated site or anything else that might be generated as part of your build.txt target/ Maven's POM. Standard location for application resources.Appendix B: Standard Conventions B. Standard Directory Structure Table B-1: Standard directory layout for maven project content Standard Location Description pom. Standard location for application configuration files. target/generated-sources/<plugin-id> Standard location for generated sources. Better Builds With Maven 269 .
0</modelVersion> <name>Maven Default Project</name> <!-.maven.maven.org/maven2</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <!-.Plugin Repository Conventions --> <pluginRepositories> <pluginRepository> <id>central</id> <name>Maven Plugin Repository</name> <url>http://repo1.org/maven2</url> <layout>default</layout> <snapshots> <enabled>false</enabled> </snapshots> <releases> <updatePolicy>never</updatePolicy> </releases> </pluginRepository> </pluginRepositories> <!-..0.2..Reporting Conventions --> <reporting> <outputDirectory>target/site</outputDirectory> </reporting> . Maven's Super POM <project> <modelVersion>4.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> <!-.Repository Conventions --> <repositories> <repository> <id>central</id> <name>Maven Repository Switchboard</name> <layout>default</layout> <url>http://repo1. </project> Better Builds With Maven 270 .Appendix B: Standard Conventions B.
Compile the test source code into the test destination directory Run tests using a suitable unit testing framework. ready for packaging.Appendix B: Standard Conventions B. Generate resources for inclusion in the package. Description Validate the project is correct and all necessary information is available. Install the package into the local repository. Generate any source code for inclusion in compilation. This may involve things such as setting up the required environment. Process the test source code. such as a JAR. for example to filter any values. Post-process the generated files from compilation. Generate any test source code for inclusion in compilation. Process the source code. Copy and process the resources into the test destination directory. Better Builds With Maven 271 . 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. This may including cleaning up the environment. Take the compiled code and package it in its distributable format. Copy and process the resources into the destination directory. Create resources for testing. These tests should not require the code be packaged or deployed. Done in an integration or release environment. copies the final package to the remote repository for sharing with other developers and projects. Run any checks to verify the package is valid and meets quality criteria. Perform actions required after integration tests have been executed. for example to do byte code enhancement on Java classes. Process and deploy the package if necessary into an environment where integration tests can be run. Perform actions required before integration tests are executed. for example to filter any values. for use as a dependency in other projects locally.3. Compile the source code of the project.
http://checkstyle.org/axis/java/userguide.org/ Checkstyle .http://java.org/Maven2+plugin Cargo Merging War Files Plugin . Sun Developer Network .apache. Joshua.codehaus.html#WSDL2JavaBuildingStubsSkeletonsAndDataTypesFromWSDL Axis Tool Plugin .org/Containers Cargo Container Deployments .codehaus.http://cargo.http://cargo.codehaus.apache.org/axistools-maven-plugin/ Cargo Containers Reference .org/Merging+WAR+files Cargo Reference Documentation .http://cargo.codehaus.http://mojo.sf.codehaus.org/Deploying+to+a+running+container Cargo Plugin Configuration Options .eclipse.net/config.http://cargo. 2001 http://www.http://ws.http://cargo.org/axis/java/ AxisTools Reference Documentation .Bibliography Bibliography Online Books des Rivieres. Evolving Java-based APIs. Effective Java.html Better Builds With Maven 272 .com/docs/books/effective/ Web Sites Axis Building Java Classes from WSDLhttp://ws.html Bloch. Jim. June 8.sun.codehaus.org/eclipse/development/java-api-evolution.
org/tomcat-5.net/availablechecks.org/guides/introduction/introduction-to-archetypes.http://maven.apache.org/guides/introduction/introduction-to-thelifecycle.http://pmd.html Ruby on Rails .html Xdoclet .sourceforge.org/jetty6/maven-plugin/index.net/ Clirr .apache.www.apache.org/plugins/maven-clover-plugin/ DBUnit Java API .codehaus.com Introduction to Archetypes .http://www.0-doc/manager-howto.http://pmd.apache.http://maven.codehaus.http://xdoclet.html Introduction to the Build Life Cycle – Maven .apache.net/howtomakearuleset.http://clirr.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.html XDoclet Maven Plugin .org/plugins/maven-ejb-plugin/ ibiblio.http://checkstyle.Bibliography Checkstyle Available Checks .apache.sourceforge.mortbay.com/j2ee/reference/api/ Maven 2 Wiki .html Maven Plugins .codehaus.html Jester .http://xdoclet.org XDoclet2 Maven Plugin .sun.http://www.org/ PMD Best Practices .sf.html Xdoclet2 .http://maven.http://tomcat.net/xdoclet/ant/xdoclet/modules/ejb/EjbDocletTask.http://jetty.maven.rubyonrails.org/xdoclet-maven-plugin/ XDoclet Reference Documentation http://xdoclet.www.net J2EE Specification .au/products/simian/ Tomcat Manager Web Application .com.codehaus.html Cobertura .sourceforge.http://maven.http://jester.http://mojo.org/ Simian .redhillconsulting.net/ EJB Plugin Documentation .html Jdiff .sf.html POM Reference .http://maven.http://xdoclet.http://maven.http://cobertura.ibiblio.org/download.org/jdiff-maven-plugin Jetty 6 Plugin Documentation .org/Maven2+Plugin Better Builds With Maven 273 .org/maven-model/maven.http://xdoclet.sourceforge.net/ XDoclet EjbDocletTask .http://mojo.codehaus.net/ Clover Plugin .org/plugins/ Mojo .http://mojo.http://java.net/bestpractices.sf.apache.http://dbunit.apache.sf.sf.org Maven Downloads .sf.html PMD Rulesets .http://maven.apache.