Raven: Scripting Java Builds with Ruby MATTHIEU RIOU

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1 Raven: Scripting Java Builds with Ruby MATTHIEU RIOU

2 Raven: Scripting Java Builds with Ruby Copyright 2007 by Matthieu Riou All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. ISBN-13 (pbk): ISBN-10 (pbk): X Printed and bound in the United States of America (POD) Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. Java and all Java-based marks are trademarks or registered trademarks of Sun Microsystems, Inc. in the US and other countries. Apress, Inc. is not affiliated with Sun Microsystems, Inc., and this book was written without endorsement from Sun Microsystems, Inc. Lead Editor: Steve Anglin Technical Reviewer: Matthew Foemmel Editorial Board: Steve Anglin, Ewan Buckingham, Gary Cornell, Jason Gilmore, Jonathan Gennick, Jonathan Hassell, James Huddleston, Chris Mills, Matthew Moodie, Jeff Pepper, Paul Sarknas, Dominic Shakeshaft, Jim Sumser, Matt Wade Project Manager: Sofia Marchant Copy Edit Manager: Nicole Flores Copy Editor: Marilyn Smith Assistant Production Director: Kari Brooks-Copony Compositor: Richard Ables Cover Designer: Kurt Krames Manufacturing Director: Tom Debolski Distributed to the book trade worldwide by Springer-Verlag New York, Inc., 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax , orders-ny@springer-sbm.com, or visit For information on translations, please contact Apress directly at 2855 Telegraph Avenue, Suite 600, Berkeley, CA Phone , fax , info@apress.com, or visit The information in this book is distributed on an as is basis, without warranty. Although every precaution has been taken in the preparation of this work, neither the author(s) nor Apress shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in this work. The source code for this book is available to readers at in the Source Code/ Download section.

3 Contents About the Author v About the Technical Reviewer vii Introduction ix CHAPTER 1 Dreams of Build The First Acronym: DSL No App Is an Island: Dependencies More on Dreams CHAPTER 2 Raven Takes Off The Mandatory Installation Guide The Native Ruby Way The JRuby Way Your First Rakefile Building Something Real Compiling Putting It in a JAR What's Up, Doc (Ruby Doc, That Is)? Going to War Peacefully: WAR Files The True Nature of Tasks Summary CHAPTER 3 Wait, I Have Dependencies! The Jewelry Business: RubyGems Brilliance: How RubyGems Works Crafting: Using RubyGems Raven Gets Brilliant: Handling Dependencies Installing Dependencies Choosing a Version Installing a Project Surrendering Autonomy: The dependency Task Building Classpaths: The lib-dir Task Doing It Your Way: Adding Dependencies Explicitly Test Time: The junit Task Summary CHAPTER 4 Divide and Conquer: Multimodule Projects iii

4 iv ABOUT THE AUTHOR Modules to Gems A Full Project Build A Common Rakefile to Eliminate Redundancy One Task to Bind Them All Cleanup Summary CHAPTER 5 Public or Private Repository Automatic Dependency Installation: The Grand Unified Repository Keeping It Personal: Your Own Repository From a Maven Repository From Your Own Libraries The Direction to Your Repository Summary

5 About the Author MATTHIEU RIOU has developed software for vendors and also as a freelance consultant, mostly for banks and financial institutions. His technological expertise is centered on Java and J2EE, with a strong web services tint. Matthieu has also been working on several open source projects and has founded Twister, a Web Services Business Process Execution Language (WS-BPEL) orchestration engine. Since its creation, the orchestration engine project has been donated to the Apache Software Foundation and renamed Apache ODE. Matthieu is still actively contributing on ODE, thanks to his current employer, Intalio, Inc. Additionally, he teaches a few classes for a French university, the Conservatoire National des Arts et Metiers. Matthieu has been enamored with the Ruby language for several years. Raven is his first attempt to bring this love to the open source world. In his free time, Matthieu enjoys playing guitar and surfing on the California waves. After having deeply loved Paris for several years, he is now enjoying San Francisco just as much. v

6 vi ABOUT THE AUTHOR

7 About the Technical Reviewer MATTHEW FOEMMEL is a software architect at Business Logic Corporation, based in Chicago, Illinois. He can be reached at foemmelm@businesslogic.com. vii

8 viii ABOUT THE TECHNICAL REVIEWER

9 Introduction In this book, we're not going to change the world or solve any fundamentally complex problem. There won't be any transactional or concurrency issues requiring several minutes (or sometimes hours) of deep thoughts. Building a Java project is an accumulation of trivial issues. There's nothing mysterious about it. But as often, the devil is in the details, and there are a lot of details to address when creating a build system. I've worked on and have seen countless projects where tremendous amounts of time were spent working on the build. Why? Let's see what building a Java project is about: * Compiling classes using javac * Building a JAR file to run your program or reuse it in another project * Managing the project dependencies to produce a compile classpath and try to help as much as possible with the runtime classpath * Integrating other external tools to run programs like Javadoc, JUnit, XDoclet, and so on And that's pretty much it. Did you see anything hard to do in this list? I didn't. So why are the solutions you find (mostly the two usual suspects: Apache Ant and Apache Maven) so time-consuming? I've seen people banging their heads against the walls from frustration, and I've often been very close myself to verifying how flat my forehead could be made. There are multiple answers to this question. A part of it is the overuse of XML, whereas build scripts (as the name says) are supposed to be about scripting. Yes, Ant includes some control statements, but that doesn't make it a full-blown dynamic language. It has been designed as a purely declarative language, and control structures have been added afterward-a bit like a hack. And because it has XML all over the place, it's so verbose! The syntax is just not quite optimal (I'm also thinking of Maven Project Object Models, or POMs, here). Another part of the answer is dogma-forcing you into certain practices that don't fit your own project. For example, with Maven, there's only one artifact produced per module, and the way around this practice is pretty painful. So if you have single file used by two modules, what do you do? Make a module with it. These theories about how things should be done just make it harder for you to write simple builds. There are actually many more reasons, but my goal here isn't to whine about these or emphasize the shortcomings of other tools. My goal is to show you how simple problems can be solved simply. Raven was born out of my frustration with build problems. I started asking myself, How would I like my build system to be? I first selected a powerful scripting language: Ruby. Then I've looked at the simple and efficient tools that already exist in Ruby in the build and dependency management space (RubyGems and Raven). And I started developing. In this book, you will learn what I came up with. You will discover how Raven is built and how to best use it. My hope is that I have been focused enough in that work and have kept Raven as simple as could be. ix

10 x INTRODUCTION