Introduction to project industrialization using Maven YaJUG 06/10/2009. Copyright Pierre-Antoine Grégoire License Creative Commons 2.

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1 Introduction to project industrialization using Maven YaJUG 06/10/2009

2 Event October Best Practices and Tools for your build environments

3 Speaker Pierre-Antoine Grégoire I.T.Architect at Occasional committer in open source projects Dislikes buzzwords (SOA, EDA ), likes to conceptualize and build architectures Thinks having fun and working seriously (both at the same time) should be mandatory!

4 Who are you? Who in the audience is currently coding at work? Who in the audience is managing the lucky coders? Who is already using Maven 2+? Who is planning on using it and came to have more information?

5 Planning Software development is engineering A bit of history Why Maven? An introduction to Maven Drawbacks of Maven Best practices Maven 3.x preview Maven in a Software development suite Textual content under Copyright Pierre-Antoine Grégoire License Creative

6 Software development is engineering Since the early days of modern engineering, automation of build processes has been the key to: Productivity improvements Quality insurance Failure-Proofing Why would software development be any different?

7 Software development is engineering How do you really enable automation of build? Build has to be reproducible Build has to produce the final production artifact Build has to be as easy to maintain as possible and well documented Build has to contribute to the standardization effort

8 Planning Software development is engineering A bit of history Why Maven? An introduction to Maven Drawbacks of Maven Best practices Maven 3.x preview Maven in a Software development suite Textual content under Copyright Pierre-Antoine Grégoire License Creative

9 A bit of history Software craftmens are lazy, so they are looking for efficiency (or the other way around ) One command line to launch for a build, OK Two command lines to launch for a build, BAD enough More forget it Disclaimer: I m one of these lazy craftmen

10 A bit of history A simple script (.sh,.bat) is already a possible solution More advanced command-line tools have been available for a long time make created in 1977 at Bells Labs by Stuart Feldman Still very much used nowadays Apache Ant created by James Duncan Davidson Was at first a platform-independent build system for Tomcat because Sun s build system for Servlet RI (From which Tomcat was derived) was specific to Solaris. Released separately in 2000

11 A bit of history Two main categories in current tools Scripting tools Ant and derived (XML) Rake (Ruby based) Gradle (Groovy based) many others Artifact oriented tools Maven Debian Package Creation

12 A bit of history Maven 1.x is now a 10 years old project, mostly motionless since 2007 (no insult intended to people still using it or committing to it) Maven 2.x is the de facto standard for Java and Java EE build Most open source projects are switching to Maven for their build system It s now five years old

13 Planning Software development is engineering A bit of history Why Maven? An introduction to Maven Drawbacks of Maven Best practices Maven 3.x preview Maven in a Software development suite Textual content under Copyright Pierre-Antoine Grégoire License Creative

14 Why Maven? Nowadays, build tools are not really used by developers directly. IDEs are increasing their functionalities scope, Compilation is almost always done on the fly Package and server startup is monitored by rich Uis Step-by-step debugging is a killer feature Build tools like Maven 2 are used to build the package you will put into production! This should never be done by an IDE, nor by hand!

15 Why Maven? If you are not already using it: Now is the best moment to start being aware Maven is mature Maven is getting better and better Maven can be used online, offline, and in enterprise environment If you are already using it: Hang on! The best is yet to come! Focus on necessary things and don t get frustrated by petty details

16 Planning Software development is engineering A bit of history Why Maven? An introduction to Maven Drawbacks of Maven Best practices Maven 3.x preview Maven in a Software development suite Textual content under Copyright Pierre-Antoine Grégoire License Creative

17 An introduction to Maven Maven 2 is a tool with multiple facets: a BUILD tool a DEPENDENCY MANAGEMENT tool a DOCUMENTATION tool

18 An introduction to Maven Project Object Model pom.xml mvn Generated artifacts (jar, war, ear ), Documentation, statistics (test results, quality metrics, javadoc, web site)

19 An introduction to Maven A project can easily be cut into modules thanks to Maven 2 By simply declaring project metadata and optionally configuring a few plug-ins, you can: Build your project (compile, generate sources ) Launch tests and gather results (Junit, TestNG, Selenium etc) Package (Jar, War, Ejb, War etc) Document and generate reports

20 An introduction to Maven Project Object Model (POM) Basic project information groupid, artifactid, version Inheritance, or Aggregation through sub-modules (we ll explain the difference later on) Build section Project layout (sources and resources folders etc) Build plugins configuration Reporting section Reports configuration Some other advanced environment settings

21 An introduction to Maven A plug-in is made of a MOJO (Maven POJO) which is simply a java class with Maven-specific metadata. A plug-in can define goals and reports Goals can be called directly: mvn plugin:goal Goals can be bound to one or multiple phases Reports are used during site generation mvn site

22 An introduction to Maven Phase compile test mojo mojo package mojo Plug-ins install deploy mojo mojo Lifecycle Mojos define Goals (fine grained tasks)

23 An introduction to Maven When you invoke a phase, Maven 2 will go through all the phases until the one specified, executing the bound goals: mvn package compile compiler:compile test surefire:test package jar:jar

24 An introduction to Maven There are many more phases than in previous examples in the default lifecycle By default, all the basic necessary plug-ins for the build phase are already bound to phases It is easy to have information about plugins: mvn help:describe So.. what s left to do, and what s all the fuss about the complexity of Maven 2?

25 An introduction to Maven Dependencies: A blessing and a curse Blessing: Curse: almost all java build tools nowadays leverage the Maven 2 repositories (cf. Ivy, Ant, Gradle etc) easier to find/discover/use java libraries Transitive dependencies can rapidly trigger a dependency hell! Curse: Harder to stabilize builds

26 An introduction to Maven What really made Maven different from other builds systems in the first place? REPOSITORIES!!! Before Maven, it was really hard to find java libraries, and harder to ensure a coherent use of these libraries (I m saying hard, not impossible ) Nowadays, it s still very hard to find some jars with a decent/coherent versioning (discretely winking in the general direction of Sun participants...), let alone to find their sources or javadocs

27 An introduction to Maven Local repository Corporate repository/ proxy Public repository

28 An introduction to Maven Local repository: Local cache for artifacts Local private sandbox It should be possible to erase it regularly Very useful for offline builds By default in user home s.m2/ folder Can be moved to another place through Maven 2 runtime settings.xml file $MAVEN_HOME/conf/settings.xml Local repository Corporate repository/ proxy Public repository

29 An introduction to Maven Corporate repository/proxy Very useful tool The first necessary step towards a corporate use of maven Can be as simple as a corporate http server exposing a repository Even better: install a repository management tool Can proxy external repositories Can filter unwanted artifacts Local repository Corporate repository/ proxy Public repository Build even without internet access! (well at least for the repository management tool)

30 An introduction to Maven Public repositories Good for dependencies harvesting Should be proxied in corporate environments or even for your personal use! A lot of mis-configured dependencies A lot of alpha/beta Maven 2 plugins Be cautious when adding public repositories to a build process! Local repository Corporate repository/ proxy Public repository

31 An introduction to Maven Other key features of Maven: POM Inheritance/Aggregation Archetypes Launching Tests many more

32 An introduction to Maven POM Inheritance vs. POM Aggregation POM Inheritance: a POM and all its parent POMs will be flattened at runtime In the end only one effective POM in memory This is mostly used to share common configuration POM Aggregation: declare modules in a given project If a command is issued against a project, it will be also issued against all its modules This is mostly used to organize builds and gather projects that should be built simultaneously

33 An introduction to Maven Project Archetypes You can build template projects and make them available as artifacts in the repositories Allows to share best practices without neither inheritance nor aggregation mvn archetype:create-from-project mvn archetype:generate Many Archetypes already configured in the default catalog You can easily build a custom or corporate catalog mvn archetype:generate DarchetypeCatalog= archetypes.xml

34 An introduction to Maven Launching Tests Maven 2 allows to launch various types of tests: Unit tests: Junit 3.x or 4.x, TestNG, UI Tests: Selenium, Canoo Webtest Functional tests: Fitnesse, Greenpepper WebServices tests: SOAPUi And many more

35 Planning Software development is engineering A bit of history Why Maven? An introduction to Maven Drawbacks of Maven Best practices Maven 3.x preview Maven in a Software development suite Textual content under Copyright Pierre-Antoine Grégoire License Creative

36 Drawbacks of Maven If you don t embrace the standardization brought by Maven 2, you ll soon feel limited by Maven 2 Additionally, standardization can be quite expensive! Measure the implied cost by testing on 2 subsequent projects (one to absorb the POC effect, and one for measure) By default Maven 2 has its own folder structure normalization, unknown to IDEs (though this is not completely true anymore) Last but not least: Maven 2 error reporting is SO BAAAAD!

37 Worst practices You want more drawbacks? GET MORE OF THEM! Use maven-antrun-plugin a lot! So coool, this way you can use Maven and not Ant! Build very intricated projects with modules having modules themselves, and lots of inheritances all around! Niiice! This allows you to spend more time with your favorite tool: Maven 2 in order to find out where your damn properties/dependencies are defined! Replace your IDE with Maven and try to add all of your IDE s functionalities as Maven plugins!!!!! You got my point ;)

38 Planning Software development is engineering A bit of history Why Maven? An introduction to Maven Drawbacks of Maven Best practices Maven 3.x preview Maven in a Software development suite Textual content under Copyright Pierre-Antoine Grégoire License Creative

39 Best practices They will allow you to overcome Maven 2 s drawbacks Embrace the standardization brought by Maven 2, don t fight it Use POM Inheritance and <dependencymanagement> (with import scope), <pluginmanagement> to tame the transitive dependencies. (don t mistake these for <dependencies>, <plugins> ) Use a Repository Manager: Sonatype Nexus: Jfrog Artifactory:

40 Best practices Don t use Maven s integrated reporting anymore It was meant for Apache project s web sites static documentation The amount of time spent in order to build them is not worth it in enterprise environment Keep your build as simple as possible Generate test statistics data and other metrics data in order to exploit them in Software quality tools: Sonar: Squale:

41 Best practices If you provide a standard environment, try to make Maven plugins have a match in the IDE If Maven 2 launches Checkstyle, provide the Checkstyle Eclipse plugin to your projects. Launch your builds regularly and possibly in a neutral zone (not on the developer s desktop!) in order to ensure rule number one is respected: Build must be reproducible. Use the dependency and versions plugins to handle dependencies and diagnose dependencies mismatches or errors

42 Best practices Documentation and information: Site Plugins And many others Project Wiki Users Wiki

43 Best practices Books Free electronic editions: Definitive Guide: Better Builds with Maven: Upcoming book by Arnaud Héritier and Nicolas De Loof

44 Planning Software development is engineering A bit of history Why Maven? An introduction to Maven Drawbacks of Maven Best practices Maven 3.x preview Maven in a Software development suite Textual content under Copyright Pierre-Antoine Grégoire License Creative

45 Maven 3.x Preview DISCLAIMER!!! Everything mentioned here could end up being COMPLETELY FALSE!!! (though project is now well advanced)

46 Maven 3.x Preview New release planned for this autumn/winter Lots of refactorings of the insides of Maven 2 Not immediately obvious (in a way this is better than the complete product change between Maven 1 and 2) Will allow to tackle upcoming challenges and regular issues of Maven 2 in a more elegant manner Simplifies plug-in development Efficient embedder Maven 2 has lots of singletons and such and is therefore improper for use in multithreaded environments (CIM, IDE)

47 Maven 3.x Preview Backward compatibility Loads of Integration testing is done to ensure backwards compatibility Stricter validation of the POM Configured plugins should have their versions specified (a warning appears otherwise) Site/reporting is now completely extracted from the Maven core Currently the Site plugin doesn t work with Maven 3, yet should until the final release (though reports still work) Recommended to switch to the use of external quality monitoring tools

48 Maven 3.x Preview If you plan to migrate or want to evaluate: Maven+3.x+Compatibility+Notes Presentation by Jason van Zyl (Sonatype) Presentation My first impressions: Maven 3 looks awesome! Embedder is a killer feature The IDE can literally listen for the Build process, and be part of it, not just launch it.

49 Maven 3.x Preview What will be new to users: Versionless parent elements Better version delegation Better error and integrity reporting XML Pom format using attributes instead of elements Scripted POM Formats (pom.{rb groovy py}) What will be new to plugin developers: Plugin extension points Annotations instead of old javadoc tags Lifecycle extension points Queryable lifecycle

50 Maven in a Software development suite Maven is now very well integrated in IDEs NetBeans 6.5+ now has very good support for Maven 2 Eclipse 3.x has very good support also, with preview of Maven 3.x embedder (blazingly fast!) IntelliJ IDEA seems to have excellent support also (though this is why you pay for it isn t it?) Maven works very well with Quality monitoring tools Maven 3 will most likely increase the embedding of Maven and its use for other JVM Languages and possibly for other platforms

51 References and Thanks Many thanks to Arnaud Héritier He allowed me to be inspired by some of its recent slides presented to the French Ch ti JUG He also was kind enough to review this presentation ;) Many thanks to Jason van Zyl for its Maven 3 presentation I was heavily inspired by