The Maven2 Revolution
A new approach to project
development
Dror Bereznitsky
AlphaCSP
Copyright AlphaCSP Israel 2006 - The Ultimate Development Environment Seminar

Agenda
• What is Maven?
• Core Concepts of Maven 2
– Project Object Model
– The Build Lifecycle
– Maven Plugins
– The dependency Mechanism
– Repositories
• Maven vs. Ant
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What is Maven ?
Copyright AlphaCSP Israel 2006 - The Ultimate Development Environment Seminar

A Build Survey
How much time do you spend creating and
managing your build files?
How many times have you created a new
build script from scratch?
Can someone new to your project can
immediately build, test, deploy it without
looking at documentation?
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A Build Survey
If you answered :
1. Too much time
2. More than I can remember
3. No way
you are probably not working with
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What is Maven?
A new approach to project development
• Configure your build don’t script it
• Define what to build not how
• Reuse of build logic
• Coherent Organization of Dependencies
A development tool – not building blocks
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Maven’s Primary Goal
What is Maven’s project goal ?
Maven's primary goal is
to allow a developer to
understand the complete
state of a project
in the shortest period of time
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The Primary Goal ..
The way to achieve this goal is:
• Making the build process easy
• Providing a uniform build system
• Providing guidelines for
best practices development
• Providing quality project information
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Main Features
• Superior dependency management
• A large repository of libraries and metadata
• Multiple projects handling
• Extensible, easy to write plugins
• Coherent site of project information
• Release management and distribution
publication
• Multiple language support – C++, Java …
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Core Concepts of Maven 2
Copyright AlphaCSP Israel 2006 - The Ultimate Development Environment Seminar

Project Object Model
Define What, not How
• All the information required for the build is
contained in a single POM,
“Project Object Model”, XML file
• The developer provides information about
what is being built and not how
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Project Object Model ..
The POM contains detailed METADATA
information about the project:
– Versioning and configuration management
– Dependencies
– Project structure
– Application and testing resources
And much more …
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A POM Example
All the information required for the build in a single file
1 <project>
2 <modelVersion>4.0.0</modelVersion>
3 <groupId>com.alphacsp</groupId>
4 <artifactId>my-app</artifactId>
5 <packaging>jar</packaging>
6 <version>1.0-SNAPSHOT</version>
7 <dependencies>
8 <dependency>
9 <groupId>junit</groupId>
10 <artifactId>junit</artifactId>
11 <version>3.8.1</version>
12 <scope>test</scope>
13 </dependency>
14 </dependencies>
15 </project>
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The Super POM
How this is possible using a 15 line file?
• Maven's implicitly use its Super POM
• Super POM carries with it all the default
conventions that Maven encourages
• Super POM is the parent of all POMs
• Analog of the Java language's
java.lang.Object class.
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The Super POM ..
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Standard Directory Layout
• A common directory
layout –
immediately feel at home
in any Maven project
• Based on best practices
• Simplifies the POM
• Can be created using
Archetypes
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The Build Lifecycle
• Software projects generally follow similar
build paths: preparation, compilation,
testing, packaging, installation, etc.
• Maven2 is based around the central concept
of a build lifecycle – the process for
building and distributing a particular artifact
is clearly defined
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Phases and Goals
The build life cycle consists of a series of phases
where each phase can perform one or more
actions, or goals
compile test
deploy package
install
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The Build Lifecycle
The lifecycle phase invokes the plugins it needs to
complete its task and other dependant lifecycles
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The 80/20 Rule
• Using the default lifecycle mapping, Maven
can build a basic project with little or no
modification – 80% case
• in certain circumstances, a project requires
special tasks in order to build successfully
• Maven can integrate these custom tasks
into the build process through its
extensible plugin framework.
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Maven Plugins
Maven is actually a platform that executes
plugins within a build life cycle in order to
perform the build tasks
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Maven Plugins ..
• With most projects, the plugins provided
“out of the box” by Maven are enough.
• More plugins can be found at the Apache
Maven Project and CodeHaus Mojo project.
• If needed, you can write custom plugins to
perform special build tasks.
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Maven Mojo
“mojo” – maven old java object
• Plug-in developers only need to make
their individual goal, “mojo”, perform a
single task.
• A “mojo” has a set of inputs and
outputs.
• Plug-ins consist of one or more “mojos”
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Mojo Example
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Maven-Anno-Mojo
Let you use java 5.0 annotations syntax
instead of doclets for writing your mojos
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Maven-Anno-Mojo ..
• Inheritance between plugins
• All the benefits of Java 5.0 – generics,
autoboxing …
• Delegation of execution to POJOs
• Natural Ant java tasks integration – not XML
based
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The Dependency Mechanism
Maven excels in dependency management
• Transitive dependencies
• Dependency Scope
• Dependency Management
• Dependency exclusion
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The Dependency Mechanism ..
Just Define your dependencies and forget about
them - maven will do the rest for you:
• Download the dependency
• Resolve all transient dependencies
• Add dependencies to compilation and test
classpath/include path
• Bundle dependencies when needed
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The Dependency Mechanism …
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Maven 2 Repositories
Maven repositories
shares the same
hierarchical structure
that hold the build
artifacts –
• Group
• Artifact
• Version
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Maven 2 Repositories ..
There are two types of repositories:
• Remote - any type of repository, accessed by a
variety of protocols (file://, http://...).
http://repo1.maven.org is the central repository
• Local - a local cache of the
remote downloads and the latest build artifacts
Usually at : ${user.home}/.m2/repository
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Remote Repository
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Local Repository
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Site Generation
Maven is famous for its
Site generation that
includes:
a reference to the build
server
Javadoc
source XRef
issue tracking reference
test and quality reports
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Site examples – code coverage
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Site examples – Surefire report
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Site – Custom Look & Feel
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IDE Support
Maven has some neat plug-ins for IDE project
generation, including:
– IntelliJ IDEA
– Eclipse
– Netbeans
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IDE Support ..
• The IDE projects created include:
– All the dependencies 3rd party/internal
– Dependency source linking
• The created project is ready to compile, test
, debug and run.
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Multiple Language Support
• Maven supports
multiple development
languages such as
Java , C++, C, C#,
Fortran and more.
• Different languages
has their own
common standard
layout.
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Maven vs. Ant
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Maven vs. Ant
OK, but Ant is working fine !
•Ant provides building blocks for a toolset - Maven
provides a working tool
•Ant has no build lifecycle, repositories, standard
project layout, dependency management …
you have to do it by yourself !
•Ant scripts become complex
•Ant scripts are not reusable – promotes duplication
•Ant is becoming legacy and not moving fast ahead
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MyApp – Ant Build File – 141 lines
141 Lines of code !!!
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MyApp - Maven Build File – 17 lines
17 Lines of code
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Maven vs. Ant ..
From our experience in Ant migration
projects there is a 1:30 ratio in
the number of lines of code
between Maven2 and Ant.
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Your Turn Now
Q&A
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Copyright AlphaCSP Israel 2006 - The Ultimate Development Environment Seminar