Maven

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Maven

• Next generation build and project setup tool

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Why another build tool?

• Every Ant script is different. Why?
• Maven uses convention over configuration
• Maven conventions make it easier to learn a new
  project
• Ant can be flexible
• Maven and Ant are not incompatible - you can use
  the strengths of both

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Build lifecycle

• With Ant, you have to define your own build
  lifecycle.
• Maven defines a standard build lifecycle for each
  type of project - jar, war, ear, etc.
• The actual work is performed by Maven plugins,
  which are wired to different phases of the build
  lifecycle. The default wiring is sufficient for
  most projects.
• The default lifecycles allow most projects to be
  built automatically, with minimum configuration

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Configuring Maven

• Every module in your project has a maven xml
  configuration file called a POM (project object
  model).
• Each module has a packaging type. When you
  build that module this determines the type of
  artifact which results, and the build lifecycle
  eg .jar, .war or .ear
• Each built artifact has a group and name to
  identify it, plus a version - defined in the .pom
  ath the point the build took place.
• Over time, the version number will be incremented.

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Dependency management in Maven

• Nothing in Ant helps you manage dependencies
  between modules.
• Maven can manage your dependencies for you -
  using the concept of an Artifact Repository
• Set up your modules dependencies by listing them
  in the .pom
• When the Maven build runs, Maven will look for
  the dependencies in your local artifact repository

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Maven Repositories - local and remote

• Maven repositories are nothing more than a set of
  folders containing versioned artifacts (.jars,
  .wars etc) and their matching .poms
• They conform to a well know directory structure,
  based on module group, name and version
• A Maven repository can be set up under a web
  server, so the contents can be served
• Maven build will look for a dependency in your
  local repository first, then try your teams
  repository, and finally the maven central
  repository it is a bit like DNS

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Transitive dependencies in maven

• Why include the .poms in the artifact
  repository?
• Maven can automatically go and find your
  dependencies for you, including all the indirect
  transitive dependencies.
• From version 7, Intellij can read your .poms and
  autoconfigure your Intellij project, downloading
  any required libraries and.

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Enough talking - show me the code
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Other Maven features

• Plugins

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Common problems

• Missing artifacts. Not every project is a Maven
  project (yet!)- use maven installinstall-file
• Maven central repository can be slow (set up your
  maven configuration to use the mirrors)
• Finding the documentation. Each plugin has its
  own documentation. Use the links on our wiki.