Matthew McCullough's Maven 3.0 presentation to Øredev 2010 in Malmö, Sweden.

1. Maven 3.0
What’s new in
by Matthew McCullough, Ambient Ideas, LLC

2. In the beginner’s mind
there are
many possibilities.
In the expert’s mind
there are few.

3. In the beginner’s mind
there are
many possibilities.
In the expert’s mind
there are few.

4. This Talk

5. Maven and You
❖Who will enjoy this talk?
❖Current Maven user
❖Familiar with POM syntax
❖Interested in preparing for Maven 3.0
❖Comfortable with betas

6. Maven and Me
❖ Tenure
❖ Using it for 8 years since 0.7
❖ Contributing to the codebase via patches
❖ Authoring archetypes
❖ 30 open source how-to projects

7. Maven and Me
❖ Tenure
❖ Using it for 8 years since 0.7
❖ Contributing to the codebase via patches
❖ Authoring archetypes
❖ 30 open source how-to projects
❖ Mentoring
❖ 3 virtual Sonatype classes a month
❖ Several on-site classes around the globe per year
❖ 30+ global conference and user group talks to date
❖ 50+ enterprise Maven-consulting clients

8. Maven and Me
❖ Tenure
❖ Using it for 8 years since 0.7
❖ Contributing to the codebase via patches
❖ Authoring archetypes
❖ 30 open source how-to projects
❖ Mentoring
❖ 3 virtual Sonatype classes a month
❖ Several on-site classes around the globe per year
❖ 30+ global conference and user group talks to date
❖ 50+ enterprise Maven-consulting clients
❖ Writing
❖ O’Reilly: Maven The Definitive Guide by Tim O’Brien
❖ Promotional materials, testimonial on the back cover
❖ DZone Maven RefCard
❖ 8th most-downloaded card of all time

9. The
Roadmap

10. 3.0

11. Compatibility
❖Tested against 100s of Maven 2 projects
❖Legacy simulation layers
❖Using for 6 months almost exclusively
❖450+ integration tests

15. 603!

16. Speed
❖Performance tuned
❖Benchmarks
❖ Disk I/O
❖ Network I/O
❖ CPU
❖ Memory

17. Maven Speed Test

19. Quick
❖ Faster execution
❖ 10% faster in the demo
❖ Multi-threaded downloads
❖ Parallel plugin execution
❖ Java 5 optimized builds

22. Efficient
❖ Memory conservative
❖ 73% less in the demo
❖ Tuned data structures

23. ❖Largely re-written for quality, flexibility
❖30% smaller code base
❖Continuous integration running test suite
Code

24. Extensibility
❖Layers of abstraction
❖Plugin classloader partitioning
❖Plexus to Guice IOC rewrite
❖Fully embeddable
❖Basis for derived tools

25. How can you keep up with Maven 3?

26. http://maven.apache.org/docs/3.0/release-notes.html

27. http://delicious.com/matthew.mccullough/maven

28. POMs &
Maven 3.0

29. POM XML Syntax
❖ No POM syntax changes for Maven 3.0
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>com.ambientideas</groupId>
<artifactId>sample-barestbones</artifactId>
<version>1.0-SNAPSHOT</version>
</project>

30. POM XML Validations
❖ Heavily validated against common mistakes
❖ Forward-test with Maven 3.0
❖Switch back to 2.x for production
❖ 3.0 POMs run better on 2.x

31. POM XML Validations
❖Warns when plugin versions are
not specified

32. “Plugin version omitted” warning

34. POM XML Validations
❖ Blocks duplicate dependencies
❖Examined in same POM only
❖Conflict resolution used otherwise
<dependency>
<artifactId>junit</modelVersion>
<groupId>junit</groupId>
<version>3.8.1</version>
</dependency>
...
<dependency>
<artifactId>junit</modelVersion>
<groupId>junit</groupId>
<version>3.8.2</version>
</dependency>

35. “Duplicate dependency” error

37. Help URLs
❖ Wiki page URLs now shown for all error
messages

38. Help URLs
❖ Wiki page URLs now shown for all error
messages

40. Parent POM References
❖ Parent POMs now prefer to resolve from
repositories
❖Better consistency on multi-module builds
❖ Version-less parent references may be
allowed (not ready yet)
❖Will require <relativePath> tag
❖MNG-624

41. <project>
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.ambientideas</groupId>
<artifactId>sample-multimodulejava-parent</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
</project>

42. <project>
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.ambientideas</groupId>
<artifactId>sample-multimodulejava-parent</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
</project>

43. <project>
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.ambientideas</groupId>
<artifactId>sample-multimodulejava-parent</artifactId>
<relativePath>../</relativePath>
</parent>
</project>

45. Profiles Consolidated
•Profiles.xml external file support removed
•Folded into pom.xml
•Already a best-practice
•Necessary for Polyglot Maven

46. Parallel Builds

47. Parallel Build Approach
•Examines reactor build plan
•Threads up to what’s possible
•Governed by your provided limits

48. https://cwiki.apache.org/MAVEN/parallel-builds-in-maven-3.html

49. Parallel Build Syntax
•Four threads
mvn -T 4 install

50. Parallel Build Syntax
•Two threads per core
mvn -T 2C install

51. Serial Building

53. Parallel Building

55. Artifact Behavior
Changes

56. Maven 1.0 Deprecated
• Maven 1.0 repository support removed
<layout>legacy</layout>

57. SNAPSHOT Datestamps
•Deprecated
<uniqueVersion>
false
</uniqueVersion>
•SNAPSHOTs now always deployed
with date-stamps

58. Artifact Resolution Caching
•Caches lookups whether found or missing
•Stored in:
~/.m2/repo/.../<artifact>.lastUpdated
•Sample contents:
#Last modified on: Thu Dec 31 10:42:13 MST 2009
#Thu Dec 31 10:42:13 MST 2009
http://localhost:8081/nexus/content/groups/public=12333938
•Overridden by:
mvn <phase> -U

59. Plugin Behavior
Changes

60. Core Changes: Plugins
❖Plugin version auto-selection favors
RELEASEs over SNAPSHOTs
❖Affects command-line invocation of plugins

61. #Maven 2.x
#Will run the newest SNAPSHOT, if one is cached locally
mvn archetype:generate
#...actually running
mvn org.apache.maven.plugins:maven-archetype-plugin:1.0-SNAPSHOT:generate
#Maven 3.x
#Will always run the newest RELEASE in Maven 3.x
mvn archetype:generate
#...actually running
mvn org.apache.maven.plugins:maven-archetype-plugin:2.0:generate
Command Line

62. Core Changes: Plugins
❖Plugins versions cannot be specified as
RELEASE or LATEST
❖Affects pom.xml configuration and command
line fully-qualified invocation

63. ...
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-toolchains-plugin</artifactId>
<version>LATEST</version>
</plugin>
...
pom.xml

64. ...
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-toolchains-plugin</artifactId>
<version>LATEST</version>
</plugin>
...
pom.xml

65. Core Changes: Plugins
❖Plugins only resolved from
<pluginRepository> locations

66. http://cwiki.apache.org/MAVEN/maven-3x-compatibility-notes.html

67. Site Plugin
❖Near-complete rewrite
❖Separation of <reporting> from core Maven
codebase
❖Preparation for Maven 3.1 pom.xml syntax
changes

70. Not a technical rant on Maven vs. Ant

71. mvnshell

72. http://shell.sonatype.org/

73. http://shell.sonatype.org/

76. What is mvnshell?
❖High performance console
❖Maven 3.x add-on

77. The shell and its commands

79. Color highlighting

81. Speed of Builds

83. Performance of Shell
❖220% faster in the demo
❖No JVM warm-up time
❖Strategies for caching

84. Subcommands, archetypes

86. polyglot

87. http://polyglot.sonatype.org/

88. http://polyglot.sonatype.org/

90. What is polyglot Maven?
❖Maven 3 superset
❖A full distribution of Maven
❖Enabled by Maven 3 embedding
❖Multi-language mvn command

91. What is polyglot Maven?
❖POM file converter
❖translate tool
❖Any-to-Any language translation

92. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://
www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://
maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.ambientideas</groupId>
<artifactId>sample-dependency</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>Sample Project - One Dependency</name>
<url>http://github.com/matthewmccullough/maven-training/</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
pom.xml

93. Translating a POM from XML toYAML

95. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://
www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://
maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.ambientideas</groupId>
<artifactId>sample-dependency</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>Sample Project - One Dependency</name>
<url>http://github.com/matthewmccullough/maven-training/</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
pom.xml

96. modelVersion: 4.0.0
artifactId: sample-dependency
groupId: com.ambientideas
name: Sample Project - One Dependency
packaging: jar
url: http://github.com/matthewmccullough/maven-training/
version: 1.0-SNAPSHOT
dependencies:
- {artifactId: junit, groupId: junit, optional: false, scope: test,
type: jar, version: 3.8.1}
pom.yaml

97. (defproject main "com.ambientideas:sample-dependency:1.0-SNAPSHOT"
:model-version "4.0.0"
:add-default-plugins false
:name "Sample Project - One Dependency"
:packaging "jar"
:url "http://github.com/matthewmccullough/maven-training/"
:test-dependencies [["junit:junit:3.8.1"]])
pom.clj

98. project { m =>
m.artifactId = "sample-dependency"
m.dependency { d =>
d.artifactId = "junit"
d.groupId = "junit"
d.optional = false
d.scope = "test"
d._type = "jar"
d.version = "3.8.1"
}
m.groupId = "com.ambientideas"
m.modelVersion = "4.0.0"
m.name = "Sample Project - One Dependency"
m.packaging = "jar"
m.url = "http://github.com/matthewmccullough/maven-training/"
m.version = "1.0-SNAPSHOT"
}
pom.scala

99. project {
modelVersion '4.0.0'
groupId 'com.ambientideas'
artifactId 'sample-dependency'
version '1.0-SNAPSHOT'
name 'Sample Project - One Dependency'
url 'http://github.com/matthewmccullough/maven-training/'
dependencies {
dependency {
groupId 'junit'
artifactId 'junit'
version '3.8.1'
scope 'test'
}
}
}
pom.groovy

100. Translating a POM and building from it

102. Polyglot DSLs
❖A true DSL framework
❖Maven lifecycle hooks
❖Can modify execution plan
❖Supplement the lifecycle

103. Polyglot Macros
❖Maven-specific macros
❖Allows for more concise POMs
❖Groovy polyglot showcasing this
❖Freeform scripting in Groovy

104. project {
modelVersion '4.0.0'
$artifact('com.ambientideas', 'sample-dependency’, '1.0-SNAPSHOT')
name 'Sample Project - One Dependency'
url 'http://github.com/matthewmccullough/maven-training/'
dependencies {
dependency('junit', 'junit’, '3.8.1', ‘test')
}
}
pom.groovy with macros

105. Where did we start from again?

106. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://
www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://
maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.ambientideas</groupId>
<artifactId>sample-dependency</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>Sample Project - One Dependency</name>
<url>http://github.com/matthewmccullough/maven-training/</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
pom.xml

107. M2Eclipse

109. Upgrading M2Eclipse
❖Latest version, 0.10
❖Code quality improvements
❖Performance increases
❖Packaging changes
❖Two distinct update sites
❖ Core: http://m2eclipse.sonatype.org/sites/m2e
❖ Extensions: http://m2eclipse.sonatype.org/sites/m2e-extras

110. Eclipse Versions Supported
❖3.4
❖3.5
❖3.6

111. Dependencies
❖ Visualizes conflicts
❖ Graph and text form
❖ Dependency resolution tree
❖ Answers “where is X being brought in from?”

112. Dependency conflicts

114. Dependencies
❖ Easy exclusions
❖ Uses Eclipse refactoring engine

115. Exclusions

117. Class Search
❖ Search the entire central repository for
❖ Artifact
❖ Package
❖ Classname
❖ Lucene database
❖ Incremental updates

118. Class Search

120. Resources

121. Free Books
http://books.sonatype.com

122. Examples
❖Ambient sample projects
❖http://github.com/matthewmccullough/maven-training
❖Sonatype sample projects
❖http://www.sonatype.com/products/maven/
documentation/book-defguide

123. Maven 3.1

124. Maven 3.1

125. Maven 3.1 POM Changes
❖ Backwards compatibility by modelVersion
❖ Final identifier TBD for 3.1 POM syntax
❖ Allows 3.1 to read 3.0, 2.0 POMs
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>com.ambientideas</groupId>
<artifactId>sample-barestbones</artifactId>
<version>1.0-SNAPSHOT</version>
</project>

126. Maven 3.1 POM Changes
❖pom.xml syntax changes
❖Site plugin takes over <reporting>

127. Maven 3.1 POM Changes
❖“Mixins” for direct dependencies
❖Sometimes desired over POM inheritance

128. Maven 3.1 POM Changes
❖Plugin security manager
❖settings.xml as default implementation

129. Summary

130. Summary
•Validations
•Performance
•Compatibility
•Toolchain
•Shell
•Polyglot
•M2Eclipse

131. Maven 3.0
What’s new in
Email
Twitter
Blog
Matthew McCullough
matthewm@ambientideas.com
@matthewmccull
http://ambientideas.com/blog

132. Maven 3.0
What’s new in
Email
Twitter
Blog
Matthew McCullough
matthewm@ambientideas.com
@matthewmccull
http://ambientideas.com/blog

133. References

134. ❖Maven 3 Core
❖ Homepage
❖ http://maven.apache.org/
❖ Source Code
❖ http://svn.apache.org/viewvc/maven/maven-3/trunk
❖ Wiki
❖ http://cwiki.apache.org/MAVEN/maven-3x.html
❖ Bug Tracking
❖ http://jira.codehaus.org/browse/MNG
❖ Compatibility
❖ http://cwiki.apache.org/MAVEN/maven-3x-compatibility-notes.html
❖ Blog Posts
❖ http://www.sonatype.com/people/2009/11/maven-3x-paving-the-desire-lines-
part-two/
❖ Bookmarks
❖ http://delicious.com/matthewmccullough/maven

135. ❖Maven 3 Site Plugin
❖ Source Code
❖ https://svn.apache.org/repos/asf/maven/plugins/branches/
maven-site-plugin-3.x/
❖ Wiki
❖ http://cwiki.apache.org/MAVEN/maven-3x-and-site-plugin.html

136. ❖Maven Shell
❖ Source Code
❖ http://github.com/sonatype/mvnsh/
❖ Wiki
❖ https://docs.sonatype.org/display/MVNSH
❖ Homepage
❖ http://shell.sonatype.org/

137. ❖Polyglot Maven
❖ Homepage
❖ http://polyglot.sonatype.org/
❖ Source Code
❖ http://github.com/sonatype/polyglot-maven
❖ Wiki
❖ https://docs.sonatype.org/display/PMAVEN/
❖ Groovy Macros
❖ https://docs.sonatype.org/display/PMAVEN/Groovy

138. ❖M2Eclipse
❖ Homepage
❖ http://m2eclipse.sonatype.org/
❖ Update Sites
❖ http://m2eclipse.sonatype.org/sites/m2e
❖ http://m2eclipse.sonatype.org/sites/m2e-extras