The document provides information about Maven, an open source build automation tool. It describes what Maven is used for, how it manages project dependencies and builds through plugins bound to phases in a build lifecycle. Key Maven concepts discussed include the project object model (POM) file, GAV coordinates used to identify projects, and Maven's use of a "super POM" to inherit common configuration.

1. Maven
technical session
Dmitry

2. Bakaleinik
January

3. 2015

4. Maven
expert; know-it-all
ComingfromtheHebrewwordHebrew ‫מבין‬(mevin),
mavencanhavetwodefinitions.
Incommoncontextsmeansexpert.
However,insarcasticsettings,itisusedas“know-it-all”.
– YiddishSlangDictionary

5. The maven project was originally started as an attempt to
simplify the build processes.
Maven addresses two aspects of building software:
First, it describes how software is built, and second, it describes its
dependencies.
pom.xml
compiled code
artifact jar/war/
othertests coverage
documentation
quality report

6. What maven can do?
Centralize project information such as build metadata, properties, version
control systems, developers in project object model file (pom.xml).
Manage our build process; does project build tasks such as compilation,
unit testing, integration testing, quality metrics, documentation generation
as it required for the successful delivery.
Manage project library and resources dependencies.
Manage project artifacts deployment to corporate/public repositories.

7. Maven plugins
Maven is actually a plugin execution framework where every task is
actually done by plugins.
A plugin provides a set of actions or commands (in maven terminology
called goals) that can be executed to perform a task.
There are plugins for building, testing, source control management,
running a web server, generating project files and much more.
Some basic plugins are included in every project by default, and they have
sensible default settings.

8. Maven plugins suite
Core
clean
compiler
deploy
failsafe
install
resources
site
surefire
verifier
Reporting
Changelog
Changes
Checkstyle
Clover
Javadocs
PMD
Surefire-reports
Local servers
Cargo
jaxme
jetty
tomcat
Tools
Ant
Antlr
Antrun
Archetype
Assembly
Help
Release
Packaging
jar war ear ejb
rar pom shade
IDE integration
eclipse
idea

9. Maven plugins suite
Core
clean
compiler
deploy
failsafe
install
resources
site
surefire
verifier
Reporting
Changelog
Changes
Checkstyle
Clover
Javadocs
PMD
Surefire-reports
Local servers
Cargo
jaxme
jetty
tomcat
Tools
Ant
Antlr
Antrun
Archetype
Assembly
Help
Release
Packaging
jar war ear ejb
rar pom shade
IDE integration
eclipse
idea
And

10. much

11. more…⋯

12. Maven plugin goals

13. Maven plugin goals
A plugin generally provides a set of goals and which can be executed using
following syntax:
mvn [plugin-name]:[goal-name]

14. Maven plugin goals
A plugin generally provides a set of goals and which can be executed using
following syntax:
mvn [plugin-name]:[goal-name]
For example, a Java project can be compiled with the maven-compiler-
plugin's compile-goal by running following command:
my-project-dir mvn compiler:compile

15. Maven plugin goals
A plugin generally provides a set of goals and which can be executed using
following syntax:
mvn [plugin-name]:[goal-name]
For example, a Java project can be compiled with the maven-compiler-
plugin's compile-goal by running following command:
my-project-dir
You can get information about plugin and its goals using maven help
plugin:
mvn help:describe -Dplugin=compiler

16. Maven plugin goals
A plugin generally provides a set of goals and which can be executed using
following syntax:
mvn [plugin-name]:[goal-name]
For example, a Java project can be compiled with the maven-compiler-
plugin's compile-goal by running following command:
my-project-dir
You can get information about plugin and its goals using maven help
plugin:
mvn help:describe -Dplugin=compiler

17. Project Object Model (POM)

18. Project Object Model (POM)
A Project Object Model or POM is the fundamental unit of work in Maven.
It’s an XML file that contains information about the project and configuration
details used by Maven to build the project.
The configuration that can be specified in the POM are the project dependencies,
the plugins or goals that can be executed, the build profiles, and so on.
When executing a task or goal, Maven looks for the POM in the current working
directory, but you can explicitly tell to maven path of POM file:
mvn -f path/to/pom.xml

19. Simplest pom.xml

20. Coordinates.What???
Every maven project is identified by its GAV coordinates.
groupId (G) - It’s an identifier for a collection of related modules.
This is usually a hierarchy that starts with the organization that produced the
modules, and then possibly moves into increasingly more specialized projects,
e.g. com.sap.ui5 or com.sap.fiori.
G
A
V

21. Coordinates.What???
artifact (A) - It’s a unique identifier or a simple name that is given to a
module within a group
There can be multiple modules in a group.
If a group has a module called webapp, its artifactId will be“webapp”.
G
A
V

22. Coordinates.What???
version (V) - It’s an identifier for the release or build number of project,
e.g. 1.0 or 1.0-SNAPSHOT
G
A
V

23. Coordinates.What???
version (V) - It’s an identifier for the release or build number of project,
e.g. 1.0 or 1.0-SNAPSHOT
Now what’s this SNAPSHOT?
G
A
V

24. Versioning strategy
There are two types of versions: release and snapshot.
Releases - a version that is assumed never to change.
Only to be used for a single state of the project when it is released and then updated to the
next snapshot
Snapshot - used by projects during development as it implies that development is still
occurring that project may change
G
A
V

25. Simplest pom.xml

26. Simplest pom.xml
mvn install

27. Simplest pom.xml
mvn install
{
compile code
run tests
package as jar
deploy to local repo

28. How all this can be done
from 6 lines of xml?

29. Super POM

30. Super POM
The modelVersion property defines the super POM
file (org/apache/maven/model/pom-4.0.0.xml)

31. Super POM
The modelVersion property defines the super POM
file (org/apache/maven/model/pom-4.0.0.xml)

32. Super POM
The modelVersion property defines the super POM
file (org/apache/maven/model/pom-4.0.0.xml)
Standard

33.
directory

34.
layout

35. Super POM
The modelVersion property defines the super POM
file (org/apache/maven/model/pom-4.0.0.xml)
properties
interpolation

36. Super POM
The modelVersion property defines the super POM
file (org/apache/maven/model/pom-4.0.0.xml)

37. Super POM
The modelVersion property defines the super POM
file (org/apache/maven/model/pom-4.0.0.xml)
Work with the same analogy as objectsinheritance
Effec%ve'POM'
POM'
Parent'
POM'
Super'
POM'

38. Super POM
The modelVersion property defines the super POM
file (org/apache/maven/model/pom-4.0.0.xml)
Work with the same analogy as
To see the merged pom:
mvn help:effective-pom Effec%ve'POM'
POM'
Parent'
POM'
Super'
POM'

39. Property references
env.*
Environment variables exposed by OS or Shell
${env.JAVA_HOME}
project.*
POM elemens
${project.groupId} ${project.parent.groupId}
settings.*
Maven settings.xml properties
${settings.localRepository}
Custom properties
${foo}

40. Build Lifecycle
In maven, the build is run is a predefined ordered set of steps called the
build lifecycle.
The individual steps are called phases and the same phases are run for
every maven build using the default lifecycle, no matter what it produce.
The build task that will be performed during each phase are determined by
the configuration in the project file, and in particular in the selected
packaging.

41. Build lifecycle
Validate
• Validate the project is correct
and all necessary information
is available
Compile
• Compile the source code of
the project
Test
• Test the compiled code using
a suitable unit testing
framework. These tests
should not require the code
be packaged or deployed
Package
• Take the compiled code and
package it in distributable
format, such as a JAR
Integration-test
• Process and deploy the
package if necessary into a
environment where
integration tests can run
Verify
• Run any checks to verify the
package is valid and meets
the quality criteria
Install
• Install the package into the
local repository, for use as a
dependency for other
projects locally
Deploy
• Done in integration or release
environment, copies the final
package to the local
repository, then deploy the
installed package in a
specified environment.
Default
Lifecycle
(collectionofbuildphases)

42. Build lifecycle
mvn install
Validate
• Validate the project is correct
and all necessary information
is available
Compile
• Compile the source code of
the project
Test
• Test the compiled code using
a suitable unit testing
framework. These tests
should not require the code
be packaged or deployed
Package
• Take the compiled code and
package it in distributable
format, such as a JAR
Integration-test
• Process and deploy the
package if necessary into a
environment where
integration tests can run
Verify
• Run any checks to verify the
package is valid and meets
the quality criteria
Install
• Install the package into the
local repository, for use as a
dependency for other
projects locally
Deploy
• Done in integration or release
environment, copies the final
package to the local
repository, then deploy the
installed package in a
specified environment.
X

43. Build lifecycle
Validate
• Validate the project is correct
and all necessary information
is available
Compile
• Compile the source code of
the project
Test
• Test the compiled code using
a suitable unit testing
framework. These tests
should not require the code
be packaged or deployed
Package
• Take the compiled code and
package it in distributable
format, such as a JAR
Integration-test
• Process and deploy the
package if necessary into a
environment where
integration tests can run
Verify
• Run any checks to verify the
package is valid and meets
the quality criteria
Install
• Install the package into the
local repository, for use as a
dependency for other
projects locally
Deploy
• Done in integration or release
environment, copies the final
package to the local
repository, then deploy the
installed package in a
specified environment.
X mvn clean install
+Pre-clean
Clean
• Remove all
previous build files
Post-clean

44. Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy

45. jslint plugin
jslint
Compiler plugin
compile testCompile
Cargo plugin
deploy run
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Clean plugin
clean

46. jslint plugin
jslint
Compiler plugin
compile testCompile
Cargo plugin
deploy run
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Clean plugin
clean

47. jslint plugin
jslint
Compiler plugin
compile testCompile
Cargo plugin
deploy run
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Clean plugin
clean
Each plugin comes
with its goals bound
to lifecycle phases
In

48. maven

49. terminology

50. such

51. binding

52. called

53. MOJO

54.
Its

55. also

56. predefines

57. goal

58. configuration

59. jslint plugin
jslint
Compiler plugin
compile testCompile
Cargo plugin
deploy run
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Clean plugin
clean
Each plugin comes
with its goals bound
to lifecycle phases

60. jslint plugin
jslint
Compiler plugin
compile testCompile
Cargo plugin
deploy run
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Clean plugin
clean
Each plugin comes
with its goals bound
to lifecycle phases

61. jslint plugin
jslint
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Each plugin comes
with its goals bound
to lifecycle phases

62. jslint plugin
jslint
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Each plugin comes
with its goals bound
to lifecycle phases

63. jslint plugin
jslint
Mapping
Lifecycle
Clean Validate Compile
Test Package
Integration-
test
Verify Install Deploy
Each plugin comes
with its goals bound
to lifecycle phases
TIP: to disable
a preconfigured
plugin execution
change phase to
“none”

64. Package type

65. The specific goals bound to each phase default to a set of goals specific to a
project’s packaging.
Package type

66. The specific goals bound to each phase default to a set of goals specific to a
project’s packaging.
A project with packaging jar has a different set of default goals from a project
with a packaging of war.The packaging element affects the steps required to
build a project.
Package type

67. Package type

68. JAR is the default packaging type, the most common, and thus the most
commonly encountered lifecycle configuration.
Package type

69. JAR is the
commonly encountered lifecycle configuration.
POM is the simplest packaging type.The artifact that it generates is itself
only, rather than a JAR, SAR, or EAR.There is no code to test or compile, and
there are no resources the process.
Package type

70. JAR is the
commonly encountered lifecycle configuration.
POM is the simplest packaging type.The artifact that it generates is itself
only, rather than a JAR, SAR, or EAR.There is no code to test or compile, and
there are no resources the process.
TheWAR packaging type is similar to the JAR type.The exception being the
package goal of war:war. Note that the war:war goal requires a web.xml
configuration in your src/main/webapp/WEB-INF directory.
Package type

71. Dependencies mechanism
The cornerstone of the POM is its
dependency list. Because most
every project depends upon
others to build and run correctly.
It happens with the Coordinates!

72. Dependencies
One powerful aspect of Maven is in its handling of project relationships; that
includes inheritance, aggregation (multi-module projects) and dependencies
(it also includes transitive dependencies).

73. Dependencies
One powerful aspect of Maven is in its handling of project relationships; that
includes inheritance, aggregation (multi-module projects) and dependencies
(it also includes transitive dependencies).
Whats it transitive dependencies?
Maven brings the dependencies of the project dependencies, allowing your
dependency list to focus solely on project requirements.

74. Dependencies
One powerful aspect of Maven is in its handling of project relationships; that
includes inheritance, aggregation (multi-module projects) and dependencies
(it also includes transitive dependencies).
Whats it transitive dependencies?
Maven brings the dependencies of the project dependencies, allowing your
dependency list to focus solely on project requirements.
Dependency management has a long tradition of being a complicated mess for
anything but the most trivial of projects. Maven solves both problems through a
common local repository from which to link projects correctly, versions and all.

75. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath

76. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath
This is the default scope, used if
none is specified. Compile
dependencies are available in all
classpaths. Furthermore, those
dependencies are propagated to
dependent projects.

77. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath
This is much like compile, but
indicates you expect the JDK or a
container to provide it at
runtime. It is only available on
the compilation and test
classpath, and is not transitive.

78. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath
This scope indicates that the
dependency is not required for
compilation, but is for execution.
It is in the runtime and test
classpaths, but not the compile
classpath.

79. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath
This scope indicates that the
dependency is not required for
normal use of the application,
and is only available for the test
compilation and execution
phases.

80. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath
This scope is similar to provided
except that you have to provide
the JAR which contains it
explicitly.The artifact is always
available and is not looked up in
a repository.

81. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath
This scope used to import
dependencies defined in
configuration of the other
project

82. Scopes
compile provided
runtime test
system import
Compile Test Runtime
Classpath

83. Repositories
Local repository in %USER_HOME%/.m2/repository
Remote repository
Example: http://repo1.maven.org/maven2 or
another internal company repository, like nexus.wdf.sap.corp
The repository contains dependencies and plugins, can store any kind of
artifact: jar, war, pom, ejb, ear.
The repository can be managed by a“repository manager”like Nexus

84. Lifecycle
Maven
Project
pom.xml
source code

85. Lifecycle
Maven
Project
pom.xml
source code
reads the configuration

86. Lifecycle
Maven
Project
pom.xml
source code
fetches the dependencies
M2 local repo

87. Lifecycle
Maven
Project
pom.xml
source code
M2 local repo
NEXUS
fetches missing dependencies from the Internet into M2

88. Lifecycle
Maven
Project
pom.xml
source code
M2 local repo
NEXUS
fetches missing dependencies from the Internet into M2

89. Lifecycle
Maven
Project
pom.xml
source code
M2 local repo
NEXUS
target folder
copies the dependencies

90. Lifecycle
Maven
Project
pom.xml
source code
M2 local repo
NEXUS
target folder
build the project

91. Lifecycle
Maven
Project
pom.xml
source code
M2 local repo
NEXUS
target folder
deploys artifact to local repository

92. Lifecycle
Maven
Project
pom.xml
source code
M2 local repo
NEXUS
target folder

93. Inheritance
Parent
Project
Child
Project
Extends

94. Aggregation
Project A
Project B
Project C
cd A
mvn clean install
cd ..
cd B
mvn clean install
cd ..
cd C
mvn clean install
Depends
Depends
}8 lines!!!

95. Aggregation
Project A
Project B
Project C
Reactor

96. Aggregation
Project A
Project B
Project C
Reactor

97. Debugging maven
Output full error stack trace:
maven anygoal -e
Output for debugging
maven anygoal -X

98. settings.xml
The settings.xml file contains configuration of Maven execution. Settings in this file are
settings which apply to many projects and which should not be bundled to any specific
project, or distributed to an audience.These include values such as the local repository
location, alternate remote repository servers, and authentication information.

99. settings.xml
The settings.xml file contains configuration of Maven execution. Settings in this file are
settings which apply to many projects and which should not be bundled to any specific
project, or distributed to an audience.These include values such as the local repository
location, alternate remote repository servers, and authentication information.
Maven provides 2 settings files:
Local settings.xml at %USER_HOME%/.m2/settings.xml
Global settings.xml at %M2_HOME%/conf/settings.xml

100. settings.xml
The settings.xml file contains configuration of Maven execution. Settings in this file are
settings which apply to many projects and which should not be bundled to any specific
project, or distributed to an audience.These include values such as the local repository
location, alternate remote repository servers, and authentication information.
Maven provides 2 settings files:
Local settings.xml at %USER_HOME%/.m2/settings.xml
Global settings.xml at %M2_HOME%/conf/settings.xml
These files are not bundled with Maven project and don’t get distributed

101. settings.xml
The settings.xml file contains configuration of Maven execution. Settings in this file are
settings which apply to many projects and which should not be bundled to any specific
project, or distributed to an audience.These include values such as the local repository
location, alternate remote repository servers, and authentication information.
Maven provides 2 settings files:
Local settings.xml at %USER_HOME%/.m2/settings.xml
Global settings.xml at %M2_HOME%/conf/settings.xml
These files are not bundled with Maven project and don’t get distributed
If both files exists, their content get merged

102. settings.xml
The settings.xml file contains configuration of Maven execution. Settings in this file are
settings which apply to many projects and which should not be bundled to any specific
project, or distributed to an audience.These include values such as the local repository
location, alternate remote repository servers, and authentication information.
Maven provides 2 settings files:
Local settings.xml at %USER_HOME%/.m2/settings.xml
Global settings.xml at %M2_HOME%/conf/settings.xml
These files are not bundled with Maven project and don’t get distributed
If both files exists, their content get merged
Local settings.xml overrides the global one

103. settings.xml
The settings.xml file contains configuration of Maven execution. Settings in this file are
settings which apply to many projects and which should not be bundled to any specific
project, or distributed to an audience.These include values such as the local repository
location, alternate remote repository servers, and authentication information.
Maven provides 2 settings files:
Local settings.xml at %USER_HOME%/.m2/settings.xml
Global settings.xml at %M2_HOME%/conf/settings.xml
These files are not bundled with Maven project and don’t get distributed
If both files exists, their content get merged
Local settings.xml overrides the global one

104. settings.xml
The settings.xml file contains configuration of Maven execution. Settings in this file are
settings which apply to many projects and which should not be bundled to any specific
project, or distributed to an audience.These include values such as the local repository
location, alternate remote repository servers, and authentication information.
Maven provides 2 settings files:
Local settings.xml at %USER_HOME%/.m2/settings.xml
Global settings.xml at %M2_HOME%/conf/settings.xml
These files are not bundled with Maven project and don’t get distributed
If both files exists, their content get merged
Local settings.xml overrides the global one

105. Common criticism of maven
Poor documentation - Lots of maven documentation is automatically generated and
is generally pretty horrible.
Simple things are pretty counterintuitive in maven, e.g. copying a file
Maven adds to the number of places you need to look when something breaks -
both your source code, local repository and the remote repository.
Everything breaks if someone changes an artifactId or groupId
Doesn’t work well if your network connectivity is unreliable or unavailable
A huge output log

106. Maven + NPM + Grunt
eirslett/frontend-maven-plugin
This plugin downloads/installs Node and NPM locally for your project, runs
NPM install, installs bower dependencies, run Grunt and/or gulp and/or
Karma. It's supposed to work onWindows, OS X and Linux.

107. Maven + NPM + Grunt
eirslett/frontend-maven-plugin
This plugin downloads/installs Node and NPM locally for your project, runs
NPM install, installs bower dependencies, run Grunt and/or gulp and/or
Karma. It's supposed to work onWindows, OS X and Linux.

108. Thanks