What are the element defined in pom.xml ?

pom.xml elements

• project : Root element
• modelVersion : Set to 4.0.0
• groupId : ID for project group
• artifactId : Project / Artifact Id
• version : Project version under given group

• packaging : Packaging type - jar / war / ...
• name : Name of maven project
• url : Project URL

• dependencies : Dependencies of the project
• dependency : A dependency under dependencies element
• groupId, artifactId, version
• scope : Scope of Maven project :
               compiled / provided / runtime / system / test

Example
<project ...>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.shaan.project</groupId>
  <artifactId>myapp</artifactId>

  <version>1.0</version>

  <packaging>jar</packaging>

  <name>My sample App</name>

  <url>http://maven.apache.org</url>

  <dependencies>

     <dependency>

          <groupId>junit</groupId>  

          <artifactId>junit</artifactId>  

          <version>4.2.2</version>  

          <scope>test</scope>

     </dependency>

     ...

  </dependencies>  

  ...

</project>

What is pom.xml and how it is different from project.xml ?

pom.xml

• POM = Project Object Model
• contains project info and configuration - dependencies, source dir, test dir, build dir
• Maven reads pom.xml and execute the target

pom.xml vs. project.xml

• Before Maven 2, project.xml is used
• pom.xml is used in Maven 2 and later versions

What is the fully qualified artifact name of Maven project ?

<groupId>:<artifactId>:<version>

How to check installed Maven version ?

Check maven version
mvn -version

How to install Maven ?

1. Download Maven
Download the zip from http://maven.apache.org/download.cgi and extract in your local system

2. Set MAVEN_HOME
In env vars, add MAVEN_HOME = <home-dir-of-maven>

3. Add Maven to Path variable
In path variable, add / append path of Maven
%MAVEN_HOME%/bin

4. Verify maven installation
mvn -version

What is the Build life cycle of Maven project ?

1. validate : Validate if the project is correct
2. compile : Compile the source code
3. test : Test the compiled source code using test framework
4. package : Make packaged distribution of the compiled code 
5. verify : Run checks on integration test results
7. install : Install package into local repo
8. deploy : Copy the package to remote repo

Local repo vs. Central repo vs. Remote repo

Local repo

• created by maven in local system when you run any maven command.

Central repo

• created on internet by maven community (Not a full set of libraries)

Remote repo

• Also on internet by different vendors and used inside pom.xml 

What are the functions of a Build tool ?

• Generate documentation from source code
• Compile source code
• Create jar/war/tzg package of compiled code, properties files and dependent JARs
• Sync the package to the repository

Which problems can be solved by Maven ?

• Managing dependent libraries
• In case of using frameworks, there must be a lot of JARs to include in project.

• Enforcing correct project structure
• according to frameworks used (JEE, Struts, Spring etc.)

• Project Build and Deployment

What are different repository types in Maven ?

Maven repo

• A directory of JAR file with pom.xml file
• used to search the dependencies
• Order of searching dependencies : Local -> Central -> Remote

1. Local

• in local system (Default : %USER_HOME%/.m2 directory)
• To change location : MAVEN_HOME/conf/settings.xml
• Directory automatically created when you run any maven command

Change location of local repo in settings.xml
<settings>
  <localRepository>/path</localRepository> 
</settings>


2. Central

• Repo created by Maven on internet (Location : http://repo1.maven.org/maven2/)
• contains common libraries

3. Remote

• Available on internet
• Some libraries which are not available on Central repo , they can be found in Remote repo
• Libraries (to use from Remote repo) are specified in pom.xml

Using libraries from Remote repo
<project>
  ....
  <dependencies>
     <dependency>
         <groupId>org.apache.wicket</groupId>
         <artifactId>wicket</artifactId>
         <version>1.4.21</version>
     </dependency>
  </dependencies>
</project>