$Revision: 1.8 $	$Name: $	$Date: 2006/04/13 13:54:09 $	Working with maven 2
$Source: /ppw/training/maven/repository/maven2/src/html/helloWorld.html,v $

Hello World

Create a Project Directory

Create a fresh, prepped maven project directory
- mvn archetype:create -DgroupId=be.peopleware.training.maven -DartifactId=helloWorld
- Using the default archetype for a jar with a HelloWorld main()
Note download of necessary plugins and libraries the plugins depend on, on first need!
- This may take a while
- Only once
This creates a project directory
- Standard directory layout
- With a POM

Quick Look at Initial Directory Layout

Standard layout for jar-projects

.
`-- helloWorld	project directory
\|-- pom.xml	POM
`-- src	things that change (things to put under version control)
\|-- main	the main source, the core of the project
\| `-- java	the main Java source
\| `-- be \| `-- peopleware \| `-- training \| `-- maven	Java package structure (copied from groupId)
\| `-- App.java	sample HelloWorld `main()`
`-- test	the test source
`-- java	the test Java source
`-- be `-- peopleware `-- training `-- maven	Java package structure like in `helloWorld/src/main/java`
`-- AppTest.java	sample JUnit test class

Quick Look at the POM

Project Object Model
helloWorld/pom.xml
Core of maven: declarative description of project meta-information

<project xmlns="http://maven.apache.org/POM/4.0.0"	the POM is an XML file, with a namespace
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"	the namespace for XML schemata
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">	schemaLocation makes it possible for XML editors to download the schema for a namespace from an URL
<modelversion>4.0.0</modelversion>	POM's have a version, so that maven can check whether the used version of the program can cope with the syntax of the POM
<groupid>be.peopleware.training.maven</groupid>	artifacts are gathered in groups, to avoid naming conflicts; also used as package name by archetype :-(
<artifactid>helloWorld</artifactid>	the name of the artifact to be created in this project
<packaging>jar</packaging>	the type of the artifact to be created; this defines what to do exactly during the build
<version>1.0-SNAPSHOT</version>	the version of the artifact we are currently working on; `SNAPSHOT` means we are working toward version `1.0`, but we are not ready to release yet
<name>Maven Quick Start Archetype</name>	the human-readable name of the artifact to be created (change this)
<url>http://maven.apache.org</url>	the URL where information about this project can be found (change this)
<dependencies>	the list of other artifacts this project depends on; they will be downloaded as needed from a remote repository (change this)
<dependency>	this project depends on JUnit
<groupid>junit</groupid>	the JUnit artifact is stored in group junit
<artifactid>junit</artifactid>	the JUnit artifact is called junit
<version>3.8.1</version>	we want version 3.8.1 of JUnit
<scope>test</scope>	we only need JUnit during test of our project
</dependency> </dependencies> </project>

Create the Artifact

cd helloWorld
mvn package
- Validate project setup
- Prepare main resource files
- Compile main Java code
- Prepare test resource files
- Compile test Java code
- Run the tests
  - Creates a report
- Produce the artifact
  - package main class files and main resources in a jar
Note download of necessary plugins and libraries the plugins depend on, on first need!
- This may take a while
- Only once
New directory is created for build temps and result
- target

helloWorld/ \|-- pom.xml \|-- src/ \| \|-- …
`-- target/	generated material (things not to put under version control: add to `.cvsignore`/`.svnignore`/…)
\|-- classes/ \| `-- be/ \| `-- peopleware/ \| `-- training/ \| `-- maven/ \| `-- App.class	result of compilation of main Java source and copy of main resources
\|-- exported-pom.xml	consolidated POM (there is more than what we saw earlier; have a look)
\|-- helloWorld-1.0-SNAPSHOT.jar	the created artifact; note the compound name `artifactId-version.jar`
\|-- surefire-reports/	test reports
\| \|-- TEST-be.peopleware.training.maven.AppTest.xml	XML version of test report
\| `-- be.peopleware.training.maven.AppTest.txt	text version of test report
`-- test-classes/ `-- be/ `-- peopleware/ `-- training/ `-- maven/ `-- AppTest.class	result of compilation of test Java source and copy of test resources

There is More in the Default Build Lifecycle

Integration tests
Other verifications
Local installation of the artifact
Deploy the artifact

The `jar` Has Even More

unzip the jar

helloWorld-1.0-SNAPSHOT.jar/ \|-- META-INF/
\| \|-- MANIFEST.MF	maven generate a manifest (have a look); maven has put the version information and other build information here
\| `-- maven/	maven information is also meta-information
\| `-- be.peopleware.training.maven/ \| `-- helloWorld/	there is room for meta-information on several maven projects here
\| \|-- pom.properties	meta-information on the POM (meta-meta-information)
\| `-- pom.xml	the exported (consolidated) POM
`-- be/ `-- peopleware/ `-- training/ `-- maven/ `-- App.class

Version information in the manifest according to the Java™ Product Versioning standard
- More or less: no maven support yet for the separation between specification and implementation

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven
Built-By: jand
Build-Jdk: 1.4.2_09
Extension-Name: helloWorld
Implementation-Title: helloWorld
Implementation-Version: 1.0-SNAPSHOT

Create the Site

A website documenting the current state of the project
mvn site
Note download of necessary plugins and libraries the plugins depend on, on first need!
- This may take a while
- Only once
New directory in target
- target/site
Open target/site/index.html
Site contains:
- Meta-information: for users and developers
  - name, version, date
  - dependencies
  - license
  - references to issue tracking (bug db)
  - references to mailing lists, newsgroups
  - where and how to get the source
  - who are the developers
  - …
- User and developer documentation
- Reports on progress, quality of project
  - test reports
  - style reports
  - metrics
  - …
With this small POM, most is empty
- We need to add information and choices to the POM for a more complete site
Later, site can also be automatically deployed to the project/url

Create a Project Directory

Quick Look at Initial Directory Layout

Quick Look at the POM

Create the Artifact

There is More in the Default Build Lifecycle

The jar Has Even More

Create the Site

The `jar` Has Even More