How to do a modular project architecture with Maven in Eclipse? - eclipse

Question

First of all im a little newbie in Maven+Eclipse world, so please excuse me if im not explaining myself good.
Im trying to implement Maven to existing Java old projects, the architecture im trying to achive is something like this (i put an image to explain myself a little better):
The project Utils have the most of the libs, that genericlly will be used for the other projects, and some classes that will be useful for the others (like date comparison method and mathematic method etc...), this project is working well with mvn install, generating the respective .war file.
The questions are:
The N Web Modules projects must have the project Utils as a
depedency and the most of dependencies too. I
don't know how to achive this in the pom.xml of N Web Modules
projects.
I don't know if it is posible in
Eclipse+Maven: Try to do some Parent Web Project that
implements the other projects and in one single mvn install the
parent project build and install the rest of the childs
(including Utils and N Web Modules).
I hope you can orientate and help me with this.

Answer 1

I think you are looking for Multi-Module projects
http://books.sonatype.com/mvnex-book/reference/multimodule.html
You can put various subprojects in one larger project and build them all at once. Furthermore, modules can depend on other modules (as long as this is not circular) and they are build in the correct order.

Answer 2

The project Utils have the most of the libs, that genericlly will be
used for the other projects, and some classes that will be useful for
the others (like date comparison method and mathematic method etc...),
this project is working well with mvn install, generating the
respective .war file.
One advise, you should extract classes used by other projects in a maven project with a JAR packaging and not leave them in a WAR packaging.
In Maven, generally, dependencies are provided as JAR.
It may also be provided as WAR by configuring the maven-war-plugin with some specific properties such as attachClasses but it looks like a trick and it also may create side effects.
Here are some information on how to do it.
But the documentation doesn't advise this way :
If you need to re-use this JAR/WAR in another project, the recommended
approach is to move the classes to a separate module that builds a
JAR, and then declare a dependency on that JAR from your webapp as
well as from any other projects that need it.
About your two questions.
The N Web Modules projects must have the project Utils as a dependency
and the most of dependencies too. I don't know how to achive this in
the pom.xml of N Web Modules projects.
Just include it as a dependency in the dependencies element of the consumer project :
<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>mygroup</groupId>
<artifactId>project1-consumer</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
...
<dependencies>
<dependency>
<groupId>mygroup</groupId>
<artifactId>util</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
...
</dependencies>
</project>
I don't know if it is posible in Eclipse+Maven: Try to do some Parent
Web Project that implements the other projects and in one single mvn
install the parent project build and install the rest of the childs
(including Utils and N Web Modules).
What you are looking for is designing a multi-module project.
It relies on a aggregator pom that declares each module.
Note that this module has to be specified with a pom packaging as it doesn't produce a consumable artifact.
You could define something like that :
<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>mygroup</groupId>
<artifactId>myaggregatorpom</artifactId>
<packaging>pom</packaging>
<version>1.0-SNAPSHOT</version>
<modules>
<module>util</module>
<module>project1-consumer</module>
<module>project2-consumer</module>
</modules>
</project>