Re: [maven] Re: Auto building parent and sibling projects as needed

Guillaume Polet Mon, 12 Sep 2011 00:01:43 -0700

Le 11/09/2011 17:37, Jason Pyeron a écrit :

-----Original Message-----
From: Guillaume Polet
Sent: Sunday, September 11, 2011 4:07
To: Maven Users List
Subject: [maven] Re: Auto building parent and sibling
projects as needed


The problem is that a child does not know where the sources
of its parents are located,

Is it not the point of<relativePath>../pom.xml</relativePath>?

No, this simply indicates where to look relatively to find a pom.xml ifit is not installed in your local repository (or a remote one where itcould be fetched from).

and therefore it is completely
unable to trigger its build. You probably have set up one or
more parent aggregator projects and you mapped this hierarchy
onto the file/directory structure but this is not mandatory
at all. You can very well use a parent just to define the
default version to use for dependencies, or the default
target of the compiler, other properties that are common
through all your projects and many more things.
You should probably read again the first two paragraphs here:

http://maven.apache.org/guides/introduction/introduction-to-the-pom.html#Project
_Inheritance_vs_Project_Aggregation

Read that before and again. See the bottom of the email and attachment (the
poms).

The first one explains the benefits of inheritance while the
second explain the aggregation.

Hope this helps you clear things out.

Still stuck at the same place, but thanks for confirming what I read.

Cheers,
Guillaume

Le 11/09/2011 06:21, Jason Pyeron a écrit :

I am trying to understand why maven's reactor would not add

a parent

and a parent's children to the build when it is detected that the
dependency is not in the repository.

Is there a use case to NOT auto build? Or is there a

technical hurdle

to overcome to accomplish this in the reactor design?

Could I be missing a concept on maven usage?

I have a project which has a very large set of parent/child/sibling
dependencies I am migrating from our ant build system. When an
engineer needs to make changes on their part it would be

best for them

to execute mvn from that parts directory.

Hard to say why your second build is failing. I just tried a similarsetup and it worked in all cases:

parent:

<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/4.0.0http://maven.apache.org/maven-v4_0_0.xsd";>

<modelVersion>4.0.0</modelVersion>
<groupId>test</groupId>
<artifactId>parent</artifactId>
<packaging>pom</packaging>
<name>parent</name>
<version>1.0.0-SNAPSHOT</version>
<modules>
<module>B</module>
<module>A</module>
</modules>
</project>
A:

<modelVersion>4.0.0</modelVersion>
<groupId>test</groupId>
<artifactId>A</artifactId>
<name>A</name>
<version>1.0.0-SNAPSHOT</version>
<packaging>pom</packaging>
<parent>
<groupId>test</groupId>
<artifactId>parent</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath>
</parent>
</project>
B:

<modelVersion>4.0.0</modelVersion>
<groupId>test</groupId>
<artifactId>B</artifactId>
<name>B</name>
<version>1.0.0-SNAPSHOT</version>
<packaging>pom</packaging>
<parent>
<groupId>test</groupId>
<artifactId>parent</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>test</groupId>
<artifactId>A</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</project>

With the directory hierarchy:
* parent
    * A
    * B
and the results from the build:
D:\tmp\parent>mvn package
[INFO] Scanning for projects...