Tag Archives: plugin

Maven How-To: Merging Plugin Configuration in Complex Projects


January 12, 2011 By Bentmann Benjamin

In projects with many parent POMs, profiles, and plugin management sections, one can easily end up in a situation where the effective configuration for a plugin is the result of merging many configuration blocks from the various POM sources together.

Not knowing the details of this merge process naturally leads to some confusion about why an effective configuration looks the way it looks, or why changes to some parent POM’s configuration don’t have the desired effects in child POMs.

This post attempts to shed some light on this confusion, and provides you with a sense of how Maven merges plugin configuration from multiple sources.   This post uses attributes which are available in Maven 3.0.2.

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Retrieving a plugin's documentation


December 13, 2010 By Anders Hammar

One of the key things driving the adoption of Maven, is the rich set of plugins available. Whenever you want to add some functionality to the build process, or possibly even just want to do a one-time job, chances are that there is already a plugin for that.

When you want to use Maven plugins, you need to get more information about them to know how to use them. Most often, there is online documentation that describes the goals and parameters. However, sometimes no such documentation exists or you just cannot find it. Also, the online documentation very often describes the latest version of the plugin – but what if you have to use an older version?

This blog post will explain the different options you have to retrieve information about a plugin, just by using Maven itself.

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DIY: Retrieving a Maven plugin's documentation


June 9, 2010 By Anders Hammar

One of the key things driving the adoption of Maven, is the rich set of plugins available. Whenever you want to add some functionality to the build process, or possibly even just want to do a one-time job, chances are that there is already a plugin for that.

When you want to use Maven plugins, you need to get more information about them to know how to use them. Most often, there is on-line documentation that describes the goals and parameters. However, sometimes no such documentation exists or you just cannot find it. Also, the on-line documentation very often describes the latest version of the plugin – what if you have to use an older version?

I recently faced a closed-source plugin, with no documentation. This blog post will explain the different options you have to retrieve information about a plugin, just by using Maven itself.

As mentioned above, the simplest way of viewing a plugin’s documentation is to use the one provided on-line. Normally in HTML and created by the Maven Site Plugin, this is what we have got used to with most open source plugins.

Not only does this documentation describe the available goals and its parameters, but it most often also provides examples and other useful information. If available, this should normally be your first choice. However, there are at least two other ways of retrieving information from a plugin about it’s goals and parameters. These come in handy when there is no other documentation, but also when you want to be sure to find the goals and parameters of a specific version of the plugin.

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How to make a plugin that runs once during a build


May 22, 2009 By Brian Fox

With it’s default behavior, Maven runs a plugin invocation for each project in a multi-module build. For plugins that operate on a single project at a time, this is what the author wants.

Some plugins are what we call “aggregators” which means they actually do want all the information about the full multi-module build before execution. These plugins, when run on a tree of projects cause Maven to resolve all the children before calling the plugin’s execute() method. In this mode a plugin executes just once, but effectively on the whole tree at once. (as a side note, you never want to bind an aggregator goal in your pom as this would cause the plugin to run an n! recursive build since the lifecycle would step into each child and execute the aggregator…which would cause Maven to reresolve all the children, etc)

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