Java Magazine - November/December 2011

//java architect /

Understanding the Hudson Plug-in
Development Framework: Part I

WINS TON PRAKASH AND SUSAN DUNCAN

Use the Hudson Plug-in Interface tool to create, build, run, and debug custom plug-ins that extend Hudson
to meet the specific needs of your projects.

JAVA IN ACTION

This article is for beginners who are interested in understanding the fundamentals of Hudson plug-in development. Hudson is a popular open source continuous integration (CI) tool written purely in Java. Apart from being an open source product, the popularity of Hudson is due to its extensible nature, which uses plug-ins and the plug-in developer ecosystem.

Plug-ins allow developers to do everything from customize the way builds are done and results are displayed to enable integration with application lifecycle management (ALM) systems such as software configuration management (SCM), testing and analysis tools, and so on. More than 400 Hudson plug-ins, supporting various aspects of CI, are available for free installation.

Hudson provides a
series of extension points
that allow developers
to extend Hudson’s functional-
ity. The Hudson Plug-in Interface
(HPI) tool helps developers create,
build, run, and debug plug-ins.

Tip: The HPI tool is a Maven plug-in. Hudson extensively uses Maven, another popular open source software project management and comprehension tool, which can be downloaded from maven.apache.org.

Generating the skeleton plug-in.

The first step is to create the skeleton plug-in, which is a bare-bones plug-in. The following simple command tells Maven to create the Hudson plug-in skeleton’s source code using the HPI tool:

Tip: Maven might throw the following error:

[ERROR] No plug-in found for prefix 'hpi' in the current project ..

If it does, add the following entry in the ~/.m2/settings.xml file:

<plug-inGroups> <plug-inGroup> org.jvnet.hudson. tools</plug-inGroup> </plug-inGroups>

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mvn hpi:create

Hudson’s popularity is due to its extensible nature.

Maven downloads all the required software to execute the command and prompts you for the groupID and artifactID.

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PHOTOGRAPH BY BOB ADLER

Creating and Tuning a
Hudson Plug-in
First, we’ll look at how to
create a Hudson plug-in
using the HPI tool, create
and run a project for the
plug-in, and view the
plug-in in action on the
Hudson test server.

Enter the groupId of your plug-in:
org.sample.hudson
Enter the artifactId of your
plug-in:
sample-plug-in

The name of the generated folder depends on the value you entered for the artifactId. The file structure of the generated folder will have the following layout: