# Develop Plugins

This document describes how to write an XJC plugin to extend the code generation of XJC.

## What Can A Plugin Do?

An XJC plugin participates in the code generation from a schema. It can define its own customizations that users can use to control it, it can access the code that the JAXB RI generates, it can generate additional classes/methods/fields/annotations/comments, and it can also replace some of the pluggability points in the compilation process, such as XML name -> Java name conversion.

As a show case of what a plugin can do, take a look at plugins hosted at JAXB2-commons.

### Quick Start

To write a plugin, do the following simple steps.

1. Write a class, say, `org.acme.MyPlugin` by extending `com.sun.tools.xjc.Plugin`. See javadoc for how to implement methods.

2. Write the name of your plugin class in a text file and put it as `/META-INF/services/com.sun.tools.xjc.Plugin` in your jar file.

Users can then use your plugins by declaring an XJC ant task with your jar files.

    <taskdef name="xjc" classname="com.sun.tools.xjc.XJCTask">
        <classpath>
            <fileset dir="jaxb-ri/lib" includes="*.jar"/>
            <fileset dir="your-plugin" includes="*.jar"/>
        </classpath>
    </taskdef>

### Resources

Although we will do our best to maintain the compatibility of the interfaces, it is still subject to change at this point.