Recipe 12.2 Creating plugin.xml

12.2.1 Problem

You want to do the minimal work required to create a new plug-in.

12.2.2 Solution

At a minimum, every plug-in needs a plugin.xml file that tells Eclipse about it. And if you have a plugin.xml file, you have a plug-in—even one that doesn't have any code. Start off plugin.xml with a standard XML declaration, add a <plugin> element, and set the id, name, version, and provider-name attributes of this element. Then store plugin.xml in a folder in the plugins directory to install this rudimentary plug-in.

12.2.3 Discussion

To get a handle on how Eclipse views plug-ins, we'll create a minimal plug-in now, which has only a plugin.xml file. This file is called the plug-in manifest, and it tells Eclipse all about the plug-in and where to find the Java support code, if any. Because, as far as Eclipse is concerned, all you need to create a plug-in is a plug-in manifest, we'll create one now as an example.

Use any text editor that can save plain text, including Eclipse, to create a plug-in manifest for a plug-in named org.cookbook.simple. Here's what plugin.xml looks like when specifying the plug-in's name, ID, version number, and provider name:

<?xml version="1.0" encoding="UTF-8"?>
<plugin
    id="org.cookbook.simple"
    name="Simple Plug-in"
    version="1.0.0"
    provider-name="Plug-in Power Corp.">
</plugin>

Plug-ins are stored in the eclipse/plugins folder, in folders reflecting their name and version number. To indicate that we're creating version 1.0.0 of this simple plug-in, store plugin.xml as eclipse/plugins/org.cookbook.simple_1.0.0/plugin.xml, then restart Eclipse.

This new plug-in doesn't do anything, but to confirm that Eclipse is treating it as a bona fide plug-in, take a look at the plug-in registry, which you can open by selecting Help About Eclipse Platform and clicking the Plug-in Details button. You'll see the new, simple plug-in in the plug-in registry, as shown at the bottom of Figure 12-1.

Figure 12-1. The simple plug-in in the plug-in registry

That provides an introduction to working with plug-in manifests. To start creating code for plug-ins, take a look at the next couple of recipes.

12.2.4 See Also

Recipe 12.3 on creating a menu-based plug-in using wizards; Chapter 11 and Chapter 12 of Eclipse (O'Reilly).