Plugin Development

Introduction

A plugin in Pebble is simply a class that implements a particular plugin interface. These are enabled/disabled per blog, and can have configuration properties to go with them.

As of Pebble 2.5, rather than users having to enter the class names of plugins into Pebble manually, Pebble supports a plugin descriptor so that plugins can register themselves, and users can turn plugins on and off using check boxes. These plugins will look like this in the interface:

Plugin descriptor

A plugin descriptor is a file called pebble-plugins.xml located in the base directory of the plugins JAR file. It looks like this:

<pebble-plugins>
  <page-decorator name="Facebook Connect Support" class="net.sourceforge.pebble.openid.FacebookOpenIdSupportDecorator">
    <description>
      <![CDATA[
      Provides support for other Facebook Connect plugins. This plugin is required to be enabled for the Facebook OpenId
      Comment Author Provider plugin to work. In order for this integration, you need a Facebook application ID, which
      needs to be configured below. For instructions on setting up a Facebook application, see
      <a href="http://wiki.developers.facebook.com/index.php/Connect/Setting_Up_Your_Site">here</a>.
    ]]>
    </description>
    <config key="facebook.app.id" name="Facebook Application ID" type="string"/>
  </page-decorator>
</pebble-plugins>

Plugin Points

A plugin descriptor may declare multiple plugins. Here are the different plugin points:

Plugin Point	Interface	Description
permalink-provider	`net.sourceforge.pebble.api.permalink.PermalinkProvider`	Defines permalinks to blog entries
content-decorator	`net.sourceforge.pebble.api.decorator.ContentDecorator`	Decorates blog entries, comments and trackbacks
blog-listener	`net.sourceforge.pebble.api.event.blog.BlogListener`	Listens for blog events
blog-entry-listener	`net.sourceforge.pebble.api.event.blogentry.BlogEntryListener`	Listens for blog entry events
comment-listener	`net.sourceforge.pebble.api.event.comment.CommentListener`	Listens for comment events
comment-confirmation-strategy	`net.sourceforge.pebble.api.confirmation.CommentConfirmationStrategy`	Strategy for confirming/rejecting comments
trackback-listener	`net.sourceforge.pebble.api.event.trackback.TrackBackListener`	Listens for trackback events
tracback-confirmation-strategy	`net.sourceforge.pebble.api.confirmation.TrackBackConfirmationStrategy`	Strategy for confirming/rejecting trackbacks
lucene-analyzer	`org.apache.lucene.analysis.Analyzer`	A Lucene analyzer for blog indexes
logger	`net.sourceforge.pebble.logging.AbstractLogger`	For logging events that occur in Pebble
page-decorator	`net.sourceforge.pebble.api.decorator.PageDecorator`	Decorates generated pages
open-id-comment-author-provider	`net.sourceforge.pebble.api.openid.OpenIdCommentAuthorProvider`	Provider for OpenID login for comments

Plugin Properties

Each plugin has a name, class and description. The description is HTML that will be placed in the description field of the plugin. Additionally, plugins may optionally have configuration parameters. Each configuration parameter has a key, a name, and a type. Valid types are string, textarea, password and checkbox.