# Jive Messenger Plugin Developer Guide

## Introduction

Plugins enhance the functionality of Jive Messenger. This document is a developer's guide for creating plugins.

## Structure of a Plugin

Plugins live in the `plugins` directory of `messengerHome`. When a plugin is deployed as a JAR or WAR file, it is automatically expanded into a directory. The files in a plugin directory are as follows:

Plugin Structure

    myplugin/
     |- plugin.xml      <- Plugin definition file
     |- readme.html     <- Optional readme file for plugin, which will be displayed to end users
     |- changelog.html  <- Optional changelog file for plugin, which will be displayed to end users
     |- icon_small.gif  <- Optional small (16x16) icon associated with the plugin
     |- icon_large.gif  <- Optional large (32x32) icon associated with the plugin
     |- classes/        <- Resources your plugin needs (i.e., a properties file)
     |- lib/            <- Libraries (JAR files) your plugin needs
     |- web             <- Resources for Admin Console integration, if any
         |- WEB-INF/
             |- web.xml           <- Generated web.xml containing compiled JSP entries
             |- web-custom.xml    <- Optional user-defined web.xml for custom servlets
         |- images/

The `web` directory exists for plugins that need to add content to the Jive Messenger Admin Console. Further details are below.

The `plugin.xml` file specifies the main Plugin class. A sample file might look like the following:

Sample plugin.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <plugin>
        <!-- Main plugin class -->
        <class>org.example.ExamplePlugin</class>

        <!-- Plugin meta-data -->
        <name>Example Plugin</name>
        <description>This is an example plugin.</description>
        <author>Jive Software</author>
        <version>1.0</version>
        <date>07/15/2005</date>
        <url>http://www.jivesoftware.org/pluginX</url>
        <minServerVersion>2.2.0</minServerVersion>

        <!-- Admin console entries -->
        <adminconsole>
            <!-- More on this below -->
        </adminconsole>
    </plugin>

The meta-data fields that can be set in the plugin.xml file:

- name -- the name of the plugin.
- description -- the description of the plugin.
- author -- the author of the plugin.
- version -- the version of the plugin.
- date -- the date the plugin was released. The date must be in the form MM/DD/YYYY, such as 07/15/2005.
- url -- a URL where additional information about the plugin is available.
- minServerVersion -- the minimum version of Jive Messenger required to run the plugin (supported by Jive Messenger 2.1.2 and later). If the server version is less than the required value, the plugin will not be started.
- parentPlugin -- the name of the parent plugin (given as "foo" for the "foo.jar" plugin). When a plugin has a parent plugin, the parent plugin's class loader will be used instead of creating a new class loader. This lets plugins work together more closely. A child plugin will not function without its parent present.

Several additional files can be present in the plugin to provide additional information to end-users (all placed in the main plugin directory):

- `readme.html` -- Optional readme file for plugin, which will be displayed to end users.
- `changelog.html` -- Optional changelog file for plugin, which will be displayed to end users.
- `icon_small.gif` -- Optional small (16x16) icon associated with the plugin.
- `icon_large.gif` -- Optional large (32x32) icon associated with the plugin.

Your plugin class must be implement the `Plugin` interface from the Jive Messenger API as well as have a default (no argument) contructor. The Plugin interface has methods for initializing and destroying the plugin.

Sample plugin implementation

    package org.example;

    import org.jivesoftware.messenger.container.Plugin;
    import org.jivesoftware.messenger.container.PluginManager;

    import java.io.File;

    /**
     * A sample plugin for Jive Messenger.
     */
    public class ExamplePlugin implements Plugin {

        public void initialize(PluginManager manager, File pluginDirectory) {
            // Your code goes here
        }

        public void destroy() {
            // Your code goes here
        }
    }

## Modifying the Admin Console

Plugins can add tabs, sections, and pages to the admin console. There are a several steps to accomplishing this:

- An <adminconsole/> section must be added to the `plugin.xml` file.
- JSP files must be compiled and put into the classpath of the plugin. A `web.xml` file containing the compiled JSP servlet entries must be put into the `web/` directory of the plugin. Note: the Jive Messenger build script can assist with compiling JSPs and creating the web.xml. This is detailed below.
- Any images required by your JSP pages must live in `web/images/` directory. Only GIF and PNG images are supported.

The `<adminconsole />` section of `plugin.xml` defines additional tabs, sections and entries in the Admin Console framework. A sample `plugin.xml` file might look like the following:

Sample plugin.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <plugin>
        <!-- Main plugin class -->
        <class>org.example.ExamplePlugin</class>

        <!-- Admin console entries -->
        <adminconsole>
            <tab id="mytab" name="Example" url="my-plugin-admin.jsp" description="Click to manage...">
                <sidebar id="mysidebar" name="My Plugin">
                   <item id="my-plugin" name="My Plugin Admin"
                       url="my-plugin-admin.jsp"
                       description="Click to administer settings for my plugin" />
                </sidebar>
            </tab>
        </adminconsole>
    </plugin>

In this example, we've defined a new tab "Example", a sidebar section "My Plugin" and a page "My Plugin Admin". We've registered `my-plugin-admin.jsp` as the page. You can override existing tabs, sections, and items by using the existing id attribute values in your own `<adminconsole>` defintion.

### Admin Console Best Practices

There are several best practices to consider when making changes to the Jive Messenger admin console via a plugin. The general theme is that plugins should integrate seamlessly:

- Integrate into existing tabs and sidebar sections whenever possible instead of creating your own. Only create new tabs for very significant new functionality.
- Don't use the word "plugin" in names of tabs, sidebars and items. For example, instead of having an item called "Gateway Plugin", it could be called "Gateway Settings".
- Try to match the UI of the existing admin console in your custom plugin pages.
- There is no need to create an admin console entry to show plugin meta-data. Instead, let Jive Messenger inform the user about which plugins are installed and provide plugin management.

## Using the Jive Messenger Build Script

The Jive Messenger build script will help you build and develop plugins. It looks for plugin development directories in the following format:

Plugin Structure

    myplugin/
     |- plugin.xml      <- Plugin definition file
     |- readme.html     <- Optional readme file for plugin
     |- changelog.html  <- Optional changelog file for plugin
     |- icon_small.gif  <- Optional small (16x16) icon associated with the plugin
     |- icon_large.gif  <- Optional large (32x32) icon associated with the plugin
     |- classes/        <- Resources your plugin needs (i.e., a properties file)
     |- lib/            <- Libraries your plugin needs
     |- src/
         |- java        <- Java source code for your plugin
         |   |- com
         |       |- mycompany
         |           |- *.java
         |- web
             |- *.jsp      <- JSPs your plugin uses for the admin console
             |- images/    <- Any images your JSP pages need (optional)
             |- WEB-INF
                 |- web.xml    <- Optional file where custom servlets can be registered

The build script will compile source files and JSPs and create a valid plugin structure and JAR file. Put your plugin directories in the `src/plugins` directory of the source distribution and then use `ant plugins` to build your plugins.

Any JAR files your plugin needs during compilation should be put into the `lib` directory. These JAR files will also be copied into the plugin's generated `lib` directory as part of the build process.

If you create a src/web/WEB-INF/web.xml file, any servlets registered there will be initialized when the plugin starts up. Only servlet registrations and servlet mappings will be honored from the web.xml file. Note: this feature is implemented by merging your custom web.xml file into the web.xml file generated by the JSP compilation process.

## Implementing Your Plugin

Plugins have full access to the Jive Messenger API. This provides a tremendous amount of flexibility for what plugins can accomplish. However, there are several integration points that are the most common:

1. Register a plugin as a Component. Components receive all packets addressed to a particular sub-domain. For example, `test_component.example.com`. So, a packet sent to `joe@test_component.example.com` would be delivered to the component. Note that the sub-domains defined as components are unrelated to DNS entries for sub-domains. All XMPP routing at the socket level is done using the primary server domain (example.com in the example above); sub-domains are only used for routing within the XMPP server.
2. Register a plugin as an IQHandler. IQ handlers respond to IQ packets with a particular element name and namespace. The following code snippet demonstrates how to register an IQHandler:

         IQHandler myHandler = new MyIQHander();
         IQRouter iqRouter = XMPPServer.getInstance().getIQRouter();
         iqRouter.addHandler(myHandler);

3. Register a plugin as a PacketInterceptor to receive all packets being sent through the system and optionally reject them. For example, an interceptor could reject all messages that contained profanity or flag them for review by an administrator.
4. You can store persistent plugin settings as Jive Messenger properties using the JiveGlobals.getProperty(String) and JiveGlobals.setProperty(String, String) methods. Make your plugin a property listener to listen for changes to its properties by implementing the `org.jivesoftware.messenger.event.PropertyEventListener` method. You can register your plugin as a listener using the PropertyEventDispatcher.addListener(PropertyEventListener) method. Be sure to unregister your plugin as a listener in your plugin's destroyPlugin() method.

## Plugin FAQ

Can I deploy a plugin as a directory instead of a JAR?

No, all plugins must be deployed as JAR or WAR files. When a JAR or WAR is not present for the plugin, Jive Messenger assumes that the file has been deleted and that the users wants to destroy the plugin, so it also deletes the directory.

What license agreement are plugins subject to?

Because Jive Messenger is released under the Open Source GPL license, any plugins developed must also be released under the GPL or a compatible Open Source license. It is a violation of the license agreement to create plugins that are not Open Source. Please visit Jive Software if you need different licensing terms for Jive Messenger, including the right to create commercial plugins.