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GroovyNotificationTutorial

Version 2.2 by Vincent Massol on 2008/11/17

Notifications

Warning

The notification mechanism is being refactored and will most likely change in XWiki Core 1.4. Thus if you're using the code below you'll have to update your code when you'll upgrade to XWiki Core 1.4.

XWiki supports notifications and it's possible to do some action when a document is modified, when a document's objects are modified, etc. 

This tutorial explains how to implement an action in a XWiki page that responds to document changes. This is done in Groovy. It can also be implemented as a Plugin.

We need to write 2 pages:

  • A page containing a Groovy class that registers against the XWiki Event Manager and that has the method to be called when the event happens.
  • Another page that parses the Groovy page and loads it in the Groovy context.

Groovy Notification Class

Your Groovy needs to extend the com.xpn.xwiki.notify.XWikiDocChangeNotificationInterface as shown below.

/* Groovy Class #* */

import com.xpn.xwiki.api.*;
import com.xpn.xwiki.notify.*;
import com.xpn.xwiki.*;
import com.xpn.xwiki.doc.*;

public class MyGroovyClass implements XWikiDocChangeNotificationInterface
{
    def xwiki;
    def rule;

    public MyGroovyClass()
    {
        this.rule = new DocChangeRule(this);
    }

    public void init(xwiki)
    {
        this.xwiki = xwiki;
        xwiki.getXWiki().getNotificationManager().addGeneralRule(this.rule);
    }

    public void cleanup()
    {
        xwiki.getXWiki().getNotificationManager().removeGeneralRule(this.rule);
    }

    public void notify(XWikiNotificationRule rule, XWikiDocument newdoc, XWikiDocument olddoc,
        int event, XWikiContext context)
    {
        // Do some action here.
    }
}

/* *# */

In this example we've used a DocChangeRule rule. There are also other rules.

Calling the Groovy Class

#set($mygroovyclass = $xwiki.parseGroovyFromPage("MySpace.MyGroovyClass"))
$mygroovyclass.init($xwiki)

Example: IRC notification on document change

Warning

The code below uses the parseGroovyFromPage method which takes 2 parameters. The second one is the name of page containing JARS as attachments. These JARs are put in the classloader used by Groovy when parsing the page. This feature is only working in XWiki Core 1.3 and later.

  • Step 1: Groovy Class
/* Groovy Class #* */

import org.jibble.pircbot.*;
import java.util.*;
import com.xpn.xwiki.api.*;
import com.xpn.xwiki.notify.*;
import com.xpn.xwiki.*;
import com.xpn.xwiki.doc.*;

public class XWikiBot extends PircBot implements XWikiDocChangeNotificationInterface
{
    def xwiki;
    def channel;
    def rule;

    public XWikiBot()
    {
        this.setName("xwikibot");
        this.rule = new DocChangeRule(this);
    }

    public void init(xwiki, channel)
    {
        this.xwiki = xwiki;
        this.channel = channel;
        xwiki.getXWiki().getNotificationManager().addGeneralRule(this.rule);
    }

    public void cleanup()
    {
        xwiki.getXWiki().getNotificationManager().removeGeneralRule(this.rule);
    }

    public void notify(XWikiNotificationRule rule, XWikiDocument newdoc, XWikiDocument olddoc,
        int event, XWikiContext context)
    {
        sendMessage(this.channel, newdoc.getFullName() + " was modified - " + newdoc.getExternalURL("view", context));
    }
}

/* *# */
  • Step 2: Add the PircBot JAR as an attachment to the MySpace.MyGroovyClass page created in step 1.
  • Step 3: Calling page
## Start by looking for a bot in the servlet context
#set ($sc = $context.getContext().getEngineContext().getServletContext())

## If the bot isn't in the servlet context, start the bot and put in the context
#set ($bot = $sc.getAttribute("ircbot"))
#if (!$bot)
  Bot is not started, starting it...
  #set($bot = $xwiki.parseGroovyFromPage("MySpace.MyGroovyClass", "MySpace.MyGroovyClass"))
  #set ($channel = "#xwiki")
  $bot.init($xwiki, $channel)
  $bot.connect("irc.freenode.net")
  $bot.joinChannel($channel)
  $sc.setAttribute("ircbot", $bot)
  Bot started!

## If the parameter passed is stop then stop the bot
#elseif ($request.action && $request.action == "stop")
  $bot.cleanup()
  $bot.disconnect()
  $sc.setAttribute("ircbot", null)
  Bot disconnected!

#else
  Bot already started, doing nothing...

#end
  • Step 4: Creating a Scheduler job so that the Bot is restarted automatically if the server is restarted for example.

Create a Scheduler job, set it to run every 5 minutes for example and use the following Groovy script in the job:

// Start by looking for a bot in the servlet context
def sc = context.getEngineContext().getServletContext()

// If the bot isn't in the servlet context, start the bot and put in the context
def bot = sc.getAttribute("ircbot")
if (bot == null) {
  // Bot is not started, starting it...
  bot = xwiki.parseGroovyFromPage("MySpace.MyGroovyClass", "MySpace.MyGroovyClass")
  def channel = "#xwiki"
  bot.init(xwiki, channel)
  bot.connect("irc.freenode.net")
  bot.joinChannel(channel)
  sc.setAttribute("ircbot", bot)
  // Bot started!
}

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