As requested, the Atom PubSub bridge

This module offersr an AtomPub interface to ejabberd PubSub data. Currently in two unfinished flavors, one for use with yaws embedded. One for use with ejabberd_http server

Howto

You need to have Yaws available. It will start in embedded mode, with the mod_yaws module (included). To build, edit the Makefile to match your erlang install and make Put the resulting beams in some place where ejabberd will find them.

Also you’ll need to set the BASEURL macro in atom_pubsub.erl to your webserver hostname.

You’ll also need to add the module to your ejabberd.cfg in the mmodules section:

{mod_yaws,[{logdir, "/tmp/"},
    {servers, [
    {"localhost", 5224, "/opt/var/yaws/www", [
     {dir_listing, true},
     {appmods, {"/atom",     atom_pubsub}}
     ]}
   ]}
  ]}

What you get

The AtomPub interface passes the Atom Protocol Exerciser (though some warnings remain).

It means that any AtomPub clients will be able to post to a specific node in your PubSub tree.

It also means that your PubSub tree will also be available as an AtomFeed.

Of course, each time an item is posted through AtomPub or PubSub on a node you are subscribed to, you’ll get the notification.

Can I have it with OpenFire and Epeios ?

That’s not possible. At some point, there’s no way around hitting directly the PubSub mnesia tables. So you can’t extract the code as a component.

Moreover, it only works with PubSub nodes derived from the default node type. (because of the mnesia tables stuff)

What’s next ?

I’ll update the code soon. A few of things I’d like to implement :

• remove all calls to mnesia and work through mod_pubsub API.
• add HEAD, etag and slug support (that’s a patch for ejabberd though)
• remove that baseurl horrible macro
• add node subscription through REST
• as soon as ejabberd 2.1 is published remove dependency from yaws
• add binary collections support

Mickaël Rémond from Process-One kindly offered to host atom-pubsub on the ejabberd_modules svn.

svn co https://svn.process-one.net/ejabberd-modules/atom_pubsub/trunk/

There’s a quick port to the ejabberd_http server at this location : You need to be running ejabberd 2.1 or current trunk to have it work.

svn co https://svn.process-one.net/ejabberd-modules/atom_pubsub/branches/ejabberd_http_branch/

Check out the README for installation.

Shoot your questions in the comment or via email (anything on this weblog domain goes to my inbox)

En fait, non. Je l’ai coupé. Je le remettrais un jour.

En attendant pour me joindre via XMPP : cstar chez ohmforce point com

(Celui d’Ohm Force, s’il tombe, je me fais taper sur les doigts).

What is mod_rpc ?

mod_rpc is an ejabberd module which will handle rpc queries … in a modular way.

It is is easily extensible, and is designed to access the mnesia database from XMPP clients.

It plugs in the access control list to allow or prevent access to the rpc modules.

Installing mod_rpc

Download the mod_rpc.erl file and copy it over your ejabberd src/ directory. make ejabberd.

Do not restart yet, we have some configuration to do !

Using mod_rpc

Let’s say you want to publish two functions, echo and mult. The code would go as follow :

rpc_test.erl :

-module(rpc_test).
-export([handle/2]).

handle(_State, {call, echo, [A]}) -> {response, [A]};
handle(_State, {call, mult, [A, B]}) -> {response, [A*B]};

Copy into your ejabberd source directory and make.

Now you need to configure access to your functions. In

ejabberd.cfg

% 2 groups : admins, and the rest.
{access, rpc_admin, [{allow, admin}]}.
{access, rpc_all, [{allow, all}]}.
%...

%... in modules configuration
%...
  {mod_register,   [{access, register}]},
  {mod_rpc, [{access, [{rpc_test, rpc_admin}] }]}, % only admins can call echo and mult
  {mod_roster,     []},
%....

Now start ejabberd. (of course you could do the hot code stuff if you want)

From now on I have rpc_test@rpc.localhost answering to my rpc queries.

Let’s test from ruby using xmpp4r. Get the SVN version for jabber-RPC support.

require 'xmpp4r'
require 'xmpp4r/rpc/helper/client'
require 'xmpp4r/rpc/helper/server'
include Jabber
jid = JID::new('cstar@localhost') #this one is admin !
cl = Client::new(jid)
cl.connect
cl.auth("PASS")
rpc= RPC::Client.new(cl, 'rpc_test@rpc.localhost')
puts rpc.call("echo", 'Test string') # outputs Test string
puts rpc.call("mult", 2,4) # outputs ... 8

If you try with a non-admin user, you’d get

Jabber::AuthenticationFailure: not-authorized

About Groovy Jabber-RPC

I have been playing with it, and it does not work directly out of the box. The groovy lib will try to see if rpc_test@rpc.localhost is in the user roster.

Patching to making it work is quite simple ; In file xmlrpc-groovy/src/main/java/groovy/net/xmlrpc/JabberRPCServerProxy.java

Just replace : request.setTo(getId(connection.getRoster(), this.to)); (line 102)

with : request.setTo(this.to);

And the following will work :

import groovy.net.xmlrpc.*
import org.jivesoftware.smack.XMPPConnection

def clientConnection = new XMPPConnection("localhost")
clientConnection.connect()
clientConnection.login("cstar", "PASS") 
def serverProxy = new JabberRPCServerProxy(clientConnection, "rpc_test@rpc.localhost")
serverProxy.echo("test")
clientConnection.disconnect()

Necessary caveats

This is my first foray in developping a module in ejabberd, I still have to check how this actually scales. I only have one process handling all queries, which is not very concurrency oriented programming :)

Thanks

The guys from ejabberd, for making software really easy to use and extend ;)

Download :

mod_rpc.erl

Feedback

I really welcome enhancements and fixes (especially regarding the concurrency stuff!)

License

Don’t sue me, don’t remove copyright/name kind of license.