xmpp

I've decided to make an official release of a few of my currently most active projects so that it'll be easier for anyone to try out. So today I've released:

- bridge 0.3.6: Simple library for handling XML. This one is just a fix release and won't break any of your application if you were using it.
- headstock 0.2.0: XMPP library using Kamaelia and bridge. My main focus on this release was the support of PubSub.
- jlib 0.1.0: Python library of PyQt4 widgets to add XMPP to your applications. This one is rather new and still pretty limited but it's already fun to use.

There you go, neither headstock nor jlib are considered to be production ready but are stable enough in terms of design and implementation so that you may already start playing with them. I hope you'll have fun.

I've been recently working on a library called jlib that providing PyQt4 objects and widgets that can be integrated to a PyQt4 application. In other words jlib is not a new Jabber client but a toolbox to enjoy the benefit of XMPP. The XMPP work is performed by headstock, jlib only glues headstock to PyQt4 through the use of signals/slots.

jlib is not ready yet but here is a preview of a few widgets I've already started working on. Ultimately my main interests is in creating a decent toolbox of widgets centered towards XMPP PubSub.

Alright I haven't been able to move as fast as I wanted on this one for a whole set of reason but if you're interested in having a look at where I'm heading at please read this.

Following my previous posts about my work on mixing AtomPub and XMPP together in a single application I've worked yesterday on the basic workflow of the application I write.

The first use case is to create a profile using OpenID.

1. When landing on the application main page the user can enter his (or her) OpenID which will redirect him to his OpenID provider for validation.
2. Once validated and accepted the user comes back to the application which shows a simple profile page pre-filled with information using the simple registration extension of OpenID.
3. Upon submitting his profile for registration the application stores the profile following the format described in XEP-0154. It also creates a node in a Jabber PubSub service that will be used as the top-level node of the user. It finally creates a workspace specific to the user within the AtomPub service.

Note the the application I'm writing will conflate two similar notions into one and make them context free:

1. node in PubSub
2. collection in AtomPub

Both terms will refer to a channel in the application. So sub-nodes of the user top-level node will be called a channels and each collection within the user workspace will also be called a channel. In other words publishing data to a channel means publishing data to both the PubSub node and the AtomPub collection at the same time no matter the protocol chosen to perform the operation. The channel convention is arbitrary but helpful as it hides the underlying protocol away.

Once a user is registered to the application he can log in using his OpenID. After logging in the user can register, start and stop the internal XMPP client associated with his account. The first step is to register it from the application. Once registered the client can be started and stopped at will.

When the internal XMPP client is registered the user ought to use his favorite Jabber client to register a new account to the Jabber server. Then he should subscribe to the internal client's contact list that will automatically accept it (probably in a better scenario subscription should be moderated from the user's profile page).

The second use case is to create channels

1. The user could create channels using either his Jabber client or using the AtomPub interface.
2. In both cases the application would create both the according PubSub sub-node to the user's top-level node and the appropriate AtomPub collection.

The third use case is to publish data to channels with XMPP

1. The user uses his own Jabber client to send a message to the internal jabber client like this: “publish channel Hello world”. This would translate into “Publish 'Hello world' to channel” where channel is the name of the channel to publish to.
2. The jabber server would forward this message to the internal client who upon parsing it would understand it must publish the sent data to the according PubSub node. First it would enclose the data into the atom:content of an atom entry and publish that entry as the node's item.
3. When the item is published the Jabber server would send a notification back to the internal client which could then create and store the according AtomPub member entry to the appropriate collection. The entry would become visible via the Atom feed of the collection.

Note that waiting for the notification to be propagated back to store the atom entry within the collection rather than doing it immediately when publishing to the PubSub node is not gratuitous. Indeed the user could publish items directly from an external client that understands PubSub. By doing it the way described above we ensure that even in such a case the internal client will be informed a new item was published to a node it is subscribed to and therefore the application will keep in sync' no matter what.

The fourth use case is to publish data to channels with AtomPub

This would be similar to the previous use case except the entry point would be the AtomPub interface and that of course a message would be sent through XMPP accordingly.

Deleting items from channels would work in the same fashion.

Of course the user's channels would then be publicly available and other users could subscribe to the Atom feed, to the internal XMPP client or to the user's PubSub nodes.

From there on the application could be extended so that for instance users can comment to each other and ensure that the channels' items contain that information, for instance using RFC 4685 within each item.

These are few things I've been working on. The application is not ready yet and it might take a few days for it to complete and hopefully some of you will be interested in testing it then.

Regarding the platform used, Python and the following products:

1. headstock through Kamaelia for the XMPP layer
2. amplee for the AtomPub interface
3. CherryPy 3.1 for the HTTP serving
4. amara for the XML handling

Via Peter Saint-André we learn that facebook is adding XMPP as a mean to connect and use its services. Independently from what usage is made of Facebook this is a great news for the Jabber community in general and the protocol itself as it demonstrates that, unlike some nay-sayers used to claim in the past, XMPP will be the the true sibling to HTTP when it comes to social networking and delivering near real-time data on a large scale. Indeed, considering that media companies like the BBC, are looking at using too (even if it's purely at a research level for now) it seems to me that XMPP has great years ahead.

I find that interesting though that Google, which has had a Jabber network for years now, has never been able to actually push much that way. I mean Orkut and Google Talk have been able to communicate for quite some time and yet it seems the Facebook prospect is more exciting for the Jabber community than Google's usage ever was. Maybe it comes down to the fact Orkut is a pale shadow of Facebook.

On a personal level, I won't complain that Google doesn't push advertisement through Google Talk of course but one may wonder why it doesn't do so from a business point of view. well probably they know having ads that way would drive their customers away, as they say (emphasis mine):

There are no ads in your chat sessions or your Quick Contacts list. Once a chat is saved, however, it becomes just like a Gmail message. And just as you may see relevant ads next to your Gmail messages, there now may be ads alongside your saved chats. Ads are only displayed when you're viewing a saved chat, and as with all ads in Gmail, they are matched entirely by computers. Only ads classified as Family-Safe are shown and we are constantly improving our technologies to prevent displaying any inappropriate ads. One of the things many Gmail users have told us is how much they appreciate the unobtrusive text ads in Gmail, as opposed to the large, irrelevant, blinking banner ads they often see in other services, and many have even cited the usefulness of the ads in Gmail.

We'll see how Facebook handles it considering the big fiasco Beacon was.

As a developer I've long felt frustrated at how limited the Google Talk standalone application is. Google Talk gadget is a bit better featured but it pains me having to use it when I prefer its big brother. Still both are very limited. To be fair though most well known IM clients speaking XMPP are limited in regards to what the protocol and its extensions offer. It's sad so little support PubSub and even those that do are somewhat basic in their support.

Let's hope we'll more and more XMPP applications out of the context of instant messaging or with a larger scope like microblogging.

Matthew Wood, from the BBC Radio Labs, posted a few days ago an exciting note regarding fun he was having with XMPP and services such as last.fm to inform user, via XMPP messages, of BBC radios broadcasting music they might like based on thier last.fm profile. I thought this was fantastic but I was even more excited when I read another note where he explained that he was using PubSub as a mean to carry and distribute metadata about BBC shows using Atom entries as the metadata format.

This evening I spent three hours expanding on the simple chat example coming with headstock to talk with the PubSub service. Then I integrated amplee as a way to offer an AtomPub interface at the same time. This means that when the demo starts both a XMPP client, connecting to Matt's service, and an AtomPub server, using amplee and served by CherryPy, are started. The XMPP client asks the server about PubSub nodes. For each node representing BBC channels I create an atompub collection within its own workspace. Simultaneously I subscribe to those nodes. I then ask the XMPP server for items belonging to those nodes and for each item, representing metadata about a show for instance, I create an atom entry that I store within the AtomPub store.

This means one can then simply subscribe with a feed reader to a given collection and/or a XMPP PubSub node. All of this happening on the fly starting from an empty AtomPub service document.

Eventually I will add support so that when an Atom entry is POSTed to a AtomPub collection, the according PubSub stanza is pushed towards the service (I doubt Matt's service accepts it though) allowing for microblogging support.

The source code of the example can be found here. If you want to understand how it works you might want to read this quick word I wrote about Kamaelia first which is at the core of headstock.

There has been quite a lot of discussions around the use of XMPP in a web context and how to blend HTTP and XMPP protocols for a better social network experience.

I've been working on implementing XMPP for a while now on my spare time and even though it's been a much slower effort I would have liked, I've been able to have a fantastic fun with it. Most recently I've started integrating XMPP PubSub along with AtomPub using my AtomPub implementation, amplee.

The idea is to use amplee as an AtomPub library from within XMPP PubSub handlers. For instance I map AtomPub collections to PubSub nodes . When an atom entry is published to a node and that the client receives an acknowledgment of that publication, the handler uses amplee to store the entry in the AtomPub collection as well, respecting of course the RFC specification. Similarly if an item is deleted, the handler uses amplee to remove the entry from the collection. This works both ways, we can also run an AtomPub web service which issues the right XMPP stanzas according to the operation carried. So a POST on a collection would publish the atom entry to the XMPP server. The web service would obviously expose the Atom feed of the collection.

This is just a stub, but the idea here is to associate both protocols so that they cooperate to expand the audience of your network. It'd be easy to consider allowing people commenting to a blog entry using their XMPP client. You blog entry would for instance advert the XMPP service and node name where to publish items. The user could then subscribe to than node and publish items.

That's one reason why I had written amplee as an AtomPub library that could work outside of the HTTP protocol. RFC 5023 defines the protocol using HTTP but the root idea behind it works well in the context of XMPP and maybe AtomPub is the protocol that will rule them all.

Following my post on XMPP yesterday, one comment by Steven Kryskalla raised the point of the Mozilla extension: xmpp4moz. This extension is indeed an excellent showcase of what I wish could see more in the browser. However, while I knew about that extension I chose not to discuss about it as I wanted to stress over the need of a standard XMPP API, built-into browsers. This would imply a discussion shared by all the browser vendors and I thought inducing that Mozilla was already there could have disrupted the message. That being said xmpp4moz is a great piece of work and would definitely be an appropriate ground for more discussion.

What I think xmpp4moz does right is to use E4X to represent XMPP stanzas rather than providing its own datamodel. That means that the API stays quite at a low level but also means it's much quicker to grasp and more flexible.

I think ultimately what I'd like to see is a standard API that allows me from Javascript to do XMPP connection, authentication, session and binding. Then provide a nice interface to register handlers for given stanzas. By standard API I obviously meant that the same Javascript works the same way in any browser. Yeah I'm demanding like that.

Why Javascript? Two reasons that I can think of:

- The Ajax crazy party has pushed dramatically the competition across Javascript supporters and proved it was a valid and solid solution all along.
- Javascript is now the programing language with the best support inside browsers, no point going for something different.

Overall, considering how small XMPP-core is, I don't believe this is an impossible goal. The guys behind xmpp4moz have demonstrated it. What is tough with XMPP is not to provide support for the core but to start supporting its myriad of extensions that make the protocol so rich. But if people don't even have an access to the core they won't be able to build applications at all.

I've been a long fan of the XMPP protocol and I've started implementing it using the fantastic Kamaelia. With all the GSoC discussion around it appeared that lots of people were more and more interested in seeing XMPP becoming the natural partner of HTTP in the maze that the Internet has quickly become. Consequently Peter Saint-André created today the Social mailing-list to all people interested in discussing how XMPP could be used in what is that social web of yours.

I'm totally biased but I think there is more to XMPP than IM, the protocol and its suite of extensions provide great power applicable to RIA, whether they reside inside our outside the browser. For instance, I do believe that rather than using Comet one ought to use XMPP to push notifications to the client. In such a case one might consider the client as a node in a cloud of lazily interconnected nodes and then start thinking of the browser as more than a HTML rendering engine and without the resort to abuse HTTP for things it was never meant to support.

I wish browser vendors could start implementing XMPP within the browser as that would provide a fantastic incentive for more applications based on the power of XMPP.