Johan de Koning

Hummm… XMPP and WCF? Is this not a blog page about Android or other Google related stuff. That’s partly true but as a Microsoft .Net developer I am more interested in combining the best of both world. I like Google and Microsoft products. I really like the open source vision of Google. But when it comes to development tools I prefer using Microsoft.

So that’s me, living between both worlds. Using the best of both worlds to develop good implementations. And that is where this new blog post are about.

Some time ago Google launched Google Wave presentation (http://wave.google.com/help/wave/about.html) When I watched the presentation, I was (and still am) impressed.

At my previous job, we developed a real time location aware application. A huge amount of data was collected by the location systems, was processed by the server and was made visible on the clients. The made visible part is a tricky one, because we wanted to make use of protocols which where cross platform like SOAP. The result was a polling mechanism which sends requests on interval basis to the server to get new data.

We knew that this was not the best implementation. At that time (almost 3 years ago) we were also thicking about as a possible solution. XMPP stands for Extensible Messaging and Presence Protocol (http://xmpp.org/). A protocol which was developed already in 1999 and is based on XML. I think that the popularity of this protocol was getting a boost when Google launched their Google Talk client in augustus 2005.

I found a presentation on the Web about XMPP (http://www.slideshare.net/kellan/beyond-rest) which has a nice slide (shown in the image below). This reminds me of an episode of the Smurfs (http://en.wikipedia.org/wiki/The_Smurfs) where the Smurfs are on a long trip.

Brainy Smurf: Is it much further, Papa Smurf?
Papa Smurf: Not much further my little smurfs.
Jokey Smurf: (different location) Is it much further, Papa Smurf?
Papa Smurf: Not much further my little smurfs.
Grouchy Smurf: (third location) Is it much further, Papa Smurf?
Papa Smurf: (exasperated) Yes…it is!

Are we there yet?

So when all Smurfs are requesting data from Papa Smurf, Papa Smurf becomes overloaded. A better solution would be a Publish Subscribe implementation  (http://en.wikipedia.org/wiki/Publish/subscribe). XMPP has such extension: http://xmpp.org/extensions/xep-0060.html. This way the clients (little smurfs) don’t become bored (they can do other things) and Papa Smurfs don’t get distracted or even overloaded.

Tell me when I get there

The protocol of Google Wave is based on this model. The protocol makes use of the XMPP protocol together with some extensions. Installation document of the Google Wave Federation Prototype server can be found at http://code.google.com/p/wave-protocol/wiki/Installation Of course Google is using Java or Phyton for the example clients, and that is exactly the part where my love for Microsoft fits in. I am really interested in building a Google Wave protocol client within .Net

Because XMPP is involved, the first step would be to develop a XMPP client in .Net. There are some XMPP libraries available for .Net but those don’t have a flexible extension model. And when looking at Windows Communication Foundation, there are already some parts available for setting up the connection and send/retrieve messages. Developing an XMPP library based on the WCF technology is the first goal of these new blog posts.

What’s next?

Before looking at a WCF implemtation, it is good to know how XMPP works. Therefore I will develop a sample client which makes use of the .Net TcpClient to initiate and send/retrieve messages (no WCF involved). To test this client I will install a XMPP server called OpenFire (http://www.igniterealtime.org/projects/openfire/index.jsp). Check this blog often for new updates… and remember Papa Smurf, we are not there yet!

BTW I love to retrieve comments on this (or my other blogposts). Your feedback is really important!