Who wants to know how Windows Live Messenger actually works?
December 27th, 2006 by 
Zack Whittaker
Oh it’s really rather simple once you look at it from all the right angles! Here’s a nice little visual representation of the “Messenger Relay” system of which sends and receives all your messages. I’ve basic’d it down as much as I can because it does get tricky in places. Click the thumbnail to view a larger shot.
1. The user starts the session by double clicking a contact.
2. The user’s Windows Live ID credentials are sent across to the Windows Live ID Credentials server for further verification
3. The information is passed through a incoming only firewall to the dispatch server. This is the first point of connection for the message being sent.
4. Depending where the user is in the world, a connection will be made to the local notification server. There are main ones in Singapore, Dublic, Redmond and Reading. This keeps the connection between the two users alive, and keeps things updated such as user status, chat requests and email notifications from Windows Live Mail/Hotmail.
5. The message itself doesn’t go near the notification servers – it is passed onto the switchboard server which is the where all the messages and files are exchanged. The user starting the chat can talk to one user, whilst using another switchboard session to talk to someone else, and another switchboard session for someone else still – without even knowing it. Invitations, file transfers and video/voice chat are also sent through here.
6. The information is then relayed back through an outgoing firewall and checks the user is still online. If the user is offline by the time the message is ready to be received, then it’ll bounce back and be saved on the switchboard session until the user logs back on again. If they are online, they will receive the message.
This is all done in the space of around 2 seconds – most of the time your message will be sent at least twice around the world, in the space of 2 seconds. Not bad eh?
Posted in Networking, Windows Live Messenger | 
20 Comments »
December 27th, 2006 at 9:32 pm
Pretty complex. How exactly does Yahoo messenger fit in there?
December 27th, 2006 at 10:08 pm
Somewhere 🙂
December 28th, 2006 at 1:23 am
So thats what they do in Reading!
December 28th, 2006 at 3:44 am
For a more detailed explanation, check out this video on Channel 9: http://channel9.msdn.com/Showpost.aspx?postid=215459
December 28th, 2006 at 6:59 am
[…] MSBlog takes a look at how Windows Live Messenger works. […]
December 28th, 2006 at 7:51 am
Interesting little picture there. I wish my messages would be deliverable at all times though. Connection between my MSN mac friend (using the MSN client) and myself (using the latest beta) fails to send mine or their messages out many times.
December 28th, 2006 at 10:26 am
Hey. Singapore ain’t part of China… Its an independent nation and its code is SG. Good depiction though.
December 28th, 2006 at 11:23 am
Its still centralized system with single point of failure.
December 28th, 2006 at 11:31 am
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December 28th, 2006 at 12:11 pm
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December 28th, 2006 at 1:18 pm
I’d like to know WHEN Windows Live Messenger actually works…
December 28th, 2006 at 3:50 pm
Nice one, Zack, and now linked at Mess.be!
December 28th, 2006 at 4:21 pm
Sorry, but I have to comment on this post. It is great you try to pass on the knowledge of how Windows Live Messenger works on the server side, but your post contains several factual errors.
First of all, the data center locations. I am fairly sure there is no datacenter in Redmond. Pretty much everything Microsoft hosts is hosted in California, or other data centers around the world. It is true that the server team is working on geohosting, however, I am not sure this has been put to action for WLM yet — If not, then it is still single point of failure as Peter said.
Also, the NS (Notification Server) is only a small part of the servers. You are actually missing a pretty big layer, called the Presence Servers. Also, although “Switchboard” is still the most used name, the official name of these servers are “Mixers”.
Again, nice you want to inform people, but your blog post could have done with a bit more research, and some better descriptions and explanations, and as Scott has said before, there are already pretty good explanations (by the team themselves!) in video form.
December 29th, 2006 at 9:02 am
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December 29th, 2006 at 10:02 am
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December 29th, 2006 at 11:14 pm
[…] Los amigos de gentebeta hicieron la traduccion de articulo en ingles publicado en msblog de sobre como funciona el protocolo del Messenger de Microsoft, esta muy interesante se los recomiendo. […]
December 30th, 2006 at 11:44 am
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January 24th, 2007 at 1:50 am
[…] How WLM works…FYI Hi: I came onto this website while surfing MSBLOG » Blog Archive » Who wants to know how Windows Live Messenger actually works? and thought it’d be nice to share it with all of you. While you’re there, click on the thumbnail to see the graphical details. Some interesting facts in a nutshell: 1) When a user starts chatting, the message is first sent to a dispatch server. 2) It is then sent to a notification server. There are 4 main ones worldwide: Singapore, Dublin (Ireland), Reading (UK), and Redmond (US). 3) Finally it is routed to a switchboard server, which transmits it to the recipient. 4) The above steps are repeated while contacts are chatting to one another. Quote: […]
January 25th, 2007 at 4:29 am
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