[Standards-JIG] MUC traffic issues

Alexander Gnauck gnauck at ag-software.de
Sun Feb 19 16:40:26 UTC 2006


Hello,

i had a small discussion with Ulrich about it in the JSF meeting today, 
and we had discussions about that in the jdev room quite often in the 
last weeks.

With very busy chat servers and chat rooms all current MUC 
implementaions scale very bad, because too much bandwidth is wasted and 
too many message and presence stanzas are routed.

example:
5 users in a room room at conference.jabber.org, user1 sends a message to 
the room. All users are connected to jabber.org in the scenario

message flow:
user1 -> jabber.org -> conference.jabber.org

the messages reached conference.jabber.org which creates now 5 new 
messages, because the message must be delivered to all participants.

conference.jabber.org 	|-> jabber.org -> user1
			|-> jabber.org -> user2
			|-> jabber.org -> user3
			|-> jabber.org -> user4
			|-> jabber.org -> user5

we send 2*usercount messages. If the Muc server is build in the server 
or cluster we could reduce the messagecount by 50% with a good software 
design. But if MUC is used of the component protocol we can't.

So Ulrich proposed to use a combination of muc and pubsub to reduce the 
traffic which is a great idea.

The message flow would be the following then:

conference.jabber.org	-> MUC_Pubsub	|-> user1
					|-> user2
					|-> user3
					|-> user4
					|-> user5

We send only usercount+1 messages now.

Your thoughts

Alex




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