[Standards-JIG] XMPP bandwidth compression

Jean-Louis Seguineau/EXC/ENG jean-louis.seguineau at antepo.com
Sat Jul 3 16:47:55 UTC 2004


And probably some day someone will put forward the idea to share the
dictionary in advance instead off rebuilding it every time to speed up the
process more, and it will be called 'fast schema' :)

Jean-Louis

-----Original Message-----
Message: 9
Date: Thu, 1 Jul 2004 22:29:08 -0400
From: "Fletcher, Boyd C. J9C534" <Boyd.Fletcher at je.jfcom.mil>
Subject: RE: [Standards-JIG] XMPP bandwidth compression
To: "Jabber protocol discussion list" <standards-jig at jabber.org>
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	<1D317DC2764EAA4F8F52741F125A827B03BC5334 at postman.j9.root2k.local>
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maybe I'm not understanding Fast Infosets but it seems to me that

1) largely ignores the content of message (which sometimes can be a good
thing for IBB or Signed Content) but overall I suspect that's a bad idea.

2) it doesn't handle namespace or attribute compression (just does duplicate
substitution). Since JIDs and Namespaces make up a significant portion of
the XMPP traffic this would seem like a rather significant problem unless we
consider an entire XMPP stream as a single document.

3) It would seem to be me slower (or more expensive) to covert from XML on
the client to FI and do some content compression method before tranporting
then reverse the process on the server, than to just do some type of block
compression for the entire message. 

4) that the real advantage of FI is in fast processing of the document not
in the compression.

Though I was wrong about the requirement to know the schema before hand,
infoset's approach uses quite a bit more bandwidth than the approach of
knowing the schema before hand. Also, the way Infoset appears to implement
its optimizations appears to have the biggest impact on documents that have
lots of identical and long (greater 8 characters) strings/tags. 

So if it was used for XMPP, would we consider a single XMPP stream as a
single document?
We the small tag sizes of jabber protocol would we really gain that much
compared to a regular block compression like gzip?


boyd 




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