[jdev] Zlib compression

Stephen Pendleton spendleton at movsoftware.com
Thu Dec 1 13:21:41 CST 2005

After some investigation, I believe zlib puts the compression level,
strategy and other variable in a header when it sends/receives the block.
Therefore, as Ralph said, in the case of zlib it is not nescessary to
negotiate this as zlib will handle it automatically. So as long as we stick
to zlib we should be OK without negotiation. 

Related to this, I am about to release a test version of a PocketPC/Windows
Mobile client that includes support for the compression JEP. If anyone has a
PocketPC/Smartphone/HandheldPC and access to a server that supports the JEP
please drop me a note and I will send you a copy.


-----Original Message-----
From: Peter Saint-Andre [mailto:stpeter at jabber.org] 
Sent: Thursday, December 01, 2005 12:32 PM
To: pendleto at movsoftware.com; Jabber software development list
Subject: Re: [jdev] Zlib compression

Stephen Pendleton wrote:

> As you can see, you can specify a compression level, a compression 
> method, and a deflation method. Since the stream compression JEP 
> doesn't specify the inclusion of feature negotiations, how are 
> implementors handling this? Currently I use default values for the 
> level and compression/decompression methods and it works fine.

We talked about this a bit in the last Council meeting:


Also, the provisional version 1.1 of the JEP that I'm working on does 
include the ability to do feature negotiation:


It's not yet clear to me exactly what needs to be negotiated, for 
instance in the Council meeting Ralph Meijer suggested that it's not 
necessary to negotiate the compression levels, but others know more 
about that than I do. :-)


Peter Saint-Andre
Jabber Software Foundation http://www.jabber.org/people/stpeter.shtml

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