[Standards-JIG] changes to JEP-0138 (Stream Compression)?

Ralph Meijer jabber.org at ralphm.ik.nu
Sat Mar 26 09:40:33 UTC 2005

On Fri, Mar 25, 2005 at 04:15:06PM -0500, Stephen Pendleton wrote:
> I did write up some suggestions (below). My problem with 0138 is that it
> only supports zlib compression. There are no provisions for other
> compression methods or compression levels. It think that stream compression
> should be setup using feature negotiation.
> ----------------
> After reading through the JEP-0138, I would like to submit some ideas on
> this to the jdev community.  As was mentioned before on the list many mobile
> clients have limited processing and/or memory requirements that may preclude
> the use of zlib at certain compression levels. For example, zlib compression
> at level 3 may perform well on a typical cellphone, but level 9 may produce
> unacceptable performance. It seems to me that this would be a excellent use
> case of JEP-0020 (feature negotiation) to find out what compression levels
> and/or methods (zlib, bzip, foozip, etc) are supported on the endpoints.

As stated before, zlib doesn't require you to negotiate the compression level.
You just compress with the level your device is comfortable with. The
decompression is not leveled, in that it is not harder to decompress a stream
with level 9 than level 1.

I believe bzip shares this property, but uses large amounts of memory and
might not be suitable for mobile clients anyway.



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