[Standards] mobile optimizations (was: Re: Google Andro ï d SDK not XMPP compliant ?)

Dave Cridland dave at cridland.net
Thu Feb 14 23:03:44 UTC 2008


(Hey, where did that space come from in the subject line?)

On Thu Feb 14 22:06:19 2008, Boyd Fletcher wrote:
> 1362 byte message ­ strongly typed
> WinZip 3.13 times smaller than original
> EfficientXML 75.67 times smaller than original
> 
> 980 byte message ­ loosely type
> WinZip 1.6 times smaller than original
> Efficient XML 8.45 times smaller than original
> 
> 21437 byte message
> Winzip 6 times smaller
> Efficient XML 33 times smaller
> 
> 
Interesting, certainly. My impression has been that binary XML  
formats handle cases best where the schema is fixed, and the data is  
relatively tightly marked up, and the overall document length is low.

Our data is heavy on the text, and our overall schema varies wildly,  
and our documents are quite big.

The Efficient XML Interchange Measurements Note seems to back up this  
impression I have:

"The best improvements compared to gzipped XML in the Both case come  
for small documents, which also have sufficient schema information,  
i.e., the FixML and CBMS  groups. Here FXDI and Efficient XML (and  
ASN.1 PER in some cases) manage to achieve a clear improvement,  
sometimes even under half the size of gzipped XML. For the larger  
documents there appears to be no gain over the Document case. For  
example, there is no size difference between gzipped XML and any of  
the candidates for the Seismic document, in contrast to the Schema  
case."

To my mind, the figures and graphs there suggest that improvements  
over DEFLATE will be marginal at best for our kind of data.

But I'll do my reading, certainly, as well as getting some figures  
for some XMPP session compression using existing mechanisms -  
assuming I can. (I vaguely recall that the jabber.org server does  
XEP-0138, and I know ours does TLS compression - I could stick  
XEP-0138 in it quite quickly I think as a test).

Dave.
-- 
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