[Standards] All your problems, solved ;)

Dave Cridland dave at cridland.net
Mon Aug 27 20:55:38 UTC 2007


On Mon Aug 27 20:55:05 2007, Jonathan Chayce Dickinson wrote:
> I was perusing over a couple of MSDN articles, when I came across 
> DIME (Direct Internet Message Encapsulation). Jeez, I thought, that 
> would fix all the file issues in Jabber (like SI). So I wrote a 
> draft, any takers? What do you all think? Didn't want to push this 
> forward until I got some feedback.

DIME seems to have been orphaned by its authors, in favour of 
soap12-mtom, so I'm not convinced it'd be a good plan to go this 
route whatever the merits of the general concept.

However, as a general note, encapsulating small amounts of "binary" 
data in base64 is generally okay - you'll recover the majority of the 
33% bloat through compression (which you hopefully have via TLS, and 
may have via other means).

This isn't suitable for large amounts of data, though, since 
compression doesn't fully recover the overhead.

Moreover, compression algorithms will become "poisoned" through 
trying to compress different types of data - typically via skewing 
the Huffman encoder and destroying the backreference "dictionary". 
This is especially true if the data being transferred is already 
compressed, in this case you can observe surprisingly high increases 
in data transfer cost (ie, negative compression).

But sending bulk data through XMPP is a bad idea for a number of 
other reasons, not least of which it's trashing the server, and 
clogging your XMPP channel (thus reducing its response time).

A better method is to negotiate a peer-to-peer session suited to the 
kind of transfer you're doing, although I admit that's not exactly a 
ground-breaking suggestion. :-)

Dave.
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