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   Re: [xml-dev] Microsoft FUD on binary XML...

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Jeff Lowery wrote:
> I'm sure this has been asked before, but I missed it:
> What can be achieved by binary XML that can't be similarly achieved 
> using well-known text compression algorithms?

Do you mean gzip and friends?

If so, then the answer is "reduced complexity" and "improved 
performance"! gzip is a fairly complex algorithm, easy to get wrong, 
hard to understand, and it uses a lot of buffer space (especially when 
compressing). Plus it's quite CPU intensive.

Many have pointed out that gzipping XML produces a smaller file than 
just PER-encoding or something like that - this is certainly the case if 
the XML in question is more text than tags, since in PER the text would 
be represented just the same as in XML, in general, and all that is 
gained is the conversion of tags and structured data to compact forms. 
However, gzipped PER will generally be even smaller than gzipped XML; so 
if you have the spare resources at each end to gzip everything then you 
can regain some of the time performance you lost due to gzipping by 
using something like PER instead of XML as the stuff you compress.

So to conclude - byte stream compressors like gzip, bzip, and so on gain 
you space efficiency in transit at the cost of time and space efficiency 
at the endpoints. But byte stream compression sits at a lower level than 
XML, PER, XDR, and so on - it can be equally well applied to all of 
them, although formats with less redundant information in tend to 
produce smaller compressed versions (don't be fooled by the fact that 
the compression ratio of highly redundant data is high ;-)



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