"Memory is cheap; bandwidth is cheaper"
-- Nathaniel Borenstein
With all due respect to Nathaniel, he got this one wrong. He's not alone; many
other people, most notably the designers of the X Windows system, also got it
wrong.
Say what? CPU is cheaper than bandwidth? Fine.
Darn tootin it is.
But, like Chris said, programmers are far more expensive than either.
So whatever you do, go for interoperability and simplicity.
Simplicity can be measured in many ways. A compression scheme for which there
is no freely available highly optimized production quality version is very
complex indeed by my measure, a compression scheme for which there is a freely
available production quality version which has been ported to dozens if not
hundreds of platforms is vastly simpler.
I'd be inclined to ask for GZIP with Base 64 because I can
plug a lot of lego blocks together at the higher level. This would
probably wind up as a Content-Type: application/gzip bundle, which
I don't particularly care for, but it saves on coding costs.
You're assuming a connection between compression and content type that
does not, in fact, exist. There is absolutely no reason why gzip (or
deflate) cannot be used as a CTE.
You
scare me when you suggest zlib, because that's C that might give me
compiler/porting problems. (I run on a W-I-D-E range of platforms.)
I suggest you try it before making such assumptions. I also have to run on a
wide range of platforms, and while I've not used zlib in production (yet), I
have used it and found it to be very portable indeed.
Ned