On 17.12.2008, at 11:47, Tom Hume wrote:
There are efforts ongoing to put pressure on ISPs to either drop
transcoding altogether, or at least configure it responsibly. I'd be
interested in hearing any thoughts on technical solutions to this
problem; would it, for instance, be reasonable and/or pragmatically
defensive to include "Cache-control: no-transform" by default on HTTP
requests triggered by AJAX clients or servers?
We're sending this header currently on a large German site -
unfortunately, I've not encountered/heard of a transforming proxy yet
which actually respects this header (on the other hand, a proxy which
is coded carefully enough to actually respect the header would usually
also be coded carefully enough not to include any bugs in the
transformation, that's probably why I never encountered a proxy where
the header did actually help to circumvent a problem).
This issue is worse than it appears on first sight, because many
transforming proxies are actually buggy and cause errors in JavaScript
code, not only in AJAX data requests. So far I've only once managed to
get a mobile carrier to actually fix his bugs.
Common problems are, that some of them truncate or remove parts of
JavaScript files if they contain strings like "</" or // - even in a
string/regexp! These are obviously oversimplified, regexp-based buggy
comment filters at work.
That's the reason why we for example use a locally patched version of
jQuery where all occurrences of // and </ in strings are hidden from
those proxies by using <\/ and \/\/ instead, which usually goes
through. I submitted a jQuery feature request months ago where I
requested whether anti-transforming-proxy changes like this could be
done in the official version of jQuery so I need not always patch it
myself, unfortunately it has been ignored so far.
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