I've just resolved an issue I had with images loaded by a javascript preloader not being cached by Internet Explorer, the images
are produced in a Cocoon pipeline that uses the ImageReader.
The problem is with the 'Vary' response header that is set by the reader if the 'expires' parameter is not provided. IE will not cache
responses containing this header unless its field value is the 'User-Agent' field, for more detail see:
http://lists.over.net/pipermail/mod_gzip/2002-December/006826.html
Looking at the ResourceReader source and the associated bug report, setting the 'Vary' header was intended to prevent IE from
caching the resource when the 'expires' parameter was provided with a value of 0. The way the code is implemented the header
will also be set when the expires parameter is not provided.
Should the default behaviour of the ResourceReader be to provide non-cachable content?
Don't think so. Please provide a patch via bugzilla.
PS And switch to plain text email, html on mail lists is evil.
Vadim
