Use "If-Modified-Since" in cache updates
Brought to you by:
kherr
Currently a HEAD request is made to get the last modified date of a resource. If it's out of date a second GET request is made to get the resource.
This could be changed to a GET with "If-Modified-Since" which would return a 304 (Not Modified) response if up-to-date or act like a normal GET if out of date. This would be more efficient network usage.
See RFC 2616 for a description of "If-Modified-Since" in HTTP transactions.