RE: CT Proxies and Forward Caches

Hi Umesh,
As you mention, meta-group assignment (e.g. good/better/best) is a
deployment-specific function, i.e. one Content Provider (CP) may choose
a different set of groups and UA assignment as compared to another.
Without the direct involvement of the CT proxy in group selection, the
only way I see to reduce the cached representations is for the CP to
provide a distinct URI to UA's in a group (e.g. a URI parameter or
unique path), so the various UA's naturally get served one of a fewer
variations of the page from the cache.
 
"direct involvement of the CT proxy in group selection" implies some
kind of metadata exchange between CP and CT proxy, through which
group-related pages can be indicated, and maybe a tighter integration of
the CT proxy and cache. Both appear (to me) to be less desirable to
standardize, and at least more complex to consider.
 
Best regards,
Bryan Sullivan | AT&T
________________________________

From: public-bpwg-ct-request@w3.org
[mailto:public-bpwg-ct-request@w3.org] On Behalf Of Umesh Sirsiwal
Sent: Monday, May 19, 2008 8:12 AM
To: public-bpwg-ct@w3.org
Subject: CT Proxies and Forward Caches 



Several content transformation proxies and the Internet in general
includes forward caches. Current definition of HTTP includes indication
of transformation using Vary header. In most cases the Content
Transformation proxies and servers vary their responses based on
User-Agent header. The number of User-Agent string in is very high and
caches cannot possibly store these mean copies of the response. Most
servers are likely to classify the devices in certain meta-groups for
the purpose of content transformation. However, this meta-group is
expected to be server specific. In absence of formal method, the caches
will be left to guess the meta-group. What will be the method to solve
this?