- From: Koen Holtman <koen@win.tue.nl>
- Date: Tue, 18 Mar 1997 18:51:29 +0100 (MET)
- To: Henrik Frystyk Nielsen <frystyk@w3.org>
- Cc: koen@win.tue.nl, http-wg@cuckoo.hpl.hp.com
Henrik Frystyk Nielsen: > >At 07:21 PM 3/16/97 +0100, Koen Holtman wrote: > >>In stead of >> >> Vary: Protocol, "http://some.org/a-required-extension" >> >>you can just as well use >> >> Vary: Protocol >> Cache-control: vary-protocol="http://some.org/a-required-extension" >> >>or something, so there is no need to revise the Vary syntax: just use the >>extensible cache-control syntax to convey your extra directive. > >This is not exactly what I am trying to achieve. It is not a question of >describing which parts (headers, body, or complete message) of a response >that are cacheble or not I know the above is not a case of cache-control saying something about the cachability of some part of the response. But you are still allowed to use the cache-control extensibility mechanism to get the extension you want. If it controls caches, it can be put in cache-control. You can also define a completely new header if you want. My point is that there is no need to incompatibily extend the unextendable Vary header. [...] >>You can also use the following hack, which will get you what you want even >>under the current HTTP/1.1 spec. If you have multiple protocol headers but >>only want caches to vary on one, include an extra header like >> >>Proto-Vary: {http://some.org/a-required-extension {str "req"}} >> >>in the response, and send "Vary: proto-vary" in stead of "Vary: protocol". ^^^^^^^^ Oops! I should have written request here >>Strange, but fun. Of course, you would usually want to have a shorter >>encoding in the above proto-vary header. > >Throwing in random new headers is exactly what PEP tries to avoid Yes, you have a point. The above is a hack: if this functionality would be needed often, you are better off defining clean new mechanism. >Henrik Koen.
Received on Wednesday, 19 March 1997 02:03:16 UTC