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Re: Cache-Control Interpetation

From: Koen Holtman <koen@win.tue.nl>
Date: Mon, 1 May 2000 22:49:11 +0200 (MET DST)
Message-Id: <200005012049.WAA01665@wsooti09.win.tue.nl>
To: j.p.tdobbelsteen@freeler.nl (Joris Dobbelsteen)
Cc: www-talk@w3.org
>If a Cache-Control header is received with e.g.
>	no-store, community="UCI", max-age=30
>from your sample (another discussion).
>
>Can a client or proxy server only use the first word: "no-store". On the
>proxy I'm writing, the goal is to only look at the first word: "no-store",
>simply assuming the rest is meant as a parameter from this keyword.

You cannot make the assumption that the rest is a parameter.  HTTP/1.1
makes no guarantee that the 'most important' cache-control keyword
appears first.  You really have to look at all the keywords.  If you
only look at the first word you will fail to make the correct caching
decision in some cases.

>Thereby isn't it a better way to send something like this?????
>	no-store, community="UCI; max-age=30
>
>this way you can interpet the cache (for community-aware proxies/clients)
>should use no-store if there community is "UCI", otherwise they should use
>max-age=30????

There is some logic in your proposed syntax, but the HTTP/1.1 spec is
finished so it is probably too late to make syntax extensions like
this.

>
>
>
>Another question, where can I find information about community-aware
>caching? (RFC #?)

RFC2616 has a notion of a shared vs. private cache.  I'm not aware of
any RFC's that go deeper than that into the subject.  If you are
looking for community-aware caching software or cache optimisations, I
think conference proceedings are a better bet than RFCs.

>
>
>
>Joris Dobbelsteen
>

Koen.
Received on Monday, 1 May 2000 16:49:19 GMT

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