Re: Faster HTTP Was:Re: The Superhighway Steamroller

Marc VanHeyningen (
Wed, 6 Jul 1994 05:55:26 +0200

Phil Hallam-Baker sed:
>One idea we had a dinner last night is to have `accept groups'. To first
>order one can infer most of the image etc formats understood by the user
>agent id field. After all all mosaics are going to do gif and html, the
>CERN linemode is going to do html etc... Now the problem here is
>maintenance since the server must know what the groups mean... even if the
>group was declared long after the server came up... URL time!!!!
>OK so this >Looks< like we have an extra connection per transaction. Quelle
>horreur! In fact we cache the page - cleverly in parsed form. So we only do
>one extra GET and one parse for the accept group each time the server comes up

Of course, the precise Accept: header will be different not just for
each browser, but for each different mailcap (or other similar
configuration) file; i.e. it will be different for each site, and
plausibly different for each user. This means the browser needs to be
able to somehow create a document which specifies its current accept
status, which is possible but far from trivial or universal, and
caching will have limited benefit.

Of course, if the server is returning HTML (as it often is) it can
just return it anyway without checking at all.

>I would like to wait until the URN scheme is a little firmer though. We don't
>want CERN or NCSA being slammed by every server each time it starts up.

I don't think this would happen. All Mosaics and linemode clients are
not the same with regard to what types they accept.

>Also note that under this scheme a server that makes no use of the headers
>doesn't even bother with the URN at all.

Sensible enough...

>Aggh! I made a mistake here! Why restrict this JUST to accepts? We can
>generalize! Have a deferred header! Allow ANY header field inside it.
>So make that :-
>OK so I can't think of another use besides accept but one might appear.
>We could also add in much more info into the header knowing it would only
>be sent on a one off basis.

Accept-Encoding? Accept-Language? Ok, sort of the same thing... with
the object in question having some suitable type, of course.

- Marc

<A HREF="">Marc VanHeyningen</A>