Re: Last Call: HTTP Extension Framework to Proposed Standard

From: Roy T. Fielding (
Date: Sun, Feb 14 1999

To: Koen Holtman <>
cc: Henrik Frystyk Nielsen <>,,,
Date: Sun, 14 Feb 1999 09:45:35 -0800
From: "Roy T. Fielding" <>
Message-ID:  <>
Subject: Re: Last Call: HTTP Extension Framework to Proposed Standard 


The extension framework must not automatically prevent caching.
There is nothing in Henrik's draft that prevents an extended request
or response from including the EXISTING cache control mechanisms of
HTTP/1.1.  It is not necessary, nor is it desired, for the draft to
assume that an extended message is not cachable just because some
particular extension might not be cachable.  Therefore, your suggested
changes are contrary to the design of HTTP.

It is the responsibility of the extension to ensure that the appropriate
caching or cache-busting is applied based on the individual semantics of
each specific message.  This cannot be ascertained without knowledge of
the extension semantics, and therefore it is not part of the extension
framework for the same reason that the framework does not define actual

 ...Roy T. Fielding
    Department of Information & Computer Science    (
    University of California, Irvine, CA 92697-3425    fax:+1(949)824-1715