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From Ben Laurie <>
Subject Re: mod_proxy changes
Date Mon, 27 May 1996 19:20:33 GMT
Robert S. Thau wrote:
> A few other items which might be useful, as long as someone's hacking the
> thing:
> *) It should identify itself as an HTTP/1.0 proxy to both servers or
>    clients.  Right now, if I recall right, the protocol identifier in
>    the response is copied from the origin server's response verbatim.
>    This could cause problems in the future, when an "HTTP/1.2"
>    response from this proxy leads a client to believe that the proxy
>    has behaved in accord with PEP protocols which were in scope for
>    it, when in fact it has no idea what a PEP protocol is.
> *) At present, it passes "canonicalized" pathnames on to origin
>    servers and further proxies.  The last time I checked the HTTP/1.1
>    drafts, which was admittedly a couple of revisions ago, they
>    specified that a proxy SHOULD pass on the URI exactly as received,
>    with one exception which applies only to the OPTIONS method.
>    (Putting SHOULD in all caps signals a normative requirement ---
>    violators can be conditionally but not fully compliant).
>    I think it would only be a couple of lines of code to change this;
>    pass r->uri instead of r->filename to http_handler whereever it's
>    called.  (The draft explicitly allows for canonicalization of path
>    when checking for a cache hit, to avoid duplication of resources
>    in the cache).

This seems perverse ... if the canonicalization is valid for the cache, surely
one must assume it is valid for the URI? [yeah, I know, I should be on HTTP-WG
for this kind of argument ... but can I take the mail load?]

That is, surely:

cache(a) ~ cache(b) => a ~ b [Axiom 1 (required for correct function of cache)]
cache(a) ~ cache(canon(a)) [Axiom 2 (stated above)]

where ~ means "is equivalent to"


canon(a) ~ a [by axioms 1 and 2].



Ben Laurie                  Phone: +44 (181) 994 6435
Freelance Consultant and    Fax:   +44 (181) 994 6472
Technical Director          Email:
A.L. Digital Ltd,           URL:
London, England.

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