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Re: semantics of host field in http URI

From: Roy T. Fielding <fielding@gbiv.com>
Date: Fri, 27 Aug 2004 14:37:51 -0700
To: uri@w3.org
Message-Id: <592E2040-F871-11D8-9EF3-000393753936@gbiv.com>

On Sunday, August 8, 2004, at 11:11  PM, Adam M. Costello wrote:
> This implies that the meaning of http://www.w3.org/ might change
> depending on where it is interpreted, unless the HTTP spec requires the
> use of domain names, which it currently does not (because it depends on
> RFC-2396 for that requirement).

Which doesn't require globally-scoped FQDNs either.  All you need to
demonstrate that fact is to create a subdomain prefix within your 
domain,
e.g.,

    www.w3.org.example.com

place an HTTP server there and you will see that all of the requests
to the above "http://www.w3.org/" from within the example.com network
will go to the local domain instead. I found this out the hard way ages
ago because someone at my University had the bright idea of renaming
the College of Medicine subdomain to "*.com.uci.edu", which of course
meant that (for a very short time) every machine name in that subdomain
would mask the "*.com" global namespace, unless the user happened to
know enough about how resolvers work to add the trailing ".".

> Does the HTTP spec need to be updated
> to explicitly require domain names?  Or is it intended to relax the
> semantics of http URIs and allow http://www.w3.org/ to mean different
> things in different places?

www.w3.org already means different things in different places.
HTTP doesn't care what it means -- the protocol only cares about
how the "http" identifier is resolved, and that is consistently
implemented as lookups within locally defined name registries.
You can read all you want into what RFC 2396 might have specified,
but that is how everyone implements it and the purpose of the current
specification is to describe how the standard should be implemented.

The HTTP spec will be revised later. Meanwhile, I can assure you
that anyone implementing HTTP will prefer how it is specified in
rfc2396bis, because that is how the technology works.

....Roy
Received on Friday, 27 August 2004 21:37:37 UTC

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