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Re: Re[2]: Summary: Section 2: What does a URI identify?

From: Roy T. Fielding <fielding@apache.org>
Date: Tue, 19 Mar 2002 19:54:58 -0800
To: "Williams, Stuart" <skw@hplb.hpl.hp.com>
Cc: "'Jonathan Borden'" <jonathan@openhealth.org>, Paul Grosso <pgrosso@arbortext.com>, www-tag@w3.org, Chris Lilley <chris@w3.org>, "McBride, Brian" <bwm@hplb.hpl.hp.com>
Message-ID: <20020319195458.B1976@waka.wakasoft.com>
Use of the fragment identifier as a means for constructing an artificial
namespace is certainly possible, but isn't a reliable design.  A fragment
is a separate identifier -- a user-specifiable indirect identifier that
allows identification of a portion of any representation, within the set
of available representations, of a given resource.  In other words, it
allows a third party to identify the product of a retrieval action,
or some portion of that product, indirectly via the resource URI.
In general, that is something you want to avoid doing unless there is
no other available means for directly identifying it as a resource
with its own URI.

You could say, within the limited scope of using a URI reference
in a way that has nothing to do with identification of the current document,
that a reference containing only a fragment identifier is intended to refer
to the base URI.  However, that doesn't help you face reality.  Reality
says that this protocol element will be implemented using the same
relative URI parser as all of the other URI-reference elements, which
means that reality will give you a result that differs from what you wanted.
What is the point in defining a specification that doesn't produce
interoperable results?

The answer is that if you want a protocol element that is similar but
not quite interoperable with the protocol element specified by the
standard, then you cannot refer to that standard element.  This is just
basic common sense.  The standard exists to help people achieve interoperable
implementations, not to force people to implement all protocols using the
same elements.

....Roy
Received on Tuesday, 19 March 2002 23:13:22 GMT

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