Paul has volunteered (was Re: Overloaded URIs must GO!)

Jonathan Borden jborden at
Tue Jun 1 19:24:04 BST 1999

Paul Prescod wrote:
>But there are specifications being built on top of the namespaces
>specification that make use of the URI. These specifications are not right
>or wrong -- the namespace spec is silent about what happens if you
>dereference the URI.
>When these specifications are deployed, software will attempt to
>dereference namespace URIs. That software will not know whether to report
>inaccessible URLs as errors or retry on the hope that it is available now
>or merely assume that that namespace doesn't have an associated document.
>Do we report an error or merely continue?

    This is a very difficult problem without an easy solution.

    This problem will arise with most data whose lifespan is expected to be
long. Short term problems include network outages as well as firewall
issues. Longer term problems include changes in DNS ownership. Still longer
term problems include changes in network protocols (i.e. when http becomes a
legacy and/or unsupported protocol).

    The only good solution to this problem is to keep schemas/DTDs together
with documents and not depend on any network protocol.

    URNs aren't a solution to this problem, because URN's don't allow
dereferencing (otherwise they become another type of URL). Wouldn't it also
be an error to attempt to dereference "urn:xxx..."?

Jonathan Borden

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