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On Mon, 7 Oct 2002, Roger L. Costello wrote:
> Hi Folks,
>
......
>
> 4. RDDL (Resource Directory Description Language) is a lightweight,
> distributed mechanism for storing information about a namespace. The key
> notion of RDDL is to use namespaces in a dual role - both as an
> identifier, and as a pointer to a RDDL document. The RDDL document is a
> directory for the namespace. That is, it contains pointers to documents
> that you wish to associate with the namespace. Such documents include
> schemas, stylesheets, dictionary, spec (all the things that my client
> wants associated with a service in his registry).
>
> 5. My idea is that each client service be associated with a different
> namespace, and each namespace point to a RDDL document. Thus, the set
> of client metadata is distrbuted across all the RDDL documents. This
> yields a lightweight, distributed metadata mechanism - which is
> harmonious with the Web architecture.
How will an application know which schema applies to a given message? If
you can guarantee that message design will never change once published,
then this isn't an issue. I suspect that is not a reasonable assumption,
in which case the message will need to 'know' which version it complies
with, so that when an application dereferences the RDDL, it will have some
way of picking the 'right' schema (or style sheet, or whatever).
Otherwise, I like the idea very much - particularly having one namespace
per service type. I'm curious to know how you sold that approach -- I had
no success where I work (we're looking at XML as an application
integration tool, and end up needing messages using multiple namespaces,
the namespaces associated with non-generic data associated with the
different apps)
Ian
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