Re: Resource discovery directory [was: XML Catalog proposal]

[Jonathan Borden <jborden@mediaone.net>]

Paul Grosso wrote:

>
> As Dan Vint's message points out, calling this a catalog can
> lead to confusion.  The OASIS Entity Management catalog [3],
> John Cowan's XML-ization of it called XML Catalog [4], and
> the current OASIS Entity Resolution Technical Committee (ERTC)
> work [5] on standardizing an XML ER catalog (xmlcat) are all
> talking about a mechanism to map external identifier information
> (e.g., public ids, system ids, and namespace names) to URIs.
>
> What the current discussion is about is defining the format
> of a resource discovery "directory".  (See also Tim Bray's paper
> of Sept 1999 [6].)  I would strongly suggest we avoid the word
> "catalog" in the current discussion.

    I have no particular attachement to the term "catalog". Would either

        "XML Namespace Resource Directory" (XNRD)

    or simply

        "XML Resource Directory" (XRD) be preferable?

    The following has the best acronym:

        "XML Namespace URI Resource Directory" (XNURD).

    Open for discussion.

>
> I'd also suggest we avoid mixing ER catalogs with resource
> discovery (RD) directories.

    After further consideration and offline discussion I agree that it is
best not to mix these together.

>These things are at different
> levels and should not be mixed.  Mapping external ids is
> something that happens in the middle of an XML parsing
> process by an entity resolver (a module called by the
> XML parser itself), whereas using a RD directory to find
> a stylesheet or a metadata or relevant external code is
> something that happens "above" the level of the parser.

    My thinking was that one might create an entity resolver which resolves
external entities in a namespace dependent fashion (note, doing such is not
dependent on any particular or direct support for entities in the namespace
directory document). By this mechanism, as new namespace URIs are
encountered *during the parse phase* the namespace directory would be
resolved and parsed into a map. As elements are parsed, the map associated
with the element's namespace URI could be used in the entity resolution
process.

    Again, this mechanism which I bring up for discussion purposes, could
just as easily be supported by using a namespace resource pointing to a
catalog, e.g.:

    <xnurd:resource content-type="application/SGML-Open-Catalog"
                    xlink:arcrole="http://www.xmlns.org/OASIS-Open-Catalog"
                    xlink:href="catalog.soc">
            <p class="resource">The OASIS Open Catalog format catalog for
this namespace is: <code>...</code> ...</p>
    </xnurd:resource>

>
> I do think there is a potentially useful synergy between
> the ER catalog and the RD directory

Yes. We can explore these synergies.

Jonathan Borden
The Open Healthcare Group
http://www.openhealth.org