Re: RDF Issue #rdfms-qname-uri-mapping


> Jonathan,
> In
> you raised an issue which was captured in:
> as
> [[[
> The algorithm for mapping a QName in the RDF XML syntax to a URI is to
> concatenate the URI of the namespace with the localname part of the QName.
> In the case of namespaces, such as the XML Schema datatypes namespace,
> which do not end in a "#" character, then the URI reference generated by
> this algorithm is not the same as the conventional URI for the concept.
> ]]]
> As recorded in
> the RDFCore WG resolved to not change the algorithm for mapping qnames to
> uris and close this issue on the grounds:

I find this unacceptable for the following reasons:

1) I have received nor have I found a proper analysis or explanation for the
decision on any of the RDFCore WG archives. I will outline my objections to
the three issues raised below.

2) The problem is that there is much talk in RDFCore and WebOnt WGs about
leveraging XML Schema datatypes for both RDF and WOL. At the surface this
seems an entirely reasonable and desirable thing to do. The problem is that
XML Schema identifies types by QName, and unless there is a reasonable
translation between QNames and URIs, RDF is likely to become more broken
with time.

Since my proposed solution, Henry Thompson has explained to me how the
issues with QNames and URIs are even deeper than I first assumed, namely
that one cannot generally derive a proper URI which corresponds to the QName
that XML Schema uses to identify a particular type. It seems to me that the
RDFCore and XMLSchema WGs (at the very least) ought to develop a common,
reasonably acceptable convention as to the mapping between QNames and URIs.
Perhaps this is an issue that the TAG ought to consider (because it is a
really basic architectural issue). I have cc:'d both Henry Thompson and Tim
Bray. If either of these individuals agree that this issue ought to be
closed, then I will find that acceptable and will withdraw my current

>      1. Such a change would be a major change to the
>         mapping of  RDF/XML syntax to the model and
>         would be beyond our charter.

The RDF 'model' itself has undergone major change indeed it has been
completely rewritten. If it is not beyond the charter to completely rewrite
the 'model' how could the model-syntax mapping possibly be beyond the

>      2. It would cause the same RDF/XML to generate a
>         different  graph from existing versus revised
>         implementations

The same is true for many of the changes, even trivial changes which have
already been decided upon. This is exemplified by the following trivial RDF
1 example:

<rdf:Description about="">
    <rdf:type ID="baz" resource=""/>

since the new syntax does not interpret the unqualified attribute "about"
the same as "rdf:about", this example which was valid RDF 1 is not valid RDF
1.1 or whatever the current drafts are intended to be.

>      3. Existing code may generate wrong (illegal)
>         graphs for some RDF/XML.

see above, same story.


Received on Monday, 21 January 2002 16:21:39 UTC