Re: [xml-dev] RDDL and user interface

[Jonathan Borden <jonathan@openhealth.org>]

Eric Hanson wrote:

> Jonathan Borden (jonathan@openhealth.org) wrote:
>> ...
>> Although it is convenient to store a RDDL file so that it will be
>> returned on dereferencing a namespace URI (i.e. store the RDDL 
>> document
>> "at" the namespace URI) this is not necessary. RDDL is a *language* 
>> and
>> RDDL documents might be stored *locally* ... for example add a
>> reference to the local file in an XML catalog.
>>
>> It is true that it is *designed* to be suitable as a format to return
>> on dereferencing a namespace URI, but this does not make RDDL
>> centralized ... hardly ...
>
> Yeah ok, centralized probably isn't the right word here, and I
> didn't mean to imply that the language itself is centralized.
> Just I think there needs to be a way for third parties to
> associate resources with a namespace in such a way that they can
> be found using just the namespace.

OK, what are the rules by which this process is carried out. Who gets 
to arbitrate when there are competing visions of what is associated 
with what. Decide this, and you can pick which system to use.

>
>> On the other hand if you really want to disassociate information about
>> namespace URIs from mechanisms used to dereference the URI e.g. DNS
>> HTTP etc, RDF is an excellent choice.
>
> Will you talk more about this?  The thing that made RDDL
> attractive is:
>
> * it's designed specifically to describe a directory of resources
>   associated with a namespace
> * nature/purpose are perfect

You say "a" directory of resources? Then RDDL is an excellent choice. 
You can either use the directory provided by the owner of the DNS entry 
associated with the namespace URI or use xmlcat or something similar to 
provide a local override to associate whatever particular directory you 
wish with whatever particular URI you wish.

The more general RDF idea is that there is an RDF triple store that 
contains a whole mash of triples (associations), not necessarily from a 
single document but perhaps from any number of documents. Now you can 
certainly extact a set of RDF triples from a  RDDL document e.g. 
rddl2rdf.xslt in the case of RDDL, if you are looking for the more 
general RDF "anyone can say anything about anything" idea of what 
defines a namespace, then if anyone can add their triples to an RDF 
store, then anyone can define "what is in" the namespace.

Jonathan