- From: Carl Binding <cbd@zurich.ibm.com>
- Date: Tue, 11 Jun 2002 08:51:11 +0200
- To: "Sam Lerouge" <sam.lerouge@rug.ac.be>
- Cc: www-mobile@w3.org, www-mobile-request@w3.org
Sam, thanks for the answer; I see the point you're making and agree with the fact that XSD does not offer this deducing capabilities. Mind you however I'm not entirely convinced that a) applications will really be able to make use of sophisticated deduction and b) if such sophisticated deduction will ever be needed to describe, after all, a limited set of parameters for portable devices. We see apps being driven through profiles and bearing in mind that UAProf defines roughly 50 properties with - on the average - 3 possible values we get 3^50 combinations. how shall any application make sensible usage of this vast parameter space? Imagine a JSP or Java Servlet based web application, which - in the end - produces some markup. will application developers be able to design good applications making usage of overly sophisticated and fine-grain profile information? XML Schema would, to some extent, probably support extensions through the definition of new data types, but yes, this may not be as flexible as RDF appears to be. Eventually we'll face the issue of simplicity and useability vs academic beauty. Regards, Carl |---------+---------------------------> | | "Sam Lerouge" | | | <sam.lerouge@rug| | | .ac.be> | | | Sent by: | | | www-mobile-reque| | | st@w3.org | | | | | | | | | 10-06-02 16:42 | | | Please respond | | | to "Sam Lerouge"| | | | |---------+---------------------------> >----------------------------------------------------------------------------------------------------------------------------------------------| | | | To: <www-mobile@w3.org> | | cc: | | Subject: Re: Why RDF was a good choice | >----------------------------------------------------------------------------------------------------------------------------------------------| Hello Carl, The RDF model in itself perhaps does not provide any semantics advantages compared to XML Schema, as far as I know (I am not an RDF expert). The advantages come when you start using RDF Schema. Or better, when different vocabularies are used, that refer to other vocabularies. These "inter-vocabulary relationships" are not known in XML Schema, I believe. The previous version of the RDF Schema specification (see http://www.w3.org/TR/2000/CR-rdf-schema-20000327/) gives some basic hints on how one could use this. I think RDF is all about machine-readability, rather than human-readability. The interesting part of RDF is that a software agent that has a basic knowledge on some constructs (e.g. the CC/PP model and core vocabulary) can learn to use other vocabularies when you feed him a new RDF Schema that refers to the vocabularies he already knows. One strong point of RDF Schema is the ability to express of relationships between different vocabularies. I am thinking of a useful application: when a content provider knows that a) "requested_file --mime-type--> image/jpeg", and b) "user_agent --accepts--> [text/html, text/plain, image/jpeg, image/gif]", then he should be able to deduce the client will be able to process the data. In order to do so, he must know the relationship between the "mime-type" property, that belongs to a multimedia metadata vocabulary, and the "accepts" property, that belongs to some CC/PP vocabulary. Using RDF Schema (or one of the related technologies, such as DAML+OIL) to express both vocabularies, and their relationships, would enable the content provider to learn new vocabularies and their use. Secondly, when I am thinking about "correct use" (I'd better say "proper use") of RDF, I am thinking of using RDF Schemas to define vocabularies, and making use of the rdf:type property in RDF models. I think I wasn't very clear about that in my previous mail. Hope this wasn't too much information in one time. Sam Lerouge
Received on Tuesday, 11 June 2002 02:52:25 UTC