Gregor,
I can understand your angst, but I would like to suggest that XML schema actually only really provides good support for some aspects of OO modelling. Extending classes is a real problem.
A data model encoded in RDF can still make use of an ontology language to provide greater rigour in the way that objects are defined.
As was indicated in some of the earlier messages here, it is even possible to put together a data model which looks fundamentally just the same as one defined using XML schema but which is using RDF technologies under the covers and which consequently is easier to extend than XML schema.
For me however the biggest factors of importance in a revision of our data models would be:
1. A cleaner separation between different object classes (not all versioned in a single schema).
2. A good model to support easy extension (using a multiple inheritance approach) so that different (potentially overlapping) communities can add extra information in the ways that best suit them.
3. An underlying ontology that is sufficient for us at least to identify the object class of each record.
RDF technologies are an excellent way to do this. GML has managed to produce many of the same features, but has probably done so largely by replicating the essentials of RDF modelling.
Thanks,
Donald
--------------------------------------------------------------- Donald Hobern (dhobern@gbif.org) Programme Officer for Data Access and Database Interoperability Global Biodiversity Information Facility Secretariat Universitetsparken 15, DK-2100 Copenhagen, Denmark Tel: +45-35321483 Mobile: +45-28751483 Fax: +45-35321480 ---------------------------------------------------------------
-----Original Message----- From: Tdwg-tag-bounces@lists.tdwg.org [mailto:Tdwg-tag-bounces@lists.tdwg.org] On Behalf Of Gregor Hagedorn Sent: 24 March 2006 18:37 To: Tdwg-tag@lists.tdwg.org Subject: [Tdwg-tag] RDF instead of xml schema
Hi all,
RDF to me appears on a level of abstraction making it very hard for me to follow the documentation and discussion. Most of the examples are embedded in an artificial intelligence / reasoning use cases that I have no experience with.
I am a biologist and I feel comfortable with UML, ER-modeling, xml-schema- modeling, and - surprise - relational databases. I believe many others are as well - how many datastores are actually build upon RDBMS technology?
To me xml-schema maps nicely to both UML-like OO-modeling and Relational DBMS. I can guess about the advantages of opening this all up and seeing the world as a huge set of unstructured statement tupels. But it also scares me.
Angst is a bad advisor. But then if only a minority of the current few people involved can follow on the RDF abstraction level. A few questions I have:
* Would we be first in line to try rdf for such complex models as biodiversity informatics?
* Do Genbank/EMBL with their hundreds of employees and programmers use rdf? Internally/externally? The molecular bioinformatics is probably 1000 times larger than our biodiversity informatics.
* Why are GML, SVG etc. based on xml schema and not RDFS? Is this just historical?
* Are there any tools around that let me import RDF into a relational database (simple tools for xml-schema-based import/export are almost standard part of
databases now, or you can use comfortable graphical tools like Altova MapForce).
-- I am just trying to test some tools to help me to visualize RDFS productions (like Roger has send around) on a level comparable with the UML-like xml-schema editors (Spy, Stylus, Oracle, etc.) I will try Altova SemanticWorks and Protege over the next week. The screenshot seem to be about AI and semantic web much
more than about information models (those creatures where you try to simplify the world to make it manageable...).
Gregor---------------------------------------------------------- Gregor Hagedorn (G.Hagedorn@bba.de) Institute for Plant Virology, Microbiology, and Biosafety Federal Research Center for Agriculture and Forestry (BBA) Königin-Luise-Str. 19 Tel: +49-30-8304-2220 14195 Berlin, Germany Fax: +49-30-8304-2203
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