- From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
- Date: Fri, 7 Dec 2001 11:20:54 -0000
- To: <www-webont-wg@w3.org>
Summary: DAML+OIL is built on RDF, not XML. Conclusion from below: [[[ DAML+OIL assumes full RDF processing with a compliant RDF parser. A DAML ontology written in N3 or N-triple is still a DAML ontology. This is in contrast with other RDF dialects such as RSS [7] or CC/PP [8] where many implementations assume a rigid XML document format, with no variation from the examples in the specs. ]]] After the daml+oil walkthru walkthru I feel a need to articulate my understanding of the relationship between DAML+OIL, RDF and XML. This is either: + for the newbies to RDF for education or + a proposal for how webont should be depending on whether other people agree with me! XML [1] is a general purpose mark-up language for making documents that are both machine and human readable. RDF [2] is a data description framework which gives a way of constructing labelled directed graphs, and an understanding [3] of how these may be interpreted as a description of something. One possible serialization of an RDF graph is given in an XML form. There are other possible serializations such as N3 [4] or N-Triple [5]. It is also possible to have a graph which is not in a document and hence not serialized (e.g. in memory somewhere). There are many alternative representations of the same information in RDF/XML. DAML+OIL uses RDF to describe ontologies. Hence, a possible serialization of a DAML ontology is as an RDF/XML file. In particular, there are many different RDF/XML files that correspond to the same RDF graph. DAML+OIL places no restriction on which RDF/XML serialization is used. For example, it is legal to write a DAML+OIL ontology expanding the daml:collection lists out in full. For example the idiom <daml:Ontology rdf:about="" /> does not have to appear first, and can use an absolute URI instead of the relative URI ""; it can also use an rdf:Description node <rdf:Description rdf:type="http://www.daml.org/2001/03/daml+oil#Ontology" /> or <rdf:Description> <rdf:type rdf:resource="http://www.daml.org/2001/03/daml+oil#Ontology" /> </rdf:Description> That is DAML+OIL assumes full RDF processing with a compliant RDF parser such as ARP [6] (note my interest :) ). Also a DAML ontology written in N3 or N-triple is still a DAML ontology. This is in contrast with other RDF dialects such as RSS [7] or CC/PP [8] where many implementations assume a rigid XML document format, with no variation from the examples in the specs. Jeremy [1] "Extensible Markup Language (XML) 1.0", World Wide Web Consortium Recommendation, 1998 http://www.w3.org/TR/1998/REC-xml-19980210 [2] "RDF Model & Syntax" W3C, 1999, http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/ [3] "RDF Model Theory" W3C Working Draft 2001 http://www.w3.org/TR/rdf-mt/ [4] "N3" hmm? Berners-Lee & Connolly [5] "RDF Test Cases" W3C Working Draft 2001 http://www.w3.org/TR/rdf-testcases/ [6] "Another RDF parser", J Carroll, 2001, http://www-uk.hpl.hp.com/people/jjc/arp [7] "RDF Site Summary (RSS) 1.0", 2000, http://purl.org/rss/1.0/spec [8] "Composite Capability/Preference Profiles (CC/PP): Structure and Vocabularies" W3C Working Draft 2001 http://www.w3.org/TR/CCPP-struct-vocab/
Received on Friday, 7 December 2001 06:21:20 UTC