From our point of view the Semantic Web stack currently is used as follows: (cf. Fig. 1):
The Semantic Web Stack with Multimedia Metadata and Web Service descriptions
Fig. 1.: The Semantic Web Stack with Multimedia Metadata and Web Service descriptions.
Where (from bottom up):
* The two lowest layers, i.e. Unicode for a platform-neutral encoding and XML for the platform-neutral document representation are common to all (Semantic) Web applications
* Above the XML layer we have a rough distinction in the multimedia aspect and the Web Service aspect:
o On the Semantic Web/Multimedia tower we have both MPEG-7 and RDF/OWL for representing low and high-level features, possibly extended by rules
o On the Semantic Web/Services tower we have either the RDF/OWL/OWL-S-based branch or the WSML-based branch, both grounded on WSDL, again possibly using rules on the highest level.