3 months, 1 week ago Romy MlinzkKeymaster
Would a commitment to the more general and better established meta model of RDFS not be more flexible?
3 months ago Andreas TextorParticipant
The decision to use RDF as the basis for BAMM but not build BAMM’s vocabulary on RDFS was a conscious one. The reasons can be summarized as follows:
1. Having a well-defined closed vocabulary for the meta-model emphasizes its suitability to serve as the basis for actual implementations. In other words, only by disallowing the common RDF modeling practice modeling of using arbitrary vocabularies, the implementation of robust and interoperable tools working on and with Aspect Models becomes possible.
BAMM uses one additional mechanism to decouple model and meta-model specifications from infrastructure concerns: All model elements are identified by URNs, not by URLs. While URLs are suitable for the original Semantic Web visions in which resources on the web (which are inherently resolvable on the web) can be described using RDF, in an industrial application it might well be undesirable or even impossible to directly resolve resources from the web.
Using URNs thus has two effects: It communicates to modelers that an element is identified, but not resolved, and it forces the application to have a clean model resolution implementation in place, which can retrieve models and model elements from numerous sources, such as local file systems, package repositories, model stores (semantic hub) or the web.
Despite the usage of RDFS being possible nevertheless, this would imply and have modelers expect that they can use third-party RDF/RDFS vocabularies in Aspect Models, which they can not.
2. BAMM has no concept that is semantically equivalent to an rdfs:Class, because domain semantics are not captured by assigning individuals to sets (like RDFS and OWL do), but by reifying concepts as Characteristics. The intermediate step of running an OWL reasoner or RDFS inferencer after receiving and merging data to align it with its schema is thus unnecessary, which in turn means that there is nothing to be gained by using the RDFS vocabulary.
Additionally, consciously not using the RDFS vocabulary allows for integrated or hybrid systems that use both Aspect Models and OWL: As RDFS semantics must not be used in OWL ontologies (because this results in an undecidable ontology), integration of RDFS-based Aspect Models and OWL-based systems would not be possible. The same holds true vice versa: If BAMM would be based on OWL, integration with systems using purely RDFS semantics would be impossible.
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