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the languages suggested for OWL-S are all based on classical logic, whereas
WSML also offers the possibility to use nonmonotonic features from logic
programming.
We also see similarities in the conceptual models of OWL-S and WSMO. A
service profile in OWL-S is close to a capability of a service or goal in WSMO.
Nevertheless WSMO makes a conceptual distinction between the provider's
and the requester's view, which is not made in OWL-S.
The process model of OWL-S is conceptually similar to the WSMO ser-
vice and goal interfaces. However, the distinction between the description of
external behavior (choreography interface) and of the internal behavior (or-
chestration interface) is not made explicit in OWL-S.
WSMO mediators are not present in OWL-S. The authors of OWL-S claim,
for instance in [107], that mediators in OWL-S are simply to be viewed as
special kind of services, whereas we make the resolution of heterogeneities
on several levels (data, protocol, and process) a first-class citizen in WSMO.
As for the grounding, WSMO and OWL-S adopt similar ideas with respect
to binding to WSDL. However, the grounding is not a top-level concept in
WSMO, but is instead integrated into the WSMO interfaces. For a detailed
comparison, we refer the interested reader to [81]. Note that neither WSMO
nor OWL-S is restricted to WSDL alone as the only possible underlying tech-
nology, instead they are open for bindings to other grounding mechanisms to
be defined.
8.2 SWSF
The Semantic Web Services Framework (SWSF) [9] is a relatively recent at-
tempt towards a Semantic Web service annotation framework that greatly
profits from previous work with its roots in OWL-S and the Process Spec-
ification Language (PSL), standardized by ISO 18269. This framework is a
joint proposal by the Semantic Web Services Language Committee and was
also submitted to the W3C in September 2005. SWSF is based on two ma-
jor components: an ontology (or conceptual model) and a language used to
axiomatize it.
8.2.1 Conceptual Model
The Semantic Web Services Ontology (SWSO) has been influenced by OWL-S
and shares its three concepts of profile, model, and grounding, as described in
the previous section. Thus SWSO can be seen as an extension or refinement
of OWL-S. Although there are many similarities to the OWL-S ontologies,
one important difference is in the expressiveness of the underlying language,
which is, instead of OWL, a richer language called the Semantic Web Ser-
vice Language (SWSL). Another fundamental aspect is a richer behavioral
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