Why would the semantic web services need new logic formalisms?

Hello,

I'm trying to understand the semantic web services effort in general. I have
read about OWL-S, WSMO, SWSF and SAWSDL. There seems to be an urge to define
new logic formalisms and reasoning techniques to solve the problems. I don't
quite understand this.

The overall goal of semantic web services (SWS) is that we could express
implicit goals and the SWS machinery would then realize these goals using
the concrete services that are advertised in the web. To express these goals
we need some domain specific ontology. To describe the available services we
must also use the same or some compatible ontology. If the ontology's are
different there must be some mapping from one ontology to other.

The famous example is that we want to purchase a trip from one city to
another. To me it seems entirely feasible to define an ontology about travel
services such as plane or train lines and to run query about these services
for example with some SPARQL query engine. This query may have to be
distributed, but distributed queries are an old and I guess well understood
problem domain. The overall consensus among the SWS research field seems to
be that this kind of simple approach does not work. Instead a heavy weight
logical formalisms are developed. For example it is proposed that a rule
language is needed for expressing that a certain type of credit card needs
to be provided to use a certain service. To me this seems simply a matter of
defining such an ontology in which this requirement can be expressed. The
set of valid credit cards could be a property of the service and the agents
or mediators that understad the ontology must know that any valid request
must include a pointer to one of these credit cards.

The automatic service composition may be a good application domain for
classical planning algorithms. Simple planning based on input and output
types of services is certainly possible. But other applications of logic
programming paradigms in the field of SWS do not seem to be that well
justified.

It seems that the goal of extensive formal service descriptions is that
services that are described with them could be used by a software agent that
is not specifically developed to understand the related domain ontology. I
think a more appropriate or at least practical focus should be on how to
define, and automatically apply ontology mappings and other mediators rather
than trying to cope without shared ontologies.

The formalisms such as SWSL and WSML can be seen as an effort to develop
tools for ontology mapping, but there is a danger that we over emphasize
declarative programming paradigms. If declarative programming would be
applicable to large scale real world problems, I would expect there to be
more evidence on that. I'm in no way an expert on logic programming so I may
have missed something here.

I hope there could be some good discussion on these topics to clarify the
overal picture.

Best regards,
Jukka Villstedt