RE: Peter's slides about the MOF metamodel


 > I agree with you that it is possible to come up with multiple
 > metamodels of the same language, 

If you define "language" as including syntax, which alot of people do,
then OWL has multiple languages.

 > but this is (in my view) not so much due to the variety of syntaxes,
 > but rather due to design choices one makes.  The OMG made the design
 > choice to provide a metamodel of OWL 1 that models the OWL language
 > as an extension of the RDF language (to be precise: of the RDF data
 > model, not a specific RDF syntax). A different approach was taken in
 > the metamodel for OWL DL we developed in our group [1], which rather
 > provides a Description Logic oriented view, independent of RDF
 > (closer to the model of the abstract syntax).

Perhaps, but if your DL concrete syntax came out the same as RDF/XML,
then the metamodel would be very similar also.  Metamodels remove
concrete notational elements, preserving the abstract notational
relations (the OMG calls metamodels "abstract syntax" for this reason).

 > In any case, the metamodel for OWL 2 is intended to provide the
 > structural specification of the OWL 2 language independent of a
 > specific serialization syntax. There may be many concrete
 > syntaxes. For some syntaxes the mapping will be trivial (XML Schema),
 > for others more complex (RDF).

The more complex the mapping from metamodel to concrete syntax, the less
likely it will be useful to an audience familiar with that syntax.  I've
advocated your opinion above for many years, I can safely say it is not
possible.  :)  Metamodels reflect the syntax they're derived from.

Most people who look at textual syntaxes at all will be looking at
RDF/XML, because it is file format output from graphical tools.  They
will expect a metamodel reflecting that.  I can see how a metamodel
oriented towards "DL" or W3C abstract syntax would be useful for a
limited audience, but not the majority of OWL users.


Received on Thursday, 31 July 2008 15:12:20 UTC