WSML – a Language for WSMO - Enabling Semantic Web Services: The Web Service Modeling Ontology - page 81

An IRI (Internationalized Resource Identifier) 1 uniquely identifies a re-
source in a Web-compliant way. The proposed IRI standard is the successor
to the popular URI standard and has already been adopted in various W3C
recommendations. IRIs are delimited using an underscore and a double quote
“ ” ” and a double quote “ ” ”, for example ”http://www.wsmo.org/wsml/wsml-
syntax#” .
In order to enhance legibility, an IRI can be abbreviated to an sQName ,
which is short for “serialized QName”, and is of the following form: pre-
fix # localname . The prefix and the local part may be omitted, in which case
the name falls into the default namespace. Our concept of an “sQName” cor-
responds to the use of QNames in RDF and is slightly different from QNames
in XML, where a QName is not merely an abbreviation for an IRI, but a tuple
< namespaceURI, localname > .
Data values in WSML are either strings, integers, decimals, or structured
data values, reflecting the XML Schema datatypes. WSML defines constructs
which reflect the structure of data values. For example, the date “March 15th,
2005” is represented as date(2005,3,15) . In logical expressions, constructed
data values can be used in the same way as constructed terms. However, logical
expressions do not allow constructed terms to be nested inside constructed
data values.
7.2.2 Conceptual Syntax
The WSML conceptual syntax allows the modeling of ontologies, Web services,
goals, and mediators. It is shared between all variants, with the exception of
some restrictions which apply to the modeling of ontologies in WSML-Core
and WSML-DL.
Ontologies
An ontology in WSML consists of the elements concept , relation , instance , re-
lationInstance ,and axiom . Additionally, an ontology may have nonfunctional
properties and may import other ontologies. We start the description of
WSML ontologies with an example which demonstrates the elements of an
ontology in Listing 7.1, and then provide a detailed explanation.
Concepts
The notion of concepts (sometimes also called “classes”) plays a central role
in ontologies. Concepts form the basic terminology of the domain of discourse.
A concept may have instances and may have a number of attributes associ-
ated with it. The nonfunctional properties and the attribute definitions, are
grouped together in one frame, as can be seen from the example concept book
in Listing 7.1.
1 See IETF RFC 3987: http://www.ietf.org/rfc/rfc3987.txt