Web Services - Enabling Semantic Web Services: The Web Service Modeling Ontology - page 49

The term “Semantic Web services” comprises two building blocks that
could be fruitfully combined towards the automation of service usage:

• The Semantic Web is about adding machine-processable semantics to data.

The computer can “understand” the information and therefore process it
on behalf of the human user.

• Web services aim to employ the Web as a global infrastructure for dis-

tributed computation, for integrating various applications, and for the au-
tomation of business processes. The Web will be not only the place where
human-readable information is published, but also the place where global
computing is realized.

Both trends are visualized in Fig. 4.4. This illustrates the two natural
aspects of the evolution of the Web. Web services, with their ability to provide
an abstraction to computational resources, turn the existing Web into a more
dynamic environment, yet the Web maintains its purely syntactical nature.
The vision of Semantic Web services is to describe and annotate the various
aspects of a Web service using explicit, machine-understandable semantics,
enabling the automatic location, combination, and use of Web services. The
work in the area of the Semantic Web is being applied to Web services in
order to minimize the intervention of the human user. Semantic markup will
be exploited to automate the tasks of discovering services, executing them,
composing them, and enabling seamless interoperation between them [87],
thus, enabling intelligent Web services.
The description of Web services in a machine-understandable fashion is
expected to have a great impact in the areas of e-commerce and enterprise
application integration, as it can enable dynamic and scalable cooperation
between different systems and organizations.
Current description standards for Web services such as WSDL have one
significant drawback. To a large extent, they are restricted to the syntactic as-
pects of service interaction. They allow the description of how the service can
be invoked, which operations may be called, which policies may be supported,
etc. However, what the service does and in what order its operations have to
be called in order to achieve a certain functionality is only, if ever, described in
natural language in the entries or comments of a WSDL description or UDDI
entry.
We can imagine that the trend of Web services populating the Web will
explode in a similar way to the way in which the number of static pages on the
Web did before. Thus, when looking for suitable services to achieve a certain
task, we face obstacles similar to those we face as in filtering information from
the overwhelming amount of data on the current human-readable “static”
Web. Annotations by means of Semantic Web technologies are again the big
hope. The final convergence of these technologies is essential for the success
of Web service technologies on the scale of the Web.
The requirements for semantic descriptions of Web services correspond in
principle to the requirements for common Web service technologies. However,