Web Services - Enabling Semantic Web Services: The Web Service Modeling Ontology - page 37

in Section 4.3. We summarize the current status of the most widely used Web
service technologies in Section 4.4.

4.1 Terminology and Principles

Before we continue, let us clarify the terms “service” and “Web service” them-
selves. The English word “service” is overloaded in its meaning [111]. In the
business world, a “service” normally denotes the provision of a general busi-
ness activity which provides a certain value to the customer [6]. In computer
science, in contrast, the term “service” is often used synonymously with “Web
service”, i.e. a software component accessible over the Internet via a standard-
ized interface. Preist [111] defines these terms as follows:

• Service . A service is defined as the provision of a concrete product or

abstract value in some domain. As an example, let us consider a user who
wants to topic a flight from Madrid to Innsbruck. Following our definition
of a service, we mean the actual transport, fulfilling user constraints such
as a certain date. The provision of the service as such, and the contractual
issues around this service provision, are independent of how the supplier
and the provider interact. It is irrelevant whether the requester goes to
an airline ticket o ce or uses the airline's Web site to book the flight. We
understand the term “service” in this sense, that is, as a provision of value.

• Web service . Following Preist's definition, Web services are defined as com-

putational entities accessible over the Internet (using Web service stan-
dards and protocols) via platform- and programming-language-
independent interfaces. Returning to our previous example, an airline
might provide a software component accessible via Web service standards,
i.e. a Web service to request the booking of a flight; the Web service is an
electronic means to request a service, but not the service itself. We under-
stand the term “Web service” as a means to request a service over standard
protocols, described using widely accepted standards. Thus, a Web service
is a means to consume an actual service, or to place a contract for an
actual service.

This topic is about Web services, and we shall use the terms “service” and
“Web service” synonymously to mean the latter in the remainder of this topic
unless explicitly indicated otherwise.
A further term often used in connection with Web services is the “service-
oriented architecture”, which we introduced at the beginning of this chapter.
Since the term and its definition are still heavily discussed, we shall merely
reiterate and outline the basic principles that are common to all definitions: 1

1 This list has been extracted from a message by J.P. Morgenthal on
[e-mail] and subsequent
discussions; see http://groups.yahoo.com/group/service-orientated-
architecture/message/2709 .