, 2003). But the
BPEL itself is also a Web service, meaning that a Web service can not only be a
procedure or activity, but also a real business process with long cycle transactions.
So, in the services catalogue not only business processes are registered, but also
Web services (see the Capability Approach section).
Rabaey et al. (2003) state that the vision behind high-level description languages
such as BPEL4WS, is the paradigm shift from distributed computing to distributed
business process execution. BPEL4WS is an XML-based standard, which enables
users to specify processes as an aggregation of Web services. The service flows define
the order of activities, where a flow is a directed graph representing activities as
nodes and interactions as links connecting the nodes. The activity implementations
are described via Web services description language (WSDL) port types.
With BPEL4WS, generic (abstract) processes can be defined that contain empty
activities. The work on the business process definition can therefore be separated
from its implementation (in analogy with the object-oriented paradigm).
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