Information Technology Reference
In-Depth Information
CHAPTER
4
Analysis and Composition
of Partially-Compatible
Web Services
4.1 PROBLEMDEFINITION AND
MOTIVATING SCENARIO
With the emergence of SOA (service-oriented architecture), service
composition is gaining momentum as the potential silver bullet for the
seamless integration of heterogeneous computing resources, rapid
deployment of new business capabilities, and enhanced reuse possibili-
ties to a variety of legacy systems [108]. Existing service composition
specification languages such as BPEL (Business Process Execution
Language) and WS-CDL (Web Services Choreography Description
Language) provide the mechanisms to directly compose two (or more)
services by specifying that a message sent by one interface is received
by the other (and vice versa). This kind of interface link is achieved
by using constructs such as Partner Link in BPEL and Channel in
WS-CDL. In this chapter, we use BPEL to describe the internal logic of
Web services.
Direct composition is made based on the following assumptions:
1. The incoming messages of one service are the exact ones
provided by its partner(s); the outgoing messages of one service
are the exact ones consumed by its partner(s).
