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we present a formal method to derive service compositions that satisfy
the requirement with respect to the input/output data types. This
method is based on a Petri net decomposition technique. A prototype
system is developed to test the validity of the proposed approach. It
well utilizes the data relation in business/service portfolio to derive
composite services.
3.1 PROBLEMSTATEMENT
In software tools such as IBM Business Process Manager [32], com-
posite services can be directly derived from business processes. It seems
that business requirements represented by business processes can be
directly transformed to refined processes realized by available services.
In practice, however, some gaps remain.
First, the model elements of a business process and a service
composition are not identical. In practice, there are various kinds of
specifications, languages, and notations to model a business process
and a service composition [86]. Second, the data model in business
and service domains are heterogeneous. Therefore, direct or indirect
mappings between them are required to give an integrated and coherent
view of the two domains. The third reason is more critical. Without
proper guidance from the service domain, there is no guarantee that
the refined process model can be implemented by available services.
Hence, it is highly desired that we generate certain operational
guidance from the existing service portfolio to help refine a business
domain process into a customized process that can be implemented
by existing services to a greater extent.
On one hand, the difficulties mentioned above hamper the effective
and efficient utilization of available services. On the other hand, a
service portfolio contains abundant information to be further investi-
gated. For example, WSDL files contain the input/output data type of
operations, and WSDL files with associated data definition schemas
contain the relations among these data types, such as aggregation and
generalization. From these data relations, much guidance can be derived
to help perform better service composition.
In this section, we present how to drive data structures fromWSDL
files, how to model data structures in two domains, and how to
formulate service compositions based on them.
