A Graph And MDA Based Approach For Web Services Composition

Web services technology is presented as an effective solution to inter and intra Enterprise applications integration. However, the problem of granularity has limited its application seriously .Therefore, researchers both from industry and academy try to compose individual Web services to obtain a new value-added composite Web services. Many research organizations have presented their own Web services composition specification, such as WSDL, BPEL. WSCI, BPEM and OWL-S. These so called standards centre on the different point of view of modeling of composite Web services and have their own specialized support platform products. As a consequence, the dependencies between Web services solutions and their development and runtime environments are very strong. This implies that a migration between different environments or a migration to updated Web services specifications needs much effort.All-sided development process for composite Web services involves solutions to several problems, which, generally speaking, are discovery of useful partner Web services, calculation of their possible composition, and description of the composition model and execution of the composite service definition. We use the references of PIM and PSM idea in MDA (Model Driven Architecute) and the depth-first-search algorithm in Graph theory to solve the problem of calculation of their possible composition and description of the composition model. Based on the techniques mentioned above, we proposed a development framework of composite Web services called WSCF (Web Service Composition Framework).In WSCF, we give the concept of structure and behavior PIMs and PSMs of composite Web services. On one side, pointed to the static modeling part, we design the UML Profile for WSDL to as the modeling language of structure PSMs and give the transformation rules from structure PIMs to PSMs On the other side, pointed to the behavior modeling part, we give a method of building PIM of dynamic behavior model of Web services composition. We also give the rules of translating from PIM to BPEL and WSCI. To solve the problem of calculation of the possible Web services composition, we abstract the information of the input and output data dependency of candidate Web services and construct a so-called dependency graph. Then we design a graph-based algorithm to find the setup of Web services composition to satisfy a service request by composition in the dependency graph. This algorithm can be used to get a composition of Web services which meets a given service request efficiently. At last, we talk about how to make the WSCF to support the transaction and QoS and how to design the system prototype of WSCF.The graph-based algorithm efficiently solves the problem of the calculation of possible Web services composition and eases the description of the composition model. At the meantime, taking use of the technology of UML and MDA, WSCF can solve the problem of too many different standards in the field of Web services composition and can adapt to the dynamic change...