The Research Of Web Service Compositions In Design Time Based On SOFL

Nowadays, the research of Web Service composition is a hot field in computer science and technology, and there are many methods of Web Service composition. Although there are some standards to describe Web Services, the development of Web Service system is still a challenging problem due to the lack of complete engineering methods. The current problems is that the informal engineering method is easy for the developer to understand but ambiguous in the requirement description and system modeling, while the formal methods keep the validity of software systems through the formal description and verification, but due to their complexity of developing the large scale systems, less developers use them in the development practically.SOFL, standing for Structured Objected-Oriented Formal Language, is a formal engineering method. It provides a formal but comprehensible language for both requirements and design specifications, and a practical method for developing software systems. SOFL is mainly designed for requirements and design specifications, and does not have close relation to the current SOA(Service-Oriented Architecture) architecture.The paper researches the Web Service composition in design time to combine SOFL and Web Service together. The main research points are as follows: the SOFL description of user requirements; the transformation between SOFL CDFD(Condition Data Flow Diagram) and BPEL(Business Process Execution Language) process structure; two-stage Web Service matching mechanism; Web Service process verification based on SOFL, and the framework and prototype system of Web Service composition SOFL.The major work and contributions are as follows. This paper combines SOFL and Web Service technology together, and uses Ontology technology to conduct the matching and composition of Web Service in design time. This paper uses SOFL to describe the user requirement based on the domain ontology, and describe the precondition and postcondition of Web Services in SOFL for matching. Then, transform the CDFD in SOFL into the BPEL process structure, and search the Web Services based on each Process in SOFL by two-stage Web Service matching algorithm. After that, load the searched Web Service into the BPEL process structure, and conduct the formal verification to the composed Web Servcie process, to complete the Web Service composition in design time.In the last part of the paper, the system structure framework is introduced, and the prototype system is designed and realized. The framework describes the main module, function and process of the Web Service composition system. The paper proposes a Web Service composition system framework WSCFBS based on SOFL for Web Service composition in design time. The prototype system is also designed and developed based on WSCFBS. In this prototype system, the Web Service matching, composition, and verification are realized proposed in this paper.