Service Composition Model Based On ECA Rules

With the constantly changing and expanding business requirements in enterprises,how to effectively integrate business resources between different enterprises anddepartments so as to meet the various needs of users has become an increasingly importantissue. In this situation, Web Service came into being. Web Service bases on a series ofunderlying standards. Through some mechanisms such as registration, publication anddiscovery, the public services are provided to users. The SOA (Service OrientedArchitecture) architecture, which bases on web services, can effectively shield theunderlying heterogeneous environments of distributed computing environment, so you canbuild service-oriented, loosely coupled and flexible enterprise applications. Thus more andmore enterprises package their business functions into services and release them to users.However, a single service can not meet the rapidly changing business requirements.With service composition technology, single and fine-grained services can change intocoarse-grained, complex and valuable services by using effective arrangement orreorganization, and achieve business value. Based on this idea, in August2002, IBM,Microsoft and BEA proposed the business process execution language together, which iscalled BPEL. BPEL uses XML standard to describe how different web services reorganizeand become a new service, and it generates a standard document which is handled over toBPEL engine to execute. With the enterprise business model becoming more and morecomplex and user requirement changing dynamically, the BPEL-SOA architecture can notmeet the application requirements. It is mainly manifested in the following aspects: on theone hand, the stable business process can’t meet the dynamic needs of business; on theother hand, web service itself lacks of the ability of coordination and cooperation.Based on the current situation of business integration and its defects, this paperpresents a new way of combining SOA services, which is based on ECA rules. Throughthe introduction of event mechanism based on ECA rules, we can invoke web servicesdynamically and enhance the interaction and collaboration of Web services, so it can meetthe complex and changing business needs.Firstly, this paper introduces SOA: the current mainstream business integrationarchitecture, and then proposes a SOA-based service composition technology which iscalled BPEL. Secondly, as for the shortcomings of BPEL, the paper introduces the conceptand working model of ECA rules, which can use events to drive Web services to runautomatically according to certain rules. Finally, the paper proposes the ECA rule-basedservice composition technology, then describes the system architecture and its composition modules, and verifies its feasibility through experiments.