Service Virtualization For End-User Programming

The needs for dynamic systems integration are becoming more and more pervasive inmany application domains, such as e-government, e-commerce, supply chain, management inhandling city emergencies, etc. A common phenomenon of these application areas is theuncertainty and dynamism of user requirements. It is an observable trend to applyEnd-User-Programming (EUP) technologies to achieve just-in-time application construction.The Service Oriented Computing (SOC) technologies can integrate applications with openstandards and loose-coupling strategy, providing new chances. However, EUP is still a difficultissue due to the lack of proper business–level service abstractions as well as the divide betweenbusiness abstractions and IT services. To support reliable and flexible correlation betweenbusiness abstractions and Web services, the thesis proposes a novel service virtualizationapproach to bridging the divide. The major efforts and contributions include:A novel approach, called VINCAvirtualization, is proposed to support EUP. The uniquefeatures of our approach are: (1) it facilitates abstractions from business and IT perspectivesseparately and then relating them using virtualization operations. The approach can provide asmany as possible IT resources for a given business abstraction and hide secondary details;(2) itprovides a new mechanism for clustering services, which helps to improve the efficiency inrelating of business-level abstractions and Web services and lower the service-lookup time;(3)It introduces user-controllable policies for service transformation, service composition andservice matching. Critical guarantees are ensured by these policies for the fulfillment ofbusiness services.We put forward an algebraic system for service transformation in VINCAvirtualization on thebasis of function transformation. The semantic and syntax of service transformation operationsare discussed with the service function model and a service transformation language. Sincemost existing methods for service transformation are pragmatic, the thesis also contributes inproviding a theory for service transformation. It is different from the general service derivationlogic, which is based on service composition. Based on the algebra, a service transformation definition language, called VAL, is proposedfor general users. The syntax of VAL is designed by referring to that of SQL. Its non-processdescription feature makes it easier to use than BPEL, which also can transform serviceparameters by using XPath techniques. Other service transformation studies seldom present anyoperation languages for general users. For dynamic creation of a global service view from local services in our VINCAvirtualizationapproach, we put forward a novel service clustering mechanism based on sorting policies. Itcontains a service clustering algorithm, a creation algorithm for global service abstraction andan evolution adaptive algorithm for clustering. We also study the service clustering theory toprove the reasonableness of the clustering relation in VINCAvirtualization. The results overcomesome shortcomings of existing service clustering approaches, e.g. lack of theories and based onthe so-called "Local As View" mode.Based on the VINCAvirtualization approach, we design and develop a service virtualizationprototype for EUP. Based on the real requirements of the AMGrid project as a test bed, weprove the feasibility and validity of VINCAvirtualization. We also compare our approach with someother existing approaches by quantity measurements. The results show that our approachmakes a reasonable improvement in bridging the divide between business abstractions andWeb services, and can better guarantee smooth execution of EUP applications.