Research On Transparent Failure Takeover Of Web Services

Transparent failure takeover of Web Services has important significance in improving the reliability and availability of Web Services based systems. This thesis mainly focuses on transparent failure takeover of Web Services and runtime discovery of service replicas involved by failure takeover process.In this thesis, by considering the whole service consuming lifecycle, transparent failure takeover of Web Services is analyzed from an overall perspective. Firstly, aiming at improving current failure takeover solutions of Web Services in service provider side, group membership managements are introduced in both service containers and service replicas, with the latter specially partitioned by application boundary, and based on that, a model of reliable communication and improved passive replication based transparent failure takeover of Web Services that targeting at service container cluster environment is proposed, in this model, concepts of interceptor, message pre-copy and linked-circle view of replicas are introduced for transparency and efficiency optimization; Secondly, on the service consumer side, for the purpose of handling the failures that cannot be handled on the service provider side, a client-side and proxy-based model of transparent failure takeover of Web Services is proposed, which employs the proxy pattern, depending on that, all details of failure and failure takeover are hidden from the client; Finally, according to the requirements for reliable runtime discovery of service replicas in failure takeover of Web Services on the service consumer side, a Chord based model of discovery of service replicas is proposed.The prototype implementations are tested and the results are presented. According to the results, the proposed models can contribute a lot to the improvements of availability and reliability.