Fault Tolerance Connectors for Unreliable Web Services

Web Services are commonly used to implement service oriented architectures/applications. Service-oriented applications are large-scale distributed applications, typically highly dynamic, by definition loosely coupled and often unstable due to the unreliability of Web Services, which can be moved, deleted, and are subject to various sources of failures. In this paper, we propose customizable fault-tolerance connectors to add fault-tolerance to unreliable Web Services, thus filling the gap between clients and Web Service providers. Connectors are designed by clients, providers or dependability experts using the original WSDL description of the service. These connectors insert detection actions (e.g. runtime assertions) and recovery mechanisms (based on various replications strategies). The connectors can use identical or equivalent available service replicas. The benefits of this approach are demonstrated experimentally.