CP4TWS - A Prototype Demonstrating Context and Policies for Transactional Web Services

摘要

Transaction management has become important in Web services composition [1]. The goal is to guarantee the consistency of the business processes to implement as Web services. This demo paper presents CP4TWS prototype that validates our approach for context-driven transactional Web services using policies [2]. In this approach, context tracks Web services, policies specify Web services' transactional behaviors, and backward/forward adaptation strategies support Web services' exception handling.Fig. 1 (a) presents the running scenario, which is a composite Web service providing transportation plans to tourists. Initially, a tourist invokes Itinerary WS that proposes routes, e.g., hotel to museum. Itinerary WS consults Weather WS and requests Location WS for details on the origin and destination places. In case of bad weather, a taxi booking is made for the tourist using Taxi WS. Otherwise, the tourist uses public transport. Hotel and museum locations are submitted to Bus Schedule WS, which returns the bus numbers to ride. Traffic jams make Bus Schedule WS interact with Traffic WS regarding the status of the traffic network. This status is fed into Bus Schedule WS for adjustment needs. Each Web service in this running scenario has a dedicated state chart diagram that reflects its transactional property (e.g., pivot, retriable, compensatable). The diagram of a pivot Web service is given in Fig. 1 (b).