QoS-Aware Web Services Composition Using Transactional Composition Operator

As composite web services are often long lasting, loosely coupled, and cross application and administrative boundaries, transactional support is required. Most of the work has so far focused on relaxing some ACID properties of the traditional transaction model, with little being done on investigating how the transaction can influence the quality of service (QoS) of a composite web service. In this paper, a composition model is proposed to evaluate the quality of service (QoS) of a composite service with various transactional requirements. The proposed model is based on a transactional composition operator, which extends the traditional workflow patterns and integrates transactional properties. Using a recursive approach, the QoS of a composite service can easily be calculated, in spite of transactional requirements given by service providers or end users.