AOP Based QoS Monitoring of Dynamic Web Service Compositions

Web services are the functions used to solve a specific task. Web service composition is a process of combining the functionalities of web services in order to perform a complex task. QoS properties mutually agreed by consumer and developer and recorded in a Service Level Agreement (SLA) need to be monitored at runtime. Abiding by SLA determines whether to continue the usage of that service. Existing works monitor QoS properties of the web service compositions that are composed at design time itself. However, if the SLA is violated, an alternate service can be selected during runtime in a dynamic composition scenario. Hence, in this paper it is proposed to monitor QoS properties of compositions that are dynamically composed. Aspect Oriented Programming (AOP) based approach is adapted for monitoring and triggering alternate service composition, in case of SLA violations. The proposed approach is demonstrated for an application of Foreign exchange market that involves composing services at runtime.