Performance evaluation of dynamic composition & dynamic reconfiguration in SOA applications

Business-to-Business (B2B) applications are developed predominantly based on service-oriented architectural style which is generally realized using a set of loosely coupled web services. These web services can be selected statically during design-time or dynamically during run-time. The functional and non-functional QoS requirements are typically captured in the Service Level Agreement (SLA) that is mutually agreed between the service provider and the service consumer. Whenever an SLA violation happens, the service provider incurs a penalty. In order to minimize such penalties, the application that is built through a design-time composition of web services needs to be monitored. Whenever a violation of SLA is predicted, those statically composed web services are dynamically reconfigured. This is called as dynamic reconfiguration in SOA. In this case, even the alternate service selection happens at design-time itself. On the other hand, whenever the web services needed for an SOA application development are selected and composed dynamically at run-time, it is called as dynamic composition. The turnaround time involved in both these approaches for mission-critical applications with stringent SLA requirements is compared. It has been inferred that the dynamic reconfiguration approach not only maintained the turnaround time always within the accepted limits, it also incurred only less overhead when compared to dynamic composition approach.