Performance of COBRA-based client-server architectures.

The notion of middleware has been introduced to provide interoperability as well as transparent location of servers in heterogeneous client-server environments. Careful consideration of system architecture is required to achieve high performance. Based on implementation and measurements made on the system this research is concerned with the impact of client-server interaction architecture on the performance of a CORBA System. Using a commercially available CORBA compliant ORB software called ORBeline, four different architectures, the Handle Driven ORB, the Forwarding ORB, the Process Planner, and the Adaptive ORB have been designed and implemented for client-server interaction on a network of workstations. High level descriptions provided in the literature were used for building the first three architectures whereas the fourth is a new architecture proposed in this thesis. The measurements show that the difference among the performances of these architectures change with a change in the workload. The research will report on the relative performances of the four architectures under different workload conditions. The results provide insights into system behavior and guidelines for designers as well as users of systems. In particular the impact of inter-node delays, message size, request service times and the system load threshold level on the latency and scalability attributes of these architectures are analyzed. A discussion of how agent cloning can improve system performance is also included.