Experiences with early life-cycle performance modeling for architecture assessment

In this paper we describe our preliminary experiences of a performance modeling "Blending" approach for early life-cycle architecture assessment and risk mitigation in a large enterprise integration project. The goal was to use performance modeling to assist with defining the requirements for the system and to identify areas of architecture and technology risk which could be addressed in future phases of the project. We modified our Service Oriented Performance Modeling approach to enable useful models to be constructed from a variety of imprecise and incomplete information sources prior to the existence of concrete requirements or implementations. Activities iterated over two phases and included scenario and workload modeling in phase 1, and integration infrastructure, workload and blended modeling in phase 2. The resulting models enabled early discovery and exploration of critical assumptions and architectural alternatives. One critical assumption is explored in more detail as an example. This is the impact of the specific location of services, which was predicted to require a large variation in resource requirements across the integration infrastructure. We demonstrate this with example models and explore possible solutions based on dynamic service load balancing.