Model-driven Composition and Performance Evaluation of Pattern-Based Systems

Abstract

Software design for large-scale distributed systems requiring multiple Quality of Service (QoS) properties is increasingly moving away from traditional, stove-piped, "build-from-scratch" architectures to modern, "build-from-composition" architectures wherein system functionality is realized by composing pattern-based off-the-shelf components. In this approach, the QoS properties of the composed system depend on how individual components are configured and how they interact with each other. Validating these systems for their QoS properties at the composition stage itself is highly desirable to maximize the benefit of these new approaches since it reduces the long iterative design cycles suffered by traditional software development processes.

This thesis presents a model-driven approach for the composition-stage validation of complex systems. Model-driven technologies raise the level of abstraction of the problem by separating out orthogonal aspects (such as the structure, configuration and behavior) of the system, while still presenting the "big picture" of how any change in each aspect affects the system as a whole. The thesis describes the design of the Pattern Oriented Software Architecture Modeling Language (POSAML), which provides a system architect with intuitive abstractions of the pattern-based composable blocks. The use of POSAML and its associated interpreters in bridging the gap between system design and validation is also elaborated.