Performance modeling of a 3-tiered software system

This paper will describe performance modeling of a real-world distributed software system using Layered Queuing Network (LQN), which is a formalism for building performance models of distributed client-server systems. Analysis of LQN models quantifies performance parameters such as throughput, response time and utilization. As a result of this analysis, it is possible to ascertain the performance characteristics of a particular software architecture and design, and hence provide a basis for improvement of software system architecture and design. In this paper, we will describe how we used LQN to build a performance model of a 3-tiered software system, and how analysis of the performance model using LQN tools allowed us to identify potential bottlenecks in the system and to improve the design of the system and the software implementation strategies.