A Fluid Flow Approach to Usability Analysis of Multi-user Systems

The analysis of usability aspects of multi-user systems, such as co-operative work systems and pervasive systems, pose particular problems because group behavior of their users may have considerable impact on usability. Model-based analysis of such features leads to state-space explosion because of the sheer number of entities to be modeled when automatic techniques such as model checking are used. In this paper we explore the use of a recently proposed scalable model-based technique based on solving sets of Ordinary Differential Equations (ODEs). Starting from a formal model specified using the Performance Evaluation Process Algebra (PEPA), we show how different groupware usage patterns may be modeled and analyzed using this approach. We illustrate how the approach can explore different design options and their impact on group behavior by comparing file access policies in the context of a groupware application.