A software maintenance management model based on queueing networks

A model of the software maintenance process within a medium-sized organization is described. We set out both the abstract model and its implementation as part of a management tool, the Intelligent Software Maintenance Management System (ISMMS) prototype. The ISMMS provides a simulation environment for two sorts of management activities. In interactive mode, the characteristics of a particular set of maintenance tasks can be fed into the simulation, and decisions on the allocation of real personnel, tools and resources tested. In automatic mode, a spectrum of tasks is generated and different automatic allocation strategies are statistically evaluated against these. In both modes, the simulation draws on a database which is customized to accurately reflect the particular resources and characteristics of the organization using the model. The abstract maintenance process underlying the prototype is described in terms of queues arranged in a topological network. This provides a clean design which has been successfully implemented using a three-layer software architecture in the prototype; the abstract queueing model is implemented as a synchronized predicate-net which in turn is implemented in Prolog, and we describe the implementation here, as well as its behaviour from the users point of view.