Test Facility for a Message-Switching System

A comprehensive test environment is important in the development and maintenance of any large computer system. In particular, when dealing with a message-switching system, special attention must be given to message loading, traffic mixes, and network configuration variables. Two methods of controlling these variables to test the system are: (i) The use of real terminals and operators to drive the system, or (ii) Simulation of terminal and operator system interactions to exercise the system as though it were in live operation. The second method was used in our approach because it leads to more comprehensive, more controlled, and easily repeatable tests. We describe the concept of "using the system to test the system"-- a test facility is created from an existing system configuration. The system described is BISCOM,* a large-scale, computer-based, store-andforward message switcher. * Business Information Systems Communication System 857 Early in the development of BISCOM, the need for a comprehensive facility was recognized. The important factor in the creation of the facility was the need for a controlled test environment--one in which the operation of BISCOM could be observed and measured.