Mixpert: A Maintainable Configurer’s Assistant

Abstract

Configuration of systems requires their components to be selected and arranged according to a schema of some kind. This task demands a lot of skill and experience since typically many components require setting up and dependencies exist between them. To assist the configurer’s task, computer systems have been developed. These advise on the setting of new parameter values and check that a configuration is complete and consistent, possibly flagging non-optimal parameter settings and suggesting more suitable values.

Complex systems may have many possible configurations, a combinatorial explosion being likely to result if one tried to describe them all. It is for this reason that production rules rather than procedural languages have usually been used to represent configuration systems [1]. A problem with the rule-based approach is that the systems are difficult to maintain, a team of computer specialists being required to do this. Since systems requiring configuration frequently change, maintenance of configuration systems is a big issue and one which is addressed by the prototype system described in this paper.

Within the Shell Group of companies, computer systems have been developed to support its worldwide operations. A prototype computer-based configurer’s assistant, which has generic application, is described; it has been developed to assist in the configuration of one such system. The prototype, called Mixpert, can be updated by configurers, who are not programmers, to coincide with upgrades to the system to be configured, knowledge about early versions of the system being retained if required. In this way, Mixpert can process configuration settings for operating companies running different versions of the system. Within the prototype, an integrated set of tools is provided, bringing together disparate sources of information for use in defining and maintaining a configuration’s parameters. The system has been developed in the object-oriented programming language Smalltalk/V286 and runs on a PC.