Implementing Design Patterns with Object-Oriented Rules
Gary M. Weiss, Johannes P. Ros · 1998
ANSWER-4ESS, an operation support system for maintaining and monitoring the 4ESS switches distributed in the AT&T network, recently became the first product to use the R++ languagean extension to C++ that adds support for objectoriented (OO) rules. This article shows how these rules not only implement the intelligent behavior of an expert system, but also facilitate inter-object communication and enable frequently occurring design patterns to be implemented in a way that leads to more understandable, maintainable, and reusable code. Most of AT&T's long-distance traffic is controlled by the 140 4ESS switches distributed throughout the AT&T network. Automatic Network Surveillance with Expert Rules (ANSWER) is the operation support system responsible for monitoring and maintaining these switching systems. ANSWER's main purpose is to perform alarm filtering: It takes as input alarms from the 4ESS switches and outputs an alert once it has identified a problem that requires human interventi...