Analyzing Event Chains of Private Branch Exchange Systems Modeled with UML 2.0

This paper analyzes event chains of private branch exchange (PBX) systems modeled with UML 2.0. UML 2.0 is a de-facto industrial standard as a real-time object-oriented modeling language. Our PBX UML 20 model adopts proxy design pattern and the event chains are derived from a bottom proxy layer that accepts exte rnal inputs. It is critical to correctly analyze event chains for a system to meet any real-time req uirements such as deadlines. This case study is to guide for designing real-time object-oriented models for any other kinds of complex realtime communications systems