Scenario-based Approach to Evolution of Communication Software

Significant amounts of legacy software create a “barrier” for adoption of advanced software engineering techniques in the communications industry. To overcome this barrier, algorithms, methods and powerful tools for automated extraction of formal descriptions of the legacy communication software are required. In this paper we present a “scenario-based” approach to re-engineering of legacy telecommunication software into formal specifications. Our approach is iterative and is based on 1) extracting scenarios from the legacy software using a combination of dynamic and static strategies and 2) automatically synthesizing formal specifications from these scenarios. For Step 2) we use the MOST toolkit, which is capable of synthesizing state-machine based formal models from scenarios, formalized as extended Message Sequence Charts (MSCs). The paper provides detailed descriptions of our re-engineering methodology and compares it with related approaches. A case study is discussed where our scenario-based methodology was applied to re-engineer a small-sized telecommunications-like software system, called the ToolExchange.