A scenario based approach to the evolution of telecommunications software

Significant amounts of legacy software create a "barrier" to the adoption of advanced software engineering techniques in the telecommunications industry. To overcome this barrier, algorithms, methods, and powerful tools for automated extraction of formal models of the legacy telecommunication software are required. In this article we present a "scenario-based" approach to design recovery and evolution of legacy telecommunication software into formal models. Our approach is iterative and is based on extracting scenarios from the legacy software using a combination of dynamic and static strategies, and automatically synthesizing formal models from these scenarios. For the first step we use the KLOCwork Suite, which is capable of providing summarized structural, functional, and scenario models of existing software. For the second step we use the MOST Suite, which is capable of synthesizing state-based formal models from scenarios, formalized as extended message sequence charts. The article provides a detailed description of our design recovery methodology and compares it with related approaches. A case study is discussed where our scenario-based methodology is applied to recover the design of a small-sized telecommunications-like software system called the ToolExchange.