Detecting feature interactions in CPL

An approach for detecting feature interactions in IETF's Call Processing Language (CPL) scripts is presented. The approach is logic based in the sense that it uses a logic representation of CPL scripts, of requirements and of detection rules and, in several cases, specific detection rules are shown to be derived from requirements by logical deduction. The Simple Formal Specification Language (SFSL) is introduced to express the intentions of CPL scripts in logic format. A method for translating CPL into SFSL is presented. The rules address both interactions within a single script, and interactions between two scripts. An automatic feature interaction detection tool applying these rules was implemented in SWI-Prolog. The general method is not specific to CPL and could be used in other feature interaction research.