Communication protocols are rules whereby meaningful communication can be exchanged between different communicating entities. In general, they are complex and difficult to design and implement. Specifications of communication protocols written in a natural language (e.g. English) can be unclear or ambiguous, and may be subject to different interpretations. As a result, independent implementations of the same protocol may be incompatible. In addition, the complexity of protocols make them very hard to analyze in an informal way. There is, therefore, a need for precise and unambiguous...