We have informally attempted to give the flavor of the language and the methodology using a series of examples in the previous section. We now give more details of the language in a systematic manner. All the features of the language are explained with informal semantics. A formal denotational semantics will be presented in a separate paper.
In order to use an interface effectively and correctly, it is necessary to understand interactions among different messages supported by an interface. As examples in the previous section demonstrate, message signatures (or declarations) of an interface need to be enhanced with behavior specifications. We discuss the methodology and a specification language - Interface Behavior Description Language (IBDL), designed to support this methodology.