34. A non-transitory computer-readable storage medium encoded with a machine-readable service description for describing interaction between a requesting entity invoking a service on a communication network and a responding entity offering the service, said machine-readable service description comprising specifications of interaction between the requesting entity and the responding entity through session initiation protocol transport protocol, said specifications comprising at least a set of rules comprising input and output abstract message formats and session initiation protocol binding rules, wherein the input abstract message format comprises information relating to invoking the service by the requesting entity, and wherein the output abstract message format comprises information relating to the service provided by the responding entity, wherein a dynamic notification regarding an updated machine-readable service description comprising specifications of interaction is provided to at least one of the requesting entity or the responding entity, and wherein the updated machine-readable service description including the session initiation protocol binding rules is retrieved by the requesting entity.
34. A non-transitory computer-readable storage medium encoded with a machine-readable service description for describing interaction between a requesting entity invoking a service on a communication network and a responding entity offering the service, said machine-readable service description comprising specifications of interaction between the requesting entity and the responding entity through session initiation protocol transport protocol, said specifications comprising at least a set of rules comprising input and output abstract message formats and session initiation protocol binding rules, wherein the input abstract message format comprises information relating to invoking the service by the requesting entity, and wherein the output abstract message format comprises information relating to the service provided by the responding entity, wherein a dynamic notification regarding an updated machine-readable service description comprising specifications of interaction is provided to at least one of the requesting entity or the responding entity, and wherein the updated machine-readable service description including the session initiation protocol binding rules is retrieved by the requesting entity. 36. The non-transitory computer-readable storage medium according to claim 34 , wherein the machine-readable service description comprises headers and information whether a message body is required and, in the affirmative, content and format of the message body.