1. A peer-to-peer network system, comprising: a plurality of computers configured to implement a plurality of peer nodes coupled to a network; a class of software module provided by one or more of the peer nodes; a module class advertisement for the class of software module, wherein the module class advertisement defines a local behavior and an Application Programming Interface (API) for each of a plurality of peer-to-peer bindings that supports the class of software module, wherein the module class advertisement includes a module class identifier that uniquely identifies the class of software module, and wherein the module class advertisement further includes a role extension to the module class identifier for distinguishing two or more instances of the class of software module configured to perform different roles in a context; and a plurality of module specification identifiers that each uniquely identifies one of a plurality of module specifications of the class of software module, wherein each module specification includes an indication of an expected on-wire behavior and an indication of one or more network protocols for a particular embodiment of the class of software module.