P/S sockets: supporting publish/subscribe communication through the standard socket API

While the address-oriented datagram and reliable stream services supported by the UDP and TCP protocols are the foundation of distributed computing, other forms of communication are increasingly being used to build contemporary systems and applications. A popular alternative to datagram- and stream-based communication is the Publish/Subscribe (P/S) paradigm, where message forwarding and reception is done based on a topic or content descriptions instead of an address. Several middleware systems have been built to support this form of communication, on top of the socket API. Taking a different approach, we discuss how P/S networking can be supported through the socket API, so that this can serve as a universal interface for supporting different communication abstractions. To this end we introduce a new address family and extend the semantics of selected socket primitives to support P/S functions. Also, we describe a proof-of-concept implementation of the proposed socket extension, which features two protocols for ad-hoc and infrastructure-based P/S communication, respectively.