nanomsg is a socket library that provides several common communication
patterns.  It aims to make the networking layer fast, scalable, and easy
to use.  Implemented in C, it works on a wide range of operating systems
with no further dependencies.

The communication patterns, also called "scalability protocols", are basic
blocks for building distributed systems.  By combining them you can create
a vast array of distributed applications.  The following scalability
protocols are currently available:

  * PAIR -- simple one-to-one communication
  * BUS -- simple many-to-many communication
  * REQREP -- allows to build clusters of stateless services to process
    user requests
  * PUBSUB -- distributes messages to large sets of interested subscribers
  * PIPELINE -- aggregates messages from multiple sources and load balances
    them among many destinations
  * SURVEY -- allows to query state of multiple applications in single go

WWW: http://nanomsg.org/