http://zeromq.org

ZeroMQ \zero-em-queue\, \ØMQ\:
 Ø  Connect your code in any language, on any platform.
 Ø  Carries messages across inproc, IPC, TCP, TPIC, multicast.
 Ø  Smart patterns like pub-sub, push-pull, and router-dealer.
 Ø  High-speed asynchronous I/O engines, in a tiny library.
 Ø  Backed by a large and active open source community.
 Ø  Supports every modern language and platform.
 Ø  Build any architecture: centralized, distributed, small, or large.
 Ø  Free software with full commercial support.

官方介绍，也就是说这个算是一种通讯协议吗？

parameter server