from http://rfc.zeromq.org/spec:7 "The Majordomo Protocol (MDP) defines a reliable service-oriented request-reply dialog between a set of client applications, a broker and a set of worker applications. MDP covers presence, heartbeating, and service-oriented request-reply processing. It originated from the Majordomo pattern defined in Chapter 4 of the Guide."
This is an implementation for Haskell. Examples of use can be found in echoworker.hs and mdpclient.hs (which doubles as a helpful command line tool for issuing MDP commands)