libzmq5 4.2.1-4ubuntu1 (armhf binary) in ubuntu bionic

 ØMQ is a library which extends the standard socket interfaces with features
 traditionally provided by specialised messaging middleware products.
 .
 ØMQ sockets provide an abstraction of asynchronous message queues, multiple
 messaging patterns, message filtering (subscriptions), seamless access to
 multiple transport protocols and more.
 .
 This package contains the libzmq shared library.