ruby-ffi-rzmq-core binary package in Ubuntu Bionic amd64

 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 only the FFI wrapper for the ZeroMQ (0mq) networking
 library. It has been split from ruby-ffi-rzmq so that it can be used by any
 other ZeroMQ Ruby library that want to provide their own high-level Ruby API.

Source package