NNG, like its predecessors nanomsg (and to some extent ZeroMQ), is a
lightweight, broker-less library, offering a simple API to solve
common recurring messaging problems, such as publish/subscribe,
RPC-style request/reply, or service discovery.
The API frees the programmer from worrying about details like
connection management, retries, and other common considerations, so
that they can focus on the application instead of the plumbing.