Suggestion:

Before "Show us the code" - you need a short excerpt on "Isn't message passing expensive" where you can mention the lock free element of ZeroMQ and expand on the "N-to-N".

Message passing? Sounds messy and expensive.

Actually, message passing is just a fancy name for the hand-off of marshalled data to someone else. In the simplest, thread-to-thread case, it's as simple as passing a pointer. The "Zero" in ZeroMQ stands for "Zero Copy".

In fact, if you've done any work with threads you're probably already a message passer - you've just been doing it the hard way until now.

True message passing eliminates the need for mutexes, resource locks, condition queues and signals. That makes parallel programming easier, cleaner and in most cases it more than pays for the minor overhead of a true message passing system. ZeroMQ can compete with tools like OpenMP and TBB for sheer performance, but it can also work alongside them.

But best of all, the API doesn't change when you need to step up from passing messages between threads of a single process to multiple processes or even multiple machines. It's as easy as changing the addresses of your connections. ZeroMQ quietly handles multiple connections on a single socket for you so you don't have to worry about the fiddly networking stuff when you come to make the transition.

I'm not sure people are going to register the significance of N-to-N in the 100 word section, the transparent multiplexing of the ZeroMQ sockets is one of the mind blowing things.

Also... Have you considered perhaps considering the term "Mailbox" or "handle" or "descriptor" for the sockets? The more distance you can put between the mundane concept of a BSD/TCP socket and a ZeroMQ zap-pow-kabloom endpoint the better maybe.

- Oliver