Until now we have covered what a message queue is, which brings us to the purpose of this book, that is, ZeroMQ.
The community identifies ZeroMQ as "sockets on steroids". The formal definition of ZeroMQ is it is a messaging library that helps developers to design distributed and concurrent applications.
The first thing we need to know about ZeroMQ is that it is not a traditional message queuing system, such as ActiveMQ, WebSphereMQ, or RabbitMQ. ZeroMQ is different. It gives us the tools to build our own message queuing system. It is a library.
It runs on different architectures from ARM to Itanium, and has support for more than 20 programming languages.
ZeroMQ is simple. We can do some asynchronous I/O operations and ZeroMQ could queue the message in an I/O thread. ZeroMQ I/O threads are asynchronous when handling network traffic, so it can do the rest of the job for us. If you have worked on sockets before, you will know that it is quite painful to work on. However, ZeroMQ makes it easy to work on sockets.
ZeroMQ is fast. The website Second Life managed to get 13.4 microseconds end-to-end latencies and up to 4,100,000 messages per second. ZeroMQ can use multicast transport protocol, which is an efficient method to transmit data to multiple destinations.
Unlike other traditional message queuing systems, ZeroMQ is brokerless. In traditional message queuing systems, there is a central message server (broker) in the middle of the network and every node is connected to this central node, and each node communicates with other nodes via the central broker. They do not directly communicate with each other.
However, ZeroMQ is brokerless. In a brokerless design, applications can directly communicate with each other without any broker in the middle. We will cover this topic in depth in Chapter 2, Introduction to Sockets.