libzmq
ZeroMQ core engine in C++, implements ZMTP/3.1
ZeroMQ (libzmq) is a C++ messaging library that lets different programs or services send messages to each other using built-in patterns like publish/subscribe, push/pull, and request/reply, across threads, processes, or machines on a network.
ZeroMQ (libzmq) is a C++ library that handles sending messages between different parts of a software system, whether those parts run on the same machine or across a network. It extends the basic idea of a network socket (the standard building block for sending data between programs) to support patterns that normally require specialized middleware products.
In plain terms, ZeroMQ lets different programs or services talk to each other in several flexible ways. One program can publish messages and many others can subscribe to receive them. One program can push work items into a queue and a pool of workers can pull from it. Two programs can exchange request and reply messages. These patterns are built into the library so developers do not have to implement the coordination logic themselves.
The library handles the transport layer automatically, meaning the same code works whether programs are running in different threads on the same machine, in different processes on the same machine, or on entirely different machines connected over a network. Developers specify the connection style and the library manages the details.
ZeroMQ is written primarily in C++98 (an older, widely compatible version of C++) with some optional modern C++ features. It compiles on a very wide range of operating systems and architectures, including Linux, macOS, Windows, Android, and many server distributions. The README includes detailed tables showing tested platform and compiler combinations.
This is a low-level infrastructure library used by developers building distributed systems, data pipelines, or services that need to pass messages reliably at high speed. It is not an end-user application. Using it requires programming skills and understanding of how networked software is structured.
The project is maintained by the ZeroMQ open source community and is available under a permissive license.
Where it fits
- Wire together multiple worker processes in a pipeline where one process pushes tasks and a pool of workers pulls and processes them.
- Build a real-time event broadcast system where one publisher sends updates and many subscribers receive only the topics they care about.
- Replace a REST API with ZeroMQ request/reply sockets for lower-latency communication between two backend services on the same machine.
- Integrate libzmq into a C++ data pipeline that needs to pass high-speed messages between threads without shared memory locks.