Rust ZeroMQ bindings.

About

The zmq crate provides bindings for the libzmq library from the ZeroMQ project. The API exposed by zmq should be safe (in the usual Rust sense), but it follows the C API closely, so it is not very idiomatic. Also, support for libzmq API in "draft" state is considered out-of-scope for this crate; this includes currently, as of libzmq 4.3.3:

Newer, thread-safe socket types, such as ZMQ_CLIENT and ZMQ_SERVER.
The "poller" API.

For a more modern, idiomatic approach to libzmq bindings, including draft API features, have a look at libzmq-rs.

Compatibility

The current 0.9 release series requires libzmq 4.1 or newer. New release series of zmq may require newer libzmq versions.

Installation

rust-zmq is available from crates.io. Users should add this to their Cargo.toml file:

[dependencies]
zmq = "0.9"

As rust-zmq is a wrapper around libzmq, you need a build of libzmq version 4.1 or newer, before attempting to build the zmq crate. There are several options available:

Dynamic linking using `pkg-config`

This is probably the preferred method when you are running a recent Unix-like OS that has support for pkg-config. For example, on recent Debian-based distributions, you can use the following command to get the prerequiste headers and library installed:

apt install libzmq3-dev

If your OS of choice does not provide packages of a new-enough libzmq, you can install it from source; see https://github.com/zeromq/libzmq/releases, although in this case, you may prefer a vendored build, which automates that, see below.

The build normally uses pkg-config to find out about libzmq's location. If that is not available, the environment variable LIBZMQ_PREFIX (or alternatively, LIBZMQ_LIB_DIR and LIBZMQ_INCLUDE_DIR) can be defined to avoid the invocation of pkg-config.

Windows build

When building on Windows, using the MSCV toolchain, consider the following when trying to link dynamically against libzmq:

When building libzmq from sources, the library must be renamed to zmq.lib from the auto named libzmq-v***-mt-gd-*_*_*.lib, libzmq.lib, libzmq-mt-*_*_*.lib, etc.
The folder containing the *.dll (dynamic link library) referred to by zmq.lib must be accessible via the path for the session that invokes the Rust compiler.
The name of the *.dll in question depends on the build system used for libzmq and can usually be seen when opening zmq.lib in a text editor.

Vendored build

Starting with the upcoming release 0.9.1 (or when building from current master), you can enable the vendored feature flag to have libzmq be built for you and statically linked into your binary crate. In your Cargo.toml, you can give users the option to do so using a dedicated feature flag:

[features]
vendored-zmq = ['zmq/vendored']

Cross-compilation

When you have a cross-compiled version of libzmq installed, you should be able to cross-compile rust-zmq, assuming a platform supporting pkg-config. For example, assuming you have libzmq compiled for the i686-pc-windows-gnu target installed in ~/.local-w32, the following should work:

PKG_CONFIG_PATH=$HOME/.local-w32/lib/pkgconfig \
PKG_CONFIG_ALLOW_CROSS=1 \
cargo build --target=i686-pc-windows-gnu --verbose

Cross compilation without pkg-config should work as well, but you need set LIBZMQ_PREFIX as described above.

Usage

rust-zmq is a pretty straight forward port of the C API into Rust:

fn main() {
    let ctx = zmq::Context::new();

    let mut socket = ctx.socket(zmq::REQ).unwrap();
    socket.connect("tcp://127.0.0.1:1234").unwrap();
    socket.send("hello world!", 0).unwrap();
}

You can find more usage examples in https://github.com/erickt/rust-zmq/tree/master/examples.

Contributing

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed under the terms of both the Apache License, Version 2.0 and the MIT license without any additional terms or conditions.

See the contribution guidelines for what to watch out for when submitting a pull request.

zmq 0.9.2