Recommendations for C/C++ remote message queues

In terms of simple messaging support, ZeroMQ is hard to beat. It's available in many language bindings and supports everything from simple send and receive to pub/sub, fanout, or even a messaging pipeline. The code is also easy to digest and makes it pretty easy to switch between patterns.

Looking at their Weather Update Server sample (in 20 some odd languages) shows how easy it can be to create publish/subscribe setups:

zmq::context_t context (1);zmq::socket_t publisher (context, ZMQ_PUB);publisher.bind("tcp://*:5556");publisher.bind("ipc://weather.ipc");while(1) {    //  Send message to all subscribers    zmq::message_t message(20);    snprintf ((char *) message.data(), 20 ,        "%05d %d %d", zipcode, temperature, relhumidity);    publisher.send(message);}

I've used it on some mixed C# and Python processes without much hassle.

Personally, if I understand the question, I think that you should use a lower-level TCP connection. It has all of the guarantied delivery that you want, and has a rather good Berkley Sockets API. I've found that if your willing to implement a very simple protocol (eg. four-byte NBO message length, n bytes of data), you can get very simple, very customizable, and very simple. If you go with this, you also (as mentioned) get great C support (which means C++ support, although things aren't in classes and methods). The socket code is also very easy, and they have asynchronous IO with the standard async flags for the Linux/UNIX/POSIX IO functions (thats one of the other benefits, if you know anything about POSIX programing, you basically know the socket API).

One of the best resources for learning the socket API are:

• Beej's Guide to Network Programing: http://beej.us/guide/bgnet/, this is very good if you need the overall programming model in addition to specifics
• Man Pages: If you just need function signatures, return values, and arguments, these are all you need. I find the Linux ones to be very well written and useful (Proof: Look at my console: man, man, man, man, man, make, man, ...)

Also, for making data network-sendable, if your data is JSON, you have no worries. Because JSON is just ASCII (or UTF-8), it can be sent raw over the network with only a length header. Unless your trying to send something complicated in binary, this should be perfect (if you need complicated in binary, either look at serialization or prepare for a lot of Segmentation Fault).

Also, you probably, if you go the socket path, want to use TCP. Although UDP will give you the one-way aspect, the fact that making it reliable is pitting your home-baked solution against the top-of-the-line TCP given by the Linux kernel, TCP is an obvious option.

RabbitMQ is just one implementation of AMQP. You might want to investigate Apache Qpid or other variants that might be more C/C++ friendly. There is a libamqp for C though I have no first hand experience with it. I don't know exactly what your requirements are but AMQP, properly implemented, is industrial strength and should be orders of magnitude faster and more stable than anything you are going to build by hand in a short amount of time.