FreeBSD Manual Pages
ZMQ_PROXY(3) 0MQ Manual ZMQ_PROXY(3) NAME zmq_proxy - start built-in 0MQ proxy SYNOPSIS int zmq_proxy (void *frontend, void *backend, void *capture); DESCRIPTION The zmq_proxy() function starts the built-in 0MQ proxy in the current application thread. The proxy connects a frontend socket to a backend socket. Conceptually, data flows from frontend to backend. Depending on the socket types, replies may flow in the opposite direction. The direction is conceptual only; the proxy is fully symmetric and there is no technical difference between frontend and backend. Before calling zmq_proxy() you must set any socket options, and connect or bind both frontend and backend sockets. The two conventional proxy models are: zmq_proxy() runs in the current thread and returns only if/when the current context is closed. If the capture socket is not NULL, the proxy shall send all messages, received on both frontend and backend, to the capture socket. The capture socket should be a ZMQ_PUB, ZMQ_DEALER, ZMQ_PUSH, or ZMQ_PAIR socket. Refer to zmq_socket(3) for a description of the available socket types. EXAMPLE USAGE Shared Queue When the frontend is a ZMQ_ROUTER socket, and the backend is a ZMQ_DEALER socket, the proxy shall act as a shared queue that collects requests from a set of clients, and distributes these fairly among a set of services. Requests shall be fair-queued from frontend connections and distributed evenly across backend connections. Replies shall automatically return to the client that made the original request. Forwarder When the frontend is a ZMQ_XSUB socket, and the backend is a ZMQ_XPUB socket, the proxy shall act as a message forwarder that collects messages from a set of publishers and forwards these to a set of subscribers. This may be used to bridge networks transports, e.g. read on tcp:// and forward on pgm://. Streamer When the frontend is a ZMQ_PULL socket, and the backend is a ZMQ_PUSH socket, the proxy shall collect tasks from a set of clients and forwards these to a set of workers using the pipeline pattern. RETURN VALUE The zmq_proxy() function always returns -1 and errno set to ETERM or EINTR (the 0MQ context associated with either of the specified sockets was terminated) or EFAULT (the provided frontend or backend was invalid). EXAMPLE Creating a shared queue proxy. // Create frontend and backend sockets void *frontend = zmq_socket (context, ZMQ_ROUTER); assert (frontend); void *backend = zmq_socket (context, ZMQ_DEALER); assert (backend); // Bind both sockets to TCP ports assert (zmq_bind (frontend, "tcp://*:5555") == 0); assert (zmq_bind (backend, "tcp://*:5556") == 0); // Start the queue proxy, which runs until ETERM zmq_proxy (frontend, backend, NULL); SEE ALSO zmq_bind(3) zmq_connect(3) zmq_socket(3) zmq(7) AUTHORS This page was written by the 0MQ community. To make a change please read the 0MQ Contribution Policy at http://www.zeromq.org/docs:contributing. 0MQ 4.3.5 10/09/2023 ZMQ_PROXY(3)
NAME | SYNOPSIS | DESCRIPTION | EXAMPLE USAGE | RETURN VALUE | EXAMPLE | SEE ALSO | AUTHORS
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=zmq_proxy&sektion=3&manpath=FreeBSD+Ports+14.3.quarterly>