ZMQ_PROXY(3) 0MQ Manual ZMQ_PROXY(3)NAMEzmq_proxy - start built-in 0MQ proxy
SYNOPSIS
int zmq_proxy (const void *frontend, const void *backend, const 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 (the
0MQ context associated with either of the specified sockets was
terminated).
EXAMPLE
Creating a shared queue proxy.
// Create frontend and backend sockets
void *frontend = zmq_socket (context, ZMQ_ROUTER);
assert (backend);
void *backend = zmq_socket (context, ZMQ_DEALER);
assert (frontend);
// 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 ALSOzmq_bind(3)zmq_connect(3)zmq_socket(3)zmq(7)AUTHORS
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0MQ 4.0.1 03/10/2014 ZMQ_PROXY(3)
