1ZMQ_PROXY_STEERABLE(3) 0MQ Manual ZMQ_PROXY_STEERABLE(3)
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6 zmq_proxy_steerable - built-in 0MQ proxy with control flow
7
9 int zmq_proxy_steerable (const void *frontend, const void *backend,
10 const void *capture, const void *control);
11
13 The zmq_proxy_steerable() function starts the built-in 0MQ proxy in the
14 current application thread, as zmq_proxy() do. Please, refer to this
15 function for the general description and usage. We describe here only
16 the additional control flow provided by the socket passed as the fourth
17 argument "control".
18 If the control socket is not NULL, the proxy supports control flow. If
20 PAUSE is received on this socket, the proxy suspends its activities. If
21 RESUME is received, it goes on. If TERMINATE is received, it terminates
22 smoothly. If STATISTICS is received, the proxy will reply on the
23 control socket sending a multipart message with 8 frames, each with an
24 unsigned integer 64-bit wide that provide in the following order: -
25 number of messages received by the frontend socket - number of bytes
26 received by the frontend socket - number of messages sent out the
27 frontend socket - number of bytes sent out the frontend socket - number
28 of messages received by the backend socket - number of bytes received
29 by the backend socket - number of messages sent out the backend socket
30 - number of bytes sent out the backend socket
31 At start, the proxy runs normally as if zmq_proxy was used.
33 If the control socket is NULL, the function behave exactly as if
35 zmq_proxy(3) had been called.
36 Refer to zmq_socket(3) for a description of the available socket types.
38 Refer to zmq_proxy(3) for a description of the zmq_proxy.
39
41 cf zmq_proxy
42
44 The zmq_proxy_steerable() function returns 0 if TERMINATE is sent to
45 its control socket. Otherwise, it returns -1 and errno set to ETERM or
46 EINTR (the 0MQ context associated with either of the specified sockets
47 was terminated) or EFAULT (the provided frontend or backend was
48 invalid).
49
51 Creating a shared queue proxy.
52 // Create frontend, backend and control sockets
54 void *frontend = zmq_socket (context, ZMQ_ROUTER);
55 assert (frontend);
56 void *backend = zmq_socket (context, ZMQ_DEALER);
57 assert (backend);
58 void *control = zmq_socket (context, ZMQ_SUB);
59 assert (control);
60 // Bind sockets to TCP ports
62 assert (zmq_bind (frontend, "tcp://*:5555") == 0);
63 assert (zmq_bind (backend, "tcp://*:5556") == 0);
64 assert (zmq_connect (control, "tcp://*:5557") == 0);
65 // Subscribe to the control socket since we have chosen SUB here
67 assert (zmq_setsockopt (control, ZMQ_SUBSCRIBE, "", 0));
68 // Start the queue proxy, which runs until ETERM or "TERMINATE"
70 // received on the control socket
71 zmq_proxy_steerable (frontend, backend, NULL, control);
72 Set up a controller in another node, process or whatever.
74 void *control = zmq_socket (context, ZMQ_PUB);
76 assert (control);
77 assert (zmq_bind (control, "tcp://*:5557") == 0);
78 // pause the proxy
80 assert (zmq_send (control, "PAUSE", 5, 0) == 0);
81 // resume the proxy
83 assert (zmq_send (control, "RESUME", 6, 0) == 0);
84 // terminate the proxy
86 assert (zmq_send (control, "TERMINATE", 9, 0) == 0);
87 // check statistics
89 assert (zmq_send (control, "STATISTICS", 10, 0) == 0);
90 zmq_msg_t stats_msg;
91 while (1) {
93 assert (zmq_msg_init (&stats_msg) == 0);
94 assert (zmq_recvmsg (control, &stats_msg, 0) == sizeof (uint64_t));
95 assert (rc == sizeof (uint64_t));
96 printf ("Stat: %lu\n", *(unsigned long int *)zmq_msg_data (&stats_msg));
97 if (!zmq_msg_get (&stats_msg, ZMQ_MORE))
98 break;
99 assert (zmq_msg_close (&stats_msg) == 0);
100 }
101 assert (zmq_msg_close (&stats_msg) == 0);
102 ---
103 SEE ALSO
106 zmq_proxy(3) zmq_bind(3) zmq_connect(3) zmq_socket(3) zmq(7)
108
110 This page was written by the 0MQ community. To make a change please
111 read the 0MQ Contribution Policy at
112 http://www.zeromq.org/docs:contributing.
1130MQ 4.3.4 07/22/2023 ZMQ_PROXY_STEERABLE(3)