1ZMQ_CONNECT(3) 0MQ Manual ZMQ_CONNECT(3)
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6 zmq_connect - create outgoing connection from socket
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9 int zmq_connect (void *socket, const char *endpoint);
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12 The zmq_connect() function connects the socket to an endpoint and then
13 accepts incoming connections on that endpoint.
14 The endpoint is a string consisting of a transport:// followed by an
16 address. The transport specifies the underlying protocol to use. The
17 address specifies the transport-specific address to connect to.
18 0MQ provides the the following transports:
20 tcp
22 unicast transport using TCP, see zmq_tcp(7)
23 ipc
25 local inter-process communication transport, see zmq_ipc(7)
26 inproc
28 local in-process (inter-thread) communication transport, see
29 zmq_inproc(7)
30 pgm, epgm
32 reliable multicast transport using PGM, see zmq_pgm(7)
33 vmci
35 virtual machine communications interface (VMCI), see zmq_vmci(7)
36 udp
38 unreliable unicast and multicast using UDP, see zmq_udp(7)
39 Every 0MQ socket type except ZMQ_PAIR and ZMQ_CHANNEL supports
41 one-to-many and many-to-one semantics. The precise semantics depend on
42 the socket type and are defined in zmq_socket(3).
43 Note
45 for most transports and socket types the connection is not
46 performed immediately but as needed by 0MQ. Thus a successful call
47 to zmq_connect() does not mean that the connection was or could
48 actually be established. Because of this, for most transports and
49 socket types the order in which a server socket is bound and a
50 client socket is connected to it does not matter. The ZMQ_PAIR and
51 ZMQ_CHANNEL sockets are an exception, as they do not automatically
52 reconnect to endpoints.
53 Note
55 following a zmq_connect(), for socket types except for ZMQ_ROUTER,
56 the socket enters its normal ready state. By contrast, following a
57 zmq_bind() alone, the socket enters a mute state in which the
58 socket blocks or drops messages according to the socket type, as
59 defined in zmq_socket(3). A ZMQ_ROUTER socket enters its normal
60 ready state for a specific peer only when handshaking is complete
61 for that peer, which may take an arbitrary time.
62 Note
64 for some socket types, multiple connections to the same endpoint
65 don’t really make sense (see
66 https://github.com/zeromq/libzmq/issues/788). For those socket
67 types, any attempt to connect to an already connected endpoint is
68 silently ignored (i.e., returns zero). This behavior applies to
69 ZMQ_DEALER, ZMQ_SUB, ZMQ_PUB, and ZMQ_REQ socket types.
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72 The zmq_connect() function returns zero if successful. Otherwise it
73 returns -1 and sets errno to one of the values defined below.
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76 EINVAL
77 The endpoint supplied is invalid.
78 EPROTONOSUPPORT
80 The requested transport protocol is not supported.
81 ENOCOMPATPROTO
83 The requested transport protocol is not compatible with the socket
84 type.
85 ETERM
87 The 0MQ context associated with the specified socket was
88 terminated.
89 ENOTSOCK
91 The provided socket was invalid.
92 EMTHREAD
94 No I/O thread is available to accomplish the task.
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97 Connecting a subscriber socket to an in-process and a TCP transport.
98 /* Create a ZMQ_SUB socket */
100 void *socket = zmq_socket (context, ZMQ_SUB);
101 assert (socket);
102 /* Connect it to an in-process transport with the address 'my_publisher' */
103 int rc = zmq_connect (socket, "inproc://my_publisher");
104 assert (rc == 0);
105 /* Connect it to the host server001, port 5555 using a TCP transport */
106 rc = zmq_connect (socket, "tcp://server001:5555");
107 assert (rc == 0);
108
111 zmq_bind(3) zmq_socket(3) zmq(7)
112
114 This page was written by the 0MQ community. To make a change please
115 read the 0MQ Contribution Policy at
116 http://www.zeromq.org/docs:contributing.
1170MQ 4.3.4 01/30/2021 ZMQ_CONNECT(3)