ZMQ_CONNECT_PEER

Section: 0MQ Manual (3)
Updated: 01/30/2021
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NAME

zmq_connect_peer - create outgoing connection from socket and return the connection routing id in thread-safe and atomic way.

SYNOPSIS

uint32_t zmq_connect_peer (void *socket, const char *endpoint);

DESCRIPTION

The zmq_connect_peer() function connects a ZMQ_PEER socket to an endpoint and then returns the endpoint routing_id.

The endpoint is a string consisting of a transport:// followed by an address. The transport specifies the underlying protocol to use. The address specifies the transport-specific address to connect to.

The function is supported only on the ZMQ_PEER socket type and would return 0 with errno set to ENOTSUP otherwise.

The zmq_connect_peer() support the following transports:

tcp

: unicast transport using TCP, see zmq_tcp(7)

ipc

: local inter-process communication transport, see zmq_ipc(7)

inproc

: local in-process (inter-thread) communication transport, see zmq_inproc(7)

: unicast transport using WebSockets, see zmq_ws(7)

wss

: unicast transport using WebSockets over TLS, see zmq_wss(7)

RETURN VALUE

The zmq_connect_peer() function returns the peer routing_id if successful. Otherwise it returns 0 and sets errno to one of the values defined below.

ERRORS

EINVAL

: The endpoint supplied is invalid.

EPROTONOSUPPORT

: The requested transport protocol is not supported with ZMQ_PEER.

ENOCOMPATPROTO

: The requested transport protocol is not compatible with the socket type.

ETERM

: The 0MQ context associated with the specified socket was terminated.

ENOTSOCK

: The provided socket was invalid.

EMTHREAD

: No I/O thread is available to accomplish the task.

ENOTSUP

: The socket is not of type ZMQ_PEER.

EFAULT

: The ZMQ_IMMEDIATE option is set on the socket.

EXAMPLE

Connecting a peer socket to a TCP transport and sending a message.

/* Create a ZMQ_SUB socket */
void *socket = zmq_socket (context, ZMQ_PEER);
assert (socket);
/* Connect it to the host server001, port 5555 using a TCP transport */
uint32_t routing_id = zmq_connect (socket, "tcp://server001:5555");
assert (routing_id == 0);
/* Sending a message to the peer  */
zmq_msg_t msg;
int rc = zmq_msg_init_data (&msg, "HELLO", 5, NULL, NULL);
assert (rc == 0);
rc = zmq_msg_set_routing_id (&msg, routing_id);
assert (rc == 0);
rc = zmq_msg_send (&msg, socket, 0);
assert (rc == 5);
rc = zmq_msg_close (&msg);
assert (rc == 0);

AUTHORS

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