# zmq_connect(3) Manual Page

## NAME

zmq_connect - connect a socket

## SYNOPSIS

int zmq_connect (void *socket, const char *endpoint);

## DESCRIPTION

The zmq_connect() function shall connect the socket referenced by the socket argument to the endpoint specified by the endpoint argument.

The endpoint argument is a string consisting of two parts as follows: transport`://`address. The transport part specifies the underlying transport protocol to use. The meaning of the address part is specific to the underlying transport protocol selected.

The following transports are defined:

inproc

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

ipc

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

tcp

  unicast transport using TCP, see zmq_tcp(7)

pgm, epgm

  reliable multicast transport using PGM, see zmq_pgm(7)

With the exception of ZMQ_PAIR sockets, a single socket may be connected to multiple endpoints using zmq_connect(), while simultaneously accepting incoming connections from multiple endpoints bound to the socket using zmq_bind(). Refer to zmq_socket(3) for a description of the exact semantics involved when connecting or binding a socket to multiple endpoints.

Note | The connection will not be performed immediately but as needed by ØMQ. Thus a successful invocation of zmq_connect() does not indicate that a physical connection was or can actually be established.

## RETURN VALUE

The zmq_connect() function shall return zero if successful. Otherwise it shall return `-1` and set errno to one of the values defined below.

## ERRORS

EINVAL

  The endpoint supplied is invalid.

EPROTONOSUPPORT

  The requested transport protocol is not supported.

ENOCOMPATPROTO

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

ETERM

  The ØMQ 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.

## EXAMPLE

Connecting a subscriber socket to an in-process and a TCP transport

    /* Create a ZMQ_SUB socket */
    void *socket = zmq_socket (context, ZMQ_SUB);
    assert (socket);
    /* Connect it to an in-process transport with the address 'my_publisher' */
    int rc = zmq_connect (socket, "inproc://my_publisher");
    assert (rc == 0);
    /* Connect it to the host server001, port 5555 using a TCP transport */
    rc = zmq_connect (socket, "tcp://server001:5555");
    assert (rc == 0);

## SEE ALSO

zmq_bind(3) zmq_socket(3) zmq(7)

## AUTHORS

The ØMQ documentation was written by Martin Sustrik <sustrik@250bpm.com> and Martin Lucina <martin@lucina.net>.