SYNOPSIS
int zmq_connect (void *socket, const char *endpoint);
DESCRIPTION
The zmq_connect() function connects the socket to an endpoint and then accepts incoming connections on that endpoint.
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.
ØMQ provides the 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)
- pgm, epgm
-
reliable multicast transport using PGM, see zmq_pgm(7)
- vmci
-
virtual machine communications interface (VMCI), see zmq_vmci(7)
- udp
-
unreliable unicast and multicast using UDP, see zmq_udp(7)
Every ØMQ socket type except ZMQ_PAIR and ZMQ_CHANNEL supports one-to-many and many-to-one semantics. The precise semantics depend on the socket type and are defined in zmq_socket(3).
Note
|
for most transports and socket types the connection is not performed immediately but as needed by ØMQ. Thus a successful call to zmq_connect() does not mean that the connection was or could actually be established. Because of this, for most transports and socket types the order in which a server socket is bound and a client socket is connected to it does not matter. The ZMQ_PAIR and ZMQ_CHANNEL sockets are an exception, as they do not automatically reconnect to endpoints. |
Note
|
following a zmq_connect(), for socket types except for ZMQ_ROUTER, the socket enters its normal ready state. By contrast, following a zmq_bind() alone, the socket enters a mute state in which the socket blocks or drops messages according to the socket type, as defined in zmq_socket(3). A ZMQ_ROUTER socket enters its normal ready state for a specific peer only when handshaking is complete for that peer, which may take an arbitrary time. |
Note
|
for some socket types, multiple connections to the same endpoint don’t really make sense (see https://github.com/zeromq/libzmq/issues/788). For those socket types, any attempt to connect to an already connected endpoint is silently ignored (i.e., returns zero). This behavior applies to ZMQ_DEALER, ZMQ_SUB, ZMQ_PUB, and ZMQ_REQ socket types. |
RETURN VALUE
The zmq_connect() function returns zero if successful. Otherwise it returns
-1
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.
- 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
/* 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
AUTHORS
This page was written by the ØMQ community. To make a change please read the ØMQ Contribution Policy at http://www.zeromq.org/docs:contributing.