zmq_connect(3) ============== NAME ---- zmq_connect - create outgoing connection from socket 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. 0MQ provides the the following transports: 'tcp':: unicast transport using TCP, see linkzmq:zmq_tcp[7] 'ipc':: local inter-process communication transport, see linkzmq:zmq_ipc[7] 'inproc':: local in-process (inter-thread) communication transport, see linkzmq:zmq_inproc[7] 'pgm', 'epgm':: reliable multicast transport using PGM, see linkzmq:zmq_pgm[7] 'vmci':: virtual machine communications interface (VMCI), see linkzmq:zmq_vmci[7] 'udp':: unreliable unicast and multicast using UDP, see linkzmq:zmq_udp[7] Every 0MQ 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 linkzmq:zmq_socket[3]. NOTE: for most transports and socket types the connection is not performed immediately but as needed by 0MQ. 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 linkzmq: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 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. 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 -------- linkzmq:zmq_bind[3] linkzmq:zmq_socket[3] linkzmq:zmq[7] AUTHORS ------- This page was written by the 0MQ community. To make a change please read the 0MQ Contribution Policy at .