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101 lines
3.8 KiB
Plaintext
101 lines
3.8 KiB
Plaintext
= zmq_connect(3)
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== NAME
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zmq_connect - create outgoing connection from socket
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== SYNOPSIS
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*int zmq_connect (void '*socket', const char '*endpoint');*
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== DESCRIPTION
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The _zmq_connect()_ function connects the 'socket' to an 'endpoint' and then
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accepts incoming connections on that endpoint.
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The 'endpoint' is a string consisting of a 'transport'`://` followed by an
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'address'. The 'transport' specifies the underlying protocol to use. The
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'address' specifies the transport-specific address to connect to.
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0MQ provides the the following transports:
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'tcp':: unicast transport using TCP, see xref:zmq_tcp.adoc[zmq_tcp]
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'ipc':: local inter-process communication transport, see xref:zmq_ipc.adoc[zmq_ipc]
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'inproc':: local in-process (inter-thread) communication transport, see xref:zmq_inproc.adoc[zmq_inproc]
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'pgm', 'epgm':: reliable multicast transport using PGM, see xref:zmq_pgm.adoc[zmq_pgm]
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'vmci':: virtual machine communications interface (VMCI), see xref:zmq_vmci.adoc[zmq_vmci]
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'udp':: unreliable unicast and multicast using UDP, see xref:zmq_udp.adoc[zmq_udp]
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Every 0MQ socket type except 'ZMQ_PAIR' and 'ZMQ_CHANNEL' supports one-to-many and many-to-one
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semantics. The precise semantics depend on the socket type and are defined in
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xref:zmq_socket.adoc[zmq_socket]
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NOTE: for most transports and socket types the connection is not performed
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immediately but as needed by 0MQ. Thus a successful call to _zmq_connect()_
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does not mean that the connection was or could actually be established.
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Because of this, for most transports and socket types the order in which
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a 'server' socket is bound and a 'client' socket is connected to it does not
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matter. The _ZMQ_PAIR_ and _ZMQ_CHANNEL_ sockets are an exception, as they do not automatically
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reconnect to endpoints.
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NOTE: following a _zmq_connect()_, for socket types except for ZMQ_ROUTER,
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the socket enters its normal 'ready' state. By contrast, following a
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_zmq_bind()_ alone, the socket enters a 'mute' state in which the socket
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blocks or drops messages according to the socket type, as defined in
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xref:zmq_socket.adoc[zmq_socket] A ZMQ_ROUTER socket enters its normal 'ready' state
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for a specific peer only when handshaking is complete for that peer, which
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may take an arbitrary time.
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NOTE: for some socket types, multiple connections to the same endpoint
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don't really make sense
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(see https://github.com/zeromq/libzmq/issues/788).
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For those socket types, any attempt to connect to an already connected endpoint
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is silently ignored (i.e., returns zero). This behavior applies to ZMQ_DEALER,
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ZMQ_SUB, ZMQ_PUB, and ZMQ_REQ socket types.
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== RETURN VALUE
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The _zmq_connect()_ function returns zero if successful. Otherwise it returns
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`-1` and sets 'errno' to one of the values defined below.
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== ERRORS
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*EINVAL*::
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The endpoint supplied is invalid.
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*EPROTONOSUPPORT*::
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The requested 'transport' protocol is not supported.
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*ENOCOMPATPROTO*::
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The requested 'transport' protocol is not compatible with the socket type.
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*ETERM*::
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The 0MQ 'context' associated with the specified 'socket' was terminated.
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*ENOTSOCK*::
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The provided 'socket' was invalid.
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*EMTHREAD*::
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No I/O thread is available to accomplish the task.
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== EXAMPLE
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.Connecting a subscriber socket to an in-process and a TCP transport
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----
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/* Create a ZMQ_SUB socket */
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void *socket = zmq_socket (context, ZMQ_SUB);
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assert (socket);
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/* Connect it to an in-process transport with the address 'my_publisher' */
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int rc = zmq_connect (socket, "inproc://my_publisher");
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assert (rc == 0);
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/* Connect it to the host server001, port 5555 using a TCP transport */
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rc = zmq_connect (socket, "tcp://server001:5555");
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assert (rc == 0);
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----
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== SEE ALSO
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* xref:zmq_bind.adoc[zmq_bind]
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* xref:zmq_socket.adoc[zmq_socket]
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* xref:zmq.adoc[zmq]
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== AUTHORS
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This page was written by the 0MQ community. To make a change please
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read the 0MQ Contribution Policy at <https://zeromq.org/how-to-contribute/>.
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