'\" t .\" Title: zmq_connect .\" Author: [see the "AUTHORS" section] .\" Generator: DocBook XSL Stylesheets vsnapshot .\" Date: 10/23/2023 .\" Manual: 0MQ Manual .\" Source: 0MQ 4.3.5 .\" Language: English .\" .TH "ZMQ_CONNECT" "3" "10/23/2023" "0MQ 4\&.3\&.5" "0MQ Manual" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" zmq_connect \- create outgoing connection from socket .SH "SYNOPSIS" .sp \fBint zmq_connect (void \fR\fB\fI*socket\fR\fR\fB, const char \fR\fB\fI*endpoint\fR\fR\fB);\fR .SH "DESCRIPTION" .sp The \fIzmq_connect()\fR function connects the \fIsocket\fR to an \fIendpoint\fR and then accepts incoming connections on that endpoint\&. .sp The \fIendpoint\fR is a string consisting of a \fItransport\fR:// followed by an \fIaddress\fR\&. The \fItransport\fR specifies the underlying protocol to use\&. The \fIaddress\fR specifies the transport\-specific address to connect to\&. .sp 0MQ provides the the following transports: .PP \fItcp\fR .RS 4 unicast transport using TCP, see \fBzmq_tcp\fR(7) .RE .PP \fIipc\fR .RS 4 local inter\-process communication transport, see \fBzmq_ipc\fR(7) .RE .PP \fIinproc\fR .RS 4 local in\-process (inter\-thread) communication transport, see \fBzmq_inproc\fR(7) .RE .PP \fIpgm\fR, \fIepgm\fR .RS 4 reliable multicast transport using PGM, see \fBzmq_pgm\fR(7) .RE .PP \fIvmci\fR .RS 4 virtual machine communications interface (VMCI), see \fBzmq_vmci\fR(7) .RE .PP \fIudp\fR .RS 4 unreliable unicast and multicast using UDP, see \fBzmq_udp\fR(7) .RE .sp Every 0MQ socket type except \fIZMQ_PAIR\fR and \fIZMQ_CHANNEL\fR supports one\-to\-many and many\-to\-one semantics\&. The precise semantics depend on the socket type and are defined in \fBzmq_socket\fR(3)\&. .if n \{\ .sp .\} .RS 4 .it 1 an-trap .nr an-no-space-flag 1 .nr an-break-flag 1 .br .ps +1 \fBNote\fR .ps -1 .br .sp for most transports and socket types the connection is not performed immediately but as needed by 0MQ\&. Thus a successful call to \fIzmq_connect()\fR 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 \fIserver\fR socket is bound and a \fIclient\fR socket is connected to it does not matter\&. The \fIZMQ_PAIR\fR and \fIZMQ_CHANNEL\fR sockets are an exception, as they do not automatically reconnect to endpoints\&. .sp .5v .RE .if n \{\ .sp .\} .RS 4 .it 1 an-trap .nr an-no-space-flag 1 .nr an-break-flag 1 .br .ps +1 \fBNote\fR .ps -1 .br .sp following a \fIzmq_connect()\fR, for socket types except for ZMQ_ROUTER, the socket enters its normal \fIready\fR state\&. By contrast, following a \fIzmq_bind()\fR alone, the socket enters a \fImute\fR state in which the socket blocks or drops messages according to the socket type, as defined in \fBzmq_socket\fR(3)\&. A ZMQ_ROUTER socket enters its normal \fIready\fR state for a specific peer only when handshaking is complete for that peer, which may take an arbitrary time\&. .sp .5v .RE .if n \{\ .sp .\} .RS 4 .it 1 an-trap .nr an-no-space-flag 1 .nr an-break-flag 1 .br .ps +1 \fBNote\fR .ps -1 .br .sp for some socket types, multiple connections to the same endpoint don\(cqt really make sense (see \m[blue]\fBhttps://github\&.com/zeromq/libzmq/issues/788\fR\m[])\&. 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\&. .sp .5v .RE .SH "RETURN VALUE" .sp The \fIzmq_connect()\fR function returns zero if successful\&. Otherwise it returns \-1 and sets \fIerrno\fR to one of the values defined below\&. .SH "ERRORS" .PP \fBEINVAL\fR .RS 4 The endpoint supplied is invalid\&. .RE .PP \fBEPROTONOSUPPORT\fR .RS 4 The requested \fItransport\fR protocol is not supported\&. .RE .PP \fBENOCOMPATPROTO\fR .RS 4 The requested \fItransport\fR protocol is not compatible with the socket type\&. .RE .PP \fBETERM\fR .RS 4 The 0MQ \fIcontext\fR associated with the specified \fIsocket\fR was terminated\&. .RE .PP \fBENOTSOCK\fR .RS 4 The provided \fIsocket\fR was invalid\&. .RE .PP \fBEMTHREAD\fR .RS 4 No I/O thread is available to accomplish the task\&. .RE .SH "EXAMPLE" .PP \fBConnecting a subscriber socket to an in-process and a TCP transport\fR. .sp .if n \{\ .RS 4 .\} .nf /* Create a ZMQ_SUB socket */ void *socket = zmq_socket (context, ZMQ_SUB); assert (socket); /* Connect it to an in\-process transport with the address \*(Aqmy_publisher\*(Aq */ 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); .fi .if n \{\ .RE .\} .sp .SH "SEE ALSO" .sp \fBzmq_bind\fR(3) \fBzmq_socket\fR(3) \fBzmq\fR(7) .SH "AUTHORS" .sp This page was written by the 0MQ community\&. To make a change please read the 0MQ Contribution Policy at \m[blue]\fBhttp://www\&.zeromq\&.org/docs:contributing\fR\m[]\&.