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							112 lines
						
					
					
						
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				'\" t
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.\"     Title: zmq_proxy_steerable
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.\"    Author: [see the "AUTHORS" section]
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.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
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.\"      Date: 09/14/2016
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.\"    Manual: 0MQ Manual
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.\"    Source: 0MQ 4.1.5
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.\"  Language: English
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.\"
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.TH "ZMQ_PROXY_STEERABLE" "3" "09/14/2016" "0MQ 4\&.1\&.5" "0MQ Manual"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el       .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH "NAME"
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zmq_proxy_steerable \- built\-in 0MQ proxy with control flow
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.SH "SYNOPSIS"
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.sp
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\fBint zmq_proxy_steerable (const void \fR\fB\fI*frontend\fR\fR\fB, const void \fR\fB\fI*backend\fR\fR\fB, const void \fR\fB\fI*capture\fR\fR\fB, const void \fR\fB\fI*control\fR\fR\fB);\fR
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.SH "DESCRIPTION"
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.sp
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The \fIzmq_proxy_steerable()\fR function starts the built\-in 0MQ proxy in the current application thread, as \fIzmq_proxy()\fR do\&. Please, refer to this function for the general description and usage\&. We describe here only the additional control flow provided by the socket passed as the fourth argument "control"\&.
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.sp
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If the control socket is not NULL, the proxy supports control flow\&. If \fIPAUSE\fR is received on this socket, the proxy suspends its activities\&. If \fIRESUME\fR is received, it goes on\&. If \fITERMINATE\fR is received, it terminates smoothly\&. At start, the proxy runs normally as if zmq_proxy was used\&.
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.sp
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If the control socket is NULL, the function behave exactly as if zmq_proxy had been called\&.
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.sp
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Refer to \fBzmq_socket\fR(3) for a description of the available socket types\&. Refer to \fBzmq_proxy\fR(3) for a description of the zmq_proxy\&.
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.SH "EXAMPLE USAGE"
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.sp
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cf zmq_proxy
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.SH "RETURN VALUE"
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.sp
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The \fIzmq_proxy_steerable()\fR function returns 0 if TERMINATE is sent to its control socket\&. Otherwise, it returns \-1 and \fIerrno\fR set to \fBETERM\fR (the 0MQ \fIcontext\fR associated with either of the specified sockets was terminated)\&.
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.SH "EXAMPLE"
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.PP
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\fBCreating a shared queue proxy\fR. 
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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//  Create frontend, backend and control sockets
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void *frontend = zmq_socket (context, ZMQ_ROUTER);
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assert (backend);
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void *backend = zmq_socket (context, ZMQ_DEALER);
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assert (frontend);
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void *control = zmq_socket (context, ZMQ_SUB);
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assert (control);
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//  Bind sockets to TCP ports
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assert (zmq_bind (frontend, "tcp://*:5555") == 0);
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assert (zmq_bind (backend, "tcp://*:5556") == 0);
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assert (zmq_connect (control, "tcp://*:5557") == 0);
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// Subscribe to the control socket since we have chosen SUB here
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assert (zmq_setsockopt (control, ZMQ_SUBSCRIBE, "", 0));
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//  Start the queue proxy, which runs until ETERM or "TERMINATE"
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//  received on the control socket
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zmq_proxy_steerable (frontend, backend, NULL, control);
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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\fBSet up a controller in another node, process or whatever\fR. 
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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void *control = zmq_socket (context, ZMQ_PUB);
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assert (control);
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assert (zmq_bind (control, "tcp://*:5557") == 0);
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// pause the proxy
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assert (zmq_send (control, "PAUSE", 5, 0) == 0);
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// resume the proxy
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assert (zmq_send (control, "RESUME", 6, 0) == 0);
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// terminate the proxy
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assert (zmq_send (control, "TERMINATE", 9, 0) == 0);
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\-\-\-
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SEE ALSO
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.fi
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.if n \{\
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.RE
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.\}
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.sp
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\fBzmq_proxy\fR(3) \fBzmq_bind\fR(3) \fBzmq_connect\fR(3) \fBzmq_socket\fR(3) \fBzmq\fR(7)
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.SH "AUTHORS"
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.sp
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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[]\&.
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