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214 lines
7.6 KiB
214 lines
7.6 KiB
5 years ago
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'\" t
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.\" Title: zbeacon_v2
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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: CZMQ Manual
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.\" Source: CZMQ 3.0.2
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.\" Language: English
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.\"
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.TH "ZBEACON_V2" "3" "09/14/2016" "CZMQ 3\&.0\&.2" "CZMQ 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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.\" -----------------------------------------------------------------
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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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zbeacon_v2 \- LAN discovery and presence (deprecated)
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.SH "SYNOPSIS"
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.sp
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.nf
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// Create a new beacon on a certain UDP port\&. If the system does not
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// support UDP broadcasts (lacking a useful interface), returns NULL\&.
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// To force the beacon to operate on a given port, set the environment
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// variable ZSYS_INTERFACE, or call zsys_set_interface() beforehand\&.
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// If you are using the new zsock API then pass NULL as the ctx here\&.
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CZMQ_EXPORT zbeacon_t *
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zbeacon_new (zctx_t *ctx, int port_nbr);
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// Destroy a beacon
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CZMQ_EXPORT void
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zbeacon_destroy (zbeacon_t **self_p);
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// Return our own IP address as printable string
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CZMQ_EXPORT char *
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zbeacon_hostname (zbeacon_t *self);
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// Set broadcast interval in milliseconds (default is 1000 msec)
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CZMQ_EXPORT void
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zbeacon_set_interval (zbeacon_t *self, int interval);
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// Filter out any beacon that looks exactly like ours
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CZMQ_EXPORT void
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zbeacon_noecho (zbeacon_t *self);
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// Start broadcasting beacon to peers at the specified interval
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CZMQ_EXPORT void
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zbeacon_publish (zbeacon_t *self, byte *transmit, size_t size);
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// Stop broadcasting beacons
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CZMQ_EXPORT void
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zbeacon_silence (zbeacon_t *self);
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// Start listening to other peers; zero\-sized filter means get everything
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CZMQ_EXPORT void
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zbeacon_subscribe (zbeacon_t *self, byte *filter, size_t size);
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// Stop listening to other peers
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CZMQ_EXPORT void
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zbeacon_unsubscribe (zbeacon_t *self);
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// Get beacon ZeroMQ socket, for polling or receiving messages
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CZMQ_EXPORT void *
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zbeacon_socket (zbeacon_t *self);
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// Self test of this class
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CZMQ_EXPORT void
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zbeacon_v2_test (bool verbose);
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.fi
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.SH "DESCRIPTION"
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.sp
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The zbeacon class implements a peer\-to\-peer discovery service for local networks\&. A beacon can broadcast and/or capture service announcements using UDP messages on the local area network\&. This implementation uses IPv4 UDP broadcasts\&. You can define the format of your outgoing beacons, and set a filter that validates incoming beacons\&. Beacons are sent and received asynchronously in the background\&. The zbeacon API provides a incoming beacons on a ZeroMQ socket (the pipe) that you can configure, poll on, and receive messages on\&. Incoming beacons are always delivered as two frames: the ipaddress of the sender (a string), and the beacon data itself (binary, as published)\&.
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.sp
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This class is deprecated in CZMQ v3; it works together with zctx, zsocket, and other deprecated V2 classes\&. New applications should use the V3 zauth interface, based on zactor, together with the zsock class for sockets\&.
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.SH "EXAMPLE"
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.PP
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\fBFrom zbeacon_v2_test method\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 beacon to broadcast our service
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zctx_t *ctx = zctx_new ();
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assert (ctx);
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zbeacon_t *service_beacon = zbeacon_new (ctx, 9999);
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if (service_beacon == NULL) {
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printf ("OK (skipping test, no UDP discovery)\en");
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return;
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}
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// Create a service socket and bind to an ephemeral port
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zsock_t *service = zsock_new (ZMQ_PUB);
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assert (service);
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int port_nbr = zsock_bind (service, "tcp://127\&.0\&.0\&.1:*");
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byte announcement [2] = { (port_nbr >> 8) & 0xFF, port_nbr & 0xFF };
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zbeacon_set_interval (service_beacon, 100);
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zbeacon_publish (service_beacon, announcement, 2);
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// Create beacon to lookup service
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zbeacon_t *client_beacon = zbeacon_new (ctx, 9999);
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assert (client_beacon);
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zbeacon_subscribe (client_beacon, NULL, 0);
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// Wait for at most 1/2 second if there\*(Aqs no broadcast networking
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zsocket_set_rcvtimeo (zbeacon_socket (client_beacon), 500);
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char *ipaddress = zstr_recv (zbeacon_socket (client_beacon));
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if (ipaddress) {
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zframe_t *content = zframe_recv (zbeacon_socket (client_beacon));
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int received_port = (zframe_data (content) [0] << 8)
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+ zframe_data (content) [1];
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assert (received_port == port_nbr);
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zframe_destroy (&content);
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zbeacon_silence (service_beacon);
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zstr_free (&ipaddress);
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}
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zbeacon_destroy (&client_beacon);
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zbeacon_destroy (&service_beacon);
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zbeacon_t *node1 = zbeacon_new (ctx, 5670);
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assert (node1);
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zbeacon_t *node2 = zbeacon_new (ctx, 5670);
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assert (node2);
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zbeacon_t *node3 = zbeacon_new (ctx, 5670);
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assert (node3);
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assert (*zbeacon_hostname (node1));
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assert (*zbeacon_hostname (node2));
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assert (*zbeacon_hostname (node3));
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zbeacon_set_interval (node1, 250);
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zbeacon_set_interval (node2, 250);
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zbeacon_set_interval (node3, 250);
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zbeacon_noecho (node1);
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zbeacon_publish (node1, (byte *) "NODE/1", 6);
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zbeacon_publish (node2, (byte *) "NODE/2", 6);
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zbeacon_publish (node3, (byte *) "GARBAGE", 7);
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zbeacon_subscribe (node1, (byte *) "NODE", 4);
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// Poll on three API sockets at once
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zpoller_t *poller = zpoller_new (
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zbeacon_socket (node1),
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zbeacon_socket (node2),
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zbeacon_socket (node3), NULL);
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assert (poller);
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int64_t stop_at = zclock_mono () + 1000;
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while (zclock_mono () < stop_at) {
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long timeout = (long) (stop_at \- zclock_mono ());
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if (timeout < 0)
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timeout = 0;
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void *which = zpoller_wait (poller, timeout * ZMQ_POLL_MSEC);
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if (which) {
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assert (which == zbeacon_socket (node1));
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char *ipaddress, *beacon;
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zstr_recvx (zbeacon_socket (node1), &ipaddress, &beacon, NULL);
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assert (streq (beacon, "NODE/2"));
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zstr_free (&ipaddress);
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zstr_free (&beacon);
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}
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}
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zpoller_destroy (&poller);
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// Stop listening
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zbeacon_unsubscribe (node1);
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// Stop all node broadcasts
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zbeacon_silence (node1);
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zbeacon_silence (node2);
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zbeacon_silence (node3);
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// Destroy the test nodes
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zbeacon_destroy (&node1);
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zbeacon_destroy (&node2);
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zbeacon_destroy (&node3);
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zsock_destroy (&service);
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zctx_destroy (&ctx);
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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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.SH "AUTHORS"
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.sp
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The czmq manual was written by the authors in the AUTHORS file\&.
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.SH "RESOURCES"
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.sp
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Main web site: \m[blue]\fB\%\fR\m[]
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.sp
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Report bugs to the email <\m[blue]\fBzeromq\-dev@lists\&.zeromq\&.org\fR\m[]\&\s-2\u[1]\d\s+2>
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.SH "COPYRIGHT"
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.sp
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Copyright (c) 1991\-2012 iMatix Corporation \-\- http://www\&.imatix\&.com Copyright other contributors as noted in the AUTHORS file\&. This file is part of CZMQ, the high\-level C binding for 0MQ: http://czmq\&.zeromq\&.org This Source Code Form is subject to the terms of the Mozilla Public License, v\&. 2\&.0\&. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla\&.org/MPL/2\&.0/\&. LICENSE included with the czmq distribution\&.
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.SH "NOTES"
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.IP " 1." 4
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zeromq-dev@lists.zeromq.org
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.RS 4
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\%mailto:zeromq-dev@lists.zeromq.org
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.RE
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