1ZMQ_DEVICE(3) 0MQ Manual ZMQ_DEVICE(3)
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6 zmq_device - start built-in 0MQ device
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9 int zmq_device (int device, const void *frontend, const void *backend);
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12 The zmq_device() function starts a built-in 0MQ device. The device
13 argument is one of:
14 ZMQ_QUEUE
16 starts a queue device
17 ZMQ_FORWARDER
19 starts a forwarder device
20 ZMQ_STREAMER
22 starts a streamer device
23 The device connects a frontend socket to a backend socket.
25 Conceptually, data flows from frontend to backend. Depending on the
26 socket types, replies may flow in the opposite direction.
27 Before calling zmq_device() you must set any socket options, and
29 connect or bind both frontend and backend sockets. The two conventional
30 device models are:
31 proxy
33 bind frontend socket to an endpoint, and connect backend socket to
34 downstream components. A proxy device model does not require
35 changes to the downstream topology but that topology is static (any
36 changes require reconfiguring the device).
37 broker
39 bind frontend socket to one endpoint and bind backend socket to a
40 second endpoint. Downstream components must now connect into the
41 device. A broker device model allows a dynamic downstream topology
42 (components can come and go at any time).
43 zmq_device() runs in the current thread and returns only if/when the
45 current context is closed.
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48 ZMQ_QUEUE creates a shared queue that collects requests from a set of
49 clients, and distributes these fairly among a set of services. Requests
50 are fair-queued from frontend connections and load-balanced between
51 backend connections. Replies automatically return to the client that
52 made the original request.
53 This device is part of the request-reply pattern. The frontend speaks
55 to clients and the backend speaks to services. You should use ZMQ_QUEUE
56 with a ZMQ_XREP socket for the frontend and a ZMQ_XREQ socket for the
57 backend. Other combinations are not documented.
58 Refer to zmq_socket(3) for a description of these socket types.
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62 ZMQ_FORWARDER collects messages from a set of publishers and forwards
63 these to a set of subscribers. You will generally use this to bridge
64 networks, e.g. read on TCP unicast and forward on multicast.
65 This device is part of the publish-subscribe pattern. The frontend
67 speaks to publishers and the backend speaks to subscribers. You should
68 use ZMQ_FORWARDER with a ZMQ_SUB socket for the frontend and a ZMQ_PUB
69 socket for the backend. Other combinations are not documented.
70 Refer to zmq_socket(3) for a description of these socket types.
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74 ZMQ_STREAMER collects tasks from a set of pushers and forwards these to
75 a set of pullers. You will generally use this to bridge networks.
76 Messages are fair-queued from pushers and load-balanced to pullers.
77 This device is part of the pipeline pattern. The frontend speaks to
79 pushers and the backend speaks to pullers. You should use ZMQ_STREAMER
80 with a ZMQ_PULL socket for the frontend and a ZMQ_PUSH socket for the
81 backend. Other combinations are not documented.
82 Refer to zmq_socket(3) for a description of these socket types.
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86 The zmq_device() function always returns -1 and errno set to ETERM (the
87 0MQ context associated with either of the specified sockets was
88 terminated).
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91 Creating a queue broker.
92 // Create frontend and backend sockets
94 void *frontend = zmq_socket (context, ZMQ_XREP);
95 assert (backend);
96 void *backend = zmq_socket (context, ZMQ_XREQ);
97 assert (frontend);
98 // Bind both sockets to TCP ports
99 assert (zmq_bind (frontend, "tcp://*:5555") == 0);
100 assert (zmq_bind (backend, "tcp://*:5556") == 0);
101 // Start a queue device
102 zmq_device (ZMQ_QUEUE, frontend, backend);
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106 zmq_bind(3) zmq_connect(3) zmq_socket(3) zmq(7)
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109 This 0MQ manual page was written by Pieter Hintjens <ph@imatix.com[1]>
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112 Main web site: http://www.zeromq.org/
113 Report bugs to the 0MQ development mailing list:
115 <zeromq-dev@lists.zeromq.org[2]>
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118 Free use of this software is granted under the terms of the GNU Lesser
119 General Public License (LGPL). For details see the files COPYING and
120 COPYING.LESSER included with the 0MQ distribution.
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123 1. ph@imatix.com
124 mailto:ph@imatix.com
125 2. zeromq-dev@lists.zeromq.org
127 mailto:zeromq-dev@lists.zeromq.org
1280MQ 2.1.4 03/30/2011 ZMQ_DEVICE(3)