zmq_deviced(1)
==============

NAME
----
zmq_deviced - start built-in 0MQ devices

SYNOPSIS
--------

*zmq_deviced _DEVICE_ _FRONTEND_ _BACKEND_*

*zmq_deviced [_CONFIGFILE_]*

DESCRIPTION
-----------
Starts one or more 0MQ devices.  If you specify a DEVICE, FRONTEND, and BACKEND
then _zmq_device_ starts a single device acting as a mini-broker.  If you
specify a CONFIGFILE, you can configure _zmq_device_ to start multiple
concurrent devices with arbitrary configurations.

*Note* - zmq_deviced is not yet implemented.  This is a design.

MINI-BROKER USAGE
-----------------
Runs as a mini-broker that accepts connects to both frontend and backend. This
creates a hub-and-spoke topology in which all peers connect to the device. This
is a robust and easy to manage topology.

DEVICE is one of: *queue*, *forwarder*, or *streamer*. See
linkzmq:zmq_device[3] for a specification of these device types.

FRONTEND and BACKEND are endpoints in the format 'transport'`://`'address', See
linkzmq:zmq_bind[3] for a specification of valid transports and addresses.


CONFIGURED USAGE
----------------
CONFIGFILE is the name of an XML file, readable by 'zmq_device'.  This file
provides a specification of the devices to start and how to connect and/or bind
their frontends and backends.  If CONFIGFILE is absent or *-* then the
configuration is read from standard input.

The configuration file has this general syntax:

----
<?xml?>
<config [ iothreads="..." ] >
  <device type="...">
    <frontend [ type="..." ] >
        <set name = "..." value = "..." />...
        <bind endpoint="..." /> ...
        <connect address="..." /> ...
    </frontend>
    <backend [ type="..." ] >
        <set name = "..." value = "..." />...
        <bind address="..." /> ...
        <connect address="..." /> ...
    </backend>
  </device>
</config>
----

*iothreads*::
    specifies the number of I/O threads for the process.  Specify this only for
    high-volume scenarios. See linkzmq:zmq_init[3].
*device*::
    defines one device.  For each device element you define, 'zmq_device' will
    start a thread.
*frontend*::
    defines the frontend for the device.  Occurs once per device element.  You
    may override the default socket type.
*backend*::
    defines the backend for the device.  Occurs once per device element. You
may    override the default socket type.
*set*::
    defines a socket option for the frontend or backend.  The valid names are
    *hwm*, *swap*, *identity*, *subscribe*, *unsubscribe*, *rate*,
    *recovery_ivl*, *mcast_loop*, *sndbuf*, and *rcvbuf*. See
    linkzmq:zmq_setsockopt[3].
*bind*::
    binds the frontend or backend to the specified endpoint.  See
    linkzmq:zmq_bind[3].
*connect*::
    binds the frontend or backend to the specified endpoint.  See
    linkzmq:zmq_connect[3].

SOCKET TYPES
------------

By default 'zmq_device' uses these socket types:

*queue* device::
    frontend is *xrep*, backend is *xreq*.
*forwarder* device::
    frontend is *sub*, backend is *pub*.
*streamer* device::
    frontend is *pull*, backend is *push*.

You can override the socket type for frontend or backend.  The valid types are:
*req*, *rep*, *xreq*, *xrep*, *sub*, *pub*, *pull*, *push*, and *pair*.  See
linkzmq:zmq_socket[3].

*Note*: if you use a *sub* socket you must explicitly set a subscription filter
or your socket will not receive any data.


EXAMPLE
-------

.Creating a queue broker
----
zmq_device queue tcp://*:5050 tcp://*:5051
----

.A TCP-to-multicast proxy forwarder
----
zmq_device -
<?xml?>
<config>
  <device type="forwarder">
    <frontend>
        <!-- subscribe to everything -->
        <set name = "subscribe" value = "" />
        <!-- connect to two publishers -->
        <connect address="tcp://192.168.55.112:5055" />
        <connect address="tcp://192.168.55.114:5055" />
    </frontend>
    <backend>
        <!-- bind to epgm group via eth0 -->
        <bind address="epgm://eth0;239.192.1.1:5555" />
    </backend>
  </device>
</config>
----


SEE ALSO
--------
linkzmq:zmq_device[3]
linkzmq:zmq_init[3]
linkzmq:zmq_setsockopt[3]
linkzmq:zmq_bind[3]
linkzmq:zmq_connect[3]
linkzmq:zmq[7]