NAME

anyevent-mqtt-sub - Perl script for subscribing to an MQTT topic

VERSION

version 1.142640

SYNOPSIS

  anyevent-mqtt-sub [options] topic1 [topic2] [topic3] ...

DESCRIPTION

This script subscribes to one or more MQTT topics and prints any messages that it receives to stdout.

OPTIONS

-help

Print a brief help message.

-man

Print the manual page.

-host A.B.C.D

The host running the MQTT service. The default is 127.0.0.1.

-port NNNNN

The port of the running MQTT service. The default is 1883.

-qos N

The QoS level for the published message. The default is 0 ("MQTT_QOS_AT_MOST_ONCE").

-verbose

Include more verbose output. Without this option the script only outputs errors and received messages one per line in the form:

  topic message

With one -verbose options, publish messages are printed in a form of a summary of the header fields and the payload in hex dump and text form.

With two -verbose options, summaries are printed for all messages sent and received.

-keepalive NNN

The keep alive timer value. Defaults to 120 seconds. For simplicity, it is also currently used as the connection/subscription timeout.

-count NNN

Read the specificed number of MQTT messages and then exit. Default is 0 - read forever.

-one or -1

Short for -count 1. Read one message and exit.

--no-retain

Ignore retained messages. That is, wait for new messages rather than processing existing retained messages.

--code CODE

Use CODE for callback. The caller is responsible for ensuring that the code to be executed is safe - i.e. not "system('rm -rf /');". The code will be called with the following arguments in @_:

The topic of the received message.
The message payload.
The Net::MQTT::Message object for the message.
A condvar that can be emitted to quit the subscribe loop.
The AnyEvent::MQTT object.
An empty hash reference that can be used as a stash.

For example:

  my ($topic, $payload, $message, $quitcv, $mqtt, $stash) = @_;
  print STDERR $topic, ': ', $payload, "\n";
  $quitcv->send if ($stash->{'count'}++ > 10);

If a callback is provided with this option then the builtin callback is no longer called.

DISCLAIMER

This is not official IBM code. I work for IBM but I'm writing this in my spare time (with permission) for fun.

AUTHOR

Mark Hindess <soft-cpan@temporalanomaly.com>

COPYRIGHT AND LICENSE

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.