paho/example/example_02.lua

#!/usr/bin/lua
--
-- example_02.lua
-- ~~~~~~~~~~~~~~
-- Version: 0.2 2012-06-01
-- ------------------------------------------------------------------------- --
-- Copyright (c) 2011-2012 Geekscape Pty. Ltd.
-- All rights reserved. This program and the accompanying materials
-- are made available under the terms of the Eclipse Public License v1.0
-- which accompanies this distribution, and is available at
-- http://www.eclipse.org/legal/epl-v10.html
--
-- Contributors:
--    Andy Gelme - Initial implementation
-- -------------------------------------------------------------------------- --
--
-- Description
-- ~~~~~~~~~~~
-- Publish a sequence of messages to a specified topic.
-- Used to control some coloured RGB LEDs.
--
-- ToDo
-- ~~~~
-- - On failure, automatically reconnect to MQTT server.
-- ------------------------------------------------------------------------- --

function is_openwrt()
  return(os.getenv("USER") == "root")  -- Assume logged in as "root" on OpenWRT
end

-- ------------------------------------------------------------------------- --

if (not is_openwrt()) then require("luarocks.require") end
local lapp = require("pl.lapp")

local args = lapp [[
  Subscribe to topic1 and publish all messages on topic2
  -H,--host   (default localhost)   MQTT server hostname
  -i,--id     (default example_02)  MQTT client identifier
  -p,--port   (default 1883)        MQTT server port number
  -s,--sleep  (default 5.0)         Sleep time between commands
  -t,--topic  (default test/2)      Topic on which to publish
]]

local MQTT = require "paho.mqtt"

local mqtt_client = MQTT.client.create(args.host, args.port)

mqtt_client:connect(args.id)

local error_message = nil
local index = 1
local messages = { "c010000", "c000100", "c000001" }

while (error_message == nil) do
  mqtt_client:publish(args.topic, messages[index]);

  index = index + 1
  if (index > #messages) then index = 1 end

  socket.sleep(args.sleep)  -- seconds
  error_message = mqtt_client:handler()
end

if (error_message == nil) then
  mqtt_client:destroy()
else
  print(error_message)
end

-- ------------------------------------------------------------------------- --