paho_mqtt_sub.rb

require 'paho-mqtt'

### Create a simple client with default attributes
client = PahoMqtt::Client.new

### Register a callback on message event to display messages
message_counter = 0
client.on_message do |message|
  puts "Message recieved on topic: #{message.topic}\n>>> #{message.payload}"
  message_counter += 1
end

### Register a callback on suback to assert the subcription
waiting_suback = true
client.on_suback do
  waiting_suback = false
  puts "Subscribed"
end

### Connect to the eclipse test server on port 1883 (Unencrypted mode)
client.connect('localhost', 1883)

### Subscribe to a topic
client.subscribe(['/test/', 2])

### Waiting for the suback answer and excute the previously set on_suback callback
while waiting_suback do
  sleep 0.001
end

# Listen forever
while 1 do
  sleep 0.001
end

### Calling an explicit disconnect (Should never get here...)
client.disconnect