Message Broker MQTT

Sobre

• http://mqtt.org/

Mosquitto

Requisitos

• Instalar o mosquitto server

 $ sudo apt-get install mosquitto

• Para subscrever e publicar, instalar o mosquitto-clients

 $ sudo apt-get install mosquitto-clients

• Liberar porta de entrada 1883

Comandos

• Subscrever
  • Genérico: mosquitto_sub -h host -t subject
  • Exemplo: mosquitto_sub -h test.mosquitto.org -t testCleber
  • Exemplo: mosquitto_sub -t test.mqtt.topic
• Publicar
  • Genérico: mosquitto_pub -h host -t subject -m message
  • Exemplo: mosquitto_pub -h dweet.io -t testeCleber -m OlaMundo!
• Subscrever em todos os tópicos para depuração (modo verboso -v), observar qeue -h foi omitido pois neste exemplo está rodando no próprio servidor mosquitto:
  • mosquitto_sub -v -t \$SYS/#

Rotas Camel

• Publicar:

from("timer:test?period=2500").process(new Processor() {
  public void process(Exchange exchange) throws Exception {
    exchange.getIn().setBody("OlaMundo!");
  }
}).to("mqtt:camelArtifact?host=tcp://192.168.0.113:1883&publishTopicName=test.mqtt.topic");

• Subscrever:

from("mqtt:camelArtifact?host=tcp://192.168.0.113:1883&subscribeTopicName=test.mqtt.topic")
  .transform(body().convertToString())
  .to("log:CamelArtifactLoggerOut?level=info");

Exemplo de geração de mensagens de teste

• Gerando mensagens a cada 5 segundos (script counter_mqtt.sh)

#!/bin/bash
# /etc/rc.d/init.d/

# Source function library
. /etc/init.d/functions

COUNTING=true

start() {
	echo "Publishing in mosquitto test server"
        #Starting counter in ZERO
        COUNTER=0
        #Get current datetime put it in a variable
        CURRENTDATETIME="$(date +'%d/%m/%Y-%T')"
        #Publish in mosquitto server (must be running in the svr and TCP 1883 port opened)
        mosquitto_pub -h 192.168.0.113 -m "$COUNTER-$CURRENTDATETIME" -t mqtt_test
        while [ COUNTING ]
        do
	  sleep 5
	  COUNTER=$[$COUNTER + 1]
	  CURRENTDATETIME="$(date +'%d/%m/%Y-%T')"
	  mosquitto_pub -h 192.168.0.113 -m "$COUNTER-$CURRENTDATETIME" -t mqtt_test
        done
        return
}

stop() {
        echo -n "Shutting down : "
	echo "Stopping mosquitto test pushish messages"
        COUNTING=false
        return
}

case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    status)
        ;;
    restart)
	echo "Restarting mosquitto test pushish messages"
        COUNTING=true
        ;;
    *)
        echo "Usage:  {start|stop|status|reload|restart[|probe]"
        exit 1
        ;;
esac
exit $?

Fonte: https://www.linux.com/learn/managing-linux-daemons-init-scripts

• Colocando o gerador de mensagens na inicialização do linux

$ sudo mv counter_mqtt.sh /etc/init.d/
$ sudo chmod +x /etc/init.d/counter_mqtt.sh
$ sudo update-rc.d counter_mqtt.sh defaults

Fonte: http://stackoverflow.com/questions/7221757/run-automatically-program-on-startup-under-linux-ubuntu

Servidores públicos

• https://mosquitto.org/
• https://dweet.io/