hello-go/mqtt.go

package main

import (
	"fmt"
	//import the Paho Go mqtt library
	mqtt "github.com/eclipse/paho.mqtt.golang"
	"os"
	"time"
)

//define a function for the default message handler
var f mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
	fmt.Printf("TOPIC: %s\n", msg.Topic())
	fmt.Printf("MSG: %s\n", msg.Payload())
}

var lck chan bool

func main() {
	lck = make(chan bool)

	println(1)
	opts := mqtt.NewClientOptions().AddBroker("tcp://192.168.1.93:1883")
	opts.SetClientID("go-simple")
	opts.SetDefaultPublishHandler(f)

	println(2)
	c := mqtt.NewClient(opts)
	if token := c.Connect(); token.Wait() && token.Error() != nil {
		panic(token.Error())
	}

	println(3)
	msgReceived := func(client mqtt.Client, message mqtt.Message) {
		fmt.Printf("Received message on topic: %s Message: %s\n", message.Topic(), message.Payload())
	}

	println(4)
	if token := c.Subscribe("/wph_esp/pub", 0, msgReceived); token.Wait() && token.Error() != nil {
		fmt.Println(token.Error())
		os.Exit(1)
	}

	println(5)
	for i := 0; i < 5; i++ {
		text := fmt.Sprintf("this is msg #%d!", i)
		token := c.Publish("/wph_esp/sub", 0, false, text)
		token.Wait()
	}

	<-lck

	time.Sleep(3 * time.Second)

	println(6)
	if token := c.Unsubscribe("/wph_esp/pub"); token.Wait() && token.Error() != nil {
		fmt.Println(token.Error())
		os.Exit(1)
	}

	c.Disconnect(250)
}