main.go

/*
 * Copyright (c) 2021 IBM Corp and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    https://www.eclipse.org/legal/epl-2.0/
 * and the Eclipse Distribution License is available at
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Seth Hoenig
 *    Allan Stockdill-Mander
 *    Mike Robertson
 */

// This demonstrates how to implement your own Store interface and provide
// it to the go-mqtt client.

package main

import (
	"fmt"
	"time"

	MQTT "github.com/eclipse/paho.mqtt.golang"
	"github.com/eclipse/paho.mqtt.golang/packets"
)

// This NoOpStore type implements the go-mqtt/Store interface, which
// allows it to be used by the go-mqtt client library. However, it is
// highly recommended that you do not use this NoOpStore in production,
// because it will NOT provide any sort of guarantee of message delivery.
type NoOpStore struct {
	// Contain nothing
}

func (store *NoOpStore) Open() {
	// Do nothing
}

func (store *NoOpStore) Put(string, packets.ControlPacket) {
	// Do nothing
}

func (store *NoOpStore) Get(string) packets.ControlPacket {
	// Do nothing
	return nil
}

func (store *NoOpStore) Del(string) {
	// Do nothing
}

func (store *NoOpStore) All() []string {
	return nil
}

func (store *NoOpStore) Close() {
	// Do Nothing
}

func (store *NoOpStore) Reset() {
	// Do Nothing
}

func main() {
	myNoOpStore := &NoOpStore{}

	opts := MQTT.NewClientOptions()
	opts.AddBroker("tcp://iot.eclipse.org:1883")
	opts.SetClientID("custom-store")
	opts.SetStore(myNoOpStore)

	var callback MQTT.MessageHandler = func(client MQTT.Client, msg MQTT.Message) {
		fmt.Printf("TOPIC: %s\n", msg.Topic())
		fmt.Printf("MSG: %s\n", msg.Payload())
	}

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

	c.Subscribe("/go-mqtt/sample", 0, callback)

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

	for i := 1; i < 5; i++ {
		time.Sleep(1 * time.Second)
	}

	c.Disconnect(250)
}