robocar-arduino/mqttdevice/mqttdevice.go
2019-11-30 19:03:07 +01:00

86 lines
2.1 KiB
Go

package mqttdevice
import (
"fmt"
MQTT "github.com/eclipse/paho.mqtt.golang"
"io"
"log"
)
type Publisher interface {
Publish(topic string, payload interface{})
}
type Subscriber interface {
Subscribe(topic string, mh MQTT.MessageHandler)
}
type MQTTPubSub interface {
Publisher
Subscriber
io.Closer
}
type pahoMqttPubSub struct {
Uri string
Username string
Password string
ClientId string
Qos int
Retain bool
client MQTT.Client
}
func NewPahoMqttPubSub(uri string, username string, password string, clientId string, qos int, retain bool) MQTTPubSub {
p := pahoMqttPubSub{Uri: uri, Username: username, Password: password, ClientId: clientId, Qos: qos, Retain: retain}
p.Connect()
return &p
}
// Publish message to broker
func (p *pahoMqttPubSub) Publish(topic string, payload interface{}) {
tokenResp := p.client.Publish(topic, byte(p.Qos), p.Retain, payload)
if tokenResp.Error() != nil {
log.Fatalf("%+v\n", tokenResp.Error())
}
}
// Register func to execute on message
func (p *pahoMqttPubSub) Subscribe(topic string, callback MQTT.MessageHandler) {
tokenResp := p.client.Subscribe(topic, byte(p.Qos), callback)
if tokenResp.Error() != nil {
log.Fatalf("%+v\n", tokenResp.Error())
}
}
// Close connection to broker
func (p *pahoMqttPubSub) Close() error {
p.client.Disconnect(500)
return nil
}
func (p *pahoMqttPubSub) Connect() {
if p.client != nil && p.client.IsConnected() {
return
}
//create a ClientOptions struct setting the broker address, clientid, turn
//off trace output and set the default message handler
opts := MQTT.NewClientOptions().AddBroker(p.Uri)
opts.SetUsername(p.Username)
opts.SetPassword(p.Password)
opts.SetClientID(p.ClientId)
opts.SetAutoReconnect(true)
opts.SetDefaultPublishHandler(
//define a function for the default message handler
func(client MQTT.Client, msg MQTT.Message) {
fmt.Printf("TOPIC: %s\n", msg.Topic())
fmt.Printf("MSG: %s\n", msg.Payload())
})
//create and start a client using the above ClientOptions
p.client = MQTT.NewClient(opts)
if token := p.client.Connect(); token.Wait() && token.Error() != nil {
panic(token.Error())
}
}