September 25, 2014

How to use sango - Golang

I will explain how to use sango from Go language.

To use sango in the Go language, follow the procedure below.

  1. Get library with go get
  2. Client implementation

Confirmed environment

  • Go 1.3
  • Mqtt-golang 4572889 cc 6 f 741 a 6 10 a 3 b b 544 c 90 c 0 3 b f b 763 f

1. Get library with go get

the golang library of Paho Eclipse go get to get in.

go get git.eclipse.org/gitroot/paho/org.eclipse.paho.mqtt.golang.git

2. Client implementation

Connect

The Connect part is common to both Pub / Sub.

package main

import (
    "fmt"
    "log"
    "time"

    MQTT "git.eclipse.org/gitroot/paho/org.eclipse.paho.mqtt.golang.git"
)
func main() {
    host := "free.mqtt.shiguredo.jp"
    port := 1883
    user := "example@github"
    password := "<password>"

    // 接続用の設定を作成します
    opts := MQTT.NewClientOptions()
    opts.SetUsername(user)
    opts.SetPassword(password)

    // golangではURIで接続先を指定します。
    brokerUri := fmt.Sprintf("tcp://%s:%d", host, port)
    opts.AddBroker(brokerUri)

    // 設定を元にクライアントを作成します
    client := MQTT.NewClient(opts)

    // Connectします
    _, err := client.Start()
    if err != nil {
        log.Fatal(err)
    }
}

Subscribe

Subscribe is StartSubscription and passes a callback function to a function called.

func onMessageReceived(client *MQTT.MqttClient, message MQTT.Message) {
    fmt.Printf("Received message on topic: %s\n", message.Topic())
    fmt.Printf("Message: %s\n", message.Payload())
}

func Subscribe(client *MQTT.MqttClient) error {
    topic := "example@github/a/b"
    qos := 0

    // Subscribeするtopicを設定します
    topicFilter, err := MQTT.NewTopicFilter(topic, byte(qos))
    if err != nil {
        return err
    }

    // Subscribeします
    // onMessageReceived はメッセージが届いたら呼び出されるコールバックです
    _, err = client.StartSubscription(onMessageReceived, topicFilter)
    if err != nil {
        return err
    }

    // そのままではプロセスが終わってしまいますので、待ち受けます
    for {
        time.Sleep(1 * time.Second)
    }
}

Publish

The Publish Publish use. Alternatively, use the MQTT.Message PublishMessage There is also a function called.

func Publish(client *MQTT.MqttClient) error {
    topic := "example@github/a/b"
    qos := 0
    message := "MQTT from golang"

    receipt := client.Publish(MQTT.QoS(qos), topic, message)
    <-receipt  // Publish成功を待ち受ける

    return nil
}
Posted by r_rudi
Filed under: mqtt
Tags: mqtt