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      Cloud IoT Core 예제 코드
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        Cloud IoT Core 예제 코드

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          Article Summary

          Classic/VPC 환경에서 이용 가능합니다.

          Cloud IoT Core에서 다운로드 인증서를 사용하여 MQTT 프로토콜 기반으로 Cloud IoT Core 서버로 메시지를 발행하고 구독하는 예제를 설명합니다.

          Java

          Cloud IoT Core에 접속하여 총 5번의 메시지 발행 및 구독을 반복한 후 프로그램이 종료되는 예제 코드입니다. 메시지 발행은 factory/room1/temperature 토픽으로 발생하며, Cloud IoT Core를 거쳐 재발행된 alert 토픽을 구독합니다.

          환경 설정

          예제 파일을 실행하려면 MQTT, TLS 라이브러리가 필요합니다.

          • maven
          <dependencies>
  <dependency>
    <groupId>org.eclipse.paho</groupId>
    <artifactId>org.eclipse.paho.client.mqttv3</artifactId>
    <version>${version}</version>
  </dependency>
  <dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcpkix-jdk15on</artifactId>
    <version>${version}</version>
  </dependency>
</dependencies>
          • gradle
          implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:${version}'
implementation 'org.bouncycastle:bcpkix-jdk15on:${version}'

          예제 코드

          Java 예제 코드는 다음과 같습니다.

          import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManagerFactory;
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.security.*;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.List;


public class MqttExample {

    public static void main(String[] args) throws Exception {
        String clientId = "myClientTest";

        /*
         *** Modify file path and server ***
         */
        // MQTT server hostname
        String iotServer = "ssl://msg01.cloudiot.ntruss.com";

        String rootCaCertFilePath = "/<Your>/<file>/<path>/rootCaCert.pem";
        String clientCaChainFilePath = "/<Your>/<file>/<path>/caChain.pem";
        String clientCertFilePath = "/<Your>/<file>/<path>/cert.pem";
        String clientKeyFilePath = "/<Your>/<file>/<path>/private.pem";
        String password = "";

        /*
        Make Root CA TrustManager and Client Keystore
         */
        MqttExample mqttExample = new MqttExample();
        // CA certificate is used to **authenticate server**
        TrustManagerFactory tmf = mqttExample.getTrustManagerFactory(rootCaCertFilePath);

        // client key, certificates and cachain are sent to server to authenticate client
        KeyManagerFactory kmf = mqttExample.getKeyManagerFactory(clientCaChainFilePath, clientCertFilePath, clientKeyFilePath, password);


        /*
        MQTT Connection
         */

        // Set MQTT Client
        MqttClient mqttClient = new MqttClient(iotServer, clientId, new MemoryPersistence());
        MqttConnectOptions connOpts = new MqttConnectOptions();
        connOpts.setCleanSession(true);
        connOpts.setConnectionTimeout(60);
        connOpts.setKeepAliveInterval(60);
        connOpts.setMqttVersion(MqttConnectOptions.MQTT_VERSION_3_1);

        // create SSL socket factory
        SSLContext context = SSLContext.getInstance("TLSv1.2");
        context.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);
        connOpts.setSocketFactory(context.getSocketFactory());
        mqttClient.connect(connOpts);

        System.out.println("=== Successfully Connected");


        /*
        Subscribe & Publish Message
        Publish message on the device ---> IoT Platform(alert republish action) ---> Subscribe message on the device
         */

        mqttClient.setCallback(new MqttCallback() {
            public void connectionLost(Throwable throwable) {
                System.out.println("=== Connection lost.");
            }

            public void messageArrived(String s, MqttMessage mqttMessage) throws Exception {
                System.out.println("<<< Subscribe from IoT server. topic : " + s + ", message : " + mqttMessage.toString());
            }

            public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
                System.out.println(">>> Publish to IoT server.");
            }
        });

        /*
        Topic & Message Example
        */
        String sendTopic = "factory/room1/temperature";

        // Test for MQTT republish
        // In order to receive alert topic message, alert republish action must be set in Rule engine.
        String alertTopic = "alert";

        // Console guide example message
        String message = "{ \"deviceId\": \"device_1\", \"deviceType\": \"temperature\", \"value\": 35, \"battery\": 9, \"date\": \"2016-12-15\", \"time\": \"15:12:00\"}";


        /*
        Subscribe message
         */
        boolean isConnected = mqttClient.isConnected();
        if (isConnected) {
            mqttClient.subscribe(alertTopic);

            // You can check whether the message is being delivered normally.
//            mqttClient.subscribe(sendTopic);
        }

        /*
        Publish message
         */
        if (isConnected) {
            for (int i=0; i < 5; i++) {
                MqttMessage mqttMessage = new MqttMessage(message.getBytes());
                mqttMessage.setQos(0);
                mqttMessage.setRetained(false);

                try {
                    MqttTopic topic = mqttClient.getTopic(sendTopic);
                    MqttDeliveryToken token = topic.publish(mqttMessage);
                    token.waitForCompletion();
                    Thread.sleep(2000);

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

        /*
        Enable disconnect() and close() if you needed
         */
//        mqttClient.disconnect();
//        mqttClient.close();
    }


    /*
    Code for Certificate Access
     */

    private MqttExample() {
        init();
    }

    private KeyManagerFactory getKeyManagerFactory(String clientCaChainFilePath, String clientCertFilePath, String clientKeyFilePath, String password) throws KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException, UnrecoverableKeyException {

        // load client private key
        KeyPair key = getClientKey(clientKeyFilePath);

        // load client Cert
        Certificate clientCert = getClientCert(clientCertFilePath);

        // load client CA Chain
        List<Certificate> caChain = getClientCaChain(clientCaChainFilePath, clientCert);

        KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
        ks.load(null, null);
        int caChainSize = caChain.size();
        Certificate[] caChainArray = caChain.toArray(new Certificate[caChainSize]);
        ks.setKeyEntry("private-key", key.getPrivate(), password.toCharArray(), caChainArray);
        KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
        kmf.init(ks, password.toCharArray());

        return kmf;
    }

    private TrustManagerFactory getTrustManagerFactory(String rootCaCertFilePath) throws KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
        // load CA certificate
        X509Certificate rootCaCert = getRootCaCert(rootCaCertFilePath);

        KeyStore rootCaKeyStore = KeyStore.getInstance(KeyStore.getDefaultType());
        rootCaKeyStore.load(null, null);
        rootCaKeyStore.setCertificateEntry("ca-certificate", rootCaCert);
        TrustManagerFactory tmf = TrustManagerFactory.getInstance("X509");
        tmf.init(rootCaKeyStore);

        return tmf;
    }


    private void init() {
        Security.addProvider(new BouncyCastleProvider());
    }

    private KeyPair getClientKey(String clientKeyFilePath) throws IOException {
        PEMParser pemParser = new PEMParser(new FileReader(clientKeyFilePath));
        Object object = pemParser.readObject();
        JcaPEMKeyConverter converter = new JcaPEMKeyConverter().setProvider("BC");

        KeyPair key = converter.getKeyPair((PEMKeyPair) object);
        pemParser.close();
        return key;
    }

    private List<Certificate> getClientCaChain(String clientCaChainFilePath, Certificate clientCert) throws CertificateException, IOException {
        X509Certificate cert;
        List<Certificate> caChain = new ArrayList<Certificate>();

        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(clientCaChainFilePath));
        CertificateFactory cf = CertificateFactory.getInstance("X.509");

        while (bis.available() > 0) {
            cert = (X509Certificate) cf.generateCertificate(bis);
            caChain.add(cert);
        }

        caChain.add(0, clientCert);
        return caChain;
    }

    private X509Certificate getClientCert(String clientCertFilePath) throws CertificateException, IOException {
        return getX509Certificate(clientCertFilePath);
    }

    private X509Certificate getRootCaCert(String rootCaCertFilePath) throws CertificateException, IOException {
        return getX509Certificate(rootCaCertFilePath);
    }

    private X509Certificate getX509Certificate(String rootCaCertFilePath) throws CertificateException, IOException {
        X509Certificate caCert = null;

        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(rootCaCertFilePath));
        CertificateFactory cf = CertificateFactory.getInstance("X.509");

        while (bis.available() > 0) {
            caCert = (X509Certificate) cf.generateCertificate(bis);
        }
        return caCert;
    }
}

          동작 결과

          Java 예제 코드의 동작 결과는 다음과 같습니다.

          === Successfully Connected
>>> Publish to IoT server.
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}

          Python

          Cloud IoT Core에 접속하여 총 5번의 메시지 발행 및 구독을 반복한 후 프로그램이 종료되는 예제 코드입니다. 메시지 발행은 factory/room1/temperature 토픽으로 발생하며, Cloud IoT Core를 거쳐 재발행된 alert 토픽을 구독합니다.

          환경 설정

          예제 파일을 실행하려면 paho-mqtt 라이브러리를 설치해야 합니다.

          pip install paho-mqtt //python 2.x
python -m pip install paho-mqtt // python 2.7.9+
python3 -m pip install paho-mqtt //python 3.x
          참고

          예제 파일 내 Full Certificate Chain 값의 경우, 인증서와 체인 인증서를 연결한 Full Certificate Chain 파일을 저장할 경로를 의미합니다. Python 예제 실행 시 Full Certificate Chain 파일이 설정된 경로에 자동으로 별도 저장됩니다.

          예제 코드

          • mqttTLSClient.py

            # coding=utf-8
import argparse
import logging
import paho.mqtt.client as mqttClient
import ssl
import time
import json

def main():
    # init
    initLogger()
    initParameter()
    appendCert()

    # Connect MQTT Broker
    client = mqttClient.Client()
    if not connectTls(client, hostname, port, rootCa, fullCertChain, private):
        client.loop_stop()
        exit(1)

    attempts = 0
    while attempts < 5:
        # Subscribe message
        client.subscribe("alert",0)
        # Publish Message to Message broker
        publish(client, topic, payload)
        time.sleep(publishDelay)
        attempts += 1

    time.sleep(5)

def initLogger():
    global log
    log = logging.getLogger(__name__)
    log.setLevel(logging.ERROR)

    # stream handler (print to console)
    streamHandler = logging.StreamHandler()

    # file formatter
    formatter = logging.Formatter('[%(asctime)s] [%(levelname)s] (%(filename)s:%(funcName)s:%(lineno)d) : %(message)s')
    streamHandler.setFormatter(formatter)

    log.addHandler(streamHandler)

def initParameter():
    global rootCa
    global caChain
    global cert
    global private
    global fullCertChain

    global hostname
    global port
    global publishDelay

    global topic
    global payload

    global connected

    rootCa = '/<Your>/<file>/<path>/rootCaCert.pem'
    caChain = '/<Your>/<file>/<path>/caChain.pem'
    cert = '/<Your>/<file>/<path>/cert.pem'
    private = '/<Your>/<file>/<path>/private.pem'

    hostname = 'msg01.cloudiot.ntruss.com'
    port = 8883
    publishDelay = 1 # sec

    topic = "factory/room1/temperature"
    payload = "{ \"deviceId\": \"device_1\", \"deviceType\": \"temperature\", \"value\": 35, \"battery\": 9, \"date\": \"2016-12-15\", \"time\": \"15:12:00\"}"

    connected = False

    #fullCertChain is automatically generated by cert and caChain
    fullCertChain = './fullCertChain.pem'


def appendCert():
    filenames = [cert, caChain]
    with open(fullCertChain,'w') as outfile:
         for fname in filenames :
            with open(fname) as infile:
                outfile.write(infile.read()+"\n")

def connectTls(client, hostname, port, rootCa, fullCertChain, clientKey):
    client.on_connect = on_connect
    client.on_message = on_message
    client.on_publish = on_publish

    client.tls_set(ca_certs=rootCa, certfile=fullCertChain,
                   keyfile=clientKey, cert_reqs=ssl.CERT_REQUIRED,
                  tls_version=ssl.PROTOCOL_TLSv1_2, ciphers=None)

    ssl.match_hostname = lambda cert, hostname: True
    client.tls_insecure_set(False)
    client.connect(hostname, port=port)
    client.loop_start()

    attempts = 0

    while not connected and attempts < 5:  # Wait for connection
        time.sleep(1)
        attempts += 1

    if not connected:
        return False

    return True

def on_connect(client, userdata, flags, rc):
    if rc == 0:
        log.info("=== Successfully Connected")
        global connected  # Use global variable
        connected = True  # Signal connection
    else:
        log.error("=== Connection lost")

def on_publish(client, userdata, result):
     print(">>> Publish to IoT server.")

def publish(client, topic, payload):
    try:
        client.publish(topic, payload)
    except Exception as e:
        print("[ERROR] Could not publish data, error: {}".format(e))

def on_message(client, userdata, message):
    print("<<< Subscribe from IoT server. topic : "+ message.topic + ", message : " + str(message.payload.decode("utf-8")))


if __name__ == "__main__":
    main()

          동작 결과

          mqttTLSClient.py 실행 결과는 다음과 같습니다.

          >>> Publish to IoT server.
>>> Publish to IoT server.
>>> Publish to IoT server.
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
<<< Subscribe from IoT server. topic : alert, message : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}

          Node JS(JavaScript)

          Cloud IoT Core에 접속하여 총 5번의 메시지 발행 및 구독을 반복한 후 프로그램이 종료되는 예제 코드입니다. 메시지 발행은 factory/room1/temperature 토픽으로 발생하며, Cloud IoT Core를 거쳐 재발행된 alert 토픽을 구독합니다.

          환경 설정

          Node Js(JavaScript) 예제는 mqtt library 라이브러리를 설치해야 하며, 라이브러리를 설치하기 전에 npm(node package manager)이 설치되어 있어야 합니다.
          package.json 파일과 MqttClient.js 파일을 같은 폴더에 두고 npm install 명령어로 node library 패키지를 다운로드한 후 실행해 주십시오.

          • package.json
          {
  "name": "cloud-iot-mqtt-sample",
  "version": "0.1.0",
  "dependencies": { "mqtt": "^1.14.1" }
}

          예제 코드

          • MqttClient.js
            const mqtt = require('mqtt');
const fs = require('fs');
const path = require('path');

const HOST = "msg01.cloudiot.ntruss.com";
const PORT = 8883;
const PUBLISH_TOPIC = `factory/room1/temperature`;
const SUBSCRIBE_TOPIC = `alert`;
const QOS = 0;

const certFolderPath = "/<Your>/<file>/<path>/";
const KEY = fs.readFileSync(certFolderPath + `private.pem`);
const CERT = fs.readFileSync(certFolderPath + `cert.pem`);
const CA_CHAIN = fs.readFileSync(certFolderPath + `caChain.pem`);
const TRUSTED_CA_LIST = fs.readFileSync(certFolderPath + `rootCaCert.pem`);
const FULL_CERTIFICATION = CERT+"\n"+CA_CHAIN;

let receivedIndex = 0;

const connectionInfo = {
  port: PORT,
  host: HOST,
  key: KEY,
  cert: FULL_CERTIFICATION,
  ca: TRUSTED_CA_LIST,
  rejectUnauthorized: true,
  protocol: 'mqtts',
  connectTimeout: 60 * 1000,
  keepalive: 1000,
}

const client = mqtt.connect(connectionInfo);

// Connetion to mqtt message broker //
client.on('connect', async function () {
  console.log('=== Successfully Connected');

  for (let i = 0; i < 5; i++) {
    await sleep(1000);
    sendMessage();
  }
})

// Subscribe to Message //
function sendMessage() {
  console.log(">>> Publish to IoT server.")
  client.publish(PUBLISH_TOPIC, getMsg())
}

// Subscribe to Message //
client.subscribe(SUBSCRIBE_TOPIC, {qos:QOS});

// Receiving Message //
client.on('message', async function (topic, message) {
  console.log(`<<< Subscribe from IoT server. topic : "${topic}", message(${receivedIndex}) : ${message.toString()}`);
  receivedIndex++;

  if (receivedIndex == 5) {
    client.end();
    console.log("=== Complete.")
  }
})

client.on('close', function () {
  console.log("connection Close");
})

client.on('error', function (err) {
  console.log(err.toString());
})

function getMsg () {
  const timeStamp = Math.floor(new Date() / 1000);
  const msg = `{"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}`;
  return msg;
}

const sleep = (ms) => {
     return new Promise(resolve=>{
         setTimeout(resolve,ms);
     })
 }

          동작 결과

          Node JS(JavaScript) 예제 코드의 동작 결과는 다음과 같습니다.

          === Successfully Connected
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : "factory/room1/temperature", message(0) : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : "factory/room1/temperature", message(1) : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : "factory/room1/temperature", message(2) : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : "factory/room1/temperature", message(3) : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : "factory/room1/temperature", message(4) : {"battery":9,"date":"2016-12-15","deviceId":"device_1","deviceType":"temperature","time":"15:12:00","value":35}
=== Complete.
connection Close

          C

          Cloud IoT Core에 접속하여 총 5번의 메시지 발행 및 구독을 반복한 후 프로그램이 종료되는 예제 코드입니다. 메시지 발행은 factory/room1/temperature 토픽으로 발생하며, Cloud IoT Core를 거쳐 재발행된 alert 토픽을 구독합니다.

          환경 설정

          이 예제 파일을 실행하려면 paho mqtt 라이브러리 설치가 필요합니다.

          • CentOS

            $ sudo yum install build-essential gcc make cmake cmake-gui cmake-curses-gui
$ sudo yum install openssl-devel
$ git clone https://github.com/eclipse/paho.mqtt.c
$ cd paho.mqtt.c
$ git checkout v1.3.8
$ make
$ sudo make install

          • Ubuntu

            $ sudo apt-get install build-essential gcc make cmake cmake-gui cmake-curses-gui
$ sudo apt-get install libssl-dev
$ git clone https://github.com/eclipse/paho.mqtt.c.git
$ cd paho.mqtt.c
$ git checkout v1.3.8
$ cmake -Bbuild -H. -DPAHO_ENABLE_TESTING=OFF -DPAHO_BUILD_STATIC=ON \
    -DPAHO_WITH_SSL=ON -DPAHO_HIGH_PERFORMANCE=ON
$ sudo cmake --build build/ --target install
$ sudo ldconfig
          참고

          예제 파일 내 Full Certificate Chain Path 값의 경우, 인증서와 체인 인증서를 연결한 Full Certificate Chain 파일을 저장할 경로를 의미합니다. 예제 실행 시 Full Certificate Chain 파일이 설정된 경로에 자동으로 별도 저장됩니다.

          예제 코드

          • mqttClient.c

            #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "MQTTClient.h"

#define QOS 1
#define TIMEOUT 10000L

volatile MQTTClient_deliveryToken deliveredtoken;

// Generate fullCertChain by cert and caChain
void appendCert(char* cert, char* caChain, char* fullCertChain) {

    FILE* fpw = fopen(fullCertChain,"w");
    FILE* fpr = fopen(cert,"r");
    int size;
    char* buffer;

    fseek(fpr, 0, SEEK_END);
    size = ftell(fpr);
    buffer = (char*)malloc(size + 1);
    memset(buffer, 0, size + 1);
    fseek(fpr, 0, SEEK_SET);
    fread(buffer, size, 1, fpr);

    fputs(buffer, fpw);
    fclose(fpr);
    free(buffer);
    fputs("\n", fpw);

    fpr = fopen(caChain,"r");
    fseek(fpr, 0, SEEK_END);
    size = ftell(fpr);
    buffer = (char*)malloc(size + 1);
    memset(buffer, 0, size + 1);
    fseek(fpr, 0, SEEK_SET);
    fread(buffer, size, 1, fpr);

    fputs(buffer, fpw);
    fputs("\n", fpw);

    free(buffer);
    fclose(fpr);
    fclose(fpw);
}

void delivered( void *context, MQTTClient_deliveryToken dt )
{
    printf(">>> Publish to IoT server.\n");
    deliveredtoken = dt;
}

int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message) {
    char* payload = (char*)message->payload;
    printf("<<< Subscribe from IoT server. topic : %s , message : %s\n", topicName, payload);
    MQTTClient_freeMessage(&message);
    MQTTClient_free(topicName);
    return 1;
}

void connlost( void *context, char *cause )
{
    printf("\nConnection lost\n");
    printf("     cause: %s\n", cause);
}

int main(int argc, char *argv[])
{

    char clientId[] = "myClientTest";

    // Modify file path and server
    // MQTT server hostname
    char iotServer[] = "ssl://msg01.cloudiot.ntruss.com:8883";


    char rootCaCertFilePath[] = "/<Your>/<file>/<path>/rootCaCert.pem";
    char clientCaChainFilePath[] = "/<Your>/<file>/<path>/caChain.pem";
    char clientCertFilePath[] = "/<Your>/<file>/<path>/cert.pem";
    char clientKeyFilePath[] = "/<Your>/<file>/<path>/private.pem";

    // fullCertChain is automatically generated by cert and caChain
    char fullCertChainPath[] = "./fullCertChain.pem";
    char password[] = "";


    // Topic & Message Example
    char sendTopic[] = "factory/room1/temperature";
    char alertTopic[] = "alert";
    char payload[] = "{ \"deviceId\": \"device_1\", \"deviceType\": \"temperature\", \"value\": 35, \"battery\": 9, \"date\": \"2016-12-15\", \"time\": \"15:12:00\"}";


    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    MQTTClient_SSLOptions ssl_opts = MQTTClient_SSLOptions_initializer;
    MQTTClient_message pubmsg = MQTTClient_message_initializer;
    MQTTClient_deliveryToken token;
    int rc;
    int setCallBack;
    int attempts;

    MQTTClient_create(&client, iotServer, clientId, MQTTCLIENT_PERSISTENCE_NONE, NULL);

    // Generate fullCertChain by cert and caChain
    appendCert(clientCertFilePath, clientCaChainFilePath, fullCertChainPath);

    // MQTT Connection parameters
    ssl_opts.verify = 1;
    ssl_opts.trustStore = rootCaCertFilePath;
    ssl_opts.keyStore = fullCertChainPath;
    ssl_opts.privateKey = clientKeyFilePath;

    conn_opts.ssl = &ssl_opts;

    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;
    conn_opts.serverURIcount = 0;
    conn_opts.serverURIs = NULL;

    // Set call back
    if((setCallBack = MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered)) != MQTTCLIENT_SUCCESS)
    {
        printf("ERROR : MQTTClient_setCallbacks, setCallBack = %d\n", setCallBack);
        return setCallBack;
    }


    // Connect MQTT Broker
    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        printf("ERROR : Failed to connect, return code : %d\n", rc);
        exit(-1);
    } 


    // Subscribe message
    rc = MQTTClient_subscribe(client, alertTopic, 0);

    pubmsg.payload = payload;
    pubmsg.payloadlen = strlen(payload);
    pubmsg.qos = QOS;
    pubmsg.retained = 0;

    for(attempts=0; attempts<5; attempts++){
        // Publish message
        MQTTClient_publishMessage(client, sendTopic, &pubmsg, &token);
        rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);

        sleep(2);       //sec
    }

    sleep(2);           //sec

    // Disconnect
    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);

    return rc;
}

          예제 코드 실행

          C 예제 코드를 실행하는 방법은 다음과 같습니다.

          $ gcc -o {executable file name} {source file name}.c -l paho-mqtt3cs
$ ./{executable file name}

          동작 결과

          C 예제 코드의 동작 결과는 다음과 같습니다.

          >>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}

          C++

          Cloud IoT Core에 접속하여 총 5번의 메시지 발행 및 구독을 반복한 후 프로그램이 종료되는 예제 코드입니다. 메시지 발행은 factory/room1/temperature 토픽으로 발생하며, Cloud IoT Core를 거쳐 재발행된 alert 토픽을 구독합니다.

          환경 설정

          이 예제 파일을 실행하기 위해서는 paho mqtt 라이브러리 설치가 필요합니다.

          • CentOS

            $ sudo yum install build-essential gcc make cmake cmake-gui cmake-curses-gui
$ sudo yum install openssl-devel
$ git clone https://github.com/eclipse/paho.mqtt.c
$ cd paho.mqtt.c
$ git checkout v1.3.8
$ make
$ sudo make install

          • Ubuntu

            $ sudo apt-get install build-essential gcc make cmake cmake-gui cmake-curses-gui
$ sudo apt-get install libssl-dev
$ git clone https://github.com/eclipse/paho.mqtt.c.git
$ cd paho.mqtt.c
$ git checkout v1.3.8
$ cmake -Bbuild -H. -DPAHO_ENABLE_TESTING=OFF -DPAHO_BUILD_STATIC=ON \
    -DPAHO_WITH_SSL=ON -DPAHO_HIGH_PERFORMANCE=ON
$ sudo cmake --build build/ --target install
$ sudo ldconfig
          참고

          예제 파일 내 Full Certificate Chain Path 값의 경우, 인증서와 체인 인증서를 연결한 Full Certificate Chain 파일을 저장할 경로를 의미합니다. 예제 실행 시 Full Certificate Chain 파일이 설정된 경로에 자동으로 별도 저장됩니다.

          예제 코드

          • mqttClient.cpp
            #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <iostream>
#include <fstream>

#include "MQTTClient.h"

#define QOS 1
#define TIMEOUT 10000L

volatile MQTTClient_deliveryToken deliveredtoken;

// Generate fullCertChain by cert and caChain
void appendCert(char* cert, char* caChain, char* fullCertChain) {

    std::ifstream fin;
    std::ofstream fout;
    int size;
    char* buffer;

    fin.open(cert);
    fout.open(fullCertChain);

    fin.seekg(0,std::ios::end);
    size = fin.tellg();
    fin.seekg(0, std::ios::beg);

    buffer = (char*)malloc(size + 1);
    memset(buffer, 0, size + 1);
    fin.read(&buffer[0], size);

    fout << buffer << std::endl;
    free(buffer);
    fin.close();

    fin.open(caChain);
    fin.seekg(0,std::ios::end);
    size = fin.tellg();
    fin.seekg(0, std::ios::beg);
    buffer = (char*)malloc(size + 1);
    memset(buffer, 0, size + 1);
    fin.read(&buffer[0], size);

    fout << buffer << std::endl;
    free(buffer);
    fin.close();
    fout.close();
}

void delivered( void *context, MQTTClient_deliveryToken dt )
{
    std::cout << ">>> Publish to IoT server." << std::endl;
    deliveredtoken = dt;
}

int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message) {
    char* payload = (char*)message->payload;
    std::cout << "<<< Subscribe from IoT server. topic : " << topicName << " , message : " << payload << std::endl;
    MQTTClient_freeMessage(&message);
    MQTTClient_free(topicName);
    return 1;
}

void connlost( void *context, char *cause )
{
    std::cout << std::endl << "Connection lost" << std::endl;
    std::cout << "     cause: " << cause << std::endl;
}

int main(int argc, char *argv[])
{

    char clientId[] = "myClientTest";

    // Modify file path and server
    // MQTT server hostname
    char iotServer[] = "ssl://msg01.cloudiot.ntruss.com:8883";

    char rootCaCertFilePath[] = "/<Your>/<file>/<path>/rootCaCert.pem";
    char clientCaChainFilePath[] = "/<Your>/<file>/<path>/caChain.pem";
    char clientCertFilePath[] = "/<Your>/<file>/<path>/cert.pem";
    char clientKeyFilePath[] = "/<Your>/<file>/<path>/private.pem";

    // fullCertChain is automatically generated by cert and caChain
    char fullCertChainPath[] = "./fullCertChain.pem";
    char password[] = "";


    // Topic & Message Example
    char sendTopic[] = "factory/room1/temperature";
    char alertTopic[] = "alert";
    char payload[] = "{ \"deviceId\": \"device_1\", \"deviceType\": \"temperature\", \"value\": 35, \"battery\": 9, \"date\": \"2016-12-15\", \"time\": \"15:12:00\"}";


    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    MQTTClient_SSLOptions ssl_opts = MQTTClient_SSLOptions_initializer;
    MQTTClient_message pubmsg = MQTTClient_message_initializer;
    MQTTClient_deliveryToken token;
    int rc;
    int setCallBack;
    int attempts;

    MQTTClient_create(&client, iotServer, clientId, MQTTCLIENT_PERSISTENCE_NONE, NULL);

    // Generate fullCertChain by cert and caChain
    appendCert(clientCertFilePath, clientCaChainFilePath, fullCertChainPath);

    // MQTT Connection parameters
    ssl_opts.verify = 1;
    ssl_opts.trustStore = rootCaCertFilePath;
    ssl_opts.keyStore = fullCertChainPath;
    ssl_opts.privateKey = clientKeyFilePath;

    conn_opts.ssl = &ssl_opts;

    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;
    conn_opts.serverURIcount = 0;
    conn_opts.serverURIs = NULL;

    // Set call back
    if((setCallBack = MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered)) != MQTTCLIENT_SUCCESS)
    {
        std::cout << "ERROR : MQTTClient_setCallbacks, setCallBack = " << setCallBack << std::endl;
        return setCallBack;
    }


    // Connect MQTT Broker
    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        std::cout << "ERROR : Failed to connect, return code : " << rc << std::endl;
        exit(-1);
    } 


    // Subscribe message
    rc = MQTTClient_subscribe(client, alertTopic, 0);

    pubmsg.payload = payload;
    pubmsg.payloadlen = strlen(payload);
    pubmsg.qos = QOS;
    pubmsg.retained = 0;

    for(attempts=0; attempts<5; attempts++){
        // Publish message
        MQTTClient_publishMessage(client, sendTopic, &pubmsg, &token);
        rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);

        sleep(2);       //sec
    }

    sleep(2);           //sec

    // Disconnect
    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);

    return rc;
}

          예제 코드 실행

          C++ 예제 코드를 실행하는 방법은 다음과 같습니다.

          $ g++ -o {executable file name} {source file name}.cpp -l paho-mqtt3cs
$ ./{executable file name}

          동작 결과

          C++ 예제 코드의 동작 결과는 다음과 같습니다.

          >>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
>>> Publish to IoT server.
<<< Subscribe from IoT server. topic : alert , message : {"deviceType":"temperature","date":"2016-12-15","time":"15:12:00","battery":9,"deviceId":"device_1","value":35}
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