arduino_azure_iot_get_message.ino

#include <SPI.h>
#include <WiFi101.h>


unsigned long lastConnectionTime = 0;            
const unsigned long pollingInterval = 2L * 1000L; // 5 sec polling delay, in milliseconds


// Generate SAS key using https://github.com/Azure/azure-iot-sdks/releases
char hostname[] = "alexey.azure-devices.net";
char authSAS[] = "SharedAccessSignature sr=alexey.azure-devices.net%2fdevices%2fmyDevice&sig=D7OxGEm98bqAQDYk33d0DzPB92EuGMkjkzKBCsBBksc%3d&se=1493799405";

String deviceName = "myDevice";
char ssid[] = "xxx";      // your network SSID (name)
char pass[] = "xxxxxxxx";   // your network password
String uri = "/devices/myDevice/messages/devicebound?api-version=2016-02-03";

int status = WL_IDLE_STATUS;
WiFiSSLClient client;

void setup() {
  Serial.begin(9600);
  Serial.println("Demo for Microsoft Azure");

   // check for the presence of the shield:
   if (WiFi.status() == WL_NO_SHIELD) {
     Serial.println("WiFi shield not present");
     // don't continue:
     while (true);
   }

   // attempt to connect to Wifi network:
   while ( status != WL_CONNECTED) {
     Serial.print("Attempting to connect to SSID: ");
     Serial.println(ssid);

     status = WiFi.begin(ssid, pass);

     // wait 10 seconds for connection:
     delay(10000);
   }
  
  Serial.println("Connected to wifi");


}

void loop() {

  String response = "";
  char c;
  ///read response if WiFi Client is available
  while (client.available()) {
    c = client.read();
    response.concat(c);
  }

  if (!response.equals(""))
  {
    //if there are no messages in the IoT Hub Device queue, Azure will return 204 status code. 
    if (response.startsWith("HTTP/1.1 204"))
    {
         Serial.println("Good");
         Serial.println(response);
    }
    else
    {
         Serial.println(response);
    }
  }

  // polling..if pollingInterval has passed
  if (millis() - lastConnectionTime > pollingInterval) {
    azureHttpRequest();
  }


}

void azureHttpRequest() {

  // close any connection before send a new request.
  // This will free the socket on the WiFi shield
  client.stop();

  // if there's a successful connection:
  if (client.connect(hostname, 443)) {
    //make the GET request to the Azure IOT device feed uri
    client.print("GET ");  //Do a GET
    client.print(uri);  // On the feedURI
    client.println(" HTTP/1.1"); 
    client.print("Host: "); 
    client.println(hostname);  //with hostname header
    client.print("Authorization: ");
    client.println(authSAS);  //Authorization SAS token obtained from Azure IoT device explorer
    client.println("Connection: close");
    client.println();

    // note the time that the connection was made:
    lastConnectionTime = millis();
  }
  else {
    // if you couldn't make a connection:
    Serial.println("connection failed");
  }
}