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IoT (Java)

Overview

City Power & Light is a sample application that allows citizens to report "incidents" that have occurred in their community. It includes a landing screen, a dashboard, and a form for reporting new incidents with an optional photo. The application is implemented with several components:

Front end web application contains the user interface and business logic. This component has been implemented three times in .NET, NodeJS, and Java.
WebAPI is shared across the front ends and exposes the backend CosmosDB.
CosmosDB is used as the data persistence layer.

In this lab, you will combine the web app with an IoT device based on an Arduino-compatible board that will query the app for the number of incidents and display the refreshed number every minute.

Objectives

In this hands-on lab, you will learn how to:

Set up the developing environment to support the programming of Arduino chips.
Create your own IoT software from scratch.

Prerequisites

The source for the starter app is located in the start folder.
The finished project is located in the end folder.
Deployed the starter ARM Template HOL 1.
Completion of the HOL 5.

Exercises

This hands-on-lab has the following exercises:

Exercise 1: Set up your environment
Exercise 2: Create output that will be consumed by the device
Exercise 3: Program the device

Exercise 1: Set up your environment

To program an Arduino device on your machine you need the Arduino IDE and Visual Studio on your machine. Since a hardware connection to the device is required this will not work from a virtual machine. It is possible to use an Arduino emulator for this lab instead of the actual device and work through the exercises in a virtual machine.

You will now install the Arduino IDE and setup the board manager.

Download the Arduino IDE package from the Arduino download page. Go to www.arduino.cc/en/Main/Software and select the Windows installer. The Windows installer sets up everything you need to use the Arduino IDE. If you use the ZIP file you need to install the drivers manually. The drivers are located here: https://github.com/nodemcu/nodemcu-devkit/tree/master/Drivers.
Run the installer and accept the license agreement.
Select the components to install. Keep at least Install USB driver selected.
Select the installation folder. You should keep the default destination folder.
After setup completed close the window and run Arduino.
Arduino should look like this:
Select File -> Preferences.
Locate the Additional Boards Manager URLs property and enter the URL http://arduino.esp8266.com/stable/package_esp8266com_index.json and click OK.
Select Tools -> Board -> Boards Manager....
In the Boards Manager dialog enter esp8266 into the search field. The Arduino package esp8266 will appear. Select the latest version and click Install to download and install the package.
After the installation completed, click Close.
Select the board from the list of boards by clicking Tools -> Board -> NodeMCU 1.0 (ESP-12E Module).
Set the port by selecting the correct COM port from Tools -> Port -> Serial ports. Also make sure Upload Speed: "115200" is selected.

You have now installed all the necessary components to start programming an Arduino device on your machine.

Exercise 2: Create output that will be consumed by the device

The device will regularly call an URL to fetch the current incident count. We will add a page to our existing web application as an easy way to provide this data.

In the DevcampApplication.java file add /IoT** to the list of antMatchers.
Create a new Controller. Right-click on devCamp.WebApp.Controllers and select New -> Class.
In the New Java Class dialog enter IoTController as the name and click Finish.

The controller will just emulate the behavior of the dashboard controller. Add the following code to the newly created file:

package devCamp.WebApp.Controllers;

import java.util.List;
import java.util.concurrent.CompletableFuture;

import devCamp.WebApp.models.IncidentBean;
import devCamp.WebApp.services.IncidentService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.RequestMapping;
    
@Controller
public class IoTController {
  private static final Logger LOG = LoggerFactory.getLogger(DashboardController.class);

  @Autowired
  IncidentService service;

  @RequestMapping("/IoT")
  public String iot(Model model) {
    List<IncidentBean> list = service.getAllIncidents();
    model.addAttribute("allIncidents", list);
    return "IoT/index";
  }  
}

Create a new template. Right-click on src/main/resources and select New -> Other.... ...
In the New dialog select the HTML File template and click Next >.
Set the folder to [...]/resources/templates/IoT and the file name to index.html, then click Finish.
The template will only display the number of incidents. Add the following code to the newly created file:
```
IncidentCount=<span th:text="${allIncidents.size()}" th:remove="tag"></span>
```
Start the debugger and add /IoT to the URL to test the new view. It will contain just the number of incidents.
Publish the changes to your Azure web app and make sure the /IoT URL is reachable (see HOL 5).

You have now created the data feed for your device.

Exercise 3: Program the device

The Arduino-compatible device can handle data exchange with web applications. At first we will connect the device to a Wi-Fi, and then we will add an HTTP request to retrieve the amount of incidents from the web application.

It is important to develop projects in small chunks and to understand and test each function. Try to develop code with small functions that clearly separate the functionalities of your device and combine them step by step.

Make sure the device is connected to your USB port and open Arduino and create a new sketch.

Replace the sketch content with the following code which will connect the device to a specified wireless network. Replace the SSID and the password with proper values.

#include <ESP8266WiFi.h>

// Pins
#define LED_PIN   D4 // build-in LED in NodeMCU

// Wifi
char* ssid = "***";
char* password = "***";

void setup() {
  Serial.begin(115200); // sets up serial data transmission for status information
  
  pinMode(LED_PIN, OUTPUT);
  
  connectWifi(ssid, password);
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) {
    digitalWrite(LED_PIN, HIGH); // turn the LED off
  } else {
    delay(250);
    digitalWrite(LED_PIN, LOW);
    delay(50);
    digitalWrite(LED_PIN, HIGH);
  }
}

void connectWifi(char* ssid, char* password) {
  Serial.print("Connecting to Wi-Fi");
  
  WiFi.hostname("NodeMCU@DevCamp");
  WiFi.begin(ssid, password);
  
  uint8_t i = 0;
  while (WiFi.status() != WL_CONNECTED && i++ < 50) {
    Serial.print(".");
    delay(500);
  }
  Serial.println(".");
  
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("Could not connect to Wi-Fi");
  } else {
    Serial.print("Connected to Wi-Fi: ");
    Serial.println(ssid);
    Serial.print("IP address: ");
    Serial.println(WiFi.localIP());
  }
}

When it comes to debugging code in Arduino, Serial.print() and Serial.println() are the best way to go. Serial.begin(115200); sets up serial data transmission with 115200 baud. Select Tools -> Serial Monitor to open the Serial Monitor dialog for the selected COM port.
In the Serial Monitor dialog select 115200 baud from the list and leave the dialog open to see the output from the device.
Let's test the wireless network connection. Hit CTRL+U to compile and upload the sketch to your device. Confirm if you are asked to save the code in a local file. You can follow the upload process in the status window at the bottom. If the upload fails and you have multiple COM ports try selecting the other ports.
If the connection to your network was established, the LED on your device will start blinking. It will completely turn off if the connection has failed. The COM monitor window will also display the connection attempts made by the device.

Now we will add an HTTP request to our Arduino code. The new code will also add the method getIncidentCount() which will fetch the current incident count from the IoT view created in Exercise 2. Use the code below to replace or adapt the existing code.

#include <ESP8266WiFi.h>

// Pins
#define LED_PIN   D4 // build-in LED in NodeMCU

// Wifi
char* ssid = "***";
char* password = "***";

// Request
const int port = 80;
const char* server = "<app_name>.azurewebsites.net/IoT"; // address for request, without http://
const char* searchString = "IncidentCount="; // search for this property

void setup() {
  Serial.begin(115200); // sets up serial data transmission for status information
  
  pinMode(LED_PIN, OUTPUT);
  
  connectWifi(ssid, password);
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) {
    digitalWrite(LED_PIN, HIGH);
  } else {
    // retrieve the amount of incidents
    int incidentCount = getIncidentCount();
    
    // keep the led blinking for the amount of incidents
    for (int i = 0; i < incidentCount; i++) {
      delay(250);
      digitalWrite(LED_PIN, LOW);
      delay(50);
      digitalWrite(LED_PIN, HIGH);
    }
    // pause between requests
    delay(60000);
  }
}

void connectWifi(char* ssid, char* password) {
  Serial.print("Connecting to Wi-Fi");
  
  WiFi.hostname("NodeMCU@DevCamp");
  WiFi.begin(ssid, password);
  
  uint8_t i = 0;
  while (WiFi.status() != WL_CONNECTED && i++ < 50) {
    Serial.print(".");
    delay(500);
  }
  Serial.println(".");
  
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("Could not connect to Wi-Fi");
  } else {
    Serial.print("Connected to Wi-Fi: ");
    Serial.println(ssid);
    Serial.print("IP address: ");
    Serial.println(WiFi.localIP());
  }
}

int getIncidentCount() {
  WiFiClient client;
  if (client.connect(server, port)) {
    Serial.print("Connected to ");
    Serial.println(server);
    Serial.println("Sending request");
    
    client.print("GET /");
    client.println(" HTTP/1.1");
    client.print("Host: ");
    client.print(server);
    client.print(":");
    client.println(port);
    client.println("Connection: close");
    client.println("Accept: text/html");
    client.println();

    // waiting for server response...
    while (client.connected()) {
      // ...until the response is available
      if (client.available()) {
    // looking for search string in response data
        if (client.findUntil(searchString, "\0")) {
          int result = client.readStringUntil('\n').toInt();
          
          Serial.print(searchString);
          Serial.print("=");
          Serial.println(result);
          
          return result;
        }
      }
    }
    client.stop();

    Serial.println();
    Serial.println("Connection closed");
  } else {
    Serial.print("Connection to ");
    Serial.print(server);
    Serial.println(" failed");
  }
  return 0;
}

Replace the SSID and the password with proper values. Also replace the address in the following line with the address to the IoT view:
```
const char* server = "<app_name>.azurewebsites.net/IoT"; // address for request, without http://
```
Select Sketch -> Upload or use CTRL+U to compile and upload the sketch to your device. The device will retrieve the amount of incidents from the IoT view and flash the LED for this amount. Again you can use the COM monitor to follow the progress of the code execution on the device.

This example shows how to work with data requests, how to link the device to a data source on the internet and display the state using a simple LED.

Summary

In this hands-on lab, you learned how to:

Set up the developing environment to support the programming of Arduino chips.
Create your own IoT software from scratch.

After completing this module, you can continue on to the Stretch Goal.

View Stretch Goal instructions for Java

Copyright 2017 Microsoft Corporation. All rights reserved. Except where otherwise noted, these materials are licensed under the terms of the MIT License. You may use them according to the license as is most appropriate for your project. The terms of this license can be found at https://opensource.org/licenses/MIT.

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11-IoT

11-IoT

README.md

IoT (Java)

Overview

Objectives

Prerequisites

Exercises

Exercise 1: Set up your environment

Exercise 2: Create output that will be consumed by the device

Exercise 3: Program the device

Summary

View Stretch Goal instructions for Java

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11-IoT

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parent directory

README.md

IoT (Java)

Overview

Objectives

Prerequisites

Exercises

Exercise 1: Set up your environment

Exercise 2: Create output that will be consumed by the device

Exercise 3: Program the device

Summary

View Stretch Goal instructions for Java