AWS AppSync IoT Core Realtime Example

Update!! the project has been updated to use Amplify Gen2 to deploy the backend services in AWS.

This application demonstrates an iPhone receiving real-time updates from an IoT sensor. The solution is built with AWS AppSync and AWS IoT Core technologies.

Architecture

1. The sensor component is developed with the AWS IoT Device SDK for Javascript. The sensor is registered as a Thing in IoT Core and publishes a random temperature in a JSON payload to the Cloud every 2 seconds. The Thing Shadow also containes meta-data about then sensor specifying the sensor type as Temperature.

{
  "value": 84,
  "timestamp": 1570562147790
}

2. A rule in IoT Core subscribes to the message topic and forwards the JSON payload to a Lambda function.

3. The NodeJS Lambda function executes a GraphQL mutatation in AppSync. The mutation saves the latest value for the sensor in DynamoDB and broadcasts the latest value in real-time to the iOS application. The Lambda function uses an IAM role and policy to obtain permissions to interact with AppSync.

4. The iOS application uses the Amplify Swift package, built with the AWS SDK for Swift, to subscribe to the AppSync Sensor Value subscription. When new temperature values are received, the gauge component on the screen is updated in real-time to reflect the new sensor value.

Getting Started

Prerequisites

The following software was used in the development of this application. While it may work with alternative versions, we recommend you deploy the specified minimum version.

1. An AWS account in which you have Administrator access.

2. AWS CLI (^2.21.1) the AWS Command Line Interface (CLI) is used to configure your connection credentials to AWS.

3. Node.js (^18.19.0) with NPM (^10.1.0)

4. Xcode (16.1) Xcode is used to build and debug the mobile appliction application. You will need iOS Simulator 18.0 enabled.

Installation

Clone this code repository

git clone https://github.com/aws-samples/aws-appsync-iot-core-realtime-example.git

Switch to the mobile folder

cd aws-appsync-iot-core-realtime-example/mobile

Deploy the Infrastructure with Amplify Gen2

npm install

npx ampx sandbox

The deployment is complete when you see the following output:

File written: amplify_outputs.json

Press CTRL-C to exit the deployment.

Resources created in your account include:

• AppSync GraphQL API
• DynamoDB table
• Lambda function
• IoT Rule

Install the IoT Sensor Simulator

Open a new terminal window then switch to the app's sensor folder (aws-appsync-iot-core-realtime-example/sensor).

Install the Node.js packages, and run the Node.js app to create your sensor as a Thing in AWS IoT Core. It will also create and install the certificates your sensor needs to authenticate to IoT Core.

From the sensor folder:

npm install
node create-sensor.js

Run the App

Start the IoT Sensor

From the sensor terminal window:

node index.js

You will see output from the app as it connects to IoT Core, transmits its shadow document, and publishes new temperature messages every 2 seconds.

connected to IoT Hub

published to shadow topic $aws/things/aws-iot-mobile-demo-sensor/shadow/update {"state":{"reported":{"sensorType":"Temperature"}}}

published to topic dt/sensor-view/aws-iot-mobile-demo-sensor/sensor-value {"value":77,"timestamp":1592073890804}

published to topic dt/sensor-view/aws-iot-mobile-demo-sensor/sensor-value {"value":76,"timestamp":1592073892807}

published to topic dt/sensor-view/aws-iot-mobile-demo-sensor/sensor-value {"value":77,"timestamp":1592073894810}

Keep this app running and switch to your mobile terminal window.

Start the iPhone app

From the terminal window pointing to the mobile folder (aws-appsync-iot-core-realtime-example/mobile) and open the Xcode project:

open mobile.xcodeproj

Add Amplify Configuration File to Xcode Project

In the Xcode project select File/Add files to mobile from the main menu and add the amplify_outputs.json file generated by Amplify. Select the option to Copy the file and set mobile as the Target.

Select the "Run" arrow button to start the app.

Use the App!

You should now see a screen similar to the one at the top of this guide. If you look at the terminal window running the sensor app, you shoud see the values published to the Cloud reflected in the iPhone app's sensor gauge in real-time.

Cleanup

Once you are finished working with this project, you may want to delete the resources it created in your AWS account.

From the mobile folder:

npx ampx sandbox delete

From the sensor folder:

node delete-sensor.js

License

This sample code is made available under a modified MIT-0 license. See the LICENSE file.