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Initialization

Developing web apps with React

We provide React hooks and context providers out of the box. The library can be found on GitHub.
First, install the ux4iot-react library:
NPM
Yarn
npm install ux4iot-react
yarn add ux4iot-react
You initialize the ux4iot React library by wrapping your components with a Ux4iotContext
import {Ux4iotContextProvider} from "ux4iot-react";
...
function App() {
  return (
    <div className="App">
      <Ux4iotContextProvider 
          options={options}
      >
          <MyView />
      </Ux4iotContextProvider>
    </div>
  );
}
There are two modes of operations for the library: Development mode and production mode. The initialization differs between the two modes.
ConfigurationOptions
type InitializationOptions = {
	onSocketConnectionUpdate?: ConnectionUpdateFunction;
	reconnectTimeout?: number;
	maxReconnectTimeout?: number;
} & (InitializeDevOptions | InitializeProdOptions);
​
type InitializeDevOptions = {
	adminConnectionString: string;
};
​
type InitializeProdOptions = {
	ux4iotURL: string;
	grantRequestFunction: GrantRequestFunctionType;
};
​
Option
description
onSocketConnectionUpdate
event listener on socket connection updates
reconnectTimeout
initial timeout in milliseconds when to reconnect after a session couldn't be established
maxReconnectTimeout
maximum timeout in milliseconds of the reconnect interval after incrementation
adminConnectionString
The connection string of ux4iot-server
ux4iotUrl
the websocket url of ux4iot-server
grandRequestFunction
custom function to send grant requests to your custom security backend
​
Development Mode
const UX4IOT_ADMIN_CONNECTION_STRING = "Endpoint=...SharedAccessKey=...";
​
const devOptions: InitializeDevOptions = {
   adminConnectionString: UX4IOT_ADMIN_CONNECTION_STRING 
};
​
...
  <Ux4iotContextProvider options={devOptions}>
  ...
  </Ux4iotContextProvider>
...
You can see a complete example in the tutorial using create-react-app.
The value of the adminConnectionString option can be retrieved via the Azure portal:
You can select either the Primary or the Secondary connection string.
In production mode the admin connection string is used by the Security Backend, but as there is no Security Backend in development mode, the frontend accesses the Admin API on its own. For this reason the frontend requires the admin connection string.
Usage of Development Mode
Under no circumstances should you publish your web application in development mode. It allows anyone with access to the web application to perform any requests towards your IoT devices and it also exposes the admin connection string that must be kept secret.
Production Mode
For production mode you need to provide a security backend for managing access permissions. You also need a Grant Request Function that acts as an adapter between the ux4iot library and this backend.
const UX4IOT_WEBSOCKET_URL 'https://ux4iot-xxx.westeurope.azurecontainer.io';
​
const prodOptions: InitializeProdOptions = {
   ux4iotURL: UX4IOT_WEBSOCKET_URL
   grantRequestFunction: customGrantRequestFunction
};
​
...
  <Ux4iotContextProvider options={prodOptions}>
  ...
  </Ux4iotContextProvider>
...
The value for the ux4iotURL parameter is available on your ux4iot instance in the Azure portal:
For detailed information on how to implement the Grant Request Function, see the dedicated chapter.
reconnectTimeout & maxReconnectTimeout
When you render a Ux4iotContextProvider, it tries to establish a session by calling the /session endpoint of ux4iot. If this request fails, it will retry again after the milliseconds defined in reconnectTimeout. If the retry fails it will double the timeout and retry again after the doubled timeout or maxReconnectTimeout if maxReconnectTimeout is larger.
Example reconnectTimeout = 5000, maxReconnectTimeout = 50000
Ux4iot fails to connect to ux4iot and fails. Retries afterwards at 5, 10, 20, 40, 50, 50, 50,... seconds
Retries will not stop retrying until the session is established. The defaults are reconnectTimeout = 5000, maxReconnectTimeout = 30000
onSocketConnectionUpdate
In both Development and Production mode you can pass a function to the options of the Ux4iotContextProvider 
const devOptions: InitializeDevOptions = {
   adminConnectionString: UX4IOT_ADMIN_CONNECTION_STRING
   onSocketConnectionUpdate: (reason, description) => { /* handle update */ }
};
const prodOptions: InitializeProdOptions = {
   ux4iotURL: UX4IOT_WEBSOCKET_URL
   grantRequestFunction: customGrantRequestFunction
   onSocketConnectionUpdate: (reason, description) => { /* handle update */ }
};
It takes two arguments:
reason - can be one of four strings:
socket_connect - called when the socket is established with the server
socket_connect_error called when the client throws an error when establishing the socket
socket_disconnect - called when the socket is disconnected
ux4iot_unreachable - called when a sessionId cannot be fetched from the ux4iot instance
Every reason except for ux4iot_unreachable originates from socket.io and is documented here: https://socket.io/docs/v4/client-api/#event-connect 
description - string | undefined : error explanation provided in socket_connect_error, socket_disconnect and ux4iot_unreachable 
The full function type you need to provide is
export type ConnectionUpdateReason =
	| 'socket_connect'
	| 'socket_connect_error'
	| 'socket_disconnect'
	| 'ux4iot_unreachable';
​
export type ConnectionUpdateFunction = (
  reason: ConnectionUpdateReason,
  description?: string
) => void;
​

Option	description
onSocketConnectionUpdate	event listener on socket connection updates
reconnectTimeout	initial timeout in milliseconds when to reconnect after a session couldn't be established
maxReconnectTimeout	maximum timeout in milliseconds of the reconnect interval after incrementation
adminConnectionString	The connection string of ux4iot-server
ux4iotUrl	the websocket url of ux4iot-server
grandRequestFunction	custom function to send grant requests to your custom security backend