# Use tokens (/en/realtime-media/rtc/build/authenticate-users/authentication-workflow/react-native)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

To protect your business, it is best practice to authenticate every client that joins a channel. This guide explains how to fetch an authentication token from your token server, use it to join a channel, and renew the token when it expires.

## Understand the tech

When a user attempts to connect to an Agora channel, your app retrieves a token from the token server in your security infrastructure. Your app then sends this token to Agora SDRTN® for authentication. Agora SDRTN® reads the information stored in the token to validate the request.

The following figure shows the call flow you implement to create step-up-authentication with Agora Video Calling:

<Accordions>
  <Accordion title="Token authentication flow">
    ![token authentication flow](https://assets-docs.agora.io/images/video-sdk/token-authentication.svg)
  </Accordion>
</Accordions>

## Prerequisites

Before starting, ensure that you have:

* Implemented the [Quickstart](/en/realtime-media/rtc/get-started-sdk) in your project.

* Deployed a token server using either of the following guides:

  * [Deploy a token server](/en/realtime-media/rtc/build/authenticate-users/deploy-token-server)
  * [Deploy a middleware server](/en/realtime-media/rtc/build/authenticate-users/middleware-token-server)

## Implement basic authentication

This section shows you how to implement basic authentication by acquiring a token and using it to join a channel.

      
  
      
  
      
  
      
  
      
  
      
  
      
### Use a token to join a channel

This section shows you how to integrate token authentication in your app.

1. Open the [SDK quickstart](/en/realtime-media/rtc/get-started-sdk) project you created earlier.

2. In `ProjectName.tsx` replace the contents with the following:

**Sample code for basic authentication**

```js
import React, { useCallback, useEffect, useRef, useState } from 'react';
    import {
        PermissionsAndroid,
        Platform,
        SafeAreaView,
        ScrollView,
        StyleSheet,
        Switch,
        Text,
        View,
    } from 'react-native';

    import {
        ChannelProfileType,
        ClientRoleType,
        createAgoraRtcEngine,
        IRtcEngine,
        IRtcEngineEventHandler,
        RtcConnection,
        RtcSurfaceView,
    } from 'react-native-agora';

    // Define basic information
    const appId = '<Your app ID>';
    const channelName = 'test';
    const uid = 123; // Local user Uid

    const App = () => {
    const agoraEngineRef = useRef<IRtcEngine>(); // IRtcEngine instance
    const eventHandlerRef = useRef<IRtcEngineEventHandler>(); // IRtcEngine event handler
    const [token, setToken] = useState<string>(''); // RTC Token
    const [isJoined, setIsJoined] = useState(false); // Whether the local user has joined the channel
    const [isHost, setIsHost] = useState(true); // User role
    const [remoteUid, setRemoteUid] = useState(0); // Uid of remote user
    const [message, setMessage] = useState(''); // Message to the user

    // Send a request to obtain a token to the token server
    const fetchToken = useCallback(() => {
        // Token server URL example: http://12.123.1.123:8082/fetch_rtc_token
        const url = '<Your host URL and port>/fetch_rtc_token';
        const body = JSON.stringify({
        uid,
        ChannelName: channelName,
        role: isHost
            ? ClientRoleType.ClientRoleBroadcaster
            : ClientRoleType.ClientRoleAudience,
        });
        console.log('fetchToken', url, body);
        return fetch(url, {
            method: 'POST',
            body,
        })
        .then((res) => res.json())
        .then((res) => {
            showMessage('token ' + res.token + 'Already refreshed');
            if (+res.code === 200) {
            setToken(res.token);
            }
            return res;
        });
        }, [isHost]);

    // Use the obtained token to join the channel
    const join = useCallback(async () => {
        if (!token) {
            await fetchToken();
        } else {
        try {
            // After joining the channel, set the channel profile to live broadcast
            agoraEngineRef.current?.setChannelProfile(
            ChannelProfileType.ChannelProfileLiveBroadcasting
            );
            if (isHost) {
            agoraEngineRef.current?.startPreview();
            // Join the channel as a host
            agoraEngineRef.current?.joinChannel(token, channelName, uid, {
                publishCameraTrack: true,
                clientRoleType: ClientRoleType.ClientRoleBroadcaster,
            });
            } else {
            // Join the channel as audience
            agoraEngineRef.current?.joinChannel(token, channelName, uid, {
                clientRoleType: ClientRoleType.ClientRoleAudience,
            });
            }
        } catch (e) {
            console.log(e);
        }
    }
    }, [fetchToken, isHost, token]);

    const leave = () => {
        try {
            agoraEngineRef.current?.leaveChannel();
            setRemoteUid(0);
            setIsJoined(false);
            showMessage('Left the channel');
        } catch (e) {
            console.error(e);
        }
    };

    useEffect(() => {
        const setupVideoSDKEngine = async () => {
        try {
            if (Platform.OS === 'android') {
            await getPermission();
            }
            agoraEngineRef.current = createAgoraRtcEngine();
            eventHandlerRef.current = {
            onJoinChannelSuccess: () => {
                showMessage('Successfully joined the channel: ' + channelName);
                setIsJoined(true);
            },
            onUserJoined: (_connection, Uid) => {
                showMessage('Remote user ' + Uid + ' joined');
                setRemoteUid(Uid);
            },
            onUserOffline: (_connection, Uid) => {
                showMessage('Remote user ' + Uid + ' left the channel');
                setRemoteUid(0);
            },
            onTokenPrivilegeWillExpire(connection: RtcConnection, token: string) {
                showMessage('token ' + token + 'Expires soon');
                fetchToken();
            },
            onRequestToken(connection: RtcConnection) {
                showMessage('token expired');
                setToken('');
            },
            };
            const agoraEngine = agoraEngineRef.current;
            //Initialize engine
            agoraEngine.initialize({
                appId: appId,
                channelProfile: ChannelProfileType.ChannelProfileLiveBroadcasting,
            });
            // Register event handler
            agoraEngine.registerEventHandler(eventHandlerRef.current);
            // Start local video
            agoraEngine.enableVideo();
        } catch (e) {
            console.error(e);
        }
    };

        setupVideoSDKEngine();

        return () => {
            agoraEngineRef.current?.release();
        };
    }, []); // eslint-disable-line react-hooks/exhaustive-deps

    useEffect(() => {
        const checkJoined = () => {
        if (isJoined) {
            console.log('renewToken');
            // agoraEngineRef.current?.renewToken(token);
        } else {
            console.log('joinChannel');
            join();
        }
        };
        checkJoined();
    }, [token]); // eslint-disable-line react-hooks/exhaustive-deps

    // Render the user interface
    return (
        <SafeAreaView style={styles.main}>
        <Text style={styles.head}>Agora SDK Quickstart</Text>
        <View style={styles.btnContainer}>
            <Text onPress={join} style={styles.button}>
            Join channel
            </Text>
            <Text onPress={leave} style={styles.button}>
            Leave Channel
            </Text>
        </View>
        <View style={styles.btnContainer}>
            <Text>Audience</Text>
            <Switch
            onValueChange={(switchValue) => {
                setIsHost(switchValue);
                if (isJoined) {
                leave();
                }
            }}
            value={isHost}
            />
            <Text>Host</Text>
        </View>
        <ScrollView
            style={styles.scroll}
            contentContainerStyle={styles.scrollContainer}
        >
            {isJoined ? (
            <React.Fragment key={0}>
                <RtcSurfaceView canvas={{ uid: 0 }} style={styles.videoView} />
                <Text>Local user uid: {uid}</Text>
            </React.Fragment>
            ) : (
            <Text>Join a channel</Text>
            )}
            {isJoined && !isHost && remoteUid !== 0 ? (
            <React.Fragment key={remoteUid}>
                <RtcSurfaceView
                canvas={{ uid: remoteUid }}
                style={styles.videoView}
                />
                <Text>Remote user uid: {remoteUid}</Text>
            </React.Fragment>
            ) : (
            <Text>{isJoined && !isHost ? 'Wait for a remote user to join' : ''}</Text>
            )}
            <Text style={styles.info}>{message}</Text>
        </ScrollView>
        </SafeAreaView>
    );

    // Show message
    function showMessage(msg: string) {
        console.info(msg);
        setMessage(msg);
    }
    };

    // Define user interface style
    const styles = StyleSheet.create({
        button: {
            paddingHorizontal: 25,
            paddingVertical: 4,
            fontWeight: 'bold',
            color: '#ffffff',
            backgroundColor: '#0055cc',
            margin: 5,
        },
        main: { flex: 1, alignItems: 'center' },
        scroll: { flex: 1, backgroundColor: '#ddeeff', width: '100%' },
        scrollContainer: { alignItems: 'center' },
        videoView: { width: '90%', height: 200 },
        btnContainer: { flexDirection: 'row', justifyContent: 'center' },
        head: { fontSize: 20 },
        info: { backgroundColor: '#ffffe0', paddingHorizontal: 8, color: '#0000ff' },
    });

    const getPermission = async () => {
        if (Platform.OS === 'android') {
            await PermissionsAndroid.requestMultiple([
            'android.permission.RECORD_AUDIO',
            'android.permission.CAMERA',
            ]);
        }
    };

    export default App;
```

Replace `<Your app ID>` with your app ID, which must be consistent with the app ID you specified in the server configuration. Update `<Your host URL and port>` with the host URL and port of the local Golang server you have deployed. For example `99.9.9.99:8082`.

The sample code implements the following logic:

* Calls `joinChannel` to join a channel using the user ID, the channel name, and a token you obtain from the server. The user ID and channel name you specify must be consistent with the values you used to generate the token.

* The SDK triggers an `onTokenPrivilegeWillExpire` callback 30 seconds before the token expires. After receiving the callback, you obtain a new token from the server and call `renewToken` to pass the newly generated token to the SDK.

* If the token expires, the SDK triggers an `onRequestToken` callback. After receiving the callback, obtain a new token from the server and call `joinChannel` with the new token to rejoin the channel.

Build and run the project on the local device, the app performs the following operations:

* Obtains a token from your token server.
* Joins the channel.
* Automatically renews the token when it is about to expire.

    
  
      
  
      
  
      
  
      
  
      
  
<CalloutContainer type="warning">
  <CalloutTitle>
    Note
  </CalloutTitle>

  <CalloutDescription>
    The user ID and channel name used to join a channel must be consistent with the values used to generate the token.
  </CalloutDescription>
</CalloutContainer>

## Reference

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

      
  
      
  
      
  
      
  
      
  
      
### API reference

* [renewToken](https://api-ref.agora.io/en/video-sdk/react-native/4.x/API/class_irtcengine.html#api_irtcengine_renewtoken)
* [onTokenPrivilegeWillExpire](https://api-ref.agora.io/en/video-sdk/react-native/4.x/API/class_irtcengineeventhandler.html#callback_irtcengineeventhandler_ontokenprivilegewillexpire)
* [onRequestToken](https://api-ref.agora.io/en/video-sdk/react-native/4.x/API/class_irtcengineeventhandler.html#callback_irtcengineeventhandler_onrequesttoken)