i'm trying to join a channel but i get PlatformException(-17, request to join channel is rejected, null, null)

Question

I'm creating a channel from agora web demo as host and trying to join the channel from the flutter app as an audience i made sure both use the same channel name, app id, and I'm generating tokens through a server and Fech them to the app.

here's my code:

import 'package:agora_rtc_engine/rtc_engine.dart';
import 'package:agora_rtc_engine/rtc_remote_view.dart' as rtc_remote_view;
import 'package:agora_rtm/agora_rtm.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

import '../../utilities/agora_app_id.dart';

class StreamScreen extends StatefulWidget {
  static const routeName = '/stream';
  final String channelName;
  final String userName;
  final int userID;

  const StreamScreen({
    Key? key,
    required this.channelName,
    required this.userName,
    required this.userID,
  }) : super(key: key);

  @override
  State<StreamScreen> createState() => _StreamScreenState();
}

class _StreamScreenState extends State<StreamScreen> {
  final List<int> _audience = [];
  late RtcEngine _rtcEngine;
  AgoraRtmClient? _rtmClient;
  AgoraRtmChannel? _rtmChannel;
  String? _rtmToken;
  String? _rtcToken;

  Future<void> initAgora() async {
    _rtcEngine =
        await RtcEngine.createWithContext(RtcEngineContext(agoraAppID));
    _rtmClient = await AgoraRtmClient.createInstance(agoraAppID);

    await getRTMToken();

    await _rtcEngine.enableVideo();
    await _rtcEngine.startPreview();
    await _rtcEngine.setChannelProfile(ChannelProfile.LiveBroadcasting);
    await _rtcEngine.setClientRole(ClientRole.Audience);
    await getRTCToken();

    //join the RTC & RTM Channels

    await _rtcEngine.joinChannel(
      _rtcToken,
      widget.channelName,
      null,
      0,
    );

    //event handlers for RTC Engine
    _rtcEngine.setEventHandler(RtcEngineEventHandler(
      joinChannelSuccess: (channel, uid, elapsed) {
        //TODO: add joinChannel logic
        print('joinChannelSuccess $channel $uid');
      },
      userJoined: (uid, elapsed) {
        print('User $uid joined');
      },
      leaveChannel: (rtcStats) {
        setState(() {
          _audience.clear();
        });
      },
      tokenPrivilegeWillExpire: (rtcToken) async {
        await getRTCToken();
        await _rtcEngine.renewToken(rtcToken);
      },
    ));

    //event handlers for RTM Client
    _rtmClient?.onConnectionStateChanged = (state, reason) {
      print('Connection State changed: ' +
          state.toString() +
          ', reason: ' +
          reason.toString());
      if (state == 5) {
        _rtmChannel?.leave();
        _rtmClient?.logout();
        _rtmClient?.destroy();
        print('logged out.');
      }
    };

    //event handlers for RTM Channel
    _rtmChannel?.onMemberJoined = (member) {
      print('member joined: ' + member.userId + 'channel: ' + member.channelId);
    };

    _rtmChannel?.onMemberLeft = (member) {
      print('member left: ' + member.userId + 'channel: ' + member.channelId);
    };
  }

  @override
  void initState() {
    super.initState();
    initAgora();
  }

  @override
  void dispose() {
    _audience.clear();
    _rtcEngine.leaveChannel();
    _rtcEngine.destroy();
    _rtmChannel?.leave();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: rtc_remote_view.SurfaceView(
          channelId: widget.channelName,
          uid: widget.userID,
          zOrderOnTop: true,
          zOrderMediaOverlay: true,
        ),
        // const Toolbar(),
      ),
    );
  }

  Future<void> getRTMToken() async {
    final response = await http.get(
      Uri.parse(
          'https://*********************.com/rtm/${widget.userID}/?expiry=7000'),
    );

    if (response.statusCode == 200) {
      setState(() {
        _rtmToken = response.body;
        _rtmToken = jsonDecode(_rtmToken!)['rtmToken'];
      });
      print('rtm: ' + _rtmToken!);
    } else {
      print('Failed to fetch the token');
    }
  }

  Future<void> getRTCToken() async {
    final response = await http.get(
      Uri.parse(
          'https://******************.com/rtc/${widget.channelName}/audience/uid/${0}/?expiry=7000/'),
    );

    if (response.statusCode == 200) {
      setState(() {
        _rtcToken = response.body;
        _rtcToken = jsonDecode(_rtcToken!)['rtcToken'];
      });
      print('rtc: ' + _rtcToken!);
    } else {
      print('Failed to fetch the token');
    }
  }
}

i get this error:

#0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:607:7)
#1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:177:18)
<asynchronous suspension>
#2      _StreamScreenState.initAgora (package:malhamti_app/screens/stream/stream_screen.dart:58:5)
<asynchronous suspension>

• what am i doing wrong?
• do i need to set up the RTM channel/client, when I'm just wanting video streaming?
• What does the number -17 in the error mean?

Answer 1

Error code 17 occurs when a user is already in the channel and you try to join the channel again. Make sure that you call leaveChannel() method before leaving the channel.