TwitchLib.EventSub.Websockets

TwitchLib component to connect to Twitch's EventSub service via Websockets also known as EventSockets

Disclaimer

EventSub via Websockets is still in open beta. You can use it in production but Twitch may introduce breaking changes without prior notice. The same goes for this implementation until it reaches Version 1.0.0

Resources

If you need help on how to setup Dependency Injection in your Console or WPF Application you can have a look at these guides:

• Console: https://dfederm.com/building-a-console-app-with-.net-generic-host/
• WPF: https://laurentkempe.com/2019/09/03/WPF-and-dotnet-Generic-Host-with-dotnet-Core-3-0/

You can also find a console app example for .NET 8 and for .NET Framework 4.8 in the repo.

Installation

NuGet
Package Manager	PM>	Install-Package TwitchLib.EventSub.Websockets -Version 0.4.0
.NET CLI	>	dotnet add package TwitchLib.EventSub.Websockets --version 0.4.0
PackageReference		<PackageReference Include="TwitchLib.EventSub.Websockets" Version="0.4.0" />
Paket CLI	>	paket add TwitchLib.EventSub.Websockets --version 0.4.0

Setup

Step 1: Create a new project (Console, WPF, ASP.NET)

Step 2: Install the TwitchLib.EventSub.Websockets nuget package. (See above on how to do that)

Step 3: Step 3: Add necessary services and config to the DI Container

services.AddTwitchLibEventSubWebsockets();
services.AddHostedService<WebsocketHostedService>();

(The location of where to put this and the naming of variables might differ depending on what kind of project and general setup you have)

Step 4: Create the HostedService we just added to the DI container and connect to EventSub and listen to Events

using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using TwitchLib.EventSub.Websockets.Core.EventArgs;
using TwitchLib.EventSub.Websockets.Core.EventArgs.Channel;

namespace TwitchLib.EventSub.Websockets.Test
{
    public class WebsocketHostedService : IHostedService
    {
        private readonly ILogger<WebsocketHostedService> _logger;
        private readonly EventSubWebsocketClient _eventSubWebsocketClient;

        public WebsocketHostedService(ILogger<WebsocketHostedService> logger, EventSubWebsocketClient eventSubWebsocketClient)
        {
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));

            _eventSubWebsocketClient = eventSubWebsocketClient ?? throw new ArgumentNullException(nameof(eventSubWebsocketClient));
            _eventSubWebsocketClient.WebsocketConnected += OnWebsocketConnected;
            _eventSubWebsocketClient.WebsocketDisconnected += OnWebsocketDisconnected;
            _eventSubWebsocketClient.WebsocketReconnected += OnWebsocketReconnected;
            _eventSubWebsocketClient.ErrorOccurred += OnErrorOccurred;

            _eventSubWebsocketClient.ChannelFollow += OnChannelFollow;
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            await _eventSubWebsocketClient.ConnectAsync();
        }

        public async Task StopAsync(CancellationToken cancellationToken)
        {
            await _eventSubWebsocketClient.DisconnectAsync();
        }

        private void OnWebsocketConnected(object? sender, WebsocketConnectedArgs e)
        {
            _logger.LogInformation($"Websocket {_eventSubWebsocketClient.SessionId} connected!");

            if (!e.IsRequestedReconnect)
            {
                /*
                Subscribe to topics via the TwitchApi.Helix.EventSub object, this example shows how to subscribe to the channel follow event used in the example above.

                var conditions = new Dictionary<string, string>()
                {
                    { "broadcaster_user_id", someUserId }
                };
                var subscriptionResponse = await TwitchApi.Helix.EventSub.CreateEventSubSubscriptionAsync("channel.follow", "2", conditions,
                EventSubTransportMethod.Websocket, _eventSubWebsocketClient.SessionId);

                You can find more examples on the subscription types and their requirements here https://dev.twitch.tv/docs/eventsub/eventsub-subscription-types/
                Prerequisite: Twitchlib.Api nuget package installed (included in the Twitchlib package automatically)
                */
            }
         }

        private async void OnWebsocketDisconnected(object? sender, EventArgs e)
        {
            _logger.LogError($"Websocket {_eventSubWebsocketClient.SessionId} disconnected!");

            // Don't do this in production. You should implement a better reconnect strategy with exponential backoff
            while (!await _eventSubWebsocketClient.ReconnectAsync())
            {
                _logger.LogError("Websocket reconnect failed!");
                await Task.Delay(1000);
            }
        }

        private void OnWebsocketReconnected(object? sender, EventArgs e)
        {
            _logger.LogWarning($"Websocket {_eventSubWebsocketClient.SessionId} reconnected");
        }      
      
         private void OnErrorOccurred(object? sender, ErrorOccuredArgs e)
        {
            _logger.LogError($"Websocket {_eventSubWebsocketClient.SessionId} - Error occurred!");
        }

        private void OnChannelFollow(object? sender, ChannelFollowArgs e)
        {
            var eventData = e.Notification.Payload.Event;
            _logger.LogInformation($"{eventData.UserName} followed {eventData.BroadcasterUserName} at {eventData.FollowedAt}");
        }
    }
}

Alternatively you can also just clone the examples:

• .NET Framework 4.8 https://github.com/TwitchLib/TwitchLib.EventSub.Websockets/tree/main/TwitchLib.EventSub.Websockets.Example.NetStandard
• .NET 8 -> https://github.com/TwitchLib/TwitchLib.EventSub.Websockets/tree/main/TwitchLib.EventSub.Websockets.Example