Скачать или смотреть Understanding how to implement WebSocket connections with SignalR in ASP.NET Core 3.0

Learn how to effectively create WebSocket connections using SignalR in ASP.NET Core 3.0. This guide covers endpoints for creating a REST API and initiating WebSocket communication.
---
This video is based on the question https://stackoverflow.com/q/64698148/ asked by the user 'Genna' ( https://stackoverflow.com/u/12277641/ ) and on the answer https://stackoverflow.com/a/64716744/ provided by the user 'Genna' ( https://stackoverflow.com/u/12277641/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Return websocket from signalR in ASP .NET 3.0

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Implementing WebSocket Connections with SignalR in ASP.NET Core 3.0

In the world of web applications, enabling real-time communication is essential for creating interactive user experiences. One popular framework to achieve this is SignalR, which provides an easy way to add real-time web functionality to your applications. In this guide, we’ll address how to return a WebSocket connection using SignalR in ASP.NET Core 3.0, particularly in the context of a coding challenge.

The Challenge

You are tasked with creating a REST API that includes various endpoints, such as:

POST /login: Authenticate users and return a token.

GET /leaderboards/: Provide dummy data for game types.

GET /matches: List active matches.

POST /match/join: Initiate a WebSocket connection for players.

GET /match/room: Utilized exclusively for WebSocket communication with three specific messages: Fire, Move, and GetPlayers.

The trickiest part, however, is establishing a WebSocket connection to handle user interactions in real time.

How to Implement a WebSocket Connection with SignalR

Setting Up Your Hub

First, create a hub that will manage your WebSocket connections. A hub in SignalR serves as the central point for all connected clients.

Here's a simple example of what that might look like:

[[See Video to Reveal this Text or Code Snippet]]

Here, you have created a central hub class, MatchHub, where you define the methods that will handle different messages sent by clients. Each method uses Clients.All to broadcast messages to all connected clients.

Creating the Endpoint for WebSocket Connection

To establish a WebSocket connection from your API controller, you will need to create an endpoint that invokes the SignalR hub.

Here's how to do it:

[[See Video to Reveal this Text or Code Snippet]]

In this example, the JoinMatch method is responsible for creating a new WebSocket connection to the match/room endpoint. Here are the key steps involved:

Define the Endpoint: Use the [HttpGet] attribute to define the route for joining matches.

Build the Connection: Utilize the HubConnectionBuilder to set the URL to your SignalR endpoint.

Start the Connection: Call await connection.StartAsync(); to initiate the WebSocket connection.

Send Messages: Optionally, send initial messages to the hub like "Fire" to notify all clients.

Important Notes

WebSocket Initialization: WebSockets cannot be opened directly from a controller in a traditional manner; they are automatically opened when configured in the hub during startup.

No Join Method Needed: Since the hub is always active, you do not necessarily need a specific "Join" method unless you want to manage specific joins for users.

Use of a Client Library: The recommendation is to use the SignalR.Client NuGet library to manage connections and message handling easily.

Conclusion

Creating a WebSocket connection using SignalR within an ASP.NET Core 3.0 application is straightforward once you understand how to structure your hubs and handle connections. By implementing the steps outlined above, you'll be able to fulfill the requirements outlined in your coding challenge effectively.

Feel free to experiment further and, if time permits, extend your implementation with a database for persistent data storage. Real-time applications can be incredibly powerful, and mastering SignalR is a significant step in your development journey.