SignalR: Real-time web applications with SignalR
SignalR is a real-time web application framework developed by Microsoft that enables bi-directional communication between server and client. It allows for instant updates and notifications to be sent to clients without the need for constant polling.
How SignalR works
SignalR uses WebSockets by default to establish a persistent connection between the server and the client. If WebSockets are not supported by the browser or server, SignalR falls back to other techniques like Server Sent Events or Long Polling.
Code snippet: Setting up SignalR in ASP.NET
```csharp // Startup.cs public void ConfigureServices(IServiceCollection services) { services.AddSignalR(); } public void Configure(IApplicationBuilder app, IWebHostEnvironment env) { app.UseRouting(); app.UseEndpoints(endpoints => { endpoints.MapHubSample example: Real-time chat application
In this example, let's create a simple real-time chat application using SignalR.
```javascript // client.js const connection = new signalR.HubConnectionBuilder() .withUrl("/chatHub") .build(); connection.on("ReceiveMessage", (user, message) => { console.log(`${user}: ${message}`); }); connection.start().then(() => { connection.invoke("SendMessage", "Alice", "Hello, SignalR!"); }); ``` ```csharp // ChatHub.cs public class ChatHub : Hub { public async Task SendMessage(string user, string message) { await Clients.All.SendAsync("ReceiveMessage", user, message); } } ```Common use cases
- Real-time chat applications
- Live sports scores updates
- Collaborative document editing
Importance in interviews
SignalR is a popular topic in technical interviews, especially for web development roles. Understanding how SignalR works and its use cases can set you apart from other candidates and showcase your proficiency in real-time web applications.
Conclusion
SignalR is a powerful tool for building real-time web applications that require instant updates and notifications. By leveraging SignalR, developers can create interactive and engaging user experiences that keep users connected and informed in real-time.
