How to send notification internally?

Question

ICSM Computer · Answer

To send internal (in-app) notifications using SignalR, you can broadcast or send messages to specific users or groups
without page reloads.
Here’s a full breakdown of how to implement internal notifications in an ASP.NET Core or ASP.NET MVC + SignalR app:
1. Define a Hub
C# (NotificationHub.cs)
public class NotificationHub : Hub
{
    public async Task SendNotificationToUser(string userId, string message)
    {
        await Clients.User(userId).SendAsync("ReceiveNotification", message);
    }
    public async Task BroadcastNotification(string message)
    {
        await Clients.All.SendAsync("ReceiveNotification", message);
    }
}
You can also use Clients.Group(...), Clients.Caller, etc., based on your use case.
2. Configure SignalR in Startup
ASP.NET Core:
In Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
    services.AddSignalR();
    // Optional: Add authentication
    services.AddAuthentication(...);
}
public void Configure(IApplicationBuilder app)
{
    app.UseRouting();
    app.UseAuthentication();
    app.UseAuthorization();
    app.UseEndpoints(endpoints =andgt;
    {
        endpoints.MapHubandlt;NotificationHubandgt;("/notificationHub");
    });
}
✅ 3. Client-Side JavaScript
HTML + JS:
andlt;script src="https://cdnjs.cloudflare.com/ajax/libs/microsoft-signalr/7.0.5/signalr.min.js"andgt;andlt;/scriptandgt;
andlt;scriptandgt;
    const connection = new signalR.HubConnectionBuilder()
        .withUrl("/notificationHub")
        .build();
    connection.on("ReceiveNotification", function (message) {
        alert("Notification: " + message); // or show in your UI
    });
    connection.start().catch(function (err) {
        return console.error(err.toString());
    });
andlt;/scriptandgt;
4. Send Notifications from Backend
Example in a Controller:
public class NotificationController : Controller
{
    private readonly IHubContextandlt;NotificationHubandgt; _hub;
    public NotificationController(IHubContextandlt;NotificationHubandgt; hub)
    {
        _hub = hub;
    }
    public async Taskandlt;IActionResultandgt; NotifyUser(string userId, string message)
    {
        await _hub.Clients.User(userId).SendAsync("ReceiveNotification", message);
        return Ok();
    }
    public async Taskandlt;IActionResultandgt; NotifyAll(string message)
    {
        await _hub.Clients.All.SendAsync("ReceiveNotification", message);
        return Ok();
    }
}
5. Make Sure Authentication is Set Up for Targeted Users
For Clients.User(userId) to work:
The user must be authenticated.SignalR maps the userId from ClaimsPrincipal.NameIdentifier.
If using ASP.NET MVC (non-Core), SignalR setup is slightly different. Let me know if you're on MVC 5.
Optional Enhancements
Feature
Description
Notification queue
Store unread messages in DB
User groups
Send based on roles or teams
Toaster UI
Use libraries like toastr, noty, or custom popups
Badge counters
Show unread notification counts live

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How to send notification internally?

ICSM Computer

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1 Answers

1. Define a Hub

C# (NotificationHub.cs)

2. Configure SignalR in Startup

ASP.NET Core:

✅ 3. Client-Side JavaScript

HTML + JS:

4. Send Notifications from Backend

Example in a Controller:

5. Make Sure Authentication is Set Up for Targeted Users

Optional Enhancements

Liked By

Feature	Description
Notification queue	Store unread messages in DB
User groups	Send based on roles or teams
Toaster UI	Use libraries like toastr, noty, or custom popups
Badge counters	Show unread notification counts live