ASPReactDemo/Api/SignalR/SignalRSendService.cs

using Microsoft.AspNetCore.SignalR;

namespace Api.SignalR
{
    public class SignalRSendService(IHubContext<WeatherUpdateHub> hubContext, ILogger<SignalRSendService> logger) : BackgroundService
    {
        
        #region Override ExecuteAsync

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            while (!stoppingToken.IsCancellationRequested)
            {
                // For example, wait 10 seconds between messages.
                await Task.Delay(TimeSpan.FromSeconds(2), stoppingToken);

                // Log or do any work here.
                logger.LogInformation("Background service sending message at: {Time}", DateTime.Now);

                // Send a message to all connected clients.
                await hubContext.Clients.User("user1234").SendAsync(
                    "ReceiveMessage", // This is the client method name.
                    "Background Service", // Example sender.
                    $"Hello from the background task at {DateTime.Now:F}", // The message.
                    stoppingToken);
            }
        }

        #endregion
    }
}