berkslv

services.AddCors(options =>
{
    options.AddPolicy("ClientPermission", policy =>
    {
        policy.AllowAnyHeader()
            .AllowAnyMethod()
            .WithOrigins("http://localhost:3000")
            .AllowCredentials();
    });
});

berkslv

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllers();
    endpoints.MapHub<ChatHub>("/hubs/chat");
});

berkslv

public class ChatMessage
{
    public string User { get; set; }
    public string Message { get; set; }
}

berkslv

using Microsoft.AspNetCore.SignalR;
using WebAPI.Helpers.Models;

public class ChatHub : Hub
{
    [HubMethodName("SendMessageToAll")]
    public async Task SendMessage(ChatMessage message)
    {
        await Clients.All.SendAsync("ReceiveMessage", message);
    }