(B) Add SignalR, test using server time notifier

Clinics.Backend/API/Program.cs

@@ -3,6 +3,8 @@ using API.Options.JWT;
 using API.SeedDatabaseHelper;
 using Application.Behaviors;
 using FluentValidation;
+using Infrastructure.BackgroundServices.Notifications;
+using Infrastructure.NotificationsService;
 using MediatR;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.EntityFrameworkCore;
@@ -12,6 +14,10 @@ using Persistence.Context;
 
 var builder = WebApplication.CreateBuilder(args);
 
+
+
+// Add services to the container.
+
 #region Add Database context
 // First, get database options
 builder.Services.ConfigureOptions<DatabaseOptionsSetup>();
@@ -35,7 +41,16 @@ builder.Services.AddDbContext<ClinicsDbContext>(
     });
 #endregion
 
-// Add services to the container.
+#region Add SignalR
+builder.Services.AddSignalR();
+
+// Background services:
+builder.Services.AddHostedService<ServerTimeNotifier>();
+#endregion
+
+#region Add CORS
+
+#endregion
 
 #region Link interfaces implemented in persistence
 // Using Scrutor library
@@ -126,6 +141,10 @@ if (app.Environment.IsDevelopment())
 
 app.UseHttpsRedirection();
 
+#region Map notification HUB
+app.MapHub<NotificationHub>("notifications");
+#endregion
+
 #region CORS
 // TODO: Configure allows
 app.UseCors(policy => policy.AllowAnyHeader().AllowAnyMethod().AllowAnyHeader().AllowAnyOrigin());

Clinics.Backend/Infrastructure/BackgroundServices/Notifications/ServerTimeNotifier.cs

+using Infrastructure.NotificationsService;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Infrastructure.BackgroundServices.Notifications;
+
+public class ServerTimeNotifier : BackgroundService
+{
+    private static readonly TimeSpan Period = TimeSpan.FromSeconds(3);
+
+    #region CTOR DI
+    private readonly ILogger<ServerTimeNotifier> _logger;
+    private readonly IHubContext<NotificationHub, INotificationClient> _context;
+
+    public ServerTimeNotifier(ILogger<ServerTimeNotifier> logger, IHubContext<NotificationHub, INotificationClient> context)
+    {
+        _logger = logger;
+        _context = context;
+    }
+    #endregion
+
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        using var timer = new PeriodicTimer(Period);
+
+        while (!stoppingToken.IsCancellationRequested &&
+            await timer.WaitForNextTickAsync(stoppingToken))
+        {
+            var dateTime = DateTime.Now;
+
+            _logger.LogInformation("Executing {Service} {Time}", nameof(ServerTimeNotifier), dateTime);
+
+            await _context.Clients.All.ReceiveNotification($"Server time = {dateTime}");
+        }
+    }
+}

Clinics.Backend/Infrastructure/Infrastructure.csproj

+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>net8.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="11.9.2" />
+		<PackageReference Include="MediatR" Version="12.4.0" />
+		<PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.8" />
+		<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.8">
+			<PrivateAssets>all</PrivateAssets>
+			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
+		<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="8.0.8" />
+		<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="8.0.8">
+			<PrivateAssets>all</PrivateAssets>
+			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
+		<PackageReference Include="Scrutor" Version="4.2.2" />
+		<PackageReference Include="Swashbuckle.AspNetCore" Version="6.7.0" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<ProjectReference Include="..\Application\Application.csproj" />
+		<ProjectReference Include="..\Domain\Domain.csproj" />
+	</ItemGroup>
+
+	<ItemGroup>
+	  <Folder Include="BackgroundServices\" />
+	</ItemGroup>
+
+</Project>

Clinics.Backend/Infrastructure/NotificationsHub/NotificationHub.cs

+using Microsoft.AspNetCore.SignalR;
+
+namespace Infrastructure.NotificationsService;
+
+public class NotificationHub : Hub<INotificationClient>
+{
+    public override async Task OnConnectedAsync()
+    {
+        await Clients.Client(Context.ConnectionId).ReceiveNotification(
+            $"Connected successfully { Context.User?.Identity?.Name}");
+
+        await base.OnConnectedAsync();
+    }
+}
+
+
+public interface INotificationClient
+{
+    Task ReceiveNotification(string message);
+}
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