LightMediator

LightMediator is a lightweight library designed to simplify decoupled communication in distributed Windows services. It works with multiple notification types and supports services across different namespaces.

Features

• Lightweight and efficient.
• Supports publish-subscribe, request-response, and one-way notifications.
• Simplifies working with decoupled services in distributed systems.
• Easy to integrate with existing applications.
• Supports commands and command handlers for request-response communication.

Installation

You can install the LightMediator NuGet package using the following command:

dotnet add package LightMediator

Usage

Publish Notifications

You can publish notifications to subscribers using the LightMediator instance:

var mediator = new LightMediator();
mediator.Publish(new Notification("ServiceStarted"));

Handle Notifications

To handle notifications, create a class that implements the INotificationHandler<T> interface. Ensure that Notification implements the INotification interface:

public class Notification : INotification
{
    public string Message { get; }

    public Notification(string message)
    {
        Message = message;
    }
}

public class NotificationHandler : INotificationHandler<Notification>
{
    public Task Handle(Notification notification, CancellationToken cancellationToken)
    {
        Console.WriteLine($"Received: {notification.Message}");
        return Task.CompletedTask;
    }
}

Use Commands and Command Handlers

LightMediator also supports commands and command handlers to facilitate request-response communication.

Define a Command

A command is a class that implements the IRequest<TResponse> interface, where TResponse is the type of the response the command expects.

public class TestCommand : IRequest<TestCommandResponse>
{
    public string Message { get; set; }
}

Define a Command Handler

A command handler is a class that implements the IRequestHandler<TRequest, TResponse> interface. The handler contains the logic for processing the command.

public class TestCommandHandler : RequestHandler<TestCommand, TestCommandResponse>
{
    private readonly ILogger<TestCommandResponseHandler> _logger;
    public TestCommandHandler(ILogger<TestCommandResponseHandler> logger)
    {
      _logger = logger;
    }
    public override async Task<TestCommandResponse> Handle(TestCommand request, CancellationToken cancellationToken)
    {
        // Handle the command and return a response
        return new TestCommandResponse
        {
            ResponseMessage = $"Received command with message: {request.Message}"
        };
    }
}

Define a Command Response

The response is a class that contains the result of processing the command.

public class TestCommandResponse
{
    public string ResponseMessage { get; set; }
}

Sending a Command

You can send a command and get a response using the Send method from LightMediator.

 public class Worker : BackgroundService
 {
     private readonly ILogger<Worker> _logger;
     private readonly IMediator _mediator;
     public Worker(ILogger<Worker> logger,IMediator mediator)
     {
         _mediator = mediator;
         _logger = logger;
     }

     protected override async Task ExecuteAsync(CancellationToken stoppingToken)
     {
         while (!stoppingToken.IsCancellationRequested)
         {
             await _mediator.Send(new TestCommand()
             {
                 Title = "Test",
                 Description = "Test",
             });

             var res = await _mediator.Send<bool>(new TestCommandResponse()
             {
                 Title = "Test",
                 Description = "Test",
             });

             if (_logger.IsEnabled(LogLevel.Information))
             {
                 _logger.LogInformation("Worker running at: {time}", DateTimeOffset.Now);
             }
             await Task.Delay(1000, stoppingToken);
         }
     }
 }

Registering Commands , Notifications and Handlers

You can register handlers with the dependency injection container in your application startup:

// Add Mediator to the Dependency Injection container
builder.Services.AddLightMediator(options =>
{
    // Configure options for the mediator
    options.IgnoreNamespaceInAssemblies = true;
    options.IgnoreNotificationDifferences = true;
    options.RegisterNotificationsByAssembly = true;
    options.RegisterRequestsByAssembly = true;

    //Specify the assemblies to scan for notification and request
    options.Assemblies = new[]
    {
        Assembly.GetExecutingAssembly(),
        ServiceAExtensions.GetServiceAssembly(),
        ServiceBExtensions.GetServiceAssembly(),
        ServiceCExtensions.GetServiceAssembly()
    };
});

License

This project is licensed under the MIT License. See the LICENSE file for details.