HamedStack.MiniMediator

HamedStack.MiniMediator is a lightweight, zero-dependency, performance-friendly mediator library built for .NET. It provides an abstraction for sending commands/queries and publishing events in a clean, decoupled way — inspired by MediatR but simplified for minimal overhead, making it easy to replace MediatR if you're looking for something more lightweight and flexible.

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📦 Features

• ✅ Request/Response (Command-Query) pattern
• ✅ Notification pattern (Pub/Sub to multiple handlers)
• ✅ Pipeline behaviors (Middleware support)
• ✅ DI-ready with IServiceCollection extension
• ✅ Runtime dynamic dispatch support
• ✅ No external package dependencies
• ✅ Similar API to MediatR, making it easy to replace

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🚀 Quick Start

1. Define a Request + Handler

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

public class PingHandler : IRequestHandler<Ping, string>
{
    public Task<string> Handle(Ping request, CancellationToken cancellationToken)
    {
        return Task.FromResult($"Pong: {request.Message}");
    }
}

2. Define a Notification + Handler

public class UserCreated : INotification
{
    public string UserName { get; set; }
}

public class SendWelcomeEmail : INotificationHandler<UserCreated>
{
    public Task Handle(UserCreated notification, CancellationToken cancellationToken)
    {
        Console.WriteLine($"Welcome email sent to {notification.UserName}");
        return Task.CompletedTask;
    }
}

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🛠 Registering in Dependency Injection

You can register the MiniMediator services into your DI container by calling AddMiniMediator.

Registering with specific assemblies:

builder.Services.AddMiniMediator(typeof(Program).Assembly);

This will scan the given assembly for any request handlers and notification handlers.

Registering with all assemblies in the current AppDomain:

If you don’t provide any assemblies, MiniMediator will automatically scan all non-system assemblies in the current AppDomain for handler implementations.

builder.Services.AddMiniMediator();

This is useful when you want to automatically discover and register all handlers in the app, eliminating the need to manually specify each assembly.

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⚙️ Using IMediator

public class SomeService
{
    private readonly IMediator _mediator;

    public SomeService(IMediator mediator)
    {
        _mediator = mediator;
    }

    public async Task DoSomething()
    {
        // Sending request and getting response
        var result = await _mediator.Send(new Ping { Message = "Hello" });
        Console.WriteLine(result); // Output: Pong: Hello

        // Publishing a notification
        await _mediator.Publish(new UserCreated { UserName = "Hamed" });
    }
}

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🧱 Pipeline Behavior Example

Create a behavior to log request processing times:

public class LoggingBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : notnull
{
    public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
    {
        var name = typeof(TRequest).Name;
        Console.WriteLine($"[START] Handling {name}");

        var response = await next();

        Console.WriteLine($"[END] Finished {name}");

        return response;
    }
}

🔧 Registering Pipeline Behaviors

Add them to your DI container:

builder.Services.AddTransient(typeof(IPipelineBehavior<,>), typeof(LoggingBehavior<,>));

Pipeline behaviors can be stacked, and they execute in the order they are registered (outermost to innermost).

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💡 Advanced Use: Dynamic Dispatch

You can send dynamically typed requests or notifications:

object dynamicRequest = new Ping { Message = "Dynamic Hello" };
var result = await _mediator.Send(dynamicRequest); // returns object

object dynamicNotification = new UserCreated { UserName = "DynamicUser" };
await _mediator.Publish(dynamicNotification);

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📚 Interfaces Overview

Interface	Description
IRequest	Marker for requests with no return value
IRequest<TResponse>	Marker for requests with a return value
INotification	Marker for notifications (pub-sub)
IRequestHandler<TRequest>	Handler for void requests
IRequestHandler<TRequest, TResponse>	Handler for response-returning requests
INotificationHandler<TNotification>	Handler for notifications
IPipelineBehavior<TRequest, TResponse>	Middleware behavior in the pipeline
IMediator	Mediator interface to send/publish