MitMediator

Fast mediator for handling requests, commands, notifications, and streams with ValueTask and ordered pipelines

Features

• Supports IRequest<TResponse> and IRequest (void-style)
• Custom handlers via IRequestHandler<,> and IRequestHandler<>
• Supports both ValueTask (for modern, efficient handlers) and Task (for compatibility with MediatR-style handlers)
• Enables middleware-style pipelines using IPipelineBehavior<TRequest, TResponse>. A pipeline behavior can be defined for all or specific request types.
• Supports INotificationHandler with serial and parallel publishing
• Ordered execution of pipeline behaviors
• Simple registration through AddMitMediator() or assembly scanning
• Supports IStreamRequestHandle and IStreamPipelineBehavior

Getting Started

Installation

dotnet add package MitMediator -v 10.0.0

Example Usage

This example shows a basic setup of MitMediator that demonstrates:

• Request handling via PingRequestHandler
• Notification publishing via NotificationHandler
• Two pipeline behaviors: HeightBehavior and LowBehavior

using Microsoft.Extensions.DependencyInjection;
using MitMediator;

var services = new ServiceCollection();
services
    .AddMitMediator(typeof(PingRequestHandler).Assembly)
    .AddTransient(typeof(IPipelineBehavior<,>), typeof(HeightBehavior<,>))
    .AddTransient(typeof(IPipelineBehavior<,>), typeof(LowBehavior<,>));

var provider = services.BuildServiceProvider();
var mediator = provider.GetRequiredService<IMediator>();

// HeightBehavior: Handling PingRequest
// LowBehavior: Handling PingRequest
// PingRequestHandler: Pong
// NotificationHandler: Notification!
// LowBehavior: Handled PingRequest
// HeightBehavior: Handled PingRequest
string result = await mediator.SendAsync<PingRequest, string>(new PingRequest(), CancellationToken.None);

Console.WriteLine(result); //Pong result

public class PingRequest : IRequest<string> { }

public class PingRequestHandler : IRequestHandler<PingRequest, string>
{
    private readonly IMediator _mediator;

    public PingRequestHandler(IMediator mediator)
    {
        _mediator = mediator;
    }
    
    public ValueTask<string> HandleAsync(PingRequest request, CancellationToken cancellationToken)
    {
        Console.WriteLine("PingRequestHandler: Pong");
        _mediator.PublishAsync(new Notification(), cancellationToken);
        return ValueTask.FromResult("Pong result");
    }
}

public class LowBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : IRequest<TResponse>
{
    public async ValueTask<TResponse> HandleAsync(TRequest request, IRequestHandlerNext<TRequest, TResponse> next, CancellationToken cancellationToken)
    {
        Console.WriteLine($"LowBehavior: Handling {typeof(TRequest).Name}");
        var result = await next.InvokeAsync(request, cancellationToken);
        Console.WriteLine($"LowBehavior: Handled {typeof(TRequest).Name}");
        return result;
    }
}

public class HeightBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : IRequest<TResponse>
{
    public async ValueTask<TResponse> HandleAsync(TRequest request, IRequestHandlerNext<TRequest, TResponse> next, CancellationToken cancellationToken)
    {
        Console.WriteLine($"HeightBehavior: Handling {typeof(TRequest).Name}");
        var result = await next.InvokeAsync(request, cancellationToken);
        Console.WriteLine($"HeightBehavior: Handled {typeof(TRequest).Name}");
        return result;
    }
}

public class Notification : INotification{}

public class NotificationHandler : INotificationHandler<Notification>
{
    public ValueTask HandleAsync(Notification notification, CancellationToken cancellationToken)
    {
        Console.WriteLine($"NotificationHandler: Notification!");
        return ValueTask.CompletedTask;
    }
}