Interlink

Interlink is a lightweight and modern mediator library for .NET, designed to decouple your code through request/response and notification patterns. Built with simplicity and performance in mind, it helps streamline communication between components while maintaining a clean architecture.

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✨ Features

• 🧩 Simple mediator pattern for request/response
• 🔁 Publish/Subscribe notification system
• 🔧 Pipeline behaviors (logging, validation, etc.)
• 🧠 Clean separation of concerns via handlers
• 🪝 Dependency injection support out of the box
• 🔄 Decouples logic using handlers
• 🧩 Easy registration with AddInterlink()
• 🚀 Lightweight, fast, and no external dependencies
• 🔄 Pre and Post Processors for enhanced lifecycle control
• ✅ Compatible with .NET 8 and .NET 9
• 🔍 Assembly scanning for automatic handler registration
• 🧪 Custom service factory injection
• 🔄 Pipeline ordering via attributes or configuration
• 🔄 Handler resolution caching (delegate-based)

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💡 Why Interlink?

• Clean, intuitive API
• No bloat – just powerful mediation
• Perfect for CQRS, Clean Architecture, Modular Design
• Highly extensible with behaviors and notifications

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📦 Installation

Install Interlink via NuGet:

dotnet add package Interlink

⚙️ Setup

Register Interlink in your Startup.cs or Program.cs

builder.Services.AddInterlink();

You can optionally pass an Assembly:

builder.Services.AddInterlink(typeof(MyHandler).Assembly);

📨 Request/Response Pattern

1. Define a request:

public class GetAllPets
{
    public record Query : IRequest<List<string>>;

    public class Handler : IRequestHandler<Query, List<string>>
    {
        public Task<List<string>> Handle(Query request, CancellationToken cancellationToken)
        {
            var pets = new List<string> { "Dog", "Cat", "Fish" };
            return Task.FromResult(pets);
        }
    }
}

2. Inject and use ISender:

[ApiController]
[Route("api/[controller]")]
public class PetController(ISender sender) : ControllerBase
{
    [HttpGet]
    public async Task<IActionResult> GetAllPets(CancellationToken cancellationToken)
    {
        var pets = await sender.Send(new GetAllPets.Query(), cancellationToken);
        return Ok(pets);
    }
}

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📣 Notifications (One-to-Many)

1. Define a notification:

public class UserCreated(string userName) : INotification
{
    public string UserName { get; } = userName;
}

2. Create one or more handlers:

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

3. Publish with IPublisher:

public class AccountService(IPublisher publisher)
{
    public async Task RegisterUser(string username)
    {
        // Save to DB...
        await publisher.Publish(new UserCreated(username));
    }
}

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🧬 Pipeline Behaviors

Useful for logging, validation, performance monitoring, etc.

1. Define a behavior:

public class LoggingBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
    {
        Console.WriteLine($"Handling {typeof(TRequest).Name}");
        var response = await next();
        Console.WriteLine($"Handled {typeof(TRequest).Name}");
        return response;
    }
}

Pipeline behaviors can be manually registered like this:

builder.Services.AddInterlink(config =>
{
    config.AddBehavior(typeof(LoggingBehavior<,>));
    config.AddBehavior(typeof(LoggingBehavior2<,>)); // Add more behaviors as needed
});

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Pipeline ordering can be controlled via attributes or configuration.

[PipelineOrder(1)]
public class FirstBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
    {
        Console.WriteLine("First behavior executed");
        return await next();
    }
}

[PipelineOrder(2)]
public class SecondBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
    {
        Console.WriteLine("Second behavior executed");
        return await next();
    }
}

You can also use the AddInterlink() method to specify the order of pipeline behaviors:

builder.Services.AddInterlink(config =>
{
    config.AddBehavior(typeof(FirstBehavior<,>));
    config.AddBehavior(typeof(SecondBehavior<,>));
});

🔄 Pre and Post Processor

1. Define Pre and Post Processors:

public class MyRequestPreProcessor : IRequestPreProcessor<GetAllPets.Query>
{
    public Task Process(GetAllPets.Query request, CancellationToken cancellationToken)
    {
        Console.WriteLine("[PreProcessor] Processing GetAllPets request...");
        return Task.CompletedTask;
    }
}

public class MyRequestPostProcessor : IRequestPostProcessor<GetAllPets.Query, List<Pet>>
{
    public Task Process(GetAllPets.Query request, List<Pet> response, CancellationToken cancellationToken)
    {
        Console.WriteLine("[PostProcessor] Processing GetAllPets response...");
        return Task.CompletedTask;
    }
}

Pre and Post Processors are automatically registered when you call AddInterlink().

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📦 API Overview

IRequest<TResponse>

public interface IRequest<TResponse> { }

IRequestHandler<TRequest, TResponse>

public interface IRequestHandler<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken);
}

INotification

public interface INotification { }

INotificationHandler<TNotification>

public interface INotificationHandler<TNotification>
    where TNotification : INotification
{
    Task Handle(TNotification notification, CancellationToken cancellationToken);
}

ISender

public interface ISender
{
    Task<TResponse> Send<TResponse>(IRequest<TResponse> request, CancellationToken cancellationToken = default);
}

IPublisher

public interface IPublisher
{
    Task Publish<TNotification>(TNotification notification, CancellationToken cancellationToken = default)
        where TNotification : INotification;
}

IPipelineBehavior<TRequest, TResponse>

public delegate Task<TResponse> RequestHandlerDelegate<TResponse>();

public interface IPipelineBehavior<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next);
}

IRequestPreProcessor<TRequest>

public interface IRequestPreProcessor<TRequest>
{
    Task Process(TRequest request, CancellationToken cancellationToken);
}

IRequestPostProcessor<TRequest, TResponse>

public interface IRequestPostProcessor<TRequest, TResponse>
{
    Task Process(TRequest request, TResponse response, CancellationToken cancellationToken);
}

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🔍 Example Use Case

• CQRS: Use IRequest<TResponse> for Queries and Commands
• Event-Driven architecture: Use INotification for broadcasting domain events
• Middleware-style behaviors: Add IPipelineBehavior for logging, validation, caching, etc.

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🚀 Roadmap

✅ v1.0.0 — Core Mediator Basics (Released)

• Basic IRequest<TResponse> and IRequestHandler<TRequest, TResponse>
• ISender for sending requests
• AddInterlink() for automatic DI registration
• Clean, lightweight design
• Only .NET 9 support

✅ v1.0.1 — Core Mediator Basics (Released)

• Basic IRequest<TResponse> and IRequestHandler<TRequest, TResponse>
• ISender for sending requests
• AddInterlink() for automatic DI registration
• Clean, lightweight design
• .NET 8+ support

✅ v1.1.0 — Notifications & Pipelines (Released)

• INotification and INotificationHandler<TNotification>
• IPublisher for event broadcasting
• IPipelineBehavior<TRequest, TResponse> support
• Enhanced AddInterlink() with scanning and registration for notifications and pipelines
• Updated documentation and examples
• .NET 8+ support

✅ v1.2.0 — Pre/Post Processors (Released)

• IRequestPreProcessor<TRequest> interface
• IRequestPostProcessor<TRequest, TResponse> interface
• Pre and post hooks for request lifecycle
• Optional unit-of-work behaviors

✅ v1.2.1 — Fix Critical Bugs (Released)

• Fix critical bugs in IPipelineBehavior<TRequest, TResponse>

✅ v1.3.0 — Performance & Customization (Released)

• Handler resolution caching (delegate-based)
• Custom service factory injection support
• Pipeline ordering via attributes or configuration
• Assembly scanning filters by namespace or attribute

🌐 v1.4.0 — Extensions

• Interlink.Extensions.Logging — built-in logging behavior
• Interlink.Extensions.Validation — integration with FluentValidation
• Interlink.AspNetCore — model binding & filters for ASP.NET Core

🧪 v1.5.0 — Developer Experience

• Source generator / Roslyn analyzer for missing handler detection
• Code snippets and templates for common patterns
• Custom exception types (e.g., HandlerNotFoundException)

📅 Future Ideas

• Request cancellation and timeout behaviors
• Metrics collection and tracing support
• Dynamic or externalized pipeline config (e.g., JSON-based)

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Stay tuned for more updates! Contributions and suggestions are welcome. ✨

📜 License

MIT License © ManuHub

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