LiteBus

A lightweight, flexible in-process mediator for implementing Command Query Separation (CQS)

For detailed documentation and examples, please visit the Wiki.

Key Features

• Built in .NET 8

• Zero external dependencies - Completely standalone with no third-party dependencies

• Reduced reflection usage - Optimized for performance with minimal reflection

• DDD-friendly design - Support for plain domain events without library dependencies, keeping your domain model clean

• Comprehensive messaging types:

  • ICommand / ICommand<TResult> - For state-changing operations
  • IQuery<TResult> - For data retrieval operations
  • IStreamQuery<TResult> - For streaming large datasets via IAsyncEnumerable<T>
  • IEvent - For notifications and event-driven architecture
  • Support for POCO objects as messages without library interfaces

• Rich handler ecosystem:

  • Pre-handlers for validation and pre-processing
  • Post-handlers for notifications and side effects
  • Error handlers for centralized exception management
  • Support for generic handlers and messages
  • Handler ordering control
  • Contextual handler selection via tags and filters

• Advanced features:

  • Covariant type handling for polymorphic dispatch
  • Execution context for cross-cutting concerns
  • Aborting execution flow when needed
  • Microsoft Dependency Injection integration

Quick Example

// Define the command result
public record CreateProductCommandResult(Guid Id);

// Define a command with a result
public record CreateProductCommand(string Title) : ICommand<CreateProductCommandResult>;

// Implement a command validator
public class CreateProductCommandValidator : ICommandValidator<CreateProductCommand>
{
    public Task ValidateAsync(CreateProductCommand command, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(command.Title))
            throw new ValidationException("Product title cannot be empty");
            
        return Task.CompletedTask;
    }
}

// Implement a command handler
public class CreateProductCommandHandler : ICommandHandler<CreateProductCommand, CreateProductCommandResult>
{
    private readonly IProductRepository _repository;
    
    public CreateProductCommandHandler(IProductRepository repository)
    {
        _repository = repository;
    }
    
    public async Task<CreateProductCommandResult> HandleAsync(CreateProductCommand command, CancellationToken cancellationToken = default)
    {
        var product = new Product(Guid.NewGuid(), command.Title);
        
        await _repository.SaveAsync(product, cancellationToken);
        
        return new CreateProductCommandResult(product.Id);
    }
}

// Configure in ASP.NET Core
services.AddLiteBus(liteBus =>
{
    liteBus.AddCommandModule(module =>
    {
        module.RegisterFromAssembly(typeof(CreateProductCommand).Assembly);
    });
});

// Use in a controller or service
public class ProductsController : ControllerBase
{
    private readonly ICommandMediator _commandMediator;
    
    public ProductsController(ICommandMediator commandMediator)
    {
        _commandMediator = commandMediator;
    }
    
    [HttpPost]
    public async Task<ActionResult<CreateProductCommandResult>> CreateProduct(CreateProductCommand command)
    {
        var result = await _commandMediator.SendAsync(command);
        return Ok(result);
    }
}

Documentation

For comprehensive documentation, including detailed explanations, advanced features, and best practices, please visit the Wiki.

Installation

LiteBus is available as NuGet packages:

dotnet add package LiteBus
dotnet add package LiteBus.Extensions.MicrosoftDependencyInjection

Or specific modules:

dotnet add package LiteBus.Commands
dotnet add package LiteBus.Queries
dotnet add package LiteBus.Events

License

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