A lightweight, flexible in-process mediator for implementing Command Query Separation (CQS)
For detailed documentation and examples, please visit the Wiki.
Key Features
Built for .NET 8 and .NET 9 - Multi-targeting support for maximum compatibility
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.
