EventFlux 1.2.1

NuGet Package Information

Package	Downloads	License

EventFlux

EventFlux is a lightweight and performance-focused event processing library for .NET. It makes it easy to trigger a request and process it with multiple handlers, add pipeline behaviors, and perform deferred batch triggering.

Key Features

• Event-driven architecture
• Automatic event handler discovery and logging
• Support for deferred/batch event triggering
• Support for multiple handlers
• Add pipeline behaviors (e.g., validation, logging, cache)
• Dynamic dispatch
• Handler prerequisite query: Pre-evaluation with the CanHandle method
• Handler ordering via attribute: Multiple handlers for the same request can be executed in a defined order using [HandlerOrder(int)] attribute. Lower order values are executed first.

Quick Start

1. Install a package from NuGet (package name provided as an example):

dotnet add package EventFlux

2. Add services in Program.cs / Startup.cs:

var builder = WebApplication.CreateBuilder(args);

// Basic plugins
builder.Services
.AddEventBus(AssemblyReference.Assemblies) // or any assembly list you want
.AddEventLogging() // optional
.AddEventTimeout(); // optional

builder.Services.AddEventDispatcher();

// Example: Adding custom pipeline behavior
builder.Services.AddTransient(typeof(IEventCustomPipeline<,>), typeof(ValidationBehavior<,>));

var app = builder.Build();
app.Run();

Usage examples

• EventBus (usage awaiting an event → a response):

public class ExampleController(IEventBus _eventBus) : ControllerBase
{ 
    [HttpPost("create-user")] 
    public async Task<IActionResult> CreateUser([FromBody] CreateUserCommandRequest command) 
    { 
        CreateUserCommandResponse response = await _eventBus.SendAsync(command); 
        return Ok(response); 
    }
}

• EventDispatcher (for more dynamic/multiple redirect scenarios):

public class ExampleController(IEventDispatcher _eventDispatcher) : ControllerBase
{ 
    [HttpPost("update-user")] 
    public async Task<IActionResult> UpdateUser([FromBody] UpdateUserCommandRequest command) 
    { 
        UpdateUserCommandResponse response = await _eventDispatcher.SendAsync(command); 
        return Ok(response); 
    }
}

Example custom pipeline

public class ValidationBehavior<TRequest, TResponse> : IEventCustomPipeline<TRequest, TResponse>
where TRequest : IEventRequest<TResponse>
where TResponse : IEventResponse
{
    public async Task<TResponse> Handle(
    TRequest request,
    EventHandlerDelegate<TResponse> next,
    CancellationToken cancellationToken)
    {
        Console.WriteLine($"Validating {typeof(TRequest).Name}");

        return await next();
    }
}

CanHandle example

You can use CanHandle to perform a precondition check before calling the handler:

public class ExampleEventHandler : IEventHandler<ExampleEventRequest, ExampleEventResponse>
{
    public bool CanHandle(ExampleEventRequest @event)
        => @event.Num > 1000;

    public async Task<ExampleEventResponse> Handle(ExampleEventRequest @event)
    {
        return new() { Res = @event.Num.ToString() };
    }
}

Tests

• The project includes unit tests for EventBus and EventDispatcher. The tests verify the following:
• Correct operation of the SendAsync and PublishAsync methods
• Whether handlers are triggered according to the CanHandle method
• Correct execution of the pipeline (e.g., TimeoutBehavior, TriggerBehavior) and handler chain
• Appropriate handling of cancellation token and timeout conditions
• Correct catching or throwing of exceptions

cd .\test\EventFlux.Test\
dotnet test

Configuration and Tips

• AddEventLogging: Adds logging to monitor or debug the event flow.
• AddEventTimeout: Provides a timeout policy for long-running handlers.
• AddEventBus / AddEventDispatcher: Specify which assemblies to scan explicitly for handlers.
  • EventBus: Basic event sending and publishing.
  • EventDispatcher: Extends EventBus by allowing pipeline behaviors (IEventCustomPipeline<,>, IEventCustomPipeline<>) to be added between the request and handlers.
• Pipeline Behaviors: Inject custom logic such as validation, logging, caching, or other pre/post-processing for handlers.
• CanHandle: Implement preconditions in handlers to control whether a handler should execute.
• Error Handling: Catch exceptions within handlers to log or generate appropriate responses; unhandled exceptions may propagate depending on your implementation.
• Unit Tests: Use mocks or isolated pipeline behaviors to test handler execution, timeouts, and cancellation tokens.