Zwergenland.CleanMessageBus.Abstractions 1.2.1

CleanMessageBus

This package provides an abstraction around message busses for easy integration of events. Currently the following message brokers are supported:

• RabbitMQ

Publishing Events

• Event object must implement marker interface IIntegrationevent for integration events ot IDomainEvent for domain events

• Inject IMessageBus to desired service

• Publish event by using IMessageBus.PublishAsync(integrationEvent)

• Automatic creation of producer resource on message bus (for example exchange for rabbitmq)

• Example:

public record UserRegisteredEvent(string Username, string Email) : IIntegrationevent;

var integrationEvent = new UserRegisteredEvent("JohnDoe", "john@doe.com");
await messageBus.PublishAsync(integrationevent);

Change producer name

• Use attribute [Produces(Name="ProducerName")] to set producer name

Handling Events

• Handler must inherit from IntegrationEventHandlerBase<TIntegrationEvent> class for integration events or from DomainEventHandlerBase<TDomainEvent> for domain events
• Generic type specifies domain event type to receive
• Implementation logic must be implemented in the Handle method
• Registration happens automatically via dependency injection
• Automatic creation of consumer resource on message bus (for example queue for rabbitmq)
• Integration of CleanDomainValidation result types

Example:

public class UserRegisteredEventHandler : IntegrationEventHandlerBase<UserRegisteredEvent>
{
    public override async Task<CanFail> Handle(UserRegisteredEvent @event, CancellationToken cancellationToken)
    {
        Console.WriteLine($"User {@event.Username} with email {@event.Email} has been registered.");
        
        //TODO furhter logic in here
        
        return CanFail.Success;
    }
}

Change consumer name

• Use attribute [ConsumedBy(Name="ConsumerName")] to set consumer name
• Not allowed for domain events!

Change producer name

• Use attribute [ProducedBy(Name="ProducerName")] to set producer name

Throttle message rate

• Use attribute [Throttled(RequestInterval=1000)] to set message processing interval
• Message bus waits specified time (in ms) before processing the next event

Configuration via dependency injection

• Define assemblies containing events and handlers
• Select and configure message broker

Example:

builder.Services.AddCleanMessageBus(config => config
    .RegisterIntegrationEventsFromAssembly(Assembly.GetExecutingAssembly())
    .RegisterDomainEventsFromAssemby(Assembly.GetExecutingAssembly())
    .RegisterHandlersFromAssemby(Assembly.GetExecutingAssembly()
    .UseRabbitMq(rabbitConfig => rabbitConfig
        .WithHostname("localhost")
        .WithCredentials("username", "password")
        .UseSsl())));