Brer 1.0.13

Brer

A rabbitMQ library for ASP.NET.

Special thanks to Marco Pil

• Brer
• How do i use Brer?
  • Initial Setup
  • Registering/Decorating an EventListener
    • Handler
    • WildCardHandler
  • Publishing events.
  • Error handling.
• I want to contribute!
• I'm missing a feature!

How do i use Brer?

Brer makes use of a hostedservice in ASP.NET.

A basic brer startup example can be found here.

Initial Setup

In short one must register the Brer services as follows:

services.UseBrer(
    new BrerOptionsBuilder().WithAddress(BrerOptionsBuilder.localHost, BrerOptionsBuilder.defaultPort)
        .WithPassword(BrerOptionsBuilder.defaultLogin)
        .WithUsername(BrerOptionsBuilder.defaultLogin)
        .WithExchange("MyExchange")
        .WithQueueName("MyQueue")
        .Build()
);

Brer can also be configured using environment variables as follows:

services.UseBrer(new BrerOptionsBuilder().ReadFromEnviromentVariables().Build());

Where it will look for the following variables:

• BrerHostName
• BrerPort
• BrerExchangeName
• BrerQueueName
• BrerUserName
• BrerPassword

Registering/Decorating an EventListener

Brer will automatically scan all referencing assemblies for EventListeners.

Once a class is annoted with the EventListener attribute it will further scan the class for Handler or WildCardHandler.

If Listeners collide on topic names Handler will always take priority over WildCardHandler.

Handler

[EventListener]
public class MyEventHandler{

    [Handler(topic:"MyTopic")]
    public async Task Handle(MyEvent @event){
        // do stuff
    }

}

WildCardHandler

When using a WildCardHandler you're required to use at least 1 wild card in the topic binding.

Wild cards can contain as many * as wanted but impose some restrictions on the usage of #. Only 1 # can be used somewhere in the middle of a topic name and 1 the end. if you require more it's likely best to re-evaluate the topic naming or simply use *.

A valid format would be:

• MyGarage*.Rental.Cars.#.Internal.*.#
• #
• etc

An invalid format would be: MyGarage.#.Cars.#.Internal.*.# We use two #'s in the middle of the topic here which is not allowed.

[EventListener]
public class MyEventHandler{

    [WildCardHandler("MyTopic.#")]
    public async Task Handle(MyEvent @event){
        // do stuff
    }

}

Publishing events.

To publish an event simply inject the IBrerPublisher into your class.

public class MyEventPublisher{

    private readonly IBrerPublisher _brerPublisher;

    MyEventPublisher(IBrerPublisher brerPublisher){
        _brerPublisher = brerPublisher;
    }

    PublishEvent(){
        _brerPublisher.Publish("MyTopic", MyEvent)
    }
}

Error handling.

Brer currently does not support DLX or 'poison queues' brer does however add some message headers to give insights into exceptions and requeue counts.

These headers are:

• x-Brer-Exception
• x-Brer-Exception-Message
• x-Brer-Exception-StackTrace
• x-Brer-RequeueCount

Using these headers, you could add your own DLX / poison queue logic f.e. by checking the requeue count and if it's above 3 sending it to a poison queue. Just make sure you preserve the other headers, to make debugging & tracing a lot easier.

I want to contribute!

As of now we'd greatly appreciate adding support for different exchange types. And adding dlx support / requeue-ing messages from a dlx.

notes:

• No global usings
• Use SonarLint
• Rider/ReSharper default styling preferred

I'm missing a feature!

Simply open an issue