Upcasters are not executed in the desired order when using @Order annotation on Bean Creation Methods in a Spring Environment

[nils-christian]

This is a follow up of issue #1810.

Basic information

• Axon Framework version: 4.5.3
• JDK version: 11
• Complete executable reproducer if available (e.g. GitHub Repo): https://github.com/nils-christian/axon-upcaster-issue.git

Steps to reproduce

Clone the referenced repository. It contains a Spring Boot application (de.rhocas.axontest.axontest.AxontestApplication).
The application imports a Spring configuration containing three upcaster beans whose orders are defined by using Spring's @order annotation.

Expected behaviour

Upcaster1 is invoked before Upcaster2 and Upcaster2 before Upcaster3.

Actual behaviour

The actual order cannot be determined, but is usually 3, 1, and 2 on my machine.

The problem is, that the solution for #1810 only works if the Order annotation is used on the classes and only if the bean type is the annotated class. The code in org.axonframework.spring.config.SpringAxonAutoConfigurer.registerEventUpcasters(Configurer) uses beanFactory.getType which would return org.axonframework.serialization.upcasting.event.EventUpcaster in my case. Even if I would define the beans with Upcaster1 etc. there would still be no annotation, as the annotation is on the bean declaration not on the bean class itself.

[smcvb]

Thanks as always for drafting up an issue @nils-christian.
Although I think this wasn't clear anywhere from the documentation, what you describe is a new limitation.
As such it is more a documentation bug and an enhancement request.

I'll go look for a resolution for this, if at all possible.
The fact we don't get the bean, but the type, is to ensure that we do not initialize the upcasters too early in the configuration process.
The stage when the Spring Axon Configurer kicks in should only register the upcasters and in that function retrieve the bean.
Otherwise, Axon will come too early in the process, getting a higher chance of circular dependencies.

Lastly, I think it is clear what the workaround would be in your case.
Namely adding the annotation to the class of the upcaster instead of on the bean creation method.
Another option would be to register all the upcasters manually in an EventUpcasterChain, of course.

I hope this clarifies our intent and your options for now Nils!

[smcvb]

Good news, think I've found a solution. I will draft up a PR shortly!

[smcvb]

Closing this issue since pull request #1895 resolves it.