How to avoid Cycle detected when publish event and listen result of this one

[thanhtrixx]

Hi team,

I want to implement an example of Coffee Shop. When an Order module is received order request, there will be a brewing event to the Brewing module and after completion, the results will be sent to the Order module. You can see the document generated below:

Unfortunately when I verify:

  @Test
  fun verifiesModularStructure() {
    val modules = ApplicationModules.of(CoffeeShopApp::class.java)
    modules.verify()
  }

Then got the following error:

Cycle detected: Slice brewing -> 
                Slice order -> 
                Slice brewing

A more specific flow is as follows:
OrderController -> OrderService (publish event) -> BrewingListener (publish event) -> OrderListener

Module structure:

.
├── CoffeeshopApp.kt
├── brewing
│   ├── BrewingResultCommand.kt
│   └── internal
│       └── BrewingListener.kt
├── common
│   ├── Log.kt
│   ├── config
│   └── exception
│       ├── InvalidParamException.kt
│       └── ModuleMetadata.kt
└── order
    ├── BrewingCommand.kt
    ├── CreateOrderReqRes.kt
    ├── OrderController.kt
    ├── OrderInfo.kt
    ├── OrderService.kt
    └── internal
        ├── OrderEntity.kt
        ├── OrderListener.kt
        ├── OrderRepository.kt
        └── OtherServiceImpl.kt

Some other information:

Java: 21
Kotlin: 2.0.0
Spring Boot: 3.3.5
Spring Modulith: 1.2.4

I'm not sure if there's anything wrong here?

[jfoder]

You need to decide which module depends on which. In your case, it seems that the Order module is dependent on the Brewing module (Order requires actions from Brewing to execute a certain scenario). Therefore, in my opinion, it makes more sense for the Brewing module to expose the interface of events it can accept, while the Order module emits an event that implements this interface. This way, the Brewing module will depend on the interface it manages itself, eliminating the dependency on the Order module.

[thanhtrixx]

Finally, I found the solution. Just add metadata for order module to define it is a OPEN module and allow Cycle listen
You can find this commit: thanhtrixx/coffee-shop@b083436