Moduliths

Tech talk about Spring Boot Moduliths, given for Optis

Transcript

1. Spring Boot Moduliths
   

   View Slide

2. 🧚 The fairy tale of a growing application
   

   View Slide

3. Medimind
   Once upon a time, there was a
   small application…
   User Inventory
   Medication
   

   View Slide

4. Medimind
   Each sprint, the application grew…
   User Inventory
   Medication
   Shedule
   

   View Slide

5. Medimind
   And grew…
   User Inventory
   Medication
   Schedule
   

   View Slide

6. Medimind
   And grew even more…
   User Inventory
   Medication
   Schedule
   Prescription
   

   View Slide

7. Medimind
   Eventually nobody understood the
   application…
   User Inventory
   Medication
   Schedule
   Prescription
   Notification
   

   View Slide

8. Notification
   Microservice
   Prescription
   Microservice
   Schedule
   Microservice
   Medication
   Microservice
   User
   Microservice
   Inventory
   Microservice
   Until one day, the Architect Wizard™ arrived,
   and transformed it into microservices….
   User
   Inventory Medication Schedule
   Notification Prescription
   Mediminder gateway
   Event bus
   

   View Slide

9. Notification
   Microservice
   Prescription
   Microservice
   Schedule
   Microservice
   Medication
   Microservice
   User
   Microservice
   Inventory
   Microservice
   Peace returned, until one day a microservice
   caught fire…
   User
   Inventory Medication Schedule
   Notification Prescription
   Mediminder gateway
   Event bus
   ❌
   
   ❌
   

   View Slide

10. Notification
    Microservice
    Prescription
    Microservice
    Schedule
    Microservice
    Medication
    Microservice
    User
    Microservice
    Inventory
    Microservice
    The fire spread…
    User
    Inventory Medication Schedule
    Notification Prescription
    Mediminder gateway
    Event bus
    ❌
    
    
    ❌ ❌ ❌
    ❌ ❌
    ❌
    ❌
    

    View Slide

11. Notification
    Microservice
    Prescription
    Microservice
    Schedule
    Microservice
    Medication
    Microservice
    User
    Microservice
    Inventory
    Microservice
    The DevOps Heroes™ quickly restarted the
    microservice…
    User
    Inventory Medication Schedule
    Notification Prescription
    Mediminder gateway
    Event bus
    

    View Slide

12. Notification
    Microservice
    Prescription
    Microservice
    Schedule
    Microservice
    Medication
    Microservice
    User
    Microservice
    Inventory
    Microservice
    And added extra infrastructure to prevent
    future problems
    User
    Inventory Medication Schedule
    Notification Prescription
    Mediminder gateway
    Event bus
    
    

    View Slide

13. The end … ?
    

    View Slide

14. What did we learn? ● High coupling is evil
    ● Microservices can help
    ● Extra resources
    ● Extra code
    ● Less focus on business code
    

    View Slide

15. 🤔 Is there an alternative?
    

    View Slide

16. Medimind
    Modular monoliths
    User Inventory Medication Schedule
    Prescription Notification
    Spring Data Events
    

    View Slide

17. Spring Data Events?
    @Entity
    // Extend from AbstractAggregateRoot
    public class Schedule extends AbstractAggregateRoot {
    @OneToMany
    private List completedEvents;
    public void addCompletedEvent(LocalDate eventDate) {
    this.completedEvents.add(CompletedEvent.of(this, eventDate));
    // Call registerEvent()
    registerEvent(MedicationTakenEvent.of(this, eventDate));
    }
    }
    

    View Slide

18. Spring Data Events?
    @Component
    @RequiredArgsConstructor
    public class MedicationTakenEventListener {
    private final InventoryFacade facade;
    @TransactionalEventListener(phase = TransactionPhase.BEFORE_COMMIT)
    public void subtractFromInventory(MedicationTakenEvent event) {
    facade.removeQuantity(event.userId(), event.medicationId(),
    event.quantity());
    }
    }
    

    View Slide

19. How to prevent high
    coupling?
    ● Java access modifiers
    ● Java modules
    ● Moduliths
    

    View Slide

20. Meet Moduliths
    /ˈmɑːd
    ͡ ʒəlɪθ/
    Speciaal voor Kenneth in
    het fonetische schrift
    

    View Slide

21. Add some dependencies…
    
    org.moduliths
    moduliths-core
    
    
    org.moduliths
    moduliths-test
    test
    
    

    View Slide

22. Structure your code…
    1. Create a new package for each module
    

    View Slide

23. Structure your code…
    2. Put exposed classes in a module package
    1. Create a new package for each module
    

    View Slide

24. Structure your code…
    3. Put implementation details in a subpackage
    2. Put exposed classes in a module package
    1. Create a new package for each module
    

    View Slide

25. … And write a test
    @ModuleTest
    public class InventoryModuleTest {
    @Test
    void moduleLoads() {
    }
    }
    

    View Slide

26. … And write a test
    

    View Slide

27. Pro’s & Con’s ● Developed by Spring Data lead
    ● Favours conventions over
    configuration
    ● Easy integration with Spring Boot
    ● Only bootstraps module during tests
    ● Small community
    ● Does not replace microservices
    

    View Slide

28. Resources
    ● https://moduliths.org/
    ● https://www.youtube.com/watch?v=bVaiTPYlHFE
    ● https://github.com/g00glen00b/medication-assistant
    ● https://speakerdeck.com/g00glen00b/tech-talk-moduliths
    

    View Slide

29. 🙏 Thank you for listening!
    

    View Slide