1. Pragmatic Event-Driven Microservices
Allard Buijze –

2. Service
Service
Service

3. ‘Normal’ SQL QUERY
22 JOINS
6 SUBQUERIES

4. Layered architecture User Interface Domain Model Service Layer
Data Access Layer
Domain Model
Method invocation Cache
Worker pools
Web Cache
Session replication
Distributed 2nd level cache
Query Cache

6. Source: http://www.sabisabi.com/images/DungBeetle-on-dung.JPG

7. AxonFramework

8. Monoliths
St Breock Downs Monolith -

9. Microservices vs Monoliths
Almost all the successful microservice stories have started with a monolith that got too big and was broken up
Microservices system
Almost all the cases where I've heard of a system that was built as a microservice system from scratch, it has ended up in serious trouble.
Martin Fowler
Source:

10. Are you tall enough?
Source: martinfowler.com/bliki/MicroservicePrerequisites.html

11. Microservice journey

12. Command Query Responsibility Segregation
Events
Command model
Projections
Client

13. Location transparency
A component should neither be aware of nor make any assumptions about the location of components it interacts with.
Location transparency starts with good API design (but doesn’t end there)
A Component should not be aware, nor make any assumptions, of the location of Components it interacts with

14. Reasons to send a message
Event Something has happened

15. ‘Event-Driven’ Microservices
OrderCreated
ItemAdded
ItemRemoved
OrderConfirmed
Order service
Need to know
ordered items

16. 3 reasons to send a message
Event Something has happened
Command I want the system to do something
Query I want to know something

17. Something has happened - Event
Data change
Deadline passing
Or anything else that’s relevant in the domain

18. Publish-subscribe Want to know Something happened! Want to know

19. Exclusive consumers One of us wants to know Something happened!
Want to know

20. Competing consumers One of us wants to know Something happened!
Want to know

21. Balanced consumers One of us wants to know If (%) Something happened!
Want to know

22. I want something done - Command
Request-a-side-effect
Change data / application state
Send
Exactly 1 destination
OK / NOK reply
Maybe some data

23. Command Routing Can do something Can do something Do something!

24. I want to know something - Query
Desire for information
The response has more value than the question
(Usually) side-effect free
Different messaging patterns
Single destination
Scatter – gather query

25. Query – point to point
Result = Price
Price = 49

26. Query – scatter-gather
Price = 199
Result = Min(Price)
(wait 100ms)
If (…)
Price = 149

27. Query – scatter-gather
Price = 199
Result = Min(Price)
(wait 100ms)
If (…)
Price = 99
If (…)
Price = 149

28. ‘Event-Driven’ Microservices
OrderCreated
OrderConfirmed
ItemAdded
GetOrderDetails
ItemRemoved
OrderDetails
OrderConfirmed
Order service
Need to know
ordered items

29. At scale, different rules apply

30. How do you route all events to all components? How will this scale?

31. You Don't! It Won't!

32. As shipping module, I want to know when an order is placed
Unmanageable mess
Order Created
Item Added to Order
Shipping Address Added
Billing Address Added
Order Confirmed
As shipping module, I want to know when an order is placed

33. Bounded context
Explicitly define the context within which a model applies. Explicitly set boundaries in terms of team organization, usage within specific parts of the application, and physical manifestations such as code bases and database schemas. Keep the model strictly consistent within these bounds, but don’t be distracted or confused by issues outside.

34. Within a context, share ‘everything’

35. Between contexts, share ‘consciously’
As shipping module, I want to know when an order is placed
Order Created
+ Item Added
+ Order Confirmed
 Order Placed
Order Created
Item Added to Order
Shipping Address Added
Billing Address Added
Order Confirmed

36. Where does Axon Framework fit?
Inside each component in bounded context
Axon provides the Java APIs towards platform
EventBus, CommandBus, QueryBus
Separation of business logic and infrastructure logic

37. It’s hard to get messaging right

38. We’re all solving the same problems

39. “Just enough” intelligence
AxonIQ Messaging Platform
Understands difference between Commands, Events, Queries and their routing patterns.
Does not care about the content of these messages.
Message Broker
Sends messages. Main value add is reliability.
Enterprise Service Bus
Understands message content. Hard to configure and maintain.
dumb
smart

40. Our mission
Provide the APIs and implementations necessary for event-driven microservices to cooperate harmoniously, allowing each of them to focus on the business logic.

41. More info? Too late for that now… AxonFramework.org AxonIQ.io
Allard Buijze
@allardbz
Visit our booth
Too late for that now…