This document summarizes Ignasi Marimon-Clos' presentation on reactive microsystems. It begins with an agenda that includes a glossary of terms like reactive, message passing versus event driven. It then discusses moving from monoliths to microliths to microsystems by separating concerns like stateful and stateless services, denormalizing data, and using an event log as the source of truth. The presentation concludes by discussing how the microsystems approach can be applied within a monolith to improve scalability and resilience.

1. Ignasi Marimon-Clos - @ignasi35
Reactive Microsystems
scbcn’18

2. Ignasi Marimon-Clos - @ignasi35
Boring slide decks with lots of
boxes and caffeine deprivation
don’t go together
scbcn’18

3. @ignasi35

4. who am i ?

5. @ignasi35

6. Agenda

7. agenda
• glossary
• monolith, microlith, microsystem

8. glossary

9. glossary
• Reactive
• referred to architecture/systems
• responsive, resilient, elastic, message driven.
• See https://www.reactivemanifesto.org/
⚠ This is not a talk about reactive programming (react.js, RxJava, …)

10. glossary
• Message Passing VS Event Driven
• MP is the building block
• MP is anywhere-to-an-address —> addressable recipient
• ED is broadcasting-message —> addressable source
• See https://www.reactivemanifesto.org/

11. monolith, microlith, microsystem

12. @ignasi35
REST
Failure containment
Polyglot
Eventually Consistent (?)
Streaming data 🤔
Spatial decoupling !
(Reactive?)
Microliths
Monolith

13. @ignasi35 https://www.oreilly.com/ideas/the-evolution-of-scalable-microservices
Failure containment
Polyglot
Eventually Consistent
Streaming data
Temporal decoupling !
¿still a microlith?

14. • monolith
• microliths
• reactive microliths
Recap
• reactive microsystems ???

16. • refactor a reactive microlith with resilience and scalability in mind
microsystems
https://www.slideshare.net/jboner/from-microliths-to-microsystems

17. @ignasi35
REST

18. @ignasi35
WR WR
event-
journal
tables

19. @ignasi35
event-
journal
tables
event-
journal
tables Source of truth
Denormalised copies

20. @ignasi35
event-
journal
tables
event-
journal
tables

21. @ignasi35
event-
journal
projection
event-
ournal
event-
journal
tables

22. • CRUD
• C*UD model vs *R** model (aka Write Model vs Read Model)
• complementary eventlog
• eventlog as source of truth (in-transaction C*UD projections)
• eventlog as source of truth (eventually consistent projections)
Recap

24. • refactor a reactive microlith with resilience and scalability in mind
microsystems
https://www.slideshare.net/jboner/from-microliths-to-microsystems

25. @ignasi35
???Monolith
Recap (application level)

26. @ignasi35
event-
journal
projections
???Microlith
Recap (service level)

27. @ignasi35
event-
journal
projections
Let’s continue refactoring …
Recap (service level)

28. Journal
Snapshots
Write-side
projector
projections
IPC (broker)

29. Journal
Snapshots
Write-side
projector
projections
IPC (broker)
stateless stateful

30. • Lagom is a microservices framework promoting the creation of
services via contract-first, reactive microsystems implemented as
small clusters with a CQRS/ES persistence layer.

32. Journal
Snapshots
Write-side
projector
projections
IPC (broker)

33. Journal
Snapshots
Write-side
projector
projections
IPC (broker)

34. @ignasi35
event-
journal
projection
?Microsystems
on my
monolyth?

35. @ignasi35
•Separate stateless from stateful
•Move state to the process (not pushed on DB)
•Separate reads from writes (use different models)
•Denormalise
•… (cont’d)
Microsystems on my monolyth?

36. @ignasi35
•… (cont)
•Emit state changes
•complimentary log
•log source of truth
•Specialised nodes?
•Clustered nodes?
Microsystems on my monolyth?

37. @ignasi35
It’s not about monolith or microservices,
it’s about knowing alternatives.
Conclusion

38. Questions?

39. thank you