Slides for my talk on event driven architecture from Music City Tech 2019.

1. DECOMPOSING A MONOLITH USING
EVENT DRIVEN ARCHITECTURE

2. • 15 years in development
• VP of Engineering @
Ncontracts
• Lead instructor @ NSS
• @shortmandev
• https://blog.underwhelms.com
NATHAN GONZALEZ

3. • Learn the vocabulary
• Walk through patterns
• Talk about strategies and
implementations that have worked well
for me
• Leave feeling like we learned something
GOALS

4. THE MONOLITH

5. WEBFORMS
ANGULARJS
WEB
API

6. WEBFORMS WEB API
A N G U L A R

7. THE STRATEGY

8. STRANGLER FIG PATTERN
•Select a feature slice from the
monolith
•Rebuild that piece
•Remove the redundant functionality
•Repeat

9. HOW DO THESE NEW PIECES
COMMUNICATE?

10. HTTP API?
CEA
Monolit
h

11. ADVANTAGES
•Easy way to connect 2 systems
•HTTP is a well-known protocol

12. THE DEPENDENCY IS BACKWARDS…

13. DISADVANTAGES
•New service needs to know about
the old monolith
•Tight coupling
•Lack of resiliency

14. HTTP API?
CEA
Monolit
h

15. EVENT NOTIFICATION?
CEA
Monolit
h

18. EVENT NOTIFICATION?
CEA
Monolit
h

19. THE DEPENDENCY IS IN THE RIGHT
DIRECTION!

20. ADVANTAGES
•The monolith now has a
dependency on the new application,
as it should.
•We’ve added resiliency to our
system
•Small amount of additional
complexity

21. DISADVANTAGES
•We’ve added eventual consistency
•Additional complexity
•Very chatty

22. HOW CAN WE GET RID OF THE
EXTRA REQUESTS?

23. EVENT CARRIED
STATE TRANSFER?
CEA

25. EVENT CARRIED
STATE TRANSFER?
CEA
Monolit
h

26. LOOKS PRETTY GOOD…
WHAT’S THE CATCH?

27. ADVANTAGES
•Even more resiliency
•Decoupled system
•Data redundancy
•No extra communication
•Easy extensibility

28. DISADVANTAGES
•Data Redundancy
•Significant complexity
•Eventual Consistency

29. SCALING