These days building applications using microservice approach has become a defacto standard in many cases. Microservices are all about splitting large applications into smaller ones, which means that there must be some sort of communication between them. During this session Martins will go over how event-driven architecture can be applied for communication between various services, describe the pros and cons, and gives real world examples of how it can be used with PHP and other programming languages.

1. EVENT DRIVEN ARCHITECTURE
FOR MICROSERVICES
MARTINS SIPENKO

2. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ABOUT ME
▸ Located in Riga, Latvia
▸ martinssipenko
▸ Lead engineer @ KASKO, a fintech startup (insurance)
▸ Worked with PHP since around 2002
▸ AWS Certified
▸ Student at University of Latvia

3. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
WHY MICROSERVICES?
▸ Single responsibility services based on business logic
▸ Different technology for each service
(PHP, Golang, Node.js, AWS Lambda)
▸ Allows to scale individual service

4. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
HOW DO THE SERVICES COMMUNICATE
WITH EACH OTHER?

5. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
▸ Customer places an order
ORDER
SERVICE
THE EXAMPLE

6. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
▸ Customer places an order
▸ Then we need to generate a PDF invoice document
ORDER
SERVICE
PDF
SERVICE
THE EXAMPLE

7. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
▸ Customer places an order
▸ Then we need to generate a PDF invoice document
▸ PDF needs to be stored
ORDER
SERVICE
PDF
SERVICE
THE EXAMPLE

8. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
▸ Customer places an order
▸ Then we need to generate a PDF invoice document
▸ PDF needs to be stored
▸ Order needs to be updated with a link to PDF document
ORDER
SERVICE
PDF
SERVICE
THE EXAMPLE

9. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
INITIAL APPROACH
▸ Order service makes HTTP call to PDF service
▸ PDF is generated and stored asynchronously
▸ PDF service makes an HTTP call to update Order
ORDER
SERVICE
PDF
SERVICE
POST POST
PATCH
POST

10. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
THE PROBLEM
▸ Services have to be aware of each other
▸ PDF Service must know how to update an Order
ORDER
SERVICE
PDF
SERVICE
POST POST POST
PATCH

11. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
THE PROBLEM
▸ Services have to be aware of each other
▸ PDF Service must know how to update an Order
▸ What if we throw in more services?
ORDER
SERVICE
PDF
SERVICE
POST POST POST
PATCH
EMAIL
SERVICE Send PDF to customer
CUSTOMER
SERVICE
GET

12. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
THIS DOES NOT SCALE VERY WELL!

13. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
▸ Turn things the other way around
▸ But how will PDF service know when order was placed?
ORDER
SERVICE
PDF
SERVICE
POST POST
?
THE SECOND APPROACH

14. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
HERE COME EVENTS!

15. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
▸ All services send notifications to a central BUS
▸ There is one notification queue per service
▸ Each services queue is subscribed to BUS
▸ Each service runs a background worker that listens to
respective event queue
THE SECOND APPROACH

16. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
THE SECOND APPROACH

17. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
Order created
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
THE SECOND APPROACH

18. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
Order created
Order created
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
THE SECOND APPROACH

19. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
Order created
Order created
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
Order created
THE SECOND APPROACH

20. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
Order created
Order created
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
Ignore
Store
Ignore Ignore
Order created
THE SECOND APPROACH

21. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
Order created
Order created
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
Ignore
Store
Ignore Ignore
Order created
PDF Generated
THE SECOND APPROACH

22. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
PDF Generated
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
THE SECOND APPROACH

23. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
PDF Generated
PDF Generated
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
THE SECOND APPROACH

24. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
PDF Generated
PDF Generated
Ignore IgnoreUpdate reference Email PDF
THE SECOND APPROACH

25. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
THE SECOND APPROACH
ORDER
SERVICE
API
POST
EMAIL
SERVICE
QUEUE
CUSTOMER
SERVICE
API
ORDER
SERVICE
QUEUE
CUSTOMER
SERVICE
QUEUE
PDF
SERVICE
QUEUE
CENTRAL MESSAGE BUS
EMAIL
SERVICE
WORKER
ORDER
SERVICE
WORKER
CUSTOMER
SERVICE
WORKER
PDF
SERVICE
WORKER
PDF Generated
PDF Generated
Ignore IgnoreUpdate reference Email PDF
Order updated
Email sent

26. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
THE BENEFITS
▸ If error raises on service, the message remains in queue
▸ It will be picked up later
▸ Services don't need to know about how to make updates
to other services
▸ Adding more services is easy
▸ Scales well

27. EVENT DRIVEN ARCHITECTURE FOR MICROSERVICES
THANKS!
martinssipenko
martins.sipenko@gmail.com
https://joind.in/talk/f1078