The document discusses the advantages of event-driven architectures over traditional request-response systems, showcasing a significant reduction in processing time for tasks such as email sending and PDF generation. It highlights how Grails can facilitate this by using various plugins and asynchronous processing techniques. The presentation concludes by noting that while Grails' standard architecture works in many scenarios, it has limitations in scalability and requires careful consideration based on the specific application being built.

1. GeeCON 2015
Grails and the
real-time world
IVÁN LÓPEZ - @ilopmar

2. Hello!
I am Iván López
@ilopmar
http://greachconf.com@madridgug

3. Traditional architectures
Request-response
POST /register-user
POST /register-user
POST /register-user

4. Traditional architectures

5. Traditional architectures

6. “
A problem postponed is a
problem solved.
Really?

7. 1.
Event Driven Architectures

8. Event Drive Architectures
▷ Fire & Forget
▷ Decouple producer and consumer
▷ Immediate action in the consumer
▷ Real-time

9. Traditional architecture
POST /purchase
POST /purchase
- Receive request 5 ms
- Data validation 20 ms
- Save 40 ms
- PDF generation 200 ms
- Send email 80 ms
- Render response 50 ms
Total: 395 ms

10. “
Can we do it better?

11. Event driven architecture
POST /purchase
POST /purchase
- Receive request 5 ms No
- Data validation 20 ms No
- Save 40 ms No
- PDF generation 200 ms Yes
- Send email 80 ms Yes
- Render response 50 ms No
Total: 115 ms ~ 70% better
Can anyone else do it?

12. Event driven architecture
POST /purchase
PDF
Generation
POST /purchase
- Receive request 5 ms
- Data validation 20 ms
- Save 40 ms
- Render response 50 ms
Total: 115 ms
Send email

13. “
Don't keep your clients
waiting unnecessarily!
Can I defer it?

14. Goals
▷ Loosely coupled architecture, easy to extend
and evolve.
▷ Build high performance and scalable systems
▷ Keep the business logic where “it belongs”

15. What about Grails?
▷ Platform core plugin
▷ Events plugin
▷ Executor plugin
▷ Grails 2.3+ async

16. Synchronous example
// Send confirmation email
def user = new User(params).save()
emailService.sendRegistrationMail(user)
render view:'registerOk'

17. Synchronous example
// Send confirmation email
def user = new User(params).save()
emailService.sendRegistrationMail(user)
render view:'registerOk'
class EmailService {
public void sendRegistrationMail(User user) {
sendMail {
to user.email
subject "Confirm your account"
html g.render(template: "userEmailConfirmation")
}
}
}

18. Asynchronous example
// Platform core
def user = new User(params).save()
event 'sendRegistrationMail', user
render view:'registerOk'

19. Asynchronous example
// Platform core
def user = new User(params).save()
event 'sendRegistrationMail', user
render view:'registerOk'
class EmailService {
@grails.events.Listener
public void sendRegistrationMail(User user) {
sendMail {
to user.email
subject "Confirm your account"
html g.render(template: "userEmailConfirmation")
}
}
}

20. Asynchronous example
// Executor
def user = new User(params).save()
runAsync {
emailService.sendRegistrationMail(user)
}
render view:'registerOk'
class EmailService {
public void sendRegistrationMail(User user) {
sendMail {
to user.email
subject "Confirm your account"
html g.render(template: "userEmailConfirmation")
}
}
}

21. “
I love the smell of code in the
morning

22. What if we don't want this?
▷ Extract “dependencies” to configuration
▷ Change application behaviour modifying the
configuration

23. Spring Integration
Use inside Spring the
well-know Enterprise
Integration Patterns
http://www.enterpriseintegrationpatterns.com/

24. Spring Integration
▷ Lightweight messaging mechanism for Spring apps
▷ High level abstraction for messaging
▷ External systems integration declaring adapters

25. Message
▷ Payload
▷ Headers
▷ Immutable

26. Channels
▷ Point-to-point
▷ Publish-Subscribe

27. Endpoints
▷ Transformer
▷ Filter
▷ Router
▷ Splitter
▷ Aggregator
▷ Service activator
▷ Channel-adapter
▷ Enricher
▷ Bridge
▷ ...

28. Adapters
▷ JMS
▷ AMQP
▷ TCP
▷ UDP
▷ File
▷ FTP
▷ RMI
▷ HTTP (Rest)
▷ WS
▷ Mail
▷ JDBC
▷ XMPP
▷ Twitter
▷ RSS
▷ MongoDB
▷ Redis
▷ Gemfire
▷ Stream

29. “
Talk is cheap. Show me the
code.

30. 2.
Demo

31. 3.
Summary

32. Summary
▷ Grails standard architecture fits in most of the
cases
▷ It does not scale to infinite (and beyond!)
▷ Think about the application you are building
▷ Keep the information flow in mind

33. Thanks!
Any questions?
@ilopmar
lopez.ivan@gmail.com
https://github.com/lmivan
Iván López
http://kcy.me/22ze3