1. Serverless CQRS in Azure!
Toon Vanhoutte

2. Nice to meet you Toon Vanhoutte Lead Architect @ Codit Belgium
Microsoft Azure MVP
@toonvanhoutte
toonvanhoutte.wordpress.com

3. 159 Who we are worldwide 2000 Belgium 2004 France
2013 Portugal 2016 Switzerland
2016 UK
2016 The Netherlands
2017 Malta
159
worldwide
Customers
Entities

4. The thing we do

5. Agenda An Introduction to CQRS Serverless Technologies in Azure
Use Case: Optimize a Webshop
Conclusion

6. An introduction to CQRS

7. Proven and simple design
CRUD Architecture
Proven and simple design

8. Command Query Responsibility Segregation
Dealing with complex domain models
From a DDD perspective, where the business complexity requires two separate models for read and write models. Eg one database with write against database tables and reads done based on views that are optimized for the UI

9. Command Query Responsibility Segregation
Dealing with high performing applications
Improve performance, scalability and flexibility

10. Commands vs Queries Commands Queries Write Read Sync / Async Sync
Reliable
Volatile
Persistent
In Memory
Transactional
Non Transactional
Improve performance, scalability and flexibility
Fast
Fast

11. Different aspects of CQRS Multiple points of view
Event Sourcing
(store ordered historic events)
DDD (different models)
Scalability & Performance
(different stores)
Improve performance, scalability and flexibility

12. Highly performing and scalable solutions Scalability & Performance
Focus of this session
Highly performing and scalable solutions
Event Sourcing
(store ordered historic events)
DDD (different models)
Scalability & Performance
(different stores)
Improve performance, scalability and flexibility

13. Serverless in Azure

14. Pizza as a Service

15. Serverless Technology Options
Azure Functions
“Code triggered by events”
Azure Logic Apps
“Workflows triggered by events”
Azure Service Bus
“Reliable messaging platform”
Azure Event Grid
“Serverless event routing service”

16. Azure Functions Azure Logic Apps
Developer experience
Connectivity
Exception Handling
State
Networking
Deployment
Runtime
Monitoring
Pricing Model
Security

17. Azure Functions Azure Logic Apps
Preferred option for complex synchronous
request/response calls.
Preferred option for asynchronous fire-and-forget messaging.
Azure Functions perfectly extends Azure Logic Apps.

18. Azure Service Bus Azure Event Grid Report Command Notification
Transfer
Query
Measurement
Assignment
Job
Request
Trace
Update
Handover
© Clemens Vasters

19. Messaging Eventing Azure Service Bus Azure Event Grid Passing Intents
Reporting Facts
Command
Discrete
Transfer
Report
Query
Notification
Messaging
Eventing
Handover
Job
Measurement
Assignment
Update
Trace
Request
Series
© Clemens Vasters

20. Messaging Eventing Azure Service Bus Azure Event Grid Passing Intents
Reporting Facts
Discrete
“PriceUpdated”
“OpportunityWon”
“InvoiceBooked”
“CreateOrder”
“BookHotel”
“UpdateStock”
Messaging
Eventing
Temperature stream
Telemetry data
Audit trail
Series
© Clemens Vasters

21. Use Case

22. Find out how CQRS will save Antonio’s business!
Pizza Antonio
Find out how CQRS will save Antonio’s business!

23. Pizza Antonio
Website
€ 10
€ 12
€ 11
Submit
Query
Command

24. Pizza Antonio Query SQL Database Command Very good pizza’s
GetProducts
Command
CreateOrder
Very good pizza’s
Customers get errors when ordering pizza during peak hours

25. Pizza Antonio Query SQL Database Command
GetProducts
Command
CreateOrder
Customers don’t get any errors anymore
The orders don’t make it to the database, so no pizza

26. Pizza Antonio Query SQL Database Command
GetProducts
Command
CreateOrder
All orders make it to the database
Polling during quiet hours is rather expensive, so more expensive pizza’s

27. Pizza Antonio Query SQL Database Command
GetProducts
Command
CreateOrder
Cheaper polling mechanism, so again sharper prices
No flexible way to send order confirmations through

28. Pizza Antonio Query SQL Database Command
GetProducts
Command
CreateOrder
Flexible extension points for e.g. s
Two different URL’s and security keys for the website

29. Pizza Antonio Query SQL Database Command Uniform API for website
Azure Function Proxy
SQL Database
GetProducts
Command
CreateOrder
Uniform API for website
Loading products on the website is extremely slow during peak hours

30. Pizza Antonio Query SQL Database Command
Azure Function Proxy
SQL Database
GetProducts
Command
CreateOrder
Fast responsive times on the website
No flexible way to update products on external food delivery services

31. Pizza Antonio Query SQL Database Command Azure Function Proxy
GetProducts
Command
CreateOrder

32. Pizza Antonio Query SQL Database Command Antonio happy Customers happy
Azure Function Proxy
SQL Database
GetProducts
Command
CreateOrder
Antonio happy
Customers happy

33. Conclusion

34. CQRS is a proven design pattern!
It exists in many different variations
Azure Function Proxy
SQL Database
Query
Command
Sentinet
SQL Database
Query
Command
Azure API Mgmt
SQL Database
Query
Command
Cache

35. Lessons learned Azure Event Grid Azure Functions
Consumption plan results in cold starts, also for function proxies!
Solution:
Keep it warm (5 min)
App Service Plan
Pre-compiled functions
Event Grid puts responsibility for sequencing at receive side!
Solution:
Use it wisely
Consider Azure Service Bus if sequencing is required

36. Architectural Advise on CQRS
Do not overengineer!
Advantages
Challenges
Disadvantages
Performance
Idempotence
Complexity
Scalability
Eventual Consistency
Monitoring
Flexibility
Resiliency
Maintenance
Apply CQRS carefully on specific parts of the solution!

37. Thank you! Keep in touch. @toonvanhoutte toonvanhoutte.wordpress.com