This document discusses how microservices and domain-driven design can work together. It provides three key rules: 1) Model useful abstractions, not reality. 2) Don't build models for everyone, build context-specific models. 3) Don't design monolithic architectures, design individual services. Microservices are high cohesion, loosely coupled services that represent business capabilities with their own models, persistence, technology stacks, deployability and scalability. They allow individual failure without bringing down the whole system.

1. MICROSERVICES
Today’s Tools & Practices meet Domain-Driven Design
!
Trivento Spring Camp | March 27th, 2015 | Dennis Traub | @DTraub

2. - A sphere of knowledge, influence, or activity -
- What an organisation does, and the world it does it in -
DOMAIN

3. - A system of abstractions describing selected aspects of a Domain -
- Used to solve problems related to that Domain -
MODEL

4. SIT DOWN WITH THE EXPERTS & LISTEN

5. Customer
type = shipping
Address
type = billing
Address
Order
Line Item
Line Item
Line Item
Product
Product
Product
type = billing
Address
Order
Invoice
Vendor

6. http://wikimediafoundation.org/wiki/File:Commodore-VIC-20-FL.jpg

7. http://wikimediafoundation.org/wiki/File:Commodore-VIC-20-FL.jpghttp://backgrounds.1nova.com/wp-content/uploads/sites/27/2015/02/One-Ring-to-Rule-them-All.jpg
ONE MODEL TO RULE THEM ALL

8. We don’t model reality,
we model useful abstractions
Rule # 1

9. - A language structured around the Domain Model -
- Used by all team members and throughout the code -
UBIQUITOUS LANGUAGE

10. Customer
type = shipping
Address
type = billing
Address
Order
Line Item
Line Item
Line Item
Product
Product
Product
type = billing
Address
Order
Invoice
Vendor

11. Customer

12. Customer

14. Marketing
Target Group

15. Marketing
Website
Target Group
Visitor

16. Marketing
Website
Shopping Cart
Target Group
Visitor
Buyer

17. Marketing
Website
Recipient
Shopping Cart
Shipping
Target Group
Visitor
Buyer

18. Marketing
Website
Recipient
Shopping Cart
Shipping
Hotline
Target Group
Complainant
Visitor
Buyer

19. Marketing
Website
Recipient
Shopping Cart
Shipping
Hotline
Target Group
Complainant
Visitor
Buyer
Purchasing
Customer

20. - An explicit boundary within which a Domain Model exists -
- Inside, all terms have a specific meaning -
- They are part of the Ubiquitous Language -
BOUNDED CONTEXT

21. We don’t build a model
that works for everyone
Rule # 2

22. KEY ATTRIBUTES OF A BOUNDED CONTEXT

23. KEY ATTRIBUTES OF A BOUNDED CONTEXT
High Cohesion

24. KEY ATTRIBUTES OF A BOUNDED CONTEXT
High Cohesion
Loose Coupling

25. KEY ATTRIBUTES OF A BOUNDED CONTEXT
High Cohesion
Loose Coupling
Represents Business Capability

26. KEY ATTRIBUTES OF A BOUNDED CONTEXT
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model

27. Customer
Marketing
Website
Recipient
Shopping Cart
Shipping
Hotline
Target Group
Complainant
Visitor
Buyer
Purchasing
Customer

28. Customer
Marketing
Website
Recipient
Shopping Cart
Shipping
Hotline
Target Group
Complainant
Visitor
Buyer
Purchasing
Customer

34. Business Logic
Data Access
Presentation
our “Architecture”

35. Business Logic
Data Access
Presentation
our “Architecture”

36. http://wikimediafoundation.org/wiki/File:Commodore-VIC-20-FL.jpghttp://backgrounds.1nova.com/wp-content/uploads/sites/27/2015/02/One-Ring-to-Rule-them-All.jpg
ONE ARCHITECTURE TO RULE THEM ALL

37. We don’t design a
one-size-fits-all architecture
Rule # 3

38. KEY ATTRIBUTES OF A BOUNDED CONTEXT
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model

39. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model

40. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model

41. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model
+

42. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model
+
Individual Persistence

43. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model
+
Individual Persistence
Individual Tech Stacks

44. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model
+
Individual Persistence
Individual Tech Stacks
Individual Deployability

45. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model
+
Individual Persistence
Individual Tech Stacks
Individual Deployability
Individual Replaceability

46. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model
+
Individual Persistence
Individual Tech Stacks
Individual Deployability
Individual Replaceability
Individual Scalability

47. KEY ATTRIBUTES OF A MICROSERVICE
High Cohesion
Loose Coupling
Represents Business Capability
Context-specific Model
+
Individual Persistence
Individual Tech Stacks
Individual Deployability
Individual Replaceability
Individual Scalability
Can Fail Individually

48. 21

49. 21

50. FREE CHOICE OF ARCHITECTURAL STYLE
21
N-Layer CQRS
Forms
over
Data
Off-the-ShelfLambda

51. 21

52. FREE CHOICE OF PERSISTENCE MECHANISM
21

53. 21

54. FREE CHOICE OF LANGUAGE
21

55. We don’t model reality,
we model useful abstractions
Rule # 1
We don’t build a model
that works for everyone
Rule # 2
We don’t design a
one-size-fits-all architecture
Rule # 3

56. WHAT MICROSERVICES ARE ABOUT

57. For questions or suggestions:
!
Twitter: @DTraub
dtraub@thoughtworks.com
THANK YOU