How to Split Your System into Microservices

Splitting a system into microservices is a challenging task. This talk shows how ideas like Bounded Context, migration scenarios and technical constraints can be used to build a microservice architecture. Held at WJAX 2016.

Transcript

1. How to Split Your System into Microservices Eberhard Wolff @ewolff Fellow
2. http://continuous-delivery-buch.de/
3. http://microservices-buch.de/ http://microservices-book.com/
4. http://microservices-book.com/primer.html FREE!!!!
6. Microservices: Definition > No consistent definition > Microservices are modules > Independent deployment units > E.g. Docker container > Microservice owned by one team
7. Microservices: Definition Server / Container Server / Container Micro Service Micro Service
8. Microservices aim for decoupling
9. Why is the Split so Important? > Microservices implement a part of the logic > Allow isolated development of features > …and independent teams > If split is wrong, you won’t achieve goals. > …and there is just more complexity. > But there are even more goals!
10. Why Microservices? Strong Modularization Scaling Agile Sustainable development Replaceable Services Continuous Delivery Free choice of technology Handle Legacy efficient Independent Scaling Robustness Small teams develop and deploy independently Add services – not code Small Services Failure limited to single Microservice
11. Why Microservices? Scaling Agile Sustainable development Continuous Delivery Free choice of technology Handle Legacy efficient Independent Scaling Robustness Organization Deployment Units Technology
12. There are many reasons for microservices.
13. There are many scenarios for microservices.
14. Scenario and reason influence the split.
15. Bounded Context
17. UBIQUITOUS LANGUAGE VALUE OBJECT ENTITY
18. Address VALUE OBJECT ENTITY or
19. 529 pages
20. 529 pages Part IV
21. 529 pages Part IV Chapter 14
22. A domain model is only useful in a BOUNDED CONTEXT.
23. There is no universal data model in a large system.
24. Address for a customer VALUE OBJECT ENTITY or
25. Address for calculating the drones’ routes VALUE OBJECT ENTITY or
26. Microservice = Bounded Context
27. Create some Bounded Contexts! Sir, yes, sir!
31. Why would you build a universal data model if that is neither possible nor useful??
32. Bounded Context: Challenge > Not a way to design a great architecture > …but consequence of good domain architecture > i.e. clearly separated domains will lead to separated BOUNDED CONTEXTS > …containing logic and data > How can you find BOUNDED CONTEXTS?
33. Bounded Context: Challenge > Coarse-grained > Ideal: implement a functionality in one unit > Ideal: Independence > Might have relationships > …limiting independence
34. Divide by Use Cases > Microservice should implement a use case > …ideally without calling other microservices > Divide use cases among microservices > …then decide about the BOUNDED CONTEXT
35. Browsing Registration Creating Microservices User Registration Search Products by Keywords Browse Products by Category Checkout Payment Define Shipment Update Profile Basic customer data Preferences Recommendations Billing address Payment information All these services have data about the customer!!
36. Bounded Context Scaling Agile Sustainable development Continuous Delivery Free choice of technology Handle Legacy efficient Independent Scaling Robustness Organization Deployment Units Technology
37. What about other scenarios??
38. Existing Architecture Product Customer Warehouse Product Service Customer Service Warehouse Service iOS Android PoS Web
39. Let’s create some Bounded Contexts!
40. Existing Architecture Product Customer Warehouse Product Service Customer Service Warehouse Service iOS Android PoS Web Browsing
    
    
    
    
    
    
    
    
    
    
41. Bounded Contexts > Browsing distributed in many artifacts > Change to Browsing might influence all of them > …or not > BOUNDED CONTEXTS would be desirable
42. Migrate to Bounded Context Product Customer Warehouse Product Service Customer Service Warehouse Service iOS Android PoS Web Browsing
    
    
    
    
    
    
    
    
    
    Browsing
43. Introducing Bounded Contexts > …would change the architecture completely > …might be very hard > …and risky > Is it worth it? > Is it even doable? > Might also change the organization
44. Add services Product Customer Warehouse Product Service Customer Service Warehouse Service iOS Android PoS Web
45. Add services Product Customer Warehouse Product Service Customer Service Warehouse Service iOS Android PoS Web News- letter Web
46. Add Service > Might replace the old system stepwise > Immediate benefits > Low risk > Major reason for microservices
47. Cut existing services Product Customer Warehouse Product Service Customer Service Warehouse Service iOS Android PoS Web
48. Existing Architecture Scaling Agile Sustainable development Continuous Delivery Free choice of technology Handle Legacy efficient Independent Scaling Robustness Organization Deployment Units Technology
49. Existing Architecture > ...has an impact on the target architecture > What good is an architecture you cannot migrate into? > Might overrule everything else > Even BOUNDED CONTEXT
50. Browsing Registration External Systems User Registration Search Products by Keywords Browse Products by Category Checkout Payment Define Shipment Update Profile Browse Products by Category Payment Provider Logistic Partner
51. Browsing Registration External Systems User Registration Search Products by Keywords Browse Products by Category Checkout Update Profile Browse Products by Category Payment Provider Logistic Partner Payment Shipping
52. External Systems > Limit integration for each external system to one Microservice > External system might belong to a domain > …or BOUNDED CONTEXT > ...or not > Simplifies integration > Easier to achieve robustness
53. External Systems Scaling Agile Sustainable development Continuous Delivery Free choice of technology Handle Legacy efficient Independent Scaling Robustness Organization Deployment Units Technology
54. We expect a lot more registrations!
55. Browsing Registration External Systems User Registration Search Products by Keywords Browse Products by Category Checkout Payment Define Shipment Update Profile Browse Products by Category
56. Browsing Registration External Systems Search Products by Keywords Browse Products by Category Checkout Payment Define Shipment Browse Products by Category Regis- tration Update Profile
57. Technical Reasons > Independent scalability is just one technical reason > There are many more > Might be OK to share database in this scenario > Might even split read and write
58. CQRS > Command – Query Responsibility Segregation > Commands change data > Query provide data > Implement in separate microservices
59. Command Queue Command Command Command Command Handler Query Handler Command Store Database Read Replica
60. Technical Reasons Scaling Agile Sustainable development Continuous Delivery Free choice of technology Handle Legacy efficient Independent Scaling Robustness Organization Deployment Units Technology
61. Registration Requirements Browsing Checkout Marketing Sales Fulfillment Finance
62. Requirements > One microservice should implement one stream of requirements > Otherwise: coordinate priorities > …and therefore less independence
63. Registration Requirements Browsing Payment Marketing Sales Fulfillment Finance Shipping
64. Requirements Scaling Agile Sustainable development Continuous Delivery Free choice of technology Handle Legacy efficient Independent Scaling Robustness Organization Deployment Units Technology
65. Conclusion
66. Microservices = Bounded Context
67. Split Bounded Context Migration External Systems Technical Reasons Require- ments
68. EMail slideswjax2016@ewolff.com to get: Slides + Microservices Primer + Sample Microservices Book + Sample of Continuous Delivery Book Powered by Amazon Lambda & Microservices