Lessons Learned: Migrating an N-tier web application to microservices with NServiceBus

In this session at Microsoft TechDays 2015 in The Hague, I explained how I transformed an existing N-tier web application to a more scalable and manageable architecture in the microservices style. I presented the reasons for migrating and a 5-step migration plan.

2. Migrating N-tier applications to µServices Lessons learned Roy Cornelissen Lead Consultant @ Xpirit
6. Services as a network of independent parts
9. It depends
10. If you expect (or know) that your system is complex and/or has to scale in multiple dimensions
11. http://martinfowler.com/bliki/MicroservicePremium.html
13. User interface Views, ViewModels, DTO’s over HTTP Business layer ORM, business rules, mapping to DTO Database
14. Big Ol’ Database Integration Layer Service Layer Presentation Layer Silverlight Planning UI Integration Service WCF Application Logic Webservices
15. Layers
16. Remove a field here
17. Big Ol’ Database Integration Layer Service Layer Presentation Layer Silverlight Planning UI Integration Service WCF Application Logic Webservices horizontal Common Budget Payment Schedule
18. temporal response
19. temporal
20. Reliability Scalability Stability
21. RPC Throughput Load
22. Services keep their own state Events are used to notify changes Each service will have its own database Services use events to replicate data
23. Sales Billing Shipping SubmitOrder OrderAccepted OrderBilled OrderShipped
24. Messaging
25. applying async
26. RPC Throughput Load Messaging
28. get there?
29. step
30. Find module boundaries and define business events…
31. …and publish these events from existing code
32. Message Bus Big Ol’ Database Legacy logic Common Budget Payment Schedule Presentation Layer Budget UI Scheduling UI Organization UI Payment UI Budget Webservice Scheduling Webservice Organization Webservice Payment Webservice
34. Develop new features, on top of these events
35. Message Bus Big Ol’ Database Legacy logic Common Budget Payment Schedule Presentation Layer Budget UI Scheduling UI Organization UI Payment UI Budget Webservice Scheduling Webservice Organization Webservice Payment Webservice Export
36. Think about UI composition
37. Message Bus Big Ol’ Database Legacy logic Common Budget Payment Schedule Presentation Layer Budget UI Scheduling UI Organization UI Payment UI Budget Webservice Scheduling Webservice Organization Webservice Payment Webservice Export Composite UI
38. Migrate existing logic to the background
39. Message Bus Big Ol’ Database Legacy logic Common Budget Payment Schedule Presentation Layer Budget UI Scheduling UI Organization UI Payment UI Budget Webservice Scheduling Webservice Organization Webservice Payment Webservice Export
40. Split up the database
41. Service endpoints Presentation Layer Budget Scheduling Payment Organization Budget UI Scheduling UI Organization UI Payment UI Budget Webservice Scheduling Webservice Organization Webservice Payment Webservice Message Bus
42. 1. Define boundaries and publish events 2.Use these events to develop new features 3.Think about composite UI 4.Migrate existing logic to background 5.Split up the database
44. learned Microservices
45. Keep your transactions on a diet Design with parallelism in mind {Tx} {Tx} {Tx}
46. Prepare to make concessions at first Clean up later learned
47. Messaging makes totally different use cases possible Requires a new mindset for everyone learned
48. Take your time Prepare to take ~1 year for a transition learned
49. More moving parts means more complexity Evaluate whether you really need microservices learned
50. Get access to 2 full days of Udi Dahan's Advanced Distributed Systems Design video course. Sign up here: http://go.particular.net/DutchTechDays Access code: HIHIWE Expiration date: 15/6/2015
51. @roycornelissen roycornelissen.wordpress.com rcornelissen@xpirit.com bit.ly/XpiritMagazine
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