Polyglot heaven
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A presentation about data and how to build polyglot applications. The key component, as I see it, to build polyglot data applications is to use an event store as the master data storage and then use other types of databases as views of that data. The presentation also touches on Command Query Responsibility Segragation, CQRS, and event sourcing.
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Polyglot heaven
- 1. POLYGLOT HEAVEN How to Build an Async, Reactive Application in 2014 NDC London Tomas Jansson 04/12/2014
- 2. POLYGLOT HEAVEN How to Build an Async, Reactive Application in 2014 NDC London Tomas Jansson 04/12/2014 And this should probably be 2015 This here, a title to get accept
- 3. THIS IS ME Tomas Jansson Manager & Practice Lead .NET BEKK Oslo @TomasJansson tomas.jansson@bekk.no github.com/mastoj blog.tomasjansson.com
- 4. AGENDA WHY ASYNC AND REACTIVE? LET’S TALK DATA WHY POLYGLOT? WHAT CAN WE DO? DEMO SUMMARY
- 5. WHY ASYNC AND REACTIVE? - ASYNC Async doesn’t mean unreliable Async gives you responsiveness Data will be consistent
- 6. WHY ASYNC AND REACTIVE? - REACTIVE Message based modular React on change Eventual consistent
- 7. LET’S TALK DATA Let’s talk Data
- 8. LET’S TALK DATA Are all data the same?
- 10. LET’S TALK DATA What different kinds of data do we have?
- 11. LET’S TALK DATA Changes, state, relations, cache...
- 12. ”if all you have is a hammer, everything looks like a nail” Why polyglot?
- 13. WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS Documents
- 14. WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS Documents Document database
- 15. WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS Documents Document database Changes
- 16. WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS Documents Document database Changes Event store
- 17. WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS Documents Document database Changes Event store Relations
- 18. WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS Documents Document database Relations Graph database Changes Event store
- 19. What can we do?
- 20. Change!
- 21. 3-LAYERED ARCHITECTURE – WHY OH WHY?
- 22. 3-LAYERED ARCHITECTURE – WHY OH WHY? You are mixing your domain with your query model!
- 23. What do you think about ”Divide and Conquer?”
- 24. COMMAND QUERY RESPONSIBILITY SEGREGATION - CQRS CQRS is ”Divide and Conquer” applied on a architecutral level
- 25. CQRS WITH EVENT SOURCING - OVERVIEW ApplicationCommand Events Events Projection View
- 26. CQRS WITH EVENT SOURCING - OVERVIEW Application: f(x, ys) ys’, x: Command, ys: list of Events Projection: f(y, ys) z, y: Event, ys: list of Events, z: View
- 27. CQRS WITH EVENT SOURCING - OVERVIEW Application: f(x, ys) ys’, x: Command, ys: list of Events Projection: f(y, ys) z, y: Event, ys: list of Events, z: View Your application is a pure function! How you implement it is secondary, the events are what matters!
- 28. CQRS WITH EVENT SOURCING - TESTS [Test] public void PlaceOrder_Should_CreateAnOrder() { var productId = Guid.NewGuid(); var customerId = Guid.NewGuid(); var orderId = Guid.NewGuid(); var orderItems = Contracts.Helpers.ToFSharpList(new[] {new OrderItem(productId, 20)}); Given(new ProductCreated(productId, "a name", 20), new CustomerCreated(customerId, "John Doe")); When(new PlaceOrder(orderId, customerId, orderItems)); Then(new OrderPlaced(orderId, customerId, orderItems)); } Pure functions are easy to test
- 29. WHAT WILL I SHOW TODAY? ApplicationCommand Events Events Projection View
- 30. WHAT WILL I SHOW TODAY? ApplicationCommand Events Events Projection View HTTP
- 31. THE KEY COMPONENT This is where the ”truth” is stored
- 32. Demo!
- 34. SUMMARY Why async and reactive? • Responsive • Scalable • Modular
- 35. SUMMARY Why async and reactive? • Responsive • Scalable • Modular Why polyglot? • Not all data is the same • Not everything is a nail
- 36. SUMMARY Why async and reactive? • Responsive • Scalable • Modular Why polyglot? • Not all data is the same • Not everything is a nail Event sourcing and CQRS • CQRS is divide and conquer on an architecture level • Your application should be a function • You don’t have to write in a functional language to write functional code (but it might make it easier)
- 37. SUMMARY Why async and reactive? • Responsive • Scalable • Modular Why polyglot? • Not all data is the same • Not everything is a nail Event sourcing and CQRS • CQRS is divide and conquer on an architecture level • Your application should be a function • You don’t have to write in a functional language to write functional code (but it might make it easier)
- 39. Questions?
Notas del editor
- Trenger en ny profilbilde
- You will get a response, it is not fire and forget model your error handling Responsiveness return to the user early The data will be consistent, at some point in time
- Applications that react to changes Message based, in the form of event Things are modular fits in your head. This doesn’t mean it is not complex, the connections between the modules might be harder to see Not all system react at the same time, but it will lead to eventual consistency
- A simple question
- No! Not all data are the same, so why are we often treaten the data the same way (yes I’m thinking about SQL)
- Changes or events
- I’ve had some discussion with other people telling me that the thing I sugges is the new hammer since it is new and shiny and we should stick with SQL. But that reasoning makes SQL your hammer. I’m suggesting different tools for different problems.
- SQL is terrible at relations, if they get somewhat complex. Use SQL for reporting, then it is great!
- Standard picture from googling the ”standard” architecture 3-layered architecture
- As soon as you want to show the user some variation of the data you have to change the model where you have your domain logic makes your domain complex doing more than it is supposed to.. Domain is about behavior and changes!
- This is a technique most of us learned in college or university, so why doesn’t we use it more?
- This is a really simplified picture of CQRS, but it’s not that simplified. It comes from CQS but applied to todays context
- I do have a test helper, but it is just setting up dependencies