“Fighting with giants - GraphQL soft adoption at Revolut” talk by Andrii Los at kraków.emit(4). https://www.meetup.com/krakow-emit/events/259491687/ How to use GraphQl in your product while minimizing cost and risks? How to integrate it with TypeScript? What are the advantages and downsides of adopting it? Revolut had to answer all those questions and Andrii Los will share with you what issues they faced, how did they solve them and what are the takeaways. Andrii Los is a Senior Frontend Engineer at Revolut. He graduated from Dnipro Polytechnic University with a Master's degree in Computer Science. He's worked as a software engineer for 6 years, doing backend in Java, working with Big Data problems and more recently - working with technologies like TypeScript, React, GraphQL, CSS-in-JS.

1. GraphQL in Revolut
Soft adoption

2. Andrey Los
Backoffice and Infrastructure
Krakow, Poland

3. OverviewGraphQL. What it is?

4. Long story short
Specification
Created by Facebook, now under Linux Foundation
Schema definition language(SDL)
Query language

11. Main features
Free fully typed documentation
Powerful developer tools
Flexibility: you get what you ask, seamless deprecation
Ready to use client implementations
Code generation of types on client based on schema

12. Cons
Team has to know how to cook it right
The only format is JSON
All answers from server are 200

13. OverviewProof of concept problems

14. Proof of concept problems
People
Infrastructure
Time
Risks

15. How to keep it simple?

16. GraphQL
“server” on client

20. How it’s even possible?
Apollo Client
apollo-link-http
apollo-link-schema

21. OverviewWhat problems it solves for us?

22. Our problems
A lot of new people
Many old APIs
Problems with their documentation
Problems with process of documenting new APIs

24. Запись autocomplete из GraphiQL

25. Main problems at the beginning
Double work (Typing in GQL schema, typing in TS)
Size of the schema outgrown 3k locs in a month

26. Double work

32. Schema driven development

33. Schema
Codegen types for resolvers

34. Schema
Codegen types for resolvers
Resolvers implementation

35. Schema
Codegen types for resolvers
Resolvers implementation
Write client queries

36. Schema
Codegen types for resolvers
Resolvers implementation
Write client queries
Codegen of types for queries

37. Schema
Codegen types for resolvers
Resolvers implementation
Write client queries
View implementation
Codegen of types for queries

38. Change to schema
Re-generation of types

39. Change to schema
Re-generation of types
Broken compilation

40. Change to schema
Re-generation of types
Broken compilation
Compilation errors fix

41. Change to schema
Re-generation of types
Broken compilation
Compilation errors fix
Done

42. Huge schema grow

45. OverviewFuture

46. Future
Extraction of client “server” to a real Node server
Wide adoption at Backoffice
Extension on other projects
Native Kotlin/Java GraphQL server?

47. OverviewSummary

48. Summary
We proof of concept GraphlQL DX on production
We learned a thing or two from it
Improved our docs significantly
Improved development speed and DX
Found a lot of bugs
Next steps - even better

49. Andrey Los
Twitter: @RIP212
GitHub: @RIP21