Thoughts about HTTP layer

Transcript

1. How we have been taming Faraday

2. None

3. My first task

4. We use Faraday

5. What else can be used for HTTP calls?

6. More detailed overview

7. My experience

8. HTTParty

9. Faraday using class methods

10. Faraday using connection

11. Get back to the task

12. How bad requests are handled

13. The problematic code

14. If you wouldn’t approve it, please, raise a hand

15. What problems have we got?

16. Adding a new request requires remembering about a lot of

    things: • Which statuses can be returned? • What errors can be thrown? • How to handle the errors? • What to do with a failed request? Retries?

17. Our codebase is heavily glued to Faraday • What if

    Faraday API would be changed? • What if we would want to change the library? • What if we would need to fix/extend current implementation? • How to test it? Should we stub HTTP requests or mock objects?

18. Everything we’re trying to achieve is to get some data

19. HTTP is only an implementation detail

20. Transportation layer Business logic Gem API

21. Isolate all transportation details

22. Business logic Transportation layer Gem API

23. Isolate your dependencies

24. Business logic Transportation layer Library wrapper Gem API

25. Situation on the project Business logic Transportation layer Gem API

26. Our plan was • Look through all the places where

    Faraday is used • Collect all the features we need to implement in our wrapper • Replace step by step Faraday with our library using feature toggles

27. Features we need to support • Retries • Follow redirects

    • Raise an error on failure • Notify to Bugsnag • Parallel execution • Configure timeouts • Different request/response data format

28. An example of serial requests

29. An example of concurrent requests

30. How have we implemented that?

31. Faraday has a great feature: middleware

32. Faraday::Response::RaiseError

33. Retries

34. The hardest part was concurrent mode

35. We use Typhoeus for concurrent requests

36. Usage

37. Solution #1: Faraday supports Typhoeus adapter

38. None

39. Why is that problem for us?

40. Solution #2. Gem parallel

41. Final version

42. How to test an HTTP client?

43. None

44. Mock requests

45. Webmock

46. More about the topic

47. Summary • Write a high-level abstractions which correspond to actual

    business rules • Isolate dependencies on gems/libs • Explicit is better than implicit a.k.a keep everything you can under your control • Write tests

48. Useful links • https://github.com/lostisland/faraday/issues/1310 • https://thoughtbot.com/upcase/videos/testing-interaction-with-3rd-party-apis • https://gist.github.com/woarewe/543a1275382941ffbb87324d2b302100 • https://gist.github.com/woarewe/81e2f8d181f99511985f91926d7f2f54

    • https://gist.github.com/woarewe/16a33e3eecbd7e2af9622afb2898db28 •

49. Thanks