Thoughts about HTTP layer

Transcript

1. How we have been taming Faraday
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
39. Why is that problem for us?
40. Solution #2. Gem parallel
41. Final version
42. How to test an HTTP client?
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