Embracing Change - MBLTDev 2015

Building applications can quickly become frustrating when you need to adapt to business changes. You'll often need to re-write portions of your application. Learn how you can avoid deploying updates to your application by decoupling your application from the web API. Transform your app to be simpler and more robust by keeping business logic where it belongs, on the server.

Transcript

1. EMBRACING CHANGE KYLE FULLER
4. POLLS
11. HOW DOES IT WORK?
12. GET /questions
13. DELETE /questions/{id}
14. GET /questions/{id}
15. POST /questions/{id}/choices/{choice_id}
16. POST /questions
17. APPLICATION WAS BUILT FROM AN OUT-OF-BAND SPECIFICATION
18. TIGHT COUPLING
19. WE WANT TO CHANGE SOMETHING.
20. YOUR BOSS FINDS YOU LATE ON A FRIDAY AFTERNOON
22. I'D LIKE TO...
23. > Add validation to create question with a minimum of 2 choices
24. > Add a minimum or maximum length to questions
25. > Change delete so only admins can delete questions
26. > Change delete so you can only delete your own questions
27. > Change delete so you can't delete the initial questions
28. > Change vote so you can only vote once per question
29. > Change vote so any new votes override old votes on the same question
30. > Add a new report question feature
31. THIS WILL TAKE SOME TIME...
32. BUSINESS LOGIC
33. I HAVE TO REWRITE X
35. "ANTICIPATING CHANGE IS ONE OF THE CENTRAL THEMES OF REST"
36. REPRESENTATIONAL STATE TRANSFER
37. OUR API https://polls.apiblueprint.org/
38. OUR API > Questions (affordance)
39. QUESTIONS > questions > create (affordance)
40. QUESTION > question > choices > delete (affordance) > report (affordance)
41. CHOICE > choice > votes (count) > vote (affordance)
42. SEMANTICS NOT IMPLEMENTATION DETAILS
44. $ curl https://polls.apiblueprint.org/ {"questions_url": "/questions", "url": "/"}
45. HAL application/hal+json
47. HAL $ curl https://polls.apiblueprint.org/ -H 'Accept: application/hal+json' { "_links": { "questions": { "href": "/questions" }, "self": { "href": "/" } } }
48. HAL $ curl https://polls.apiblueprint.org/questions/1 -H 'Accept: application/hal+json' { "question": "Favourite programming language?", "_links": {"self": {"href": "/questions/1"}}, "_embed": { "choices": [ { "_links": {"self": {"href": "/questions/1/choices/1"}}, "choice": "Swift", "votes": 483 } ] } }
49. $ curl https://polls.apiblueprint.org/questions -H 'Accept: application/hal+json' { "_links": { "first": {"href": "/questions"}, "self": {"href": "/questions"}, "next": {"href": "/questions?page=2"} "last": {"href": "/questions?page=2"}, }, }
50. SIREN application/siren+json
52. SIREN { "actions": [ { "name": "vote", "href": "/questions/1/choices/3", "method": "POST" } ] }
53. SIREN { "actions": [ { "name": "create", "method": "POST", "type": "application/json", "href": "/questions", "fields": [ { "name": "question", "type": "text", "title": "Question" }, { "name": "choices", "type": "array[text]", "title": "Choices" } ] } ] }
54. HYPERDRIVE
55. API BLUEPRINT + HYPERDRIVE
56. API BLUEPRINT ## Questions Collection [/questions] ### Create a new question [POST] + Relation: create + Request (application/json) + Attributes + question (string, required) + choices (array[string], required) + Response 201 (application/json) + Attributes (Question)
57. HYPERDRIVE hyperdrive.enter("https://polls.apiblueprint.org/") { result }
58. REPRESENTOR
59. DEMO
60. hyperdrive.enter("http://localhost:8000/") // follow the 'questions' transition .flatMap { hyperdrive.request($0.transitions["questions"]) } // Follow the 'create' transition .flatMap { hyperdrive.request($0.transitions["create"], attributes: [ "question": "types of egg", "choices": ["hard boiled eggs", "soft boiled eggs"] ]) } // Select the first choice .map { $0.representors["choices"]!.first! } // Follow the 'vote' transition .flatMap { hyperdrive.request($0.transitions["vote"]) }
61. DEMO
62. /// Returns whether the user may create a question var canCreateQuestion: Bool { return representor.transitions["create"] != nil }
63. /// Returns whether the user may delete the question at the given index func canDeleteQuestion(index: Int) -> Bool { let transition = questions?[index].transitions["delete"] return transition != nil }
65. import JSONSchema let schema = Schema([ "type": "object", "properties": [ "question": ["type": "string"], "choices": ["type": "array", "minItems": 2], ], ]) schema.validate([ "question": "Favourite Conference?", "choices": [ "MBLTDev 2015" ] ])
66. > the-hypermedia-project / Hyperdrive > kylef / Starship, RxHyperdrive, JSONSchema.swift > apiaryio / polls-app, polls-api
67. > kylefuller > kyle @ fuller.li > fuller.li / slides