Mobile developers conference MBLTDev15 November 17th, Moscow Organisers: e-Legion, RAEC

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 APIhttps://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. SEMANTICSNOT 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