REST in practice - FrOSCon 2012

Transcript

1. FrOSCon, Bonn - Germany 25-26 August 2012 REST in practice? How to deal with
2. Joshua Thijssen / Netherlands Freelance consultant, developer and trainer @ NoxLogic / Techademy Development in PHP, Python, Perl, C, Java.... Blog: http://adayinthelifeof.nl Email: jthijssen@noxlogic.nl Twitter: @jaytaph 2
3. REST 3 Representational State Transfer
4. REST 3 Representational State Transfer It’s not hard:
5. REST 3 Representational State Transfer It’s not hard: like poker, or chess
6. 4 ➡ Quick REST recap ➡ Common “myths” ➡ Common “mistakes” ➡ How to do stuff @Todo:
7. 5 Quick REST recap
8. 6 Are you doing REST?
9. Restful constraints 7 ➡ Client / Server ➡ Stateless ➡ Cacheable ➡ Layered system ➡ Code on demand (optional) ➡ Uniform interface
10. Uniform interface 8 ➡ Identification through representations of resources ➡ Manipulation through representations ➡ Self-descriptive messages ➡ Hypermedia as the engine of application state (HATEOAS)
11. Are you mature enough? 9 (according to Richardson)
12. 10 http://martinfowler.com/articles/richardsonMaturityModel.html
13. 11 http://martinfowler.com/articles/richardsonMaturityModel.html Level 0: Plain Old XML ➡ HTTP is tunnel protocol ➡ POST to single URL (or worse: GET) ➡ SOAP / XML-RPC
14. 12 http://martinfowler.com/articles/richardsonMaturityModel.html Level 1: Resources ➡ Entities are resources ➡ /user/jthijssen instead of /users ➡ /user/jthijssen/talks
15. 13 http://martinfowler.com/articles/richardsonMaturityModel.html Level 2: HTTP Verbs ➡ POST or PUT for creations ➡ GET for retrievals ➡ POST or PUT for updates ➡ DELETE for deletions ➡ PATCH for partial updates
16. 14 http://martinfowler.com/articles/richardsonMaturityModel.html Level 3: Hypermedia controls ➡ HATEOAS ➡ Hypermedia as the engine of application state ➡ Using links to detect your next states ➡ One bookmark link to rule them all
17. 15 Let’s go to DisneyLand!
18. 15 Wait, wut? Let’s go to DisneyLand!
19. 16 Are you (still) doing REST?
20. 17 Common “myths”
21. REST == HTTP 18
22. REST == CRUD 19
23. URL’s are important 20
24. REST scales 21
25. COOKIES are EVIL 22
26. 23 I’ve never have eaten a cookie in my life...
27. 24 Gimme moar cookies! Om nom nom!
28. 25 Application state vs Resource state
29. ➡ User has got multiple addresses ➡ Entity X/Y/Z is set to 42 26 Resource state
30. ➡ User has got multiple addresses ➡ Entity X/Y/Z is set to 42 26 Resource state Resource state never changes through GET (or other safe) methods!
31. ➡ Which “stage” is the user in the checkout process? ➡ Which page is the user currently browsing ➡ Is the user currently logged in? ➡ Depends.... 27 Application state
32. 28 “Per client” state should be saved by the client, not on the server.
33. 28 “Per client” state should be saved by the client, not on the server. It’s called Representational STATE TRANSFER
34. 29 Common “mistakes”
35. 30 PUT or POST?
36. 30 PUT or POST? PUT when the resource URI is known PUT /user/jthijssen/talk/123
37. 30 PUT or POST? PUT when the resource URI is known POST when it’s not (server decides) PUT /user/jthijssen/talk/123 POST /user/jthijssen/talks
38. 31 PUT = idempotent, POST is not!
39. 31 PUT /user/jthijssen/talk/123 PUT = idempotent, POST is not! PUT /user/jthijssen/talk/123 PUT /user/jthijssen/talk/123
40. 31 PUT /user/jthijssen/talk/123 POST /user/jthijssen/talks PUT = idempotent, POST is not! PUT /user/jthijssen/talk/123 PUT /user/jthijssen/talk/123 POST /user/jthijssen/talks POST /user/jthijssen/talks
41. 31 PUT /user/jthijssen/talk/123 POST /user/jthijssen/talks PUT = idempotent, POST is not! PUT /user/jthijssen/talk/123 PUT /user/jthijssen/talk/123 POST /user/jthijssen/talks POST /user/jthijssen/talks POST is the worst option for caching / scalability, but use it if you don’t know what to do.
42. 32 If you need to “construct” an URI, you are doing it wrong
43. 32 url = MAIN_URL + “/” + user_id + “/talks”; rc = HTTP.post(url, data); If you need to “construct” an URI, you are doing it wrong
44. 32 url = data.link_rel(“talks”, user_id); rc = HTTP.post(url, data); url = MAIN_URL + “/” + user_id + “/talks”; rc = HTTP.post(url, data); If you need to “construct” an URI, you are doing it wrong
45. 32 url = data.link_rel(“talks”, user_id); rc = HTTP.post(url, data); url = MAIN_URL + “/” + user_id + “/talks”; rc = HTTP.post(url, data); Uri can change: server, uri, protocol, port etc.. If you need to “construct” an URI, you are doing it wrong
46. 33 Composite resources
47. Watch out with visibility 34 <xml version=”1.0” encoding=”utf-8”> <persons> <person> <name>Joshua Thijssen</name> <phone type=”cell”>0612345678</phone> <link rel=”address” href=”/users/jthijssen/address”> </person> ... <persons>
48. Watch out with visibility 35 <xml version=”1.0” encoding=”utf-8”> <persons> <person> <name>Joshua Thijssen</name> <phone type=”cell”>0612345678</phone> <address> <street>Mainstreet 1234</street> <postalcode>1234AB</postalcode> <city>Amsterdam</city> <country>Netherlands</country> </address> <link rel=”address” href=”/users/jthijssen/address”> </person> ... </persons>
49. Watch out with visibility 36 person address
50. Watch out with visibility 36 person address person address
51. Watch out with visibility 36 person address person address address
52. Watch out with visibility 36 person address person address address Duplicated cache!
53. Watch out with visibility 36 person address person address address Duplicated cache!
54. ➡ Degrades resource visibility since they contain overlapping data ➡ Use caching proxies! (maybe ESI???) ➡ Each client needs a different composite. 37
55. 38 It sounded like a good idea at the time...
57. ➡ Use HTTP (verbs) wisely 39
58. ➡ Use HTTP (verbs) wisely ➡ Etags / If-(not-)modified 39
59. ➡ Use HTTP (verbs) wisely ➡ Etags / If-(not-)modified ➡ HTTP codes 39
61. ➡ HTTP 1xx : Do I got info for you! 40
62. ➡ HTTP 1xx : Do I got info for you! ➡ HTTP 2xx : We’re cool.. 40
63. ➡ HTTP 1xx : Do I got info for you! ➡ HTTP 2xx : We’re cool.. ➡ HTTP 3xx : Take a look there.. 40
64. ➡ HTTP 1xx : Do I got info for you! ➡ HTTP 2xx : We’re cool.. ➡ HTTP 3xx : Take a look there.. ➡ HTTP 4xx : your bad! 40
65. ➡ HTTP 1xx : Do I got info for you! ➡ HTTP 2xx : We’re cool.. ➡ HTTP 3xx : Take a look there.. ➡ HTTP 4xx : your bad! ➡ HTTP 5xx : my bad! 40
66. ➡ Sometimes hard: ➡ 405 Method not allowed ➡ 501 Not implemented ➡ Who is to blame? (tip: blame client!) 41
67. 42 HTTP/1.1 200 Ok <xml> <errorcode>my-superduper-code-nobody-understands<errorcode> <error>This action is forbidden</error> </xml> Don’t return OK when it’s not:
69. ➡ Use a hypermedia format (xhtml / atom) 43
70. ➡ Use a hypermedia format (xhtml / atom) ➡ JSON is NOT a hypermedia format 43
71. ➡ Use a hypermedia format (xhtml / atom) ➡ JSON is NOT a hypermedia format ➡ JSON-LD http://json-ld.org/ 43
72. ➡ Use a hypermedia format (xhtml / atom) ➡ JSON is NOT a hypermedia format ➡ JSON-LD http://json-ld.org/ ➡ HAL http://stateless.co/hal_specification.html 43
73. 44 How to do stuff
74. How do I login into my API? 45
75. You don’t 46
76. 47 Cookie PHPSESSID: 1234ABCD PHPSESSID: 1234ABCD LoggedIn: true User: 52 IsAdmin: false Client Server
77. 48 Cookie Loggedin: true User: 52 IsAdmin:false Client Server
78. 49 Cookie Loggedin: true User: 52 IsAdmin: true Client Server
79. 50 Cookie: 0xEncryptedData Client Server
80. ➡ Authenticate / Authorize per request. ➡ Caching is possible, just don’t rely on it. ➡ If you need state, make sure it’s resource state, not session/application state. 51
81. 52 Querying for data
82. 53 /entities/search? what=restaurants&type=italian&postalcode=1234AB&radius=5000&sor t=rating&order=desc
83. 53 /entities/search? what=restaurants&type=italian&postalcode=1234AB&radius=5000&sor t=rating&order=desc /restaurants/italian/top10?postalcode=1234AB&radius=5000
84. 54 Pagination
86. 56 /restaurants?page=5 /restaurants?page=635
87. 57 /restaurants/top1000?page=5 <xml version=”1.0” encoding=”utf-8”> <restaurants> <restaurant>...</restaurant> <restaurant>...</restaurant> <link rel=”first” href=”/restaurants/top10?page=1”> <link rel=”self” href=”/restaurants/top10?page=5”> <link rel=”previous” href=”/restaurants/top10?page=4”> <link rel=”next” href=”/restaurants/top10?page=6”> <link rel=”last” href=”/restaurants/top10?page=25”> </restaurants>
88. 58 Applying hierarchy
89. 59 /directions/brussels/amsterdam Not everything implies an hierarchy:
90. 60 /directions/brussels,amsterdam /directions/amsterdam,brussels Parameters, order does matter: /directions?from=brussels&to=amsterdam /directions?from=amsterdam&to=brussels
91. 61 /distance/amsterdam;brussels /distance/brussels;amsterdam HTTP/1.1 303 See other Location: /distance/amsterdam;brussels Parameters, order does not matter: One cache system:
92. 62 Asynchronous updates
93. 63 POST /blogs HTTP/1.1 Content-type: application/vnd.myblog.article+xml ; version=1.0 <?xml version="1.0" encoding="UTF-8" ?> <article> <title>My blogpost</title> <author>John Doe</author> <content>This is the content for my blog article</content> </article> Synchronous updates
94. 63 POST /blogs HTTP/1.1 Content-type: application/vnd.myblog.article+xml ; version=1.0 <?xml version="1.0" encoding="UTF-8" ?> <article> <title>My blogpost</title> <author>John Doe</author> <content>This is the content for my blog article</content> </article> Synchronous updates HTTP/1.1 201 Created Location: /blog/20010101-myblogpost
95. 64 POST /blogs HTTP/1.1 Content-type: application/vnd.myblog.article+xml ; version=1.0 <?xml version="1.0" encoding="UTF-8" ?> <article> <title>My blogpost</title> <author>John Doe</author> <content>This is the content for my blog article</content> </article> Asynchronous updates
96. 64 POST /blogs HTTP/1.1 Content-type: application/vnd.myblog.article+xml ; version=1.0 <?xml version="1.0" encoding="UTF-8" ?> <article> <title>My blogpost</title> <author>John Doe</author> <content>This is the content for my blog article</content> </article> Asynchronous updates HTTP/1.1 202 Accepted Location: /queue/621252
97. 65 GET /queue/621252 HTTP/1.1 Asynchronous updates - waiting in queue
98. 65 GET /queue/621252 HTTP/1.1 HTTP/1.1 200 OK <?xml version="1.0" encoding="UTF-8" ?> <queue> <status>Pending</status> <eta>10 minutes</eta> <link rel="cancel" href="/queue/621252"/> </queue> Asynchronous updates - waiting in queue
99. 66 GET /queue/621252 HTTP/1.1 Asynchronous updates - in progress
100. 66 GET /queue/621252 HTTP/1.1 HTTP/1.1 200 OK <?xml version="1.0" encoding="UTF-8" ?> <queue> <status>In progress</status> <eta>3 minutes, 25 seconds</eta> </queue> Asynchronous updates - in progress
101. 67 GET /queue/621252 HTTP/1.1 Asynchronous updates - done
102. 67 GET /queue/621252 HTTP/1.1 Asynchronous updates - done HTTP/1.1 303 See Other Location: /blog/20010101-myblogarticle
103. 68 Transactions
104. 69 Don’t make transactions through multiple resources. Breaks the state constraint (plus the rest of the the internet)
105. 70 POST /account/1234?amount=-100 TransIDX: 55A50611FE
106. 70 POST /account/1234?amount=-100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted
107. 70 POST /account/1234?amount=-100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted POST /account/4567?amount=+100 TransIDX: 55A50611FE
108. 70 POST /account/1234?amount=-100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted POST /account/4567?amount=+100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted
109. 70 POST /account/1234?amount=-100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted POST /account/4567?amount=+100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted POST /commit TransIDX: 55A50611FE
110. 70 POST /account/1234?amount=-100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted POST /account/4567?amount=+100 TransIDX: 55A50611FE HTTP/1.1 202 Accepted POST /commit TransIDX: 55A50611FE Nope! This is state!
111. 71 Your API is not a RDBMS. The internet does not need more ACID.
112. 72 A transaction can been as a resource
113. 73 POST /transactions 201 Created Location: /transactions/55A50611FE Create a new transaction Another attempt:
114. 74 POST /transactions/55A50611FE POST /transactions/55A50611FE/commit POST /transactions/55A50611FE/rollback POST /transactions/55A50611FE/snapshot POST /transactions/55A50611FE/rollback/1 But now we are back to XML-RPC or worse..
115. 75 POST /transactions/55A50611FE POST /transactions/55A50611FE/commit POST /transactions/55A50611FE/rollback POST /transactions/55A50611FE/snapshot POST /transactions/55A50611FE/rollback/1 So, define services: POST /booking <xml> <amount currency=”USD”>10.000.000</amount> <from_account>12.34.56.789, my bank</from_account> <to_account>X5252P25, Cayman Islands</to_account> </xml>
116. 76 ➡ If you do REST, don’t break the constraints. ➡ Be realistic about the constraints ➡ XML-RPC, HTTP-services (even SOAP) are valid for their uses. This stuff is hard!
117. 77 ➡ Take into account that you probably are not building the next Twitter API. ➡ If you follow the REST constraints, at least your API can scale.
118. http://farm1.static.flickr.com/73/163450213_18478d3aa6_d.jpg Questions? 78
119. Thank you 79 Find me on twitter: @jaytaph Find me for development or training: www.noxlogic.nl Find me on email: jthijssen@noxlogic.nl Find me for blogs: www.adayinthelifeof.nl