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REST in practice - PHPTwente meetup

Joshua Thijssen
March 07, 2013
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REST in practice - PHPTwente meetup

Joshua Thijssen

March 07, 2013
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  1. PHPTwente, Enschede 7 maart 2013 REST in practice? How to

    deal with
  2. Joshua Thijssen Freelance consultant, developer and trainer @ NoxLogic Development

    in PHP, Python, Perl, C, Java. Lead developer of Saffire. Blog: http://adayinthelifeof.nl Email: jthijssen@noxlogic.nl Twitter: @jaytaph
  3. REST 3 Representational State Transfer It’s not hard: like poker,

    or chess
  4. 4 ➡ Quick REST recap ➡ Common “myths” ➡ Common

    “mistakes” ➡ How to do stuff @Todo:
  5. 5 Quick REST recap

  6. 6 Are you doing REST?

  7. Restful constraints 7 ➡ Client / Server ➡ Stateless ➡

    Cacheable ➡ Layered system ➡ Code on demand (optional) ➡ Uniform interface
  8. Uniform interface 8 ➡ Identification through representations of resources ➡

    Manipulation through representations ➡ Self-descriptive messages ➡ Hypermedia as the engine of application state (HATEOAS)
  9. Are you mature enough? 9 (according to Richardson)

  10. 10 http://martinfowler.com/articles/richardsonMaturityModel.html

  11. 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
  12. 12 http://martinfowler.com/articles/richardsonMaturityModel.html Level 1: Resources ➡ Entities are resources ➡

    /user/jthijssen instead of /users ➡ /user/jthijssen/talks
  13. 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
  14. 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
  15. 15 Wait, wut? Let’s go to DisneyLand!

  16. 16 Are you (still) doing REST?

  17. 17 Common “myths”

  18. REST == HTTP 18

  19. REST == CRUD 19

  20. URL’s are important 20

  21. REST scales 21

  22. COOKIES are EVIL 22

  23. 23 I’ve never have eaten a cookie in my life...

  24. 24 Gimme moar cookies! Om nom nom!

  25. 25 Application state vs Resource state

  26. ➡ 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!
  27. ➡ 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
  28. 28 “Per client” state should be saved by the client,

    not on the server. It’s called Representational STATE TRANSFER
  29. 29 Common “mistakes”

  30. 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
  31. 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.
  32. 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
  33. 33 Composite resources

  34. 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>
  35. 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>
  36. Watch out with visibility 36 person address person address address

    Duplicated cache!
  37. ➡ Degrades resource visibility since they contain overlapping data ➡

    Use caching proxies! (maybe ESI???) ➡ Each client needs a different composite. 37
  38. 38 It sounded like a good idea at the time...

  39. ➡ Use HTTP (verbs) wisely ➡ Etags / If-(not-)modified ➡

    HTTP codes 39
  40. ➡ 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
  41. ➡ Sometimes hard: ➡ 405 Method not allowed ➡ 501

    Not implemented ➡ Who is to blame? (tip: blame client!) 41
  42. 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:
  43. ➡ 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
  44. 44 How to do stuff

  45. How do I login into my API? 45

  46. You don’t 46

  47. 47 Cookie PHPSESSID: 1234ABCD PHPSESSID: 1234ABCD LoggedIn: true User: 52

    IsAdmin: false Client Server
  48. 48 Cookie Loggedin: true User: 52 IsAdmin:false Client Server

  49. 49 Cookie Loggedin: true User: 52 IsAdmin: true Client Server

  50. 50 Cookie: 0xEncryptedData Client Server “This information is of no

    concern to you. Just bring it with you every time.. ”
  51. 51 “This information is of no concern to you. Just

    bring it with you every time.. ” Are we still stateless? Does the server use the client as an (extended) file storage? Why doesn’t the client have any say in what to send?
  52. ➡ 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. 52
  53. 53 Querying for data

  54. 54 /entities/search? what=restaurants&type=italian&postalcode=1234AB&radius=5000&sor t=rating&order=desc /restaurants/italian/top10?postalcode=1234AB&radius=5000

  55. 55 Pagination

  56. 56

  57. 57 /restaurants?page=5 /restaurants?page=635

  58. 58 /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>
  59. 59 Applying hierarchy

  60. 60 /directions/brussels/amsterdam Not everything implies an hierarchy:

  61. 61 /directions/brussels,amsterdam /directions/amsterdam,brussels Parameters, order does matter: /directions?from=brussels&to=amsterdam /directions?from=amsterdam&to=brussels

  62. 62 /distance/amsterdam;brussels /distance/brussels;amsterdam HTTP/1.1 303 See other Location: /distance/amsterdam;brussels Parameters,

    order does not matter: One cache system: http://cyberroadie.wordpress.com/2012/01/05/varnish-reordering-query-string/
  63. 63 Asynchronous updates

  64. 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> Synchronous updates HTTP/1.1 201 Created Location: /blog/20010101-myblogpost
  65. 65 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
  66. 66 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
  67. 67 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
  68. 68 GET /queue/621252 HTTP/1.1 Asynchronous updates - done HTTP/1.1 303

    See Other Location: /blog/20010101-myblogarticle
  69. 69 Transactions

  70. 70 Don’t make transactions through multiple resources. Breaks the state

    constraint (plus the rest of the the internet)
  71. 71 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!
  72. 72 Your API is not a RDBMS. The internet does

    not need more ACID.
  73. 73 A transaction can been as a resource

  74. 74 POST /transactions 201 Created Location: /transactions/55A50611FE Create a new

    transaction Another attempt:
  75. 75 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..
  76. 76 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>
  77. 77 ➡ 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!
  78. 78 ➡ 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.
  79. http://farm1.static.flickr.com/73/163450213_18478d3aa6_d.jpg Questions? 79

  80. 80 https://leanpub.com/restfulapis It’s almost finished!

  81. Techademy Workshopdag 81 Aanmeldingen: info@techademy.nl Workshopdag: Varnish + PHP Speedups

    vrijdag 22 maart - Apeldoorn php5.[34] + http essentials, gearman + activemq, solr + solarium, html5+css3, mongodb + caching, scrum, git+github+travisCI, phpdocumentor
  82. Thank you 82 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