Introduction to AtomPub Web Services (IPC 2010)

Introduction to AtomPub Web Services (IPC 2010)

Since 2003, the Atom format has been used as yet another feed format like RSS, but the Atom protocol opens the door to far more uses of Atom as both a means for distribution and publication. Ben Ramsey introduces the Atom format and protocol, explaining how these can form the foundation of any publishing service and serve as a platform for rich Internet applications.

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Ben Ramsey

October 11, 2010
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  1. Ben Ramsey • International PHP Conference • 11 Oct 2010

    Introduction to AtomPub Web Services
  2. Introduction to AtomPub Web Services • Ben Ramsey Hi, I’m

    Ben. ‣VP of Engineering at Moontoast ‣Co-founder and organizer emeritus of the Atlanta PHP user group ‣Current organizer of the Nashville PHP user group ‣I blog at benramsey.com ‣I tweet at @ramsey ‣Please rate this presentation: http://joind.in/2185 2
  3. Atom & AtomPub?


  4. What’s the difference?


  5. Introduction to AtomPub Web Services • Ben Ramsey Atom: RFC

    4287 5
  6. Atom is an XML-based document format that describes lists of

    related information known as “feeds”. Feeds are composed of a number of items, known as “entries”, each with an extensible set of attached metadata. For example, each entry has a title. The primary use case that Atom addresses is the syndication of Web content such as weblogs and news headlines to Web sites as well as directly to user agents. —RFC 4287, §1
  7. Atom is an XML language.

  8. Introduction to AtomPub Web Services • Ben Ramsey AtomPub: RFC

    5023 8
  9. The Atom Publishing Protocol is an application-level protocol for publishing

    and editing Web Resources using HTTP and XML 1.0. The protocol supports the creation of Web Resources and provides facilities for: Collections: Sets of Resources, which can be retrieved in whole or in part. Services: Discovery and description of Collections. Editing: Creating, editing, and deleting Resources. The Atom Publishing Protocol is different from many contemporary protocols in that the server is given wide latitude in processing requests from clients. —RFC 5023, §1
  10. AtomPub is a  publishing protocol.

  11. Introduction to AtomPub Web Services • Ben Ramsey What about

    RSS? 11
  12. Introduction to AtomPub Web Services • Ben Ramsey Content Types

    12 ‣RSS allows only for plain text and escaped HTML content types ‣Atom provides for plain text, escaped HTML, XHTML, XML, and Base64-encoded binary data
  13. Introduction to AtomPub Web Services • Ben Ramsey Internationalization ‣RSS

    may have a language set for a feed, but doesn’t have a way to indicate language for items in the feed ‣Atom uses the xml:lang attribute to specify language on a per-element basis ‣Atom uses IRIs, which allow the usage of characters in identifiers outside of ASCII 13
  14. Introduction to AtomPub Web Services • Ben Ramsey Modularity ‣RSS

    vocabulary elements aren’t reusable in other XML vocabularies ‣Atom was designed to allow its vocabulary to be mixed with other XML vocabularies ‣Namespaces! Atom has one; RSS does not 14
  15. Introduction to AtomPub Web Services • Ben Ramsey Other Things

    ‣RSS has no schema; Atom has a RelaxNG schema ‣RSS defines no mechanism for handling relative URIs; Atom uses xml:base ‣Various implementations in RSS leads to interoperability problems ‣No standard protocol for publishing; RSS is read only 15
  16. Atom was created to solve the RSS problems.

  17. Introduction to AtomPub Web Services • Ben Ramsey Profile of

    Atom ‣Atom Syndication Format ‣An XML-based web content and metadata syndication format ‣Defined by IETF RFC 4287 ‣Fixes the “problems” of RSS ‣XML namespace: http://www.w3.org/2005/Atom 17
  18. Introduction to AtomPub Web Services • Ben Ramsey Profile of

    AtomPub ‣Atom Publishing Protocol or APP ‣A protocol for publishing and editing web resources using HTTP and XML ‣Defined by IETF RFC 5023 ‣Uses Atom as it’s XML syntax ‣XML namespace: http://www.w3.org/2007/app 18
  19. Introduction to AtomPub Web Services • Ben Ramsey Basics of

    AtomPub ‣Each resource has a unique identifier ‣The resources are well-connected ‣Resources share the same interface ‣There is no state; requests are atomic ‣Follows a resource-oriented architecture 19
  20. Introduction to AtomPub Web Services • Ben Ramsey Terminology ‣Entry

    ‣Feed/Collection ‣Category Document ‣Service Document 20
  21. Introduction to AtomPub Web Services • Ben Ramsey Content Types

    ‣Entry: 
 application/atom+xml;type=entry ‣Feed/Collection:
 application/atom+xml ‣Category Document:
 application/atomcat+xml ‣Service Document:
 application/atomsvc+xml 21
  22. Introduction to AtomPub Web Services • Ben Ramsey Designing an

    AtomPub Service 22
  23. Introduction to AtomPub Web Services • Ben Ramsey What will

    our service do? 23 ‣Expose users ‣Expose content ‣Allow users to manipulate content
  24. Step 1: Define our URIs

  25. Introduction to AtomPub Web Services • Ben Ramsey Users ‣/user

    ‣/user/{username} ‣For example: /user/ramsey 25
  26. Introduction to AtomPub Web Services • Ben Ramsey Content ‣/content

    ‣/content/{id} ‣For example: /content/1234 26
  27. Step 2: Define the relationships

  28. Introduction to AtomPub Web Services • Ben Ramsey Relationship Building

    ‣user ⇛ content:
 one to many ‣content ⇛ user:
 one to one 28
  29. Step 3: Define the interface

  30. Methods GET PUT POST DELETE Cut & Paste Copy Paste

    Over Paste After Cut
  31. Introduction to AtomPub Web Services • Ben Ramsey Actions for

    User Resources ‣Retrieve user collection:
 GET /user ‣Create a new user:
 POST /user ‣Modify an existing user:
 PUT /user/ramsey ‣Delete a user:
 DELETE /user/ramsey 31
  32. Introduction to AtomPub Web Services • Ben Ramsey Actions for

    Content Resources ‣Retrieve content:
 GET /content ‣Create new content:
 POST /content ‣Modify content:
 PUT /content/1234 ‣Remove content:
 DELETE /content/1234 32
  33. Introduction to AtomPub Web Services • Ben Ramsey Other Actions

    ‣Service discovery:
 GET / ‣Retrieve content for a particular user:
 GET /user/ramsey/content 33
  34. Introduction to AtomPub Web Services • Ben Ramsey Let’s see

    it in action 34
  35. GET / HTTP/1.1 Host: atom.example.org HTTP/1.x 200 OK Date: Mon,

    21 Sep 2009 16:33:45 GMT Content-Type: application/atomsvc+xml
  36. <?xml version="1.0" encoding="utf-8"?> <service xmlns="http://www.w3.org/2007/app" xmlns:atom="http://www.w3.org/2005/Atom" xml:base="http://atom.example.org/"> <workspace> <atom:title>Our Content

    Store</atom:title> <collection href="user"> <atom:title>Users</atom:title> <accept>application/atom+xml;type=entry</accept> <categories href="cat/user"/> </collection> <collection href="content"> <atom:title>Content</atom:title> <accept>application/atom+xml;type=entry</accept> <categories href="cat/content"/> </collection> </workspace> </service>
  37. GET /user HTTP/1.1 Host: atom.example.org HTTP/1.x 200 OK Date: Mon,

    21 Sep 2009 16:34:26 GMT Content-Type: application/atom+xml
  38. <?xml version="1.0" encoding="utf-8"?> <feed xmlns="http://www.w3.org/2005/Atom" xmlns:app="http://www.w3.org/2007/app" xml:base="http://atom.example.org/"> <title>Users</title> <updated>2009-09-21T05:21:19Z</updated> <id>tag:example.org,2009-09:user</id>

    <app:collection href="user"> <title>Users</title> <app:accept>application/atom+xml;type=entry</app:accept> <app:categories href="cat/user"/> </app:collection> <link rel="first" href="user"/> <link rel="last" href="user?p=23"/> <link rel="next" href="user?p=2"/> <entry> ... </entry> </feed>
  39. Introduction to AtomPub Web Services • Ben Ramsey Manipulating a

    User 39
  40. GET /user/ramsey HTTP/1.1 Host: atom.example.org HTTP/1.x 200 OK Date: Mon,

    21 Sep 2009 16:34:26 GMT Content-Type: application/atom+xml;type=entry
  41. <?xml version="1.0" encoding="utf-8"?> <entry xmlns="http://www.w3.org/2005/Atom" xml:base="http://atom.example.org/"> <title>ramsey</title> <author> <name>ramsey</name> </author>

    <link rel="self" href="user/ramsey"/> <link rel="edit" type="application/atom+xml;type=entry" href="user/ramsey"/> <link rel="related" href="user/ramsey/content"/> <id>tag:example.org,2008:user/ramsey</id> <updated>2009-09-21T13:45:00Z</updated> <published>2008-05-23T16:23:34Z</published> <content type="xhtml"> <div class="vcard" xmlns="http://www.w3.org/1999/xhtml"> <a class="fn">Ben Ramsey</a> <span class="tel">123-456-7890</span> </div> </content> </entry>
  42. Introduction to AtomPub Web Services • Ben Ramsey Modify the

    Entry Locally 42
  43. <?xml version="1.0" encoding="utf-8"?> <entry xmlns="http://www.w3.org/2005/Atom" xml:base="http://atom.example.org/"> <title>ramsey</title> <author> <name>ramsey</name> </author>

    <link rel="self" href="user/ramsey"/> <link rel="edit" type="application/atom+xml;type=entry" href="user/ramsey"/> <link rel="related" href="user/ramsey/content"/> <id>tag:example.org,2008:user/ramsey</id> <updated>2009-09-22T09:14:58Z</updated> <published>2008-05-23T16:23:34Z</published> <content type="xhtml"> <div class="vcard"> <a class="fn url" href="http://benramsey.com/">Ben Ramsey</a> <span class="org">Moontoast</span> <span class="tel">123-456-7890</span> </div> </content> </entry>
  44. PUT /user/ramsey HTTP/1.1 Host: atom.example.org Content-Type: application/atom+xml;type=entry {body here} HTTP/1.x

    200 OK Date: Mon, 22 Sep 2009 09:14:59 GMT Content-Type: application/atom+xml;type=entry
  45. Introduction to AtomPub Web Services • Ben Ramsey Add Some

    Content 45
  46. Introduction to AtomPub Web Services • Ben Ramsey First, a

    Few Notes 46 ‣You need authentication! ‣Perhaps you need encryption ‣You definitely need validation ‣And I’m not going to tell you how
  47. That’s out of scope.

  48. :-)

  49. But I’ll show you the basics.

  50. <?xml version="1.0" encoding="utf-8"?> <service xmlns="http://www.w3.org/2007/app" xmlns:atom="http://www.w3.org/2005/Atom" xml:base="http://atom.example.org/"> <workspace> <atom:title>Our Content

    Store</atom:title> <collection href="user"> <atom:title>Users</atom:title> <accept>application/atom+xml;type=entry</accept> <categories href="cat/user"/> </collection> <collection href="content"> <atom:title>Content</atom:title> <accept>application/atom+xml;type=entry</accept> <categories href="cat/content"/> </collection> </workspace> </service>
  51. Introduction to AtomPub Web Services • Ben Ramsey Get the

    Categories 51
  52. GET /cat/content HTTP/1.1 Host: atom.example.org HTTP/1.x 200 OK Date: Mon,

    22 Sep 2009 09:39:26 GMT Content-Type: application/atomcat+xml
  53. <?xml version="1.0"?> <app:categories xmlns:app="http://www.w3.org/2007/app" xmlns:atom="http://www.w3.org/2005/Atom" fixed="yes" scheme="http://atom.example.com/cat/content"> <atom:category term="audio"/> <atom:category

    term="video"/> <atom:category term="game"/> </app:categories>
  54. Introduction to AtomPub Web Services • Ben Ramsey Create the

    Entry Document Locally 54
  55. <?xml version="1.0" encoding="utf-8"?> <entry xmlns="http://www.w3.org/2005/Atom" xml:base="http://atom.example.org/"> <title>Perfect</title> <author> <name>Mark Phelps</name>

    </author> <id>tag:example.org,2009:content/perfect</id> <published>2009-09-22T20:12:08Z</published> <category term="audio" scheme="http://atom.example.com/cat/content"/> <content type="application/mp4"> TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWF IHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGl ... </content> </entry>
  56. POST /content HTTP/1.1 Host: atom.example.org Content-Type: application/atom+xml;type=entry {body here} HTTP/1.x

    202 Accepted Date: Mon, 22 Sep 2009 09:14:59 GMT {body contains status indicator}
  57. Introduction to AtomPub Web Services • Ben Ramsey Authentication? ‣Atom

    doesn’t specify a preference ‣WSSE Username Token ‣OAuth ‣Basic authentication ‣Digest authentication ‣??? 57
  58. Did I miss anything?

  59. Oh, yeah. Where’s the PHP code?

  60. Introduction to AtomPub Web Services • Ben Ramsey AtomPub in

    PHP ‣DOM for reading/writing ‣SimpleXML for reading ‣XMLReader for reading ‣XMLWriter for writing ‣String concatenation for writing ‣I recommend XMLReader/XMLWriter; they’re the fastest at parsing and generating XML 60
  61. Introduction to AtomPub Web Services • Ben Ramsey Wrapping Up

    ‣You can extend Atom with other XML vocabularies (Dublin Core, etc.) ‣XML Digital Signature or XML Encryption may be used, or encrypt as a bag of bits ‣Use your preferred authentication method ‣Use HTTP in a RESTful fashion ‣Use DOM or XMLReader/XMLWriter to parse Atom documents 61
  62. Introduction to AtomPub Web Services • Ben Ramsey Questions? ‣I

    blog at benramsey.com ‣I tweet at @ramsey ‣Please rate this presentation: http://joind.in/2185 ‣Read the Atom specifications:
 RFC 4287
 RFC 5023 ‣My company is Moontoast 62
  63. Introduction to AtomPub Web Services Copyright © Ben Ramsey. Some

    rights reserved. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License. For uses not covered under this license, please contact the author.
  64. Introduction to AtomPub Web Services • Ben Ramsey Photo Credits

    64 ‣Molecule display, by Christian Guthier ‣Atom, by jayneandd ‣Atomium - detail, by Constantin Barbu ‣Simplicity, by Subterranean Tourist Board ‣STEREO's Extreme UltraViolet Imager (EUVI), by NASA ‣Quantum Universe, by Gaurav ‣Fullerene Nanogears, by NASA ‣Little Atom, by Marrio ‣That Atom, by Albert O’Conner ‣Bokeh Spiral, by Eric Wüstenhagen ‣Chambered Nautilus Shell - detail, by Jitze Couperus