This document discusses the two main APIs used by WordPress - XML-RPC and AtomPub. XML-RPC uses XML over HTTP POST to transmit basic data types and allows for functions like metaWeblog.getPost. AtomPub uses HTTP methods to interact with Atom feeds and individual posts and comments. It provides a standardized way to interact with content repositories. The document also outlines tools for working with the WordPress APIs like the iPhone app and XML-RPC libraries for developers.

1. WordPress APIs
Joseph Scott
http://josephscott.org/

2. APIs - The Big Two
XML-RPC
&
AtomPub

3. XML-RPC Basics
• XML over HTTP POST
• Basic data types (int, bool, string, double,
dateTime.iso8601, base64) combined with
structs and arrays
• Supports pipelining with system.multicall
• Authentication generally in request body
• Spec - xmlrpc.com/spec

4. XML-RPC Request
<?xml version=quot;1.0quot;?>
<methodCall>
<methodName>metaWeblog.getPost</methodName>
<params>
<param> <value><int>1</int></value> </param>
<param> <value><string>admin</string></value> </param>
<param> <value><string>happiness</string></value> </param>
</params>
</methodCall>

5. XML-RPC Response
<?xml version=quot;1.0quot;?>
<methodResponse>
<params>
<param>
<value>
<struct>
<member><name>postid</name><value><string>1</string></value></member>
to
<member><name>description</name><value><string>Welcome
WordPress. This is your first post. Edit or delete it, then start
blogging!</string></value></member>
<member><name>title</name><value><string>Hello world!</string><value></
member>
...
</struct>
</value>
</param>
</params>
</methodResponse>

6. AtomPub Basics
• XML over HTTP (GET, POST, PUT, DELETE)
• Shared base with Atom feeds
• Collections (Posts, Comments, Media),
Entries (Individual posts and comments)
• Great intro from Joe Gregorio - http://
bitworking.org/news/343/intro-to-atompub-
on-youtube
• http://tools.ietf.org/html/rfc5023

7. AtomPub Request
curl -u “admin:happiness”
http://localhost/~joseph/wp/trunk/wp-app.php/post/1

8. AtomPub Response
<?xml version=quot;1.0quot; encoding=quot;utf-8quot;?>
<entry xmlns=quot;http://www.w3.org/2005/Atomquot;
xmlns:app=quot;http://www.w3.org/2007/appquot; xml:lang=quot;enquot;>
<id>http://localhost/~joseph/wp/trunk/?p=1</id>
<title type=quot;textquot;>Hello world!</title>
<updated>2008-08-08T01:01:03Z</updated>
<published>2008-08-08T01:01:03Z</published>
<app:edited>2008-08-08T01:01:03Z</app:edited>
<app:control>
<app:draft>no</app:draft>
</app:control>
<author><name>admin</name></author>
<link href=quot;http://localhost/~joseph/wp/trunk/?p=1quot; />
<content type=quot;textquot;>Welcome to WordPress. This is your first post. Edit or delete
it, then start blogging!</content>
<link rel=quot;editquot; href=quot;http://localhost/~joseph/wp/trunk/wp-app.php/post/1quot; />
<category scheme=quot;http://localhost/~joseph/wp/trunkquot; term=quot;Uncategorizedquot; />
<summary type=quot;textquot;>Welcome to WordPress. This is your first post. Edit or delete
it, then start blogging!</summary>
</entry>

9. Discovery
• Really Simple Discovery (RSD)
• http://cyber.law.harvard.edu/blogs/gems/tech/
rsd.html
<link rel=quot;EditURIquot;
type=quot;application/rsd+xmlquot; title=quot;RSDquot;
href=quot;http://localhost/wp/xmlrpc.php?rsdquot; />

10. RSD
<?xml version=quot;1.0quot; encoding=quot;UTF-8quot;?>
<rsd version=quot;1.0quot; xmlns=quot;http://archipelago.phrasewise.com/rsdquot;>
<service>
<engineName>WordPress</engineName>
<engineLink>http://wordpress.org/</engineLink>
<homePageLink>http://localhost/wp</homePageLink>
<apis>
<api name=quot;WordPressquot; blogID=quot;1quot; preferred=quot;truequot; apiLink=quot;http://localhost/
wpxmlrpc.phpquot; />
<api name=quot;Movable Typequot; blogID=quot;1quot; preferred=quot;falsequot; apiLink=quot;http://localhost/wp/
xmlrpc.phpquot; />
<api name=quot;MetaWeblogquot; blogID=quot;1quot; preferred=quot;falsequot; apiLink=quot;http://localhost/wp/
xmlrpc.phpquot; />
<api name=quot;Bloggerquot; blogID=quot;1quot; preferred=quot;falsequot; apiLink=quot;http://localhost/wp/
xmlrpc.phpquot; />
<api name=quot;Atomquot; blogID=quot;quot; preferred=quot;falsequot; apiLink=quot;http://localhost/~joseph/wp/wp-
app.php/servicequot; />
</apis>
</service>
</rsd>

11. 4,619
3,079,080

12. 2008 Totals
4,619
AtomPub
3,079,080
XML-RPC

13. 2009 Year To Date
3,312
AtomPub
703,673
XML-RPC

14. XML-RPC Blog APIs
MetaWeblog
WordPress
(metaWeblog.*)
(wp.*)
Blogger
Movable Type
(blogger.*)
(mt.*)

15. Extending MetaWeblog
• Many new fields to getPost/newPost/editPost
• wp_slug, wp_password, wp_author_id,
wp_author_display_name,
date_created_gmt, post_status,
custom_fields, mt_keywords (tags)
• dateCreated vs. date_created_gmt

16. WordPress Methods
• Comment Management, new in 2.7
(wp.getComment, wp.newComment,
wp.editComment, wp.deleteComment)
• Page management (wp.getPage, wp.editPage,
wp.newPage, etc.)
• Category Management (wp.newCategory,
wp.deleteCategory, etc.)
• Tag Management (wp.getTags - more to come)

17. Applications
Windows Live Writer
MarsEdit

18. More Applications
http://codex.wordpress.org/Weblog_Client
• Scribefire (Firefox Plugin)
• Windows- MS Word 2007, Blogdesk, Blogjet,
Raven, Flock, Qumana
• Mac - Ecto, Blogo, MacJournal, TextMate
• Linux - QTM, Gnome Blog, Drivel, BloGTK

19. iPhone App
• http://iphone.wordpress.org/
• Free & Open Source (GPL)
• ~ 165,000 downloads
• Uses XML-RPC to manage
your blog

20. iPhone App - 1.2
http://iphone.wordpress.org/2008/11/11/help-test-
wordpress-for-iphone-version-12/
• Comment Moderation
• Landscape mode
• Link creation help
• Create/edit Pages

21. iPhone App
231,079
Posts in the last 6 months

22. Developer Tools - Mac
HTTPScoop
http://www.tuffcode.com/
XML-RPC Client
http://ditchnet.org/xmlrpc/

23. Developer Tools - Windows
Fiddler
http://www.fiddlertool.com/fiddler/

24. XML-RPC for WP Devs
• Add your own XML-RPC methods
add_filter( 'xmlrpc_methods', 'joseph_attach_xmlrpc_methods' );
function joseph_attach_xmlrpc_methods( $methods ) {
$methods['joseph.hello'] = 'joseph_xmlrpc_hello';
return $methods;
}

25. XML-RPC for WP Devs
• Add your own XML-RPC methods
function joseph_xmlrpc_hello( $args ) {
if ( empty( $args[0] ) )
return new IXR_Error( 2000, __( 'No name was provided.' ) );
$salutation = quot;Hello {$args[0]}, nice to see you!quot;;
return $salutation;
}

26. XML-RPC for WP Devs
• XML-RPC Client
$rpc = new IXR_Client( 'http://example.com/xmlrpc.php' );
$status = $rpc->query( ‘demo.addTwoNumbers’, 4, 5 );
if ( !$status ) {
print ‘Error ( ‘ . $rpc->getErrorCode( ) . ‘ ): ‘;
print $rpc->getErrorMessage( ) . “n”;
exit;
}
$result = $rpc->getResponse( );

27. bbPress XML-RPC
• Part of version 1.0 (when it comes out)
• Pingback support
• bbPress Live - WordPress Plugin
• BuddyPress forums

28. Going Forward
• More data/features exposed via XML-RPC &
AtomPub
• Everything wp-admin can do?
• Likely a WordPress namespace for new
AtomPub features

29. Username
Password

30. OAuth
Username
Password

31. Applications On Top
of WordPress

32. InterPress

33. XML-RPC Developers
http://lists.automattic.com/mailman/listinfo/wp-xmlrpc

34. Thank You

35. Find Me
• http://josephscott.org/
• joseph@josephscott.org
• http://twitter.com/josephscott/
• #wordpress-dev