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

APIs - The Big Two
XML-RPC
&
AtomPub

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

XML-RPC Request
<?xml version=\"1.0\"?>
<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>

XML-RPC Response
<?xml version=\"1.0\"?>
<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>

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

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

AtomPub Response
<?xml version=\"1.0\" encoding=\"utf-8\"?>
<entry xmlns=\"http://www.w3.org/2005/Atom\"
xmlns:app=\"http://www.w3.org/2007/app\" xml:lang=\"en\">
<id>http://localhost/~joseph/wp/trunk/?p=1</id>
<title type=\"text\">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=\"http://localhost/~joseph/wp/trunk/?p=1\" />
<content type=\"text\">Welcome to WordPress. This is your first post. Edit or delete
it, then start blogging!</content>
<link rel=\"edit\" href=\"http://localhost/~joseph/wp/trunk/wp-app.php/post/1\" />
<category scheme=\"http://localhost/~joseph/wp/trunk\" term=\"Uncategorized\" />
<summary type=\"text\">Welcome to WordPress. This is your first post. Edit or delete
it, then start blogging!</summary>
</entry>

Discovery
• Really Simple Discovery (RSD)
• http://cyber.law.harvard.edu/blogs/gems/tech/
rsd.html
<link rel=\"EditURI\"
type=\"application/rsd+xml\" title=\"RSD\"
href=\"http://localhost/wp/xmlrpc.php?rsd\" />

RSD
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
<rsd version=\"1.0\" xmlns=\"http://archipelago.phrasewise.com/rsd\">
<service>
<engineName>WordPress</engineName>
<engineLink>http://wordpress.org/</engineLink>
<homePageLink>http://localhost/wp</homePageLink>
<apis>
<api name=\"WordPress\" blogID=\"1\" preferred=\"true\" apiLink=\"http://localhost/
wpxmlrpc.php\" />
<api name=\"Movable Type\" blogID=\"1\" preferred=\"false\" apiLink=\"http://localhost/wp/
xmlrpc.php\" />
<api name=\"MetaWeblog\" blogID=\"1\" preferred=\"false\" apiLink=\"http://localhost/wp/
xmlrpc.php\" />
<api name=\"Blogger\" blogID=\"1\" preferred=\"false\" apiLink=\"http://localhost/wp/
xmlrpc.php\" />
<api name=\"Atom\" blogID=\"\" preferred=\"false\" apiLink=\"http://localhost/~joseph/wp/wp-
app.php/service\" />
</apis>
</service>
</rsd>

4,619
3,079,080

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

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

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

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

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)

Applications
Windows Live Writer
MarsEdit

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

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

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

iPhone App
231,079
Posts in the last 6 months

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

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

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;
}

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.' ) );
$salutation = \"Hello {$args[0]}, nice to see you!\";
return $salutation;
}

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( );

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

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

Username
Password

OAuth
Username
Password

Applications On Top
of WordPress

InterPress

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

Thank You

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