Added code to implement Dublin Core and Creative Commons RDF metadata.

If these features are turned on (with global flags), a metadata link tag is
provided to the appropriate action ('dublincore' or 'creativecommons'). When
the wiki script receives these actions, it creates RDF files on the fly.

Also includes two valuable general functions: one to show an HTTP error
(used when the flags are turned off), and one to do content negotiation
(used to determine the MIME type for RDF files).

A helper function is also added to page output to display metadata links.

includes/DefaultSettings.php

@@ -292,5 +292,17 @@ if( !isset( $wgCommandLineMode ) ) {
 }
 
 # Show seconds in Recent Changes
-$wgRCSeconds = false
+$wgRCSeconds = false;
+
+
+# RDF metadata toggles
+
+$wgEnableDublinCoreRdf = false;
+$wgEnableCreativeCommonsRdf = false;
+
+# Override for copyright metadata.
+
+$wgRightsPage = NULL;
+$wgRightsUrl = NULL;
+$wgRightsText = NULL;
 ?>

includes/GlobalFunctions.php

@@ -845,4 +845,101 @@ function wfVarDump( $var )
 	}
 }
 
+/* Provide a simple HTTP error. */
+
+function wfHttpError($code, $label, $desc) {
+    
+    global $wgOut;
+    $wgOut->disable();
+    header("HTTP/1.0 $code $label");
+    header("Status: $code $label");
+    $wgOut->sendCacheControl();
+
+    /* Don't send content if it's a HEAD request. */
+    
+    if (strcmp($HTTP_SERVER_VARS['REQUEST_METHOD'],'HEAD') != 0) {
+	header("Content-type: text/plain");
+	print "$desc\n";
+    }
+}
+
+# Converts an Accept-* header into an array mapping string values to quality factors
+
+function wfAcceptToPrefs($accept, $def = "*/*") {
+    # No arg means accept anything (per HTTP spec)
+    if (!$accept) {
+	return array($def => 1);
+    }
+
+    $prefs = array();
+    
+    $parts = explode(",", $accept);
+    
+    foreach ($parts as $part) {
+	#FIXME: doesn't deal with params like 'text/html; level=1'
+	list($value, $qpart) = explode(";", $part);
+	if (!isset($qpart)) {
+	    $prefs[$value] = 1;
+	} else if (preg_match('/q\s*=\s*(\d*\.\d+)/', $qpart, $match)) {
+	    $prefs[$value] = $match[1];
+	}
+    }
+    
+    return $prefs;
+}
+
+/* private */ function mimeTypeMatch($type, $avail) {
+    if (array_key_exists($type, $avail)) {
+	return $type;
+    } else {
+	$parts = explode('/', $type);
+	if (array_key_exists($parts[0] . '/*', $avail)) {
+	    return $parts[0] . '/*';
+	} else if (array_key_exists('*/*', $avail)) {
+	    return '*/*';
+	} else {
+	    return NULL;
+	}
+    }
+}
+
+#FIXME: doesn't handle params like 'text/plain; charset=UTF-8'
+#XXX: generalize to negotiate other stuff
+
+function wfNegotiateType($cprefs, $sprefs) {
+    $combine = array();
+    
+    foreach (array_keys($sprefs) as $type) {
+	$parts = explode('/', $type);
+	if ($parts[1] != '*') {
+	    $ckey = mimeTypeMatch($type, $cprefs);
+	    if ($ckey) {
+		$combine[$type] = $sprefs[$type] * $cprefs[$ckey];
+	    }
+	}
+    }
+
+    foreach (array_keys($cprefs) as $type) {
+	$parts = explode('/', $type);
+	if ($parts[1] != '*' && !array_key_exists($type, $sprefs)) {
+	    $skey = mimeTypeMatch($type, $sprefs);
+	    if ($skey) {
+		$combine[$type] = $sprefs[$skey] * $cprefs[$type];
+	    }
+	}
+    }
+    
+    $bestq = 0;
+    $besttype = NULL;
+    
+    foreach (array_keys($combine) as $type) {
+	if ($combine[$type] > $bestq) {
+	    $besttype = $type;
+	    $bestq = $combine[$type];
+	}
+    }
+    
+    return $besttype;
+}
+
 ?>

includes/OutputPage.php

@@ -46,6 +46,12 @@ class OutputPage {
 	function addKeyword( $text ) { array_push( $this->mKeywords, $text ); }
 	function addLink( $rel, $rev, $target, $type="", $media="" ) { array_push( $this->mLinktags, array( $rel, $rev, $target, $type, $media ) ); }
 
+        function addMetadataLink( $type, $target ) {
+ 	    static $haveMeta = false;
+ 	    $this->addLink(($haveMeta) ? "alternate meta" : "meta", "", $target, $type);
+ 	    $haveMeta = true;
+ 	}
+
 	# checkLastModified tells the client to use the client-cached page if
 	# possible. If sucessful, the OutputPage is disabled so that
 	# any future call to OutputPage->output() have no effect. The method

includes/Skin.php

@@ -95,15 +95,30 @@ class Skin {
 
 	function initPage( &$out )
 	{
-		global $wgStyleSheetPath;
 		$fname = "Skin::initPage";
 		wfProfileIn( $fname );
 		
 		$out->addLink( "shortcut icon", "", "/favicon.ico" );
-		
+
+	        $this->addMetadataLinks($out);
+	    
 		wfProfileOut( $fname );
 	}
 	
+        function addMetadataLinks( &$out ) {
+	    global $wgTitle, $wgEnableDublinCoreRdf, $wgEnableCreativeCommonsRdf, $wgRdfMimeType, $action;
+
+	    if ($action == 'view') {
+		# note: buggy CC software only reads first "meta" link
+		if ($wgEnableCreativeCommonsRdf) {
+		    $out->addMetadataLink('application/rdf+xml', wfLocalUrl($wgTitle->getPrefixedURL(), "action=creativecommons"));
+		}
+		if ($wgEnableDublinCoreRdf) {
+		    $out->addMetadataLink('application/rdf+xml', wfLocalUrl($wgTitle->getPrefixedURL(), "action=dublincore"));
+		}
+	    }
+	}
+    
 	function outputPage( &$out ) {
 		global $wgDebugComments;
 		

index.php

@@ -108,6 +108,22 @@ if ( $search = $wgRequest->getText( 'search' ) ) {
 		case "print":
 			$wgArticle->view();
 			break;
+                case "dublincore":
+                        if (!$wgEnableDublinCoreRdf) {
+                            wfHttpError(403, "Forbidden", wfMsg("nodublincore"));
+                        } else {
+                            include_once("Metadata.php");
+                            wfDublinCoreRdf($wgArticle);
+                        }
+                        break;
+                case "creativecommons":
+                        if (!$wgEnableCreativeCommonsRdf) {
+                            wfHttpError(403, "Forbidden", wfMsg("nocreativecommons"));
+                        } else {
+                            include_once("Metadata.php");
+                            wfCreativeCommonsRdf($wgArticle);
+                        }
+                        break;
 		case "edit":
 		case "submit":
 			if( !$wgCommandLineMode && !$wgRequest->checkSessionCookie() ) {

languages/Language.php

@@ -1548,6 +1548,15 @@ amusement.",
 'tooltip-specialpages' => 'List of all special pages',
 'tooltip-upload' => 'Upload images or media files [alt-u]',
 'tooltip-specialpage' => 'This is a special page, you can\'t edit the page itself.',
+
+# Metadata
+"nodublincore" => "Dublin Core RDF metadata disabled for this server.",
+"nocreativecommons" => "Creative Commons RDF metadata disabled for this server.",
+"notacceptable" => "The wiki server can't provide data in a format your client can read.",
+
+# Attribution
+
+"anonymous" => "Anonymous user(s) of $wgSitename"
 );
 
 #--------------------------------------------------------------------------