+ /**
+ * Returns an XML string fragment with a reference to a notice as an
+ * Activity Streams noun object with the given element type.
+ *
+ * Assumes that 'activity' namespace has been previously defined.
+ *
+ * @param string $element one of 'subject', 'object', 'target'
+ * @return string
+ */
+ function asActivityNoun($element)
+ {
+ $xs = new XMLStringer(true);
+
+ $xs->elementStart('activity:' . $element);
+ $xs->element('activity:object-type',
+ null,
+ 'http://activitystrea.ms/schema/1.0/note');
+ $xs->element('id',
+ null,
+ $this->uri);
+ $xs->element('content',
+ array('type' => 'text/html'),
+ $this->rendered);
+ $xs->element('link',
+ array('type' => 'text/html',
+ 'rel' => 'alternate',
+ 'href' => $this->bestUrl()));
+ $xs->elementEnd('activity:' . $element);
+
+ return $xs->getString();
+ }
+