RDF sync works on edit from either Drupal or Fedora.

islandora_collection/islandora_collection.module

@@ -86,4 +86,29 @@ function islandora_collection_node_postupdate($node) {
   if (isset($_SERVER['HTTP_IGNORE_HOOKS']) && strcmp(strtolower($_SERVER['HTTP_IGNORE_HOOKS']), "true") == 0) {
     return;
   }
+
+  // Exit early if it's not a collection.
+  if (strcmp($node->type, ISLANDORA_COLLECTION_CONTENT_TYPE) != 0) {
+    return;
+  }
+
+  // Unfortunately, there's no way to tell if the db transaction got rolled back in this hook,
+  // so we'll default to doing it anyway so as not to miss any updates.
+  // Open to suggestions on this one.  But we gotta do post_action hooks otherwise
+  // things can get crazy if the db transaction hasn't closed.
+  $nodes = entity_uuid_load('node', array($node->uuid));
+
+  // Exit early if something has gone wrong and there's no node info.
+  if (empty($nodes)) {
+    return;
+  }
+
+  $node = array_pop($nodes);
+  $uuid = $node->uuid;
+  httprl_request("http://localhost:8080/islandora-services/rest/collection/$uuid",
+                 array(
+                   'method' => 'PUT',
+                   'data' => json_encode($node),
+                 ));
+  $response = httprl_send_request();
 }