diff --git a/blocks/comments/lib.php b/blocks/comments/lib.php
new file mode 100644
index 00000000000..4e2d828d39a
--- /dev/null
+++ b/blocks/comments/lib.php
@@ -0,0 +1,75 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * The comments block helper functions and callbacks
+ *
+ * @package   block
+ * @subpackage comments
+ * @copyright 2011 Dongsheng Cai <dongsheng@moodle.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Validate comment parameter before perform other comments actions
+ *
+ * @param stdClass $comment_param {
+ *              context  => context the context object
+ *              courseid => int course id
+ *              cm       => stdClass course module object
+ *              commentarea => string comment area
+ *              itemid      => int itemid
+ * }
+ * @return boolean
+ */
+function comments_comment_validate($comment_param) {
+    if ($comment_param->commentarea != 'page_comments') {
+        throw new comment_exception('invalidcommentarea');
+    }
+    if ($comment_param->itemid != 0) {
+        throw new comment_exception('invalidcommentitemid');
+    }
+    return true;
+}
+
+/**
+ * Running addtional permission check on plugins
+ *
+ * @param stdClass $args
+ * @return array
+ */
+function comments_comment_permissions($args) {
+    return array('post'=>true, 'view'=>true);
+}
+
+/**
+ * Validate comment data before displaying comments
+ *
+ * @param stdClass $comment
+ * @param stdClass $args
+ * @return boolean
+ */
+function comments_comment_display($comments, $args) {
+    if ($args->commentarea != 'page_comments') {
+        throw new comment_exception('invalidcommentarea');
+    }
+    if ($args->itemid != 0) {
+        throw new comment_exception('invalidcommentitemid');
+    }
+    return $comments;
+}