new file mode 100644
--- /dev/null
+++ b/library/log4php/pattern/LoggerPatternConverterSessionID.php
@@ -0,0 +1,33 @@
+<?php
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @package log4php
+ */
+
+/**
+ * Returns the active session ID, or an empty string if out of session.
+ *
+ * @package log4php
+ * @subpackage pattern
+ * @version $Revision: 1326626 $
+ * @since 2.3
+ */
+class LoggerPatternConverterSessionID extends LoggerPatternConverter {
+    public function convert(LoggerLoggingEvent $event) {
+        return session_id();
+    }
+}