diff --git a/framework/yii/elasticsearch/ActiveRecord.php b/framework/yii/elasticsearch/ActiveRecord.php
index 5f58a04..6a036cb 100644
--- a/framework/yii/elasticsearch/ActiveRecord.php
+++ b/framework/yii/elasticsearch/ActiveRecord.php
@@ -15,12 +15,29 @@ use yii\helpers\Inflector;
 use yii\helpers\Json;
 use yii\helpers\StringHelper;
 
-// TODO handle optimistic lock
-
 /**
  * ActiveRecord is the base class for classes representing relational data in terms of objects.
  *
+ * This class implements the ActiveRecord pattern for the fulltext search and data storage
+ * [elasticsearch](http://www.elasticsearch.org/).
+ *
+ * For defining a record a subclass should at least implement the [[attributes()]] method to define
+ * attributes.
+ * The primary key (the `_id` field in elasticsearch terms) is represented by `getId()` and `setId()`.
+ *
+ * The following is an example model called `Customer`:
+ *
+ * ```php
+ * class Customer extends \yii\elasticsearch\ActiveRecord
+ * {
+ *     public function attributes()
+ *     {
+ *         return ['id', 'name', 'address', 'registration_date'];
+ *     }
+ * }
+ * ```
  *
+ * You may override [[index()]] and [[type()]] to define the index and type this record represents.
  *
  * @author Carsten Brandt <mail@cebe.cc>
  * @since 2.0
diff --git a/framework/yii/elasticsearch/Cluster.php b/framework/yii/elasticsearch/Cluster.php
new file mode 100644
index 0000000..fda4175
--- /dev/null
+++ b/framework/yii/elasticsearch/Cluster.php
@@ -0,0 +1,16 @@
+<?php
+/**
+ * 
+ * 
+ * @author Carsten Brandt <mail@cebe.cc>
+ */
+
+namespace yii\elasticsearch;
+
+
+use yii\base\Object;
+
+class Cluster extends Object
+{
+	// TODO implement http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/cluster.html
+}
\ No newline at end of file
diff --git a/framework/yii/elasticsearch/Connection.php b/framework/yii/elasticsearch/Connection.php
index 73d7aad..46c1efb 100644
--- a/framework/yii/elasticsearch/Connection.php
+++ b/framework/yii/elasticsearch/Connection.php
@@ -34,6 +34,9 @@ class Connection extends Component
 		)
 	);
 
+	// http://www.elasticsearch.org/guide/en/elasticsearch/client/php-api/current/_configuration.html#_example_configuring_http_basic_auth
+	public $auth = [];
+
 	// TODO use timeouts
 	/**
 	 * @var float timeout to use for connection to redis. If not set the timeout set in php.ini will be used: ini_get("default_socket_timeout")
@@ -92,6 +95,9 @@ class Connection extends Component
 	 */
 	public function open()
 	{
+		// TODO select one node to be the active one.
+
+
 		foreach($this->nodes as $key => $node) {
 			if (is_array($node)) {
 				$this->nodes[$key] = new Node($node);