diff --git a/library/Businessprocess/BpNode.php b/library/Businessprocess/BpNode.php
index 5015b1d..34fd26c 100644
--- a/library/Businessprocess/BpNode.php
+++ b/library/Businessprocess/BpNode.php
@@ -205,16 +205,6 @@ class BpNode extends Node
         $this->state = $this->sortStateTostate($sort_state);
     }
 
-    public function countChildren()
-    {
-        return count($this->getChildren());
-    }
-
-    public function hasChildren()
-    {
-        return $this->countChildren() > 0;
-    }
-
     public function setDisplay($display)
     {
         $this->display = (int) $display;
diff --git a/library/Businessprocess/Node.php b/library/Businessprocess/Node.php
index 163d7bb..20e68b2 100644
--- a/library/Businessprocess/Node.php
+++ b/library/Businessprocess/Node.php
@@ -242,21 +242,31 @@ abstract class Node
         return $this->bp->isEditMode();
     }
 
-    public function hasChildren()
+    public function hasChildren($filter = null)
     {
         return false;
     }
 
-    public function countChildren()
-    {
-        return 0;
-    }
-
-    public function getChildren()
+    public function getChildren($filter = null)
     {
         return array();
     }
 
+    public function countChildren($filter = null)
+    {
+        return count($this->getChildren($filter));
+    }
+
+    public function hasChildren($filter = null)
+    {
+        return $this->countChildren($filter) > 0;
+    }
+
+    public function isEmpty()
+    {
+        return $this->countChildren() === 0;
+    }
+
     public function hasAlias()
     {
         return false;