diff --git a/ldapcherry/backend/__init__.py b/ldapcherry/backend/__init__.py
new file mode 100644
index 0000000..c73186c
--- /dev/null
+++ b/ldapcherry/backend/__init__.py
@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# vim:set expandtab tabstop=4 shiftwidth=4:
+#
+# The MIT License (MIT)
+# LdapCherry
+# Copyright (c) 2014 Carpentier Pierre-Francois
+
+class Backend:
+
+    def __init__(self):
+        pass
+
+    def add_group(self):
+        pass
+
+    def set_attr(self):
+        pass
+
+    def rm_group(self):
+        pass
diff --git a/ldapcherry/backend/ldap.py b/ldapcherry/backend/ldap.py
new file mode 100644
index 0000000..bc750cd
--- /dev/null
+++ b/ldapcherry/backend/ldap.py
@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+# vim:set expandtab tabstop=4 shiftwidth=4:
+#
+# The MIT License (MIT)
+# LdapCherry
+# Copyright (c) 2014 Carpentier Pierre-Francois
+
+class Backend(ldapcherry.backend.Backend):
+
+    def __init__(self, config, logger):
+        pass
diff --git a/ldapcherry/backend/samba4.py b/ldapcherry/backend/samba4.py
new file mode 100644
index 0000000..bc807ca
--- /dev/null
+++ b/ldapcherry/backend/samba4.py
@@ -0,0 +1,7 @@
+# -*- coding: utf-8 -*-
+# vim:set expandtab tabstop=4 shiftwidth=4:
+#
+# License GPLv3
+# LdapCherry
+# Copyright (c) 2014 Carpentier Pierre-Francois
+
diff --git a/ldapcherry/exceptions.py b/ldapcherry/exceptions.py
new file mode 100644
index 0000000..baa706b
--- /dev/null
+++ b/ldapcherry/exceptions.py
@@ -0,0 +1,7 @@
+# -*- coding: utf-8 -*-
+# vim:set expandtab tabstop=4 shiftwidth=4:
+#
+# The MIT License (MIT)
+# LdapCherry
+# Copyright (c) 2014 Carpentier Pierre-Francois
+
diff --git a/ldapcherry/roles.py b/ldapcherry/roles.py
new file mode 100644
index 0000000..ccefbf5
--- /dev/null
+++ b/ldapcherry/roles.py
@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+# vim:set expandtab tabstop=4 shiftwidth=4:
+#
+# The MIT License (MIT)
+# LdapCherry
+# Copyright (c) 2014 Carpentier Pierre-Francois
+
+import os
+import sys
+
+try:
+    from yaml import CLoader as Loader, CDumper as Dumper
+except ImportError:
+    from yaml import Loader, Dumper
+
+class Roles:
+
+    def __init__(self, role_file):
+        pass
+
+    def _nest(self, role_file):
+        """nests the roles (creates roles hierarchy)"""
+        pass
+
+    def write(self, out_file):
+        """write the nested role hierarchy to a file"""
+        pass
+
+    def get_roles(self, groups):
+        """get list of roles and list of standalone groups"""
+        pass
+
+    def get_groups(self, roles):
+        """get the list of groups from roles"""
+        pass