diff --git a/dbus_interface.h b/dbus_interface.h
new file mode 100644
index 0000000..1b5c953
--- /dev/null
+++ b/dbus_interface.h
@@ -0,0 +1,74 @@
+// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_DBUS_INTERFACE_H__
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_DBUS_INTERFACE_H__
+
+// This class interfaces with DBus. The interface allows it to be mocked.
+
+#include <dbus/dbus-glib.h>
+
+namespace chromeos_update_engine {
+
+class DbusGlibInterface {
+ public:
+  // wraps dbus_g_proxy_new_for_name_owner
+  virtual DBusGProxy* ProxyNewForNameOwner(DBusGConnection* connection,
+                                           const char* name,
+                                           const char* path,
+                                           const char* interface,
+                                           GError** error) = 0;
+
+  // wraps g_object_unref
+  virtual void ProxyUnref(DBusGProxy* proxy) = 0;
+
+  // wraps dbus_g_bus_get
+  virtual DBusGConnection*  BusGet(DBusBusType type, GError** error) = 0;
+  
+  // wraps dbus_g_proxy_call
+  virtual gboolean ProxyCall(DBusGProxy* proxy,
+                             const char* method,
+                             GError** error,
+                             GType first_arg_type,
+                             GType var_arg1,
+                             GHashTable** var_arg2,
+                             GType var_arg3) = 0;
+};
+
+class ConcreteDbusGlib : public DbusGlibInterface {
+  virtual DBusGProxy* ProxyNewForNameOwner(DBusGConnection* connection,
+                                           const char* name,
+                                           const char* path,
+                                           const char* interface,
+                                           GError** error) {
+    return dbus_g_proxy_new_for_name_owner(connection,
+                                           name,
+                                           path,
+                                           interface,
+                                           error);
+  }
+
+  virtual void ProxyUnref(DBusGProxy* proxy) {
+    g_object_unref(proxy);
+  }
+
+  virtual DBusGConnection*  BusGet(DBusBusType type, GError** error) {
+    return dbus_g_bus_get(type, error);
+  }
+  
+  virtual gboolean ProxyCall(DBusGProxy* proxy,
+                             const char* method,
+                             GError** error,
+                             GType first_arg_type,
+                             GType var_arg1,
+                             GHashTable** var_arg2,
+                             GType var_arg3) {
+    return dbus_g_proxy_call(
+        proxy, method, error, first_arg_type, var_arg1, var_arg2, var_arg3);
+  }
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_DBUS_INTERFACE_H__