face: ProtocolFactory registry

refs #3904

Change-Id: Ic7c8b3d6138b7c27d4189a2e15cc646055ad1294
diff --git a/daemon/face/tcp-factory.hpp b/daemon/face/tcp-factory.hpp
index 161c490..059c8e1 100644
--- a/daemon/face/tcp-factory.hpp
+++ b/daemon/face/tcp-factory.hpp
@@ -37,6 +37,9 @@
 class TcpFactory : public ProtocolFactory
 {
 public:
+  static const std::string&
+  getId();
+
   /** \brief process face_system.tcp config section
    */
   void