diff --git a/apps/ndn-app.cc b/apps/ndn-app.cc
index d29f509..7880849 100644
--- a/apps/ndn-app.cc
+++ b/apps/ndn-app.cc
@@ -64,8 +64,7 @@
 }
     
 App::App ()
-  : m_protocolHandler (0)
-  , m_active (false)
+  : m_active (false)
   , m_face (0)
 {
 }
@@ -85,12 +84,6 @@
   Application::DoDispose ();
 }
 
-void
-App::RegisterProtocolHandler (ProtocolHandler handler)
-{
-  m_protocolHandler = handler;
-}
-
 uint32_t
 App::GetId () const
 {
@@ -164,7 +157,7 @@
   // step 3. Destroy face
   if (m_face->GetReferenceCount () != 1)
     {
-      NS_LOG_ERROR ("Please a bug report on https://github.com/NDN-Routing/ndnSIM/issues:");
+      NS_LOG_ERROR ("Please a bug report on https://github.com/NDN-Routing/ndnSIM/issues");
       NS_LOG_ERROR ("At this point, nobody else should have referenced this face, but we have "
                     << m_face->GetReferenceCount () << " references");
 
diff --git a/apps/ndn-app.h b/apps/ndn-app.h
index 57d1d83..491cae4 100644
--- a/apps/ndn-app.h
+++ b/apps/ndn-app.h
@@ -35,9 +35,6 @@
 class Interest;
 class ContentObject;
 
-typedef Interest InterestHeader;
-typedef ContentObject ContentObjectHeader;
-
 class Face;
 
 /**
@@ -52,7 +49,8 @@
   /**
    * @brief A callback to pass packets to underlying NDN protocol
    */
-  typedef Callback<bool, const Ptr<const Packet>&> ProtocolHandler;
+  typedef Callback<bool, Ptr<const Interest>, Ptr<const Packet> > InterestHandler;
+  typedef Callback<bool, Ptr<const ContentObject>, Ptr<const Packet> > DataHandler;
   
   static TypeId GetTypeId ();
 
@@ -63,12 +61,6 @@
   virtual ~App ();
 
   /**
-   * @brief Register lower layer callback (to send interests from the application)
-   */
-  void
-  RegisterProtocolHandler (ProtocolHandler handler);
-
-  /**
    * @brief Get application ID (ID of applications face)
    */
   uint32_t
@@ -114,7 +106,6 @@
   StopApplication ();     ///< @brief Called at time specified by Stop
 
 protected:
-  ProtocolHandler m_protocolHandler; ///< @brief A callback to pass packets to underlying NDN protocol
   bool m_active;  ///< @brief Flag to indicate that application is active (set by StartApplication and StopApplication)
   Ptr<Face> m_face;   ///< @brief automatically created application face through which application communicates