Implementing window-based CCNx consumer.  Adding RTO estimation.

- ContentObject increases window by 1
- NACK decreases window by 1
- TO doesn't change window

If window is zero, next packet is scheduled after 0.1*RTO
diff --git a/apps/ccnx-consumer-window.h b/apps/ccnx-consumer-window.h
new file mode 100644
index 0000000..47099f6
--- /dev/null
+++ b/apps/ccnx-consumer-window.h
@@ -0,0 +1,79 @@
+/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2011 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Ilya Moiseenko <iliamo@cs.ucla.edu>
+ *         Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#ifndef CCNX_CONSUMER_WINDOW_H
+#define CCNX_CONSUMER_WINDOW_H
+
+#include "ccnx-consumer.h"
+
+namespace ns3 
+{
+
+/**
+ * @ingroup ccnx
+ * \brief CCNx application for sending out Interest packets (window-based)
+ */
+class CcnxConsumerWindow: public CcnxConsumer
+{
+public: 
+  static TypeId GetTypeId ();
+        
+  /**
+   * \brief Default constructor 
+   */
+  CcnxConsumerWindow ();
+
+  // From CcnxApp
+  // virtual void
+  // OnInterest (const Ptr<const CcnxInterestHeader> &interest);
+
+  virtual void
+  OnNack (const Ptr<const CcnxInterestHeader> &interest);
+
+  virtual void
+  OnContentObject (const Ptr<const CcnxContentObjectHeader> &contentObject,
+                   const Ptr<const Packet> &payload);
+
+  virtual void
+  OnTimeout (uint32_t sequenceNumber);
+ 
+protected:
+  /**
+   * \brief Constructs the Interest packet and sends it using a callback to the underlying CCNx protocol
+   */
+  virtual void
+  ScheduleNextPacket ();
+  
+private:
+  virtual void
+  SetWindow (uint32_t window);
+
+  uint32_t
+  GetWindow () const;
+  
+protected:
+  uint32_t m_window;
+  uint32_t m_inFlight;
+};
+
+} // namespace ns3
+
+#endif