Creating a pure virtual class CcnxConsumer.  CcnxConsumerCbr now
implements constant-rate interest generation.
diff --git a/apps/ccnx-consumer-cbr.cc b/apps/ccnx-consumer-cbr.cc
new file mode 100644
index 0000000..a41753f
--- /dev/null
+++ b/apps/ccnx-consumer-cbr.cc
@@ -0,0 +1,130 @@
+/* -*-  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>
+ */
+
+#include "ccnx-consumer-cbr.h"
+#include "ns3/ptr.h"
+#include "ns3/log.h"
+#include "ns3/simulator.h"
+#include "ns3/packet.h"
+#include "ns3/callback.h"
+#include "ns3/string.h"
+#include "ns3/boolean.h"
+#include "ns3/uinteger.h"
+#include "ns3/double.h"
+
+#include "ns3/ccnx.h"
+#include "../model/ccnx-local-face.h"
+#include "ns3/ccnx-interest-header.h"
+#include "ns3/ccnx-content-object-header.h"
+
+#include <boost/ref.hpp>
+#include <boost/lexical_cast.hpp>
+#include <boost/lambda/lambda.hpp>
+#include <boost/lambda/bind.hpp>
+
+namespace ll = boost::lambda;
+
+NS_LOG_COMPONENT_DEFINE ("CcnxConsumerCbr");
+
+namespace ns3
+{    
+    
+NS_OBJECT_ENSURE_REGISTERED (CcnxConsumerCbr);
+    
+TypeId
+CcnxConsumerCbr::GetTypeId (void)
+{
+  static TypeId tid = TypeId ("ns3::CcnxConsumerCbr")
+    .SetParent<CcnxConsumer> ()
+    .AddConstructor<CcnxConsumerCbr> ()
+
+    .AddAttribute ("MeanRate", "Mean data packet rate (relies on the PayloadSize parameter)",
+                   StringValue ("100Kbps"),
+                   MakeDataRateAccessor (&CcnxConsumerCbr::GetDesiredRate, &CcnxConsumerCbr::SetDesiredRate),
+                   MakeDataRateChecker ())
+    ;
+
+  return tid;
+}
+    
+CcnxConsumerCbr::CcnxConsumerCbr ()
+  : m_desiredRate ("100Kbps")
+{
+  NS_LOG_FUNCTION_NOARGS ();
+
+  UpdateMean ();
+}
+
+
+void
+CcnxConsumerCbr::UpdateMean ()
+{
+  double mean = 8.0 * m_payloadSize / m_desiredRate.GetBitRate ();
+  m_randExp = ExponentialVariable (mean, 10000 * mean); // set upper limit to inter-arrival time
+}
+
+void
+CcnxConsumerCbr::SetPayloadSize (uint32_t payload)
+{
+  CcnxConsumer::SetPayloadSize (payload);
+  UpdateMean ();
+}
+
+void
+CcnxConsumerCbr::SetDesiredRate (DataRate rate)
+{
+  m_desiredRate = rate;
+  UpdateMean ();
+}
+
+DataRate
+CcnxConsumerCbr::GetDesiredRate () const
+{
+  return m_desiredRate;
+}
+
+
+void
+CcnxConsumerCbr::ScheduleNextPacket ()
+{
+  if (!m_sendEvent.IsRunning ())
+    m_sendEvent = Simulator::Schedule (
+                                       Seconds(m_randExp.GetValue ()),
+                                       &CcnxConsumer::SendPacket, this);
+}
+
+///////////////////////////////////////////////////
+//          Process incoming packets             //
+///////////////////////////////////////////////////
+
+// void
+// CcnxConsumer::OnContentObject (const Ptr<const CcnxContentObjectHeader> &contentObject,
+//                                const Ptr<const Packet> &payload)
+// {
+//   CcnxConsumer::OnContentObject (contentObject, payload); // tracing inside
+// }
+
+// void
+// CcnxConsumer::OnNack (const Ptr<const CcnxInterestHeader> &interest)
+// {
+//   CcnxConsumer::OnNack (interest); // tracing inside
+// }
+
+} // namespace ns3
diff --git a/apps/ccnx-consumer-cbr.h b/apps/ccnx-consumer-cbr.h
new file mode 100644
index 0000000..59a06d7
--- /dev/null
+++ b/apps/ccnx-consumer-cbr.h
@@ -0,0 +1,83 @@
+/* -*-  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_CBR_H
+#define CCNX_CONSUMER_CBR_H
+
+#include "ccnx-consumer.h"
+
+namespace ns3 
+{
+
+/**
+ * @ingroup ccnx
+ * \brief CCNx application for sending out Interest packets at a "constant" rate (Poisson process)
+ */
+class CcnxConsumerCbr: public CcnxConsumer
+{
+public: 
+  static TypeId GetTypeId ();
+        
+  /**
+   * \brief Default constructor 
+   * Sets up randomizer function and packet sequence number
+   */
+  CcnxConsumerCbr ();
+
+  // 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);
+
+protected:
+  /**
+   * \brief Constructs the Interest packet and sends it using a callback to the underlying CCNx protocol
+   */
+  virtual void
+  ScheduleNextPacket ();
+  
+private:
+  void
+  UpdateMean ();
+
+  virtual void
+  SetPayloadSize (uint32_t payload);
+
+  void
+  SetDesiredRate (DataRate rate);
+
+  DataRate
+  GetDesiredRate () const;
+  
+protected:
+  ExponentialVariable m_randExp; // packet inter-arrival time generation (Poisson process)
+  DataRate            m_desiredRate;    // Desired data packet rate
+};
+
+} // namespace ns3
+
+#endif
diff --git a/apps/ccnx-consumer.cc b/apps/ccnx-consumer.cc
index ae56040..fcc1ccf 100644
--- a/apps/ccnx-consumer.cc
+++ b/apps/ccnx-consumer.cc
@@ -53,27 +53,19 @@
 {
   static TypeId tid = TypeId ("ns3::CcnxConsumer")
     .SetParent<CcnxApp> ()
-    .AddConstructor<CcnxConsumer> ()
     .AddAttribute ("StartSeq", "Initial sequence number",
                    IntegerValue (0),
                    MakeIntegerAccessor(&CcnxConsumer::m_seq),
                    MakeIntegerChecker<int32_t>())
 
-    .AddAttribute ("Size", "Amount of data in megabytes to request (relies on PayloadSize parameter)",
-                   DoubleValue (-1), // don't impose limit by default
-                   MakeDoubleAccessor (&CcnxConsumer::GetMaxSize, &CcnxConsumer::SetMaxSize),
-                   MakeDoubleChecker<double> ())
-
-    ///////
     .AddAttribute ("PayloadSize", "Average size of content object size (to calculate interest generation rate)",
                    UintegerValue (1040),
                    MakeUintegerAccessor (&CcnxConsumer::GetPayloadSize, &CcnxConsumer::SetPayloadSize),
                    MakeUintegerChecker<uint32_t>())
-    .AddAttribute ("MeanRate", "Mean data packet rate (relies on the PayloadSize parameter)",
-                   StringValue ("100Kbps"),
-                   MakeDataRateAccessor (&CcnxConsumer::GetDesiredRate, &CcnxConsumer::SetDesiredRate),
-                   MakeDataRateChecker ())
-    ///////
+    .AddAttribute ("Size", "Amount of data in megabytes to request (relies on PayloadSize parameter)",
+                   DoubleValue (-1), // don't impose limit by default
+                   MakeDoubleAccessor (&CcnxConsumer::GetMaxSize, &CcnxConsumer::SetMaxSize),
+                   MakeDoubleChecker<double> ())
 
     .AddAttribute ("Prefix","CcnxName of the Interest",
                    StringValue ("/"),
@@ -120,13 +112,10 @@
     
 CcnxConsumer::CcnxConsumer ()
   : m_rand (0, std::numeric_limits<uint32_t>::max ())
-  , m_desiredRate ("10Kbps")
   , m_payloadSize (1040)
   , m_seq (0)
 {
   NS_LOG_FUNCTION_NOARGS ();
-
-  UpdateMean (); // not necessary (will be called by ns3 object system anyways), but doesn't hurt
 }
 
 void
@@ -177,20 +166,6 @@
                                      &CcnxConsumer::CheckRetxTimeout, this); 
 }
 
-void
-CcnxConsumer::UpdateMean ()
-{
-  double mean = 8.0 * m_payloadSize / m_desiredRate.GetBitRate ();
-  m_randExp = ExponentialVariable (mean, 10000 * mean); // set upper limit to inter-arrival time
-}
-
-void
-CcnxConsumer::SetPayloadSize (uint32_t payload)
-{
-  m_payloadSize = payload;
-  UpdateMean ();
-}
-
 uint32_t
 CcnxConsumer::GetPayloadSize () const
 {
@@ -198,16 +173,9 @@
 }
 
 void
-CcnxConsumer::SetDesiredRate (DataRate rate)
+CcnxConsumer::SetPayloadSize (uint32_t payload)
 {
-  m_desiredRate = rate;
-  UpdateMean ();
-}
-
-DataRate
-CcnxConsumer::GetDesiredRate () const
-{
-  return m_desiredRate;
+  m_payloadSize = payload;
 }
 
 double
@@ -232,16 +200,6 @@
   NS_LOG_DEBUG ("MaxSeqNo: " << m_seqMax);
 }
 
-
-void
-CcnxConsumer::ScheduleNextPacket ()
-{
-  if (!m_sendEvent.IsRunning ())
-    m_sendEvent = Simulator::Schedule (
-                                       Seconds(m_randExp.GetValue ()),
-                                       &CcnxConsumer::SendPacket, this);
-}
-
 // Application Methods
 void 
 CcnxConsumer::StartApplication () // Called at time specified by Start
diff --git a/apps/ccnx-consumer.h b/apps/ccnx-consumer.h
index 9b28a2c..31b4eb9 100644
--- a/apps/ccnx-consumer.h
+++ b/apps/ccnx-consumer.h
@@ -66,6 +66,11 @@
   OnContentObject (const Ptr<const CcnxContentObjectHeader> &contentObject,
                    const Ptr<const Packet> &payload);
 
+
+  // Simulator::Schedule doesn't work with protected members???
+  void
+  SendPacket ();
+  
 protected:
   // from CcnxApp
   virtual void
@@ -74,31 +79,12 @@
   virtual void
   StopApplication ();
   
-private:
   /**
    * \brief Constructs the Interest packet and sends it using a callback to the underlying CCNx protocol
    */
-  void
-  ScheduleNextPacket ();
-
-  void
-  UpdateMean ();
-
-  void
-  SetPayloadSize (uint32_t payload);
-
-  uint32_t
-  GetPayloadSize () const;
-
-  void
-  SetDesiredRate (DataRate rate);
-
-  DataRate
-  GetDesiredRate () const;
+  virtual void
+  ScheduleNextPacket () = 0;
   
-  void
-  SendPacket ();
-
   /**
    * \brief Checks if the packet need to be retransmitted becuase of retransmission timer expiration
    */
@@ -119,6 +105,12 @@
   Time
   GetRetxTimer () const;
   
+  virtual void
+  SetPayloadSize (uint32_t payload);
+
+  uint32_t
+  GetPayloadSize () const;
+
   double
   GetMaxSize () const;
 
@@ -127,11 +119,8 @@
   
 protected:
   UniformVariable m_rand; // nonce generator
-
-  ExponentialVariable m_randExp; // packet inter-arrival time generation (Poisson process)
-  DataRate            m_desiredRate;    // Desired data packet rate
   uint32_t            m_payloadSize; // expected payload size
-  
+
   uint32_t        m_seq;
   uint32_t        m_seqMax;    // maximum number of sequence number
   EventId         m_sendEvent; // Eventid of pending "send packet" event
diff --git a/examples/congestion-pop.cc b/examples/congestion-pop.cc
index 51a5fa0..18cb26c 100644
--- a/examples/congestion-pop.cc
+++ b/examples/congestion-pop.cc
@@ -144,7 +144,7 @@
         Ptr<Node> node1 = Names::Find<Node> ("/sprint", lexical_cast<string> (node1_num));
         Ptr<Node> node2 = Names::Find<Node> ("/sprint", lexical_cast<string> (node2_num));
 
-        CcnxAppHelper consumerHelper ("ns3::CcnxConsumer");
+        CcnxAppHelper consumerHelper ("ns3::CcnxConsumerCbr");
         consumerHelper.SetPrefix ("/" + lexical_cast<string> (node2->GetId ()));
         consumerHelper.SetAttribute ("MeanRate", StringValue ("2Mbps"));
         consumerHelper.SetAttribute ("Size", StringValue ("1.983642578125")); //to make sure max seq # is 2000