Slight API change.  Now there is only one CcnxAppHelper that can create all CcnxApps
diff --git a/examples/ccnx-grid.cc b/examples/ccnx-grid.cc
index 51d7858..28a021b 100644
--- a/examples/ccnx-grid.cc
+++ b/examples/ccnx-grid.cc
@@ -116,13 +116,16 @@
   std::ostringstream prefix;
   prefix << "/" << producer->GetId ();
   
-  CcnxConsumerHelper consumerHelper (prefix.str ());
+  CcnxAppHelper consumerHelper ("ns3::CcnxConsumer");
+  consumerHelper.SetPrefix (prefix.str ());
   ApplicationContainer consumers = consumerHelper.Install (consumerNodes);
   
   // consumers.Start (Seconds (0.0));
   // consumers.Stop (finishTime);
     
-  CcnxProducerHelper producerHelper (prefix.str (),1024);
+  CcnxAppHelper producerHelper ("ns3::CcnxProducer");
+  producerHelper.SetPrefix (prefix.str ());
+  producerHelper.SetAttribute ("PayloadSize", StringValue("1024"));
   ApplicationContainer producers = producerHelper.Install (producer);
   
   // producers.Start(Seconds(0.0));