issues and errors occured while creating more cameras for a fog device in a Fog_based Cloud Network using surveillance system application

[sujannou]

While trying to simulate one fog device(one router) using 100 cameras in a Fog-Based Cloud Network in a surveillance system IoT application, I got the following results
"
Placement of operator object_detector on device Router-0 successful.
Placement of operator object_tracker on device Router-0 successful.
Router-0 is shifting object_detector north.
Proxy-Server is shifting object_detector north.
Cloud is shifting object_tracker north.
Cloud is shifting object_detector north.
Placement of operator object_tracker on device Cloud successful.
Placement of operator user_interface on device Cloud successful.
Placement of operator object_detector on device Router-0 successful.
Router-0 is shifting object_detector north.
Cloud is shifting object_tracker north.
Proxy-Server is shifting object_detector north.
java.lang.NullPointerException
at org.fog.placement.ModulePlacementEdgewards.shiftModuleNorth(ModulePlacementEdgewards.java:303)
at org.fog.placement.ModulePlacementEdgewards.placeModulesInPath(ModulePlacementEdgewards.java:207)
at org.fog.placement.ModulePlacementEdgewards.mapModules(ModulePlacementEdgewards.java:73)
at org.fog.placement.ModulePlacementEdgewards.(ModulePlacementEdgewards.java:54)
at org.fog.Simulation.FogSurveillanceSystem.main(FogSurveillanceSystem.java:114)
"
Can anybody help me with some of my following queries based on above simulation results?

1. What does the following means and signify?
   a. Router-0 is shifting object_detector north.
   b. Cloud is shifting object_tracker north.
   c. Cloud is shifting object_detector north.
2. Errors
   java.lang.NullPointerException
   at org.fog.placement.ModulePlacementEdgewards.shiftModuleNorth(ModulePlacementEdgewards.java:303)
   at org.fog.placement.ModulePlacementEdgewards.placeModulesInPath(ModulePlacementEdgewards.java:207)
   at org.fog.placement.ModulePlacementEdgewards.mapModules(ModulePlacementEdgewards.java:73)
   at org.fog.placement.ModulePlacementEdgewards.(ModulePlacementEdgewards.java:54)
   at org.fog.Simulation.FogSurveillanceSystem.main(FogSurveillanceSystem.java:114)

For router =1, no of cameras =5, I got the following normal results
" Placement of operator object_detector on device Router-0 successful.
Placement of operator object_tracker on device Router-0 successful.
Router-0 is shifting object_detector north.
Creating motion_detector on device Camera-0-4
Creating user_interface on device Cloud
Creating object_tracker on device Proxy-Server
Creating object_detector on device Proxy-Server
Creating motion_detector on device Camera-0-0
Creating motion_detector on device Camera-0-1
Creating motion_detector on device Camera-0-2
Creating motion_detector on device Camera-0-3"

[bbaktech]

in your case when only 5 camaras, Router-0 is not have sufficient resource(i.e MIPS,RAM) so it is shifting to Proxy,
in second case where you connected 100camaras,Router-0 has no sufficient resource it is shifting module to proxy, proxy is also not have sufficient resource to handle tuples from 100 it is also shifting to upwards to cloud, you must create cloud devise with name "cloud", but you gave it with capital Cloud. change name from Cloud to cloud it will work.