Tutorial 1: Hello World Example

The "Hello World" Experiment is simple. The script for this experiment is shown below.

#
# Define nodes used in experiment
#
defNodes('sender', [1,1]) {|node|
  node.image = nil  # assume the right image to be on disk

  node.prototype("test:proto:sender", {
    'destinationHost' => '192.168.1.2',
    'packetSize' => 1024,
    'rate' => 300,
    'protocol' => 'udp'    
  })
  node.net.w0.mode = "managed"
}

defNodes('receiver', [1,2]) {|node|
  node.image = nil  # assume the right image to be on disk
  node.prototype("test:proto:receiver" , {
    'protocol' => 'udp'
  })
  node.net.w0.mode = "master"
}

allNodes.net.w0 { |w|
  w.type = 'b'
  w.essid = "helloworld"
  w.ip = "%192.168.%x.%y"
}

#
# Now, start the application
#
whenAllInstalled() {|node|
  wait 30 

  allNodes.startApplications
  wait 40

  Experiment.done
}

Figure 1. Script for "Hello World" Experiment

Understanding the Hello World

The first part of the script creates a group called sender and assigns node1-1 to it. Next, we instruct nodehandler to assign the prototype to node1-1 using test:proto:sender Note that the sender prototype is defined using a corresponding sender.rb file and launches an underlying application on the node. In this case, the application is otg ORBIT Traffic Generator

Next, we pass command line options that will be used by nodehandler when it launches the application on the node. for e.g, the following description will launch otg –-destinationHost 192.168.1.2 —packetsize 1024 —rate 300 — protocol udp

defNodes('sender', [1,1]) {|node|                   
node.image = nil   #Default image on the node to be used for the experiment
node.prototype("test:proto:sender", {
   'destinationHost' => '192.168.1.2',
    'packetSize' => 1024,
    'rate' => 300,
    'protocol' => 'udp'
  })
node.net.w0.mode = "managed"
}

Create a group called receiver and assign node1-2 to it. Next, we instruct nodehandler to assign the prototype to node1-2 using test:proto:receiver Note that the receiver prototype is defined using a corresponding receiver.rb file and launches an underlying application on the node.In this case, the application is otr.

Next, we pass command line options that will be used by nodehandler when it launches the application on the node. for e.g, the following description will launch for e.g, the following will description will cause nodeagent to launch otr –- protocol udp

defNodes('receiver', [1,2]) {|node|
  node.image = nil  
  node.prototype("test:proto:receiver" , {
    'protocol' => 'udp'
  })
  node.net.w0.mode = "Master"
}

Configures the first wireless card on all nodes to 802.11b, essid ‘helloworld’ with ip addresses 192.168.x.y where x.y are the grid co-ordinates of the repsective nodes.

allNodes.net.w0 { |w|
  w.type = 'b'
  w.essid = "helloworld"
  w.ip = "%192.168.%x.%y"
}

Now, we start the application. This is like a barrier implementation where nodehandler waits to receive an OK message from each of the nodeagents, and only proceeds when initial configurations are OK.

whenAllInstalled() {|node|

This command will request nodeagents to launch the application corresponding to the role that the node is playing, e.g sender will launch the application otg and the receiver will launch the application otr with the command line options as specified before

allNodes.startApplications

Conduct experiment for 60 seconds

  wait 60

End of experiment – Shut down all nodes

Experiment.done