First crack at allowing Controller to be customized.

Network may now be used with custom controllers.
An example of doing this is in nox.py, which instantiates at TreeNet
using a custom Controller, NoxController, that runs nox_core rather
than the reference controller.

examples/nox.py

@@ -1,39 +1,17 @@
 #!/usr/bin/python
 
-"Create a network from scratch and use NOX as the controller."
+"Instantiate a Tree network and use NOX as the controller."
 
-from mininet import init, Controller, Switch, Host, createLink
+import time
+from mininet import init, Controller, TreeNet, Cli
 
-def scratchNet( cname='controller', cargs='ptcp:'):
-   # Create Network
-   controller = Node( 'c0', inNamespace=False )
-   switch = Node( 's0', inNamespace=False )
-   h0 = Node( 'h0' )
-   h1 = Node( 'h1' )
-   createLink( h0, switch )
-   createLink( h1, switch )
-   # Configure hosts
-   h0.setIP( h0.intfs[ 0 ], '192.168.123.1', '/24' )
-   h1.setIP( h1.intfs[ 0 ], '192.168.123.2', '/24' )
-   # Start network using kernel datapath
-   controller.cmdPrint( cname + ' ' + cargs + '&' )
-   switch.cmdPrint( 'dpctl deldp nl:0' )
-   switch.cmdPrint( 'dpctl adddp nl:0' )
-   for intf in switch.intfs:
-      switch.cmdPrint( 'dpctl addif nl:0 ' + intf )
-   switch.cmdPrint( 'ofprotocol nl:0 tcp:localhost &')
-   # Run test
-   h0.cmdPrint( 'ping -c1 ' + h1.IP() )
-   # Stop network
-   controller.cmdPrint( 'kill %' + cname)
-   switch.cmdPrint( 'dpctl deldp nl:0' )
-   switch.cmdPrint( 'kill %ofprotocol' )
-   switch.stop()
-   controller.stop()
+class NoxController( Controller ):
+   def __init__( self, name, **kwargs ):
+      Controller.__init__( self, name, 
+         controller='nox_core', cargs='-i ptcp pyswitch', 
+         cdir='/usr/local/bin', **kwargs)
    
 if __name__ == '__main__':
    init()   
-   scratchNet( cname='nox_core', cargs='-i ptcp:' )
-
-
-
+   network = TreeNet( depth=2, fanout=4, kernel=True, Controller=NoxController)
+   network.run( Cli )