Added simple console tool demo.

The console tool spawns and monitors a bunch of nodes.

examples/consoles.py

@@ -0,0 +1,149 @@
+#!/usr/bin/python
+
+"""
+consoles.py: bring up a bunch of miniature consoles on a virtual network
+
+This demo shows how to monitor a set of nodes by using
+Tkinter's createfilehandler() and Node()'s monitor().
+"""
+
+from Tkinter import *
+
+from mininet.log import setLogLevel
+from mininet.topolib import TreeNet
+
+class Console( Frame ):
+    "A simple console on a host."
+    
+    def __init__( self, parent, node, height=16, width=32 ):
+        Frame.__init__( self, parent )
+        self.node = node
+        self.height, self.width = height, width
+        self.text = self.makeWidgets( )
+        self.bindEvents()
+
+    def makeWidgets( self ):
+        "Make a label, a text area, and a scroll bar."
+        labelStyle = {
+            'font': 'Monaco 7',
+            'relief': 'sunken'
+        }
+        textStyle = { 
+            'font': 'Monaco 7',
+            'bg': 'black',
+            'fg': 'green',
+            'width': self.width,
+            'height': self.height,
+            'relief': 'sunken'
+        }
+        label = Label( self, text=self.node.name, **labelStyle )
+        label.pack( side='top', fill='x' )
+        text = Text( self, wrap='word', **textStyle )
+        ybar = Scrollbar( self, orient='vertical', command=text.yview )
+        text.configure( yscrollcommand=ybar.set )
+        text.pack( side='left', expand=True, fill='both' )
+        ybar.pack( side='right', fill='y' )
+        return text
+
+    def bindEvents( self ):
+        "Bind keyboard and file events."
+        self.text.bind( '<Return>', self.handleReturn )
+        self.text.bind( '<Control-c>', self.handleInt )
+        self.text.bind( '<KeyPress>', self.handleKey )
+        # This is not well-documented, but it is the correct
+        # way to trigger a file event handler from Tk's
+        # event loop!
+        self.tk.createfilehandler( self.node.stdout, READABLE,
+            self.handleReadable )
+
+    def append( self, text ):
+        "Append something to our text frame."
+        self.text.insert( 'end', text )
+        self.text.mark_set( 'insert', 'end' )
+        self.text.see( 'insert' )
+    
+    def handleKey( self, event  ):
+        "Handle a regular key press."
+        self.append( event.char )
+    
+    def handleReturn( self, event ):
+        "Handle a carriage return."
+        print "handleReturn"
+    
+    def handleInt( self, event=None ):
+        "Handle control-c."
+        self.node.sendInt()
+        
+    def sendCmd( self, cmd ):
+        "Send a command to our node."
+        text, node = self.text, self.node
+        node.sendCmd( cmd )
+
+    def handleReadable( self, file, mask ):
+        data = self.node.monitor()
+        self.append( data )
+
+class Consoles( Frame ):
+
+    def __init__( self, nodes, parent=None, width=4 ):
+        Frame.__init__( self, parent )
+        self.nodes = nodes
+        self.createMenuBar( font='Geneva 7' )
+        self.consoles = self.createConsoles( nodes, width )
+        self.pack( expand=True, fill='both' )
+        
+    def createConsoles( self, nodes, width ):
+        "Create a grid of consoles in a frame."
+        f = Frame( self )
+        # Create consoles
+        consoles = []
+        index = 0
+        for node in nodes:
+            console = Console( f, node )
+            consoles.append( console )
+            row = int( index / width )
+            column = index % width
+            console.grid( row=row, column=column, sticky='nsew' )
+            index += 1
+            f.rowconfigure( row, weight=1 )
+            f.columnconfigure( column, weight=1 )
+        f.pack( expand=True, fill='both' )
+        return consoles
+        
+    def createMenuBar( self, font ):
+        "Create and return a menu (really button) bar."
+        f = Frame( self )
+        buttons = [
+            ( 'Ping', self.ping ),
+            ( 'Interrupt', self.stop ),
+            ( 'Quit', self.quit )
+        ]
+        for name, cmd in buttons:
+            b = Button( f, text=name, command=cmd, font=font )
+            b.pack( side='left' )
+        f.pack( padx=4, pady=4, fill='x' )
+        return f
+    
+    def ping( self ):
+        "Tell each console to ping the next one."
+        consoles = self.consoles
+        count = len( consoles )
+        i = 1
+        for console in consoles:
+            ip = consoles[ i ].node.IP()
+            console.sendCmd( 'ping ' + ip )
+            i = ( i + 1 ) % count
+            
+    def stop( self ):
+        "Interrupt all consoles."
+        for console in self.consoles:
+            console.handleInt()
+
+    
+if __name__ == '__main__':
+    setLogLevel( 'info' )
+    net = TreeNet( depth=2, fanout=2 )
+    net.start()
+    app = Consoles( net.hosts, width=2 )
+    app.mainloop()
+    net.stop()