RE: Re: Python

["Patrick Lidstone (Personal e-mail)" <patrick@xxxxxxxxxxxx>]

Nice job, Nark!

My approach was a bit different - I extended the python engine itself so
that it was xAP aware. But I think your approach might well be more
ergonomic!

Patrick

> -----Original Message-----
> From: mark_harrison_uk2 [mailto:mph@xxxxxxx]
> Sent: 10 February 2005 16:25
> To: xAP_developer@xxxxxxx
> Subject: [xAP_developer] Re: Python
>
>
>
> --- In xAP_developer@xxxxxxx, "mark_harrison_uk2"
<mph@a...>
> wrote:
>
> ... and today, a hub-aware, heart-beat pumping, version of
> the "PythonListener" that certainly works with Stuart's .NET
> hub, and picks up messages from Patrick's embedded Rio application.
>
> Source code below. It seems very, very, little for quite a
> lot of work, but I was learning the language from scratch,
> and I've re-written it all about a dozen times today ending
> up with this, which I think is the most elegant.
>
> Mark
>
> --------------------------------------------
>
> # import some standard Python classes
>
> import time, thread, SocketServer, socket
>
> # we need to start by defining the various functions
>
> # xapHandler is what is called when a UDP packet is received
> # because of the way that the inbuilt SocketServer class
> works, # it's implemented as a class with a default handler
>
> class xapHandler(SocketServer.DatagramRequestHandler):
> 	def handle(self):
> 		print "Incoming message from ", self.client_address[0]
> 		message=self.rfile.read()
> 		header=message[message.find('{')+2:message.find('}')]
> 		print header
>
> # xapheartbeat builds a heartbeat message (once it knows its
> port) # and sends it repeatedly every sleeptime seconds
>
> def xapheartbeat(port,sleeptime,*args):
> 	print "Starting heartbeats"
>
	heartbeatmessage="xap-hbeat\n{\nv=12\nhop=1\nuid=FF001100\n"
>
> heartbeatmessage+="class=xap-hbeat.alive\nsource=scentium.pyth
> on.test."
> 	heartbeatmessage +=socket.getfqdn(socket.gethostname())
> 	heartbeatmessage+="\ninterval=60\nport="
> 	heartbeatmessage +=str(port)
> 	heartbeatmessage += "\n}"
> 	heartbeat=socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
> 	heartbeat.connect(('255.255.255.255',3639))
> 	while 1:
> 		heartbeat.send(heartbeatmessage)
>         	time.sleep(sleeptime)
>
> # xaplistener tries to open a listener socket on 3639 on the
> primary IP address # if that fails, it adds one to the
> listener port and tries again # in case you're wondering
> about the shrubbery, it's because threads have to be # called
> with two arguments, a function and a tuple of parameters, and
> I've # not sussed how to make a tuple with only one argument
>
>
> def xaplistener(baseport,shrubbery):
> 	try:
> 		print "starting listener on", baseport
> 		serv = SocketServer.UDPServer(('',baseport), xapHandler)
> 		thread.start_new_thread(xapheartbeat,(baseport,60))
> 		serv.serve_forever()
> 	except:
> 		print "sorry - ", baseport, "in use"
> 		xaplistener(baseport+1, 0)
>
> # now we get the actual routine
>
>
> if __name__=="__main__":
>
> 	print 'Copyright 2005 Mark Harrison ltd.'
> 	print 'xap listener 1.1 - heartbeating, hub aware'
> 	xaplistener(3639, 0)
>
>
>
>
>
>
>
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