The STOMP library uses threads from Python, which NOX does not support. This
will make usage of the library relatively difficult -- you'll need to add
support for multithreaded Python to NOX, or you'll need to rewrite the library
(or possibly just call it in a very unusual way) -- probably rewriting it to
use Twisted (which NOX does support) would be easiest.
Another option (probably the easiest one yet) would be to run the STOMP library
in a small external application and then communicate from that to NOX. This
communication could be done using Twisted, but NOX has the
messenger/jsonmessenger components which are meant for doing this sort of thing
and are somewhat easier.
As a sidenote, being able to more easily interface with third party Python
libraries was one of the design points for POX.
-- Murphy
On Jul 24, 2012, at 8:37 AM, Neha Jatav wrote:
> Hi,
>
> I am trying to create a listener inside the NOX script to listen to changes
> in a variable done externally. The script listener.py attached with this
> email runs fine by itself. I'm not sure where to add it in the NOX script
> because the script listener.py also needs a time.sleep() for it to listen
> indefinitely. I'd be highly obliged if you could guide me where to add the
> listener part in the NOX script. I tried to add the listener part to my NOX
> script as follows; but it didn't work. STOMP connect was setup in the
> beginning but was lost soon.
>
> # listener code starts ===================================
>
> import time
> import sys
> import os
> import stomp
> import Globals
>
> user = os.getenv("STOMP_USER") or "admin"
> password = os.getenv("STOMP_PASSWORD") or "password"
> host = os.getenv("STOMP_HOST") or "localhost"
> port = os.getenv("STOMP_PORT") or 61613
> destination = sys.argv[1:2] or ["/topic/event"]
> destination = destination[0]
>
> # listener code ends ===================================
>
> class lbtest(Component):
>
> def install(self):
> self.register_for_packet_in(self.packet_in_callback)
> .......other callback functions...............
>
> def getInterface(self):
> return str(lbtest)
>
> def __init__(self, ctxt):
> Component.__init__(self, ctxt)
> Globals.COMPONENT = self
>
> # listener code starts ===================================
>
> conn = stomp.Connection(host_and_ports = [(host, port)])
> conn.set_listener('', MyListener(conn))
> conn.start()
> conn.connect(login=user,passcode=password)
> conn.subscribe(destination=destination, ack='auto')
> Globals.log.info("Waiting for messages...")
>
> # listener code ends ===================================
>
> ......some definitions...
>
>
> # ===================================
> # Factory
> # ===================================
>
> def getFactory():
> class Factory:
> def instance(self, ctxt):
> return lbtest(ctxt)
>
> return Factory()
>
>
> # listener code starts ===================================
>
> # ===================================
> # Stomp listener for VIP change
> # ===================================
>
>
> class MyListener(object):
>
> def __init__(self, conn):
> self.conn = conn
>
> def on_error(self, headers, message):
> Globals.log.info('received an error ' + message)
>
> def on_message(self, headers, message):
> Globals.VIP=message
> Globals.log.info('New VIP: '+Globals.VIP)
>
> # listener code ends ===================================
>
> Regards,
> Neha
> <listener.py>
