[Twisted-Python] How to dispatch message to different servers

[Benjamin BERTRAND]

Le 2 mars 2013 à 14:53, Laurens Van Houtven <_ at lvh.cc> a écrit :

> Ah, but that too appears to be missing in the original code ;-)
> 
> The stuff you're doing with deferreds there seems a bit strange. In your example, why not just call sendMessage when you get the packet?

If I had only one server yes.
But the thing is I have to send the message to a different server depending on the line id.
That was my initial problem.
I don't see how I could call the sendMessage method corresponding to a specific server directly.
Or?

> 
> 
> On Sat, Mar 2, 2013 at 2:28 PM, Benjamin BERTRAND <beenje at gmail.com> wrote:
> 
> Le 2 mars 2013 à 10:08, Laurens Van Houtven <_ at lvh.cc> a écrit :
> 
>> Yes, that looks okay, but that wasn't in your original sample ;-)
>> 
>> 
> 
> Yep, sorry about that.
> I was more focused on the ServerFactory and Protocol.
> The pcap in a thread comes from the link I mentioned in my first post: http://dound.com/2009/09/integrating-twisted-with-a-pcap-based-python-packet-sniffer/
> But I know, it's better to put everything in one post. People shouldn't have to click links.
> 
>> I'm on my phone at the moment which isn't great for code review, but it looks like you only fire one deferred per line?
>> 
>> 
> 
> There is a specific deferred by line.
> I re-arm it in the messageToSend method (that wasn't in the sample either).
> In the Oldimon class, I have:
> 
>     def messageToSend(self, message):
>         self.sendMessage(message)
>         # Re-arm the deferred
>         self.factory.deferred[self.line] = defer.Deferred()
>         self.factory.deferred[self.line].addCallback(self.messageToSend)
> 
> 
>> On Mar 2, 2013 9:50 AM, "Benjamin BERTRAND" <beenje at gmail.com> wrote:
>> 
>> Le 2 mars 2013 à 04:34, exarkun at twistedmatrix.com a écrit :
>> 
>> > On 1 Mar, 09:52 pm, beenje at gmail.com wrote:
>> >> Thanks for the answer!
>> >>
>> >> I was hoping to avoid having to put something like AMP in place,
>> >> because it looked a bit overkill for my case.
>> >> I think I actually found a way :-)
>> >
>> > Unfortunately, it looks like the code that you shared will only work
>> > accidentally (if at all).  You cannot use Twisted APIs except in the
>> > reactor thread.  You will at least need to add in some code to send data
>> > back to the reactor thread before you use Twisted APIs (such as
>> > `Deferred.callback`).
>> 
>> 
>> In run_pcap, I call reactor.callFromThread(callback, x25_data, line_id). See below.
>> That seems to work with the tests I did.
>> Am I missing something?
>> 
>> /Benjamin
>> 
>> def run_pcap(device, pcap_filter, callback):
>> 
>>     def analyse_packet(hdr, data):
>>         # check the data
>>         reactor.callFromThread(callback, x25_data, line_id)
>> 
>>     p = pcapy.open_live(device, 65535, 1, 100)
>>     p.setfilter(pcap_filter)
>>     p.loop(-1, analyse_packet)
>> 
>> 
>> class Oldimon(Protocol):
>> 
>>     def __init__(self, factory):
>>         self.factory = factory
>>         self.line = None
>> 
>>     def connectionMade(self):
>>         # Check the server port to get the line
>>         # associated to this protocol
>>         port = self.transport.getHost().port
>>         self.line = LINES_PORT[port]
>>         # Add the callback for this line
>>         self.factory.deferred[self.line] = defer.Deferred()
>>         self.factory.deferred[self.line].addCallback(self.messageToSend)
>> 
>> 
>> class OldimonFactory(ServerFactory):
>> 
>>     def __init__(self, device, pcap_filter):
>>         # pcapDataReceived callback is called everytime a message
>>         # is received
>>         reactor.callInThread(run_pcap, device, pcap_filter, self.pcapDataReceived)
>>         # Dict with a deferred for each line
>>         self.deferred = dict(zip(LINES_PORT.values(), [None] * len(LINES_PORT)))
>> 
>>     def buildProtocol(self, addr):
>>         return Oldimon(self)
>> 
>>     def pcapDataReceived(self, data, line):
>>         if self.deferred[line] is not None:
>>             # Fire the callback for line
>>             d, self.deferred[line] = self.deferred[line], None
>>             d.callback(data)
>> 
>> oldimon_factory = OldimonFactory(device, pcap_filter)
>> for port in LINES_PORT.keys():
>>     reactor.listenTCP(port, oldimon_factory)
>> reactor.run()
>> 
>> 
>> >
>> > Jean-Paul
>> >
>> > _______________________________________________
>> > Twisted-Python mailing list
>> > Twisted-Python at twistedmatrix.com
>> > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
>> 
>> 
>> _______________________________________________
>> Twisted-Python mailing list
>> Twisted-Python at twistedmatrix.com
>> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
>> _______________________________________________
>> Twisted-Python mailing list
>> Twisted-Python at twistedmatrix.com
>> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
> 
> 
> _______________________________________________
> Twisted-Python mailing list
> Twisted-Python at twistedmatrix.com
> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
> 
> 
> 
> 
> -- 
> cheers
> lvh
> _______________________________________________
> Twisted-Python mailing list
> Twisted-Python at twistedmatrix.com
> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

-------------- next part --------------
An HTML attachment was scrubbed...
URL: </pipermail/twisted-python/attachments/20130302/ab9ebdea/attachment.html>