[Twisted-Python] Twisted Client

[Lucas Taylor]

On 11/10/09 6:25 AM, morbidux wrote:
> Hi all,
> 
> I'm writing a simple client / server application, that uses a small
> protocol to dialog.
> 
> I can't find in documentation any exemple that would correspond to what my
> client is supposed to do.
> 
> Here is the basics :
> 
>  every X seconds, call a function that check a file
>   if file is different, connect to server
> 
> When the client is connected, it immediatly sends data to server, using
> the connectionMade method.
> 
> Do I need to use while(1) loop or loopingCall ? What is the best way to
> write a daemon that connect to a server every X seconds ?
> 

You could setup a LoopingCall that calls your file checking function.
Your file checking function can then use
twisted.internet.protocol.ClientCreator to send your data.

A simple example:

import os
from twisted.internet import reactor
from twisted.internet.protocol import Protocol, ClientCreator
from twisted.internet.task import LoopingCall
from twisted.python import log

def gotProtocol(p, data):
    p.transport.write(data)
    p.transport.loseConnection()

def errHandler(reason):
    log.err(reason)

def checkFile():
    if os.path.exists('sentry.file'):
        c = ClientCreator(reactor, Protocol)
        c.connectTCP("localhost", 1234).addCallback(gotProtocol, 'some
data').addErrback(errHandler)

lp = LoopingCall(checkFile)
lp.start(5, now=True)

reactor.run()

--

If you want to maintain state between protocol instances, then create a
ClientFactory. You could look at how ReconnectingClientFactory is
implemented for ideas.

The Writing Clients howto should help:
http://twistedmatrix.com/projects/core/documentation/howto/clients.html


Lucas Taylor