Mailman 3 January 2008 - Twisted

[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com Jan. 19, 2008

Jan. 19, 2008

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[Twisted-Python] Newbie question about error handling.
by Brad Smith Jan. 19, 2008

Jan. 19, 2008

I'm working on a client/server twisted app based on LineReceiver, and I'd like to implement better error-handling. The code for the server looks something like this: class MyServer(LineReceiver): def lineReceived(self, line): pass # stuff happens def rawDataReceived(self, data): pass # other stuff happens # maybe some other methods too factory = Factory() factory.protocol = MyServer reactor.listenTCP(8000, factory) reactor.run() Suppose that an exception is thrown in lineReceived or rawDataReceived, maybe just something as simple as a naming error caused by a misspelled variable name. Is there any way to implement a default exception handler that would allow me to send something back to the client before the protocol dies? It would be nice to send the exception traceback to the client to help figure out what went wrong. I suppose I could wrap all of the methods in the class in a try/catch block, but that would be a lot of wrapping to do. I'd prefer to be able to do something like adding a 'defaultExceptionHandler' method to the LineReceiver derived class that would be called by the reactor. Is something like this possible? I'm still pretty new to Twisted, so I don't know all the idioms yet.

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[Twisted-Python] read all the elements of xml file
by Raj kumar Jan. 19, 2008

Jan. 19, 2008

Hi, I am using following code ---------------------------------------------------------------------------------------- content = microdom.parse(xmlfile) allnodes = content.getElementsByTagName("*") for eachnode in allnodes print "each node %s" % eachnode --------------------------------------------------------------------------------------- But getElement("*") is not working... which I used to get all the element but it is not working. If i give any tagname then it is working. how to get all the elemets with single statement. Because i have different elements in that xml file. Is there any other way to get all the elements? Am i doing anything wrong in that? Thank you in advance. Get the freedom to save as many mails as you wish. To know how, go to http://help.yahoo.com/l/in/yahoo/mail/yahoomail/tools/tools-08.html

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[Twisted-Python] Closing connections properly
by Simon Pickles Jan. 19, 2008

Jan. 19, 2008

Hi, Having a simple server based on a LineReceiver, what is the proper way to close connections and delete the class containing those connections (the class built by BuildProtocol()). Given the simple code below, Protocol.BuildProtocol is called when I client connections, and builds and instance of the class Connection. When the client disconnects, Connection.connectionLost is called, but the instance continues (__del__ is never called). I even naively tried added a 'del self' statement to the connectionLost method, but its not c++ 'delete this'! How should I delete the closed connection? Is there something in twisted I can overload, or should I use the server to track connections better and perform my deleting there? Thanks Simon Example -------------- class Connection(basic.LineReceiver): def __init__(self): self.ipAddress = "000.000.000.000" self.port = 0 logger.CON("Opening new connection") def __del__(self): # never called logger.CON("Closed connection to %s:%d" % (self.ipAddress, self.port)) def connectionMade(self): """ Overrides method in basic.LineReceiver """ self.ipAddress = self.transport.getPeer().host self.port = self.transport.getPeer().port logger.CON("Log in attempt from %s:%d" % (self.ipAddress, self.port)) def connectionLost(self, reason): """ Overrides method in basic.LineReceiver """ logger.CON("%s:%d has closed the connection, %s" % (self.ipAddress, self.port, reason)) self.transport.loseConnection() def dataReceived(self, data): """ Overrides method in basic.LineReceiver """ logger.CON("%s:%d received %s" % (self.ipAddress, self.port, data)) class Server(Protocol): factory = Factory() factory.protocol = Connection def __init__(self, maxClients): self.max_clients = maxClients logger.NET("Server started") def doStart(self): logger.NET("Port: %d" % globalVars.zoneAddress[1]) logger.NET("...... waiting for a connection ......") def doStop(self): logger.NET("Server is now closed") def buildProtocol(self, addr): logger.NET("Connection attempt....") return Connection() -- Linux user #458601 - http://counter.li.org.

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[Twisted-Python] callLater
by Eduardo Matus Jan. 17, 2008

Jan. 17, 2008

hey all.... is there a way to add tasks and then run the timer in callLater from the reactor class?? like sched module in python... because if I want to call 2 different functions at the "same" time.. reactor.callLater(3,f) reactor.callLater(3,g) the 'g' function will be called 'n' seconds after the 'f' method.... thks

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[Twisted-Python] Detect idle in a LineReceiver
by Matteo Beniamino Jan. 17, 2008

Jan. 17, 2008

I'm trying to parse messages coming from some serial ports and TCP/IP connections using a protocol derived from a basic.LineReceiver . Everything works fine. Now I'd like to detect when a client is not sending data for a certain amount of time and add a callback to handle this situation, but I don't know how to achieve this. Does anyone know if there is something I can do at Factory or Protocol level? There is no problem in changing the LineReceiver approach with something different. Thank you for your help, -- M. Beniamino

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Re: [Twisted-Python] connection pool
by Tjerk.Kusters＠imtech.nl Jan. 17, 2008

Jan. 17, 2008

>will support Deferreds so this will get easier. However, until then, you >can still have asynchronous render_GET implementations. You just have to >use NOT_DONE_YET. I have made some changes to my test code and it works. A request to module_1 is possible will there is a request to moduleSlow2. Multiple calls to moduleSlow2 have to wait until the other one finishes. But calling module_1 still works. Should be oke for my webapplication. changed it to: from twisted.web import resource, static, server from twisted.web.server import NOT_DONE_YET from twisted.internet import reactor from twisted.internet.defer import Deferred from twisted.internet.threads import deferToThread import datetime, time def tijd(): return datetime.datetime.today().strftime("%Y-%m-%dT%H:%M:%S") class module_1(resource.Resource): def render_GET(self, request): request.write(tijd()) return "" class moduleSlow2(resource.Resource): def render_GET(self, request): d = deferToThread(self.answer, request) d.addCallback(request.write) d.addCallback(lambda _: request.finish()) return NOT_DONE_YET def answer(self, request): time.sleep(10) return "finished %s" % tijd() root = static.File("d:/www") root.putChild("module1", module_1()) root.putChild("slow2", moduleSlow2()) reactor.listenTCP(8900, server.Site(root)) print "Reactor run" reactor.run( ) Regars, Tjerk

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Re: [Twisted-Python] connection pool
by Tjerk.Kusters＠imtech.nl Jan. 17, 2008

Jan. 17, 2008

>making a blocking call (CORBA) inside the reactor loop, which prevents >other connections to happen. If you don't manage to find an >asynchronous CORBA client, you should do the call inside a thread, >using reactor.callInThread for example. > >However, it would be easier to help you with an example of your code >or a more detailed description of your problem. I have create a small example program to show my problem. from twisted.web import resource, static, server from twisted.internet import reactor import datetime, time class module_1(resource.Resource): def render_GET(self, request): request.write("module 1<br>") request.write(datetime.datetime.today().strftime("%Y-%m-%dT%H:%M:%S")) return "" def doWork(): # perform call which can take some seconds to return time.sleep(10) return "ready" class module_2(resource.Resource): def render_GET(self, request): request.write("module 2<br>") request.write(doWork()) return "" root = static.File("d:/www") root.putChild("module1", module_1()) root.putChild("module2", module_2()) reactor.listenTCP(8900, server.Site(root)) print "Reactor run" reactor.run( ) When I do request http://localhost:8900/module2 an other request to http://localhost:8900/module1 has to wait on the first one to finish. So the doWork is blocking the reactor and I should perform the work in a thread. But my question is then: how can I perform the render_GET of module_2 in a thread and still return the answer back to the webpage? Hope this gives enough details on the situation. Regards, Tjerk

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Re: [Twisted-Python] connection pool
by Tjerk.Kusters＠imtech.nl Jan. 17, 2008

Jan. 17, 2008

>> I have build a webserver with Twisted 2.4 with imports of the following: >> >> from twisted.web import resource, static, server, twcgi >> from twisted.internet import reactor >> >> I'm adding several mods as child to the root with: >> >> root = static.File(settings.getSetting("html_directory")) >> root.putChild(mods.getPath(), mods >> >> The mods are classes like >> >> class module(resource.Resource): >> def render_GET(self, request): >> # do something >> >> The reactor is started as: >> reactor.listenTCP(_port, server.Site(root)) >> reactor.run( ) >> >> Some of the GET request in the mods can take some time to complete. In the >> current situation other request to the server have to wait on this request. >> >> Is it possible to make soms kind of a thread/connection pool so that more >> then one request can be handled at the same time? >> >> Regards, >> Tjerk >> >> >> _______________________________________________ >> Twisted-Python mailing list >> Twisted-Python(a)twistedmatrix.com >> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python >> > >Yes it is possible to use a thread pool, in fact twisted comes with >one. However, how you use it depends on what is taking so long for >you: > >- if it's database calls then consider using twisted.enterprise.adbapi >- http://twistedmatrix.com/projects/core/documentation/howto/enterprise.html > >- if it's python code taking so long then consider breaking your code >into shorter snippets that yield control back to twisted periodically >so that other requests don't get ignored > >- if it's network code then make sure you're using Deferred's properly >- http://twistedmatrix.com/projects/core/documentation/howto/defer.html The call can take some time because I have to wait on a response from a CORBA call. I have looked at deferred's, but can not see how this can be used to solve the problem. The render_GET(self, request) can only return when there is an answer. Is there a way to make twisted web to handle multi connections at the same time? Regards, Tjerk

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[Twisted-Python] How can I make twisted and dbus work together?
by hwan2265＠mail.usyd.edu.au Jan. 16, 2008

Jan. 16, 2008

Hi, I just put from twisted.internet import glib2reactor glib2reactor.install() on top of my script as Bastian's suggestion and it finally works. Thank you all -Huisan ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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