Mailman 3 January 2008 - Twisted

Re: [Twisted-Python] Making inlineCallback return a generator
by Andrew Francis 28 Jan '08

28 Jan '08

Hello Nitro: > def SomeFunction(x): > . > . > result = echo(x) > . > . > . >Maybe I am missing something or we're going in >circles, but how about >@inlineCallbacks >def SomeFunction(x): > result = yield echo(x) Thanks for the information. However there is something you are missing. The 'something' is that one would have to alter a particular protocol's code (the SomeFunction) to call echo(x) in this fashion. Cheers, Andrew ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

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[Twisted-Python] Stoping a deferedList
by tarjei 28 Jan '08

28 Jan '08

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi, I'm using the FtpClient to upload a set of files. I start the uploads with the following code: def fileError(self, result): log.msg("Error has happened" + result.getErrorMessage()) log.msg(result.trap(Exception)) return result def endError(self, result): log.msg("End Error has happened") self.client.quit() self.client.transport.loseConnection() result.trap(Exception) def connectionMade(self,ftpClient): "Checks if there are more files to upload and uploads them." deffereds = [] "We'll need the client to do a disconnect later" self.client = ftpClient " Create defereds for each of the different files to be uploaded" for upfile in self.ftpFiles: store, finish = ftpClient.storeFile(self._getPath( upfile.get_name() ) ) finish.addCallback(self.end).addErrback(self.fileError) store.addCallback(self.send_file, upfile ).addErrback(self.fileError) deffereds.append(store) deffereds.append(finish) self.numfiles += 1 return defer.gatherResults(deffereds).addCallback(self.success).addErrback(self.endError) Now, if an error happens during the upload of one file, then I want to stop the other files as well and close the connection. When I try to run tests using the above code, trial reports that it still has open connections. The code works fine if user has access to save the files, it is the error handling I want to get done right. What should I do to ensure that all connections get closed when an error happens? kind regards, Tarjei -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHnea3YVRKCnSvzfIRAh3RAJ9lrMzQBJOMtIo1qcuntbkZlX5HMACfZNS8 St7eOg43MC4mTR2Qh9XWAX4= =aJCZ -----END PGP SIGNATURE-----

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[Twisted-Python] Soon to be not-a-newbie?
by Simon Pickles 28 Jan '08

28 Jan '08

Twisted is a really inaccessible concept. It is very idiosyncratic with its millions of various classes and methods.... ... but if you persevere, its great! You just have to leave part of your brain behind in a field in hampshire :) I'd suffer the pain, just for deferreds! Simon -- Linux user #458601 - http://counter.li.org.

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[Twisted-Python] twistedsnmp
by Vincent Bernat 28 Jan '08

28 Jan '08

Hello ! I had to use agent part of twistedsnmp [0]. This part was primarily done to test manager part, therefore, it lacks important features like handling of deferred to return results. To circumvent this limitation, I have hacked a bit to make a small patch to allow limited use of deferred [1]. I have proposed the patch to the author but got no answer. Looking at the CVS [2], it seems that twistedsnmp is unmaintained since almost 2 years. Has anybody any news about this? Is there any reason why twistedsnmp is not integrated into Twisted? It seems that there is another implementation by ZenOSS [3] but it does not include agent part. Do you know if this implementation will supersede twistedsnmp? I attach my patch to this message for posterity (if it can be useful for other people). [0] http://twistedsnmp.sourceforge.net/ [1] Limited because you cannot use nested deferred. If you have any tip to easily implement this, you are welcome. [2] http://twistedsnmp.cvs.sourceforge.net/twistedsnmp/twistedsnmp/ [3] http://packages.qa.debian.org/p/pynetsnmp.html -- BOFH excuse #272: Netscape has crashed

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Re: [Twisted-Python] Making inlineCallback return a generator
by Andrew Francis 27 Jan '08

27 Jan '08

Hello Nitro: >@defer.inlineCallbacks >def echo(self, x): > result = yield client.getPage("http://localhost") > defer.returnValue(result) According to the documentation, defer.returnValue() returns a value. The problem in this scenario is that the inlineCallback is being used in the following context: def SomeFunction(x): . . result = echo(x) . . . you need to call return so that SomeFunction can get a result. Think of SomeFunction being the underlying code for a XmlRpc like protocol. Cheers, Andrew ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping

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Re: [Twisted-Python] Another inlinecallback question
by Andrew Francis 27 Jan '08

27 Jan '08

Hello Jean-Paul Calderone: >In other words, inlineCallbacks lets you suspend >execution, _inside_ the function you decorate with it, >until a result is available. It only lets >you do this _inside_. Outside, the decorated function >simply appears to return a Deferred. Thanks for the explanation. Currently I use Stackless to allow my code to make synchronous calls that use Twisted. I still have to study inlineCallbacks but it seems that both Stackless and inclineCallbacks approaches seem to hiccup when dealing with protocols that are invoked as a function call and expect a return. for instance, @inlineCallbacks seem to be suited for something like HTTP : @defer.inlineCallbacks def process(self): try: result = yield client.getPage(...) except Exception, err: log.err(err, "process getPage call failed") else: self.write(result) self.finish() because one can pass the inlineCallback, a reference to the request and process() does not return anything On the other hand, using a higher level mechanism (i.e., resource.render() would be more problematic - This seems to imply that if one wishes to design a protocol that works nicely with inlineCallbacks, one should provide access to the request, so that one could write: @defer.inlineCallbacks: def echo(self, request): try: result = yield client.getPage(...) except Exception, err: log.err(err, "process getPage call failed") else: request.returnValue(result) Is this a fair assessment? I recognize the way most Twisted protocols work is perfectly great for most Twisted uses. It seems that the stuff I do (WS-BPEL), that involves, for lack of a better term, process composition. And process composition manifests itself as stuff like, request handlers making requests to other web resources. Hence a desire to make this as simple as possible. Cheers, Andrew ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

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[Twisted-Python] How to get the real ClientFactory or ServerFactory object?
by 李祥曦 27 Jan '08

27 Jan '08

Hi all: I am new to twisted,i want to write a program like a proxy,which get data from simplely listen to local client,transport it request to real server,and the reply to the client.My plan is rewrite the dataReceived method in twisted.internet.protocol.Protocol and call the sendLine method in ServerFactory.But i failed beacuse i can not get the real ServerFactory object,when i set in ServerFactory testFactory=StdioProxyFactory() host = "202.108.42.15" port = 8848 reactor.connectTCP(host,port,testFactory) testFactory.protocol.server=self but it a error say testFactory.protocol.server is None when i use it How can i did like this ,or do it another way?Thanks

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com 27 Jan '08

27 Jan '08

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[Twisted-Python] Making inlineCallback return a generator rather than a Deferred
by Andrew Francis 26 Jan '08

26 Jan '08

Hello Folks: As I previously mentioned, I have the following called from a PyAMF method: @defer.inlineCallbacks def echo(self, x): result = yield client.getPage("http://localhost") because of the yield, I cannot use return result In a bout of wishful thinking, I tried the following: @defer.inlineCallbacks def __echo__(self, x): result = yield client.getPage("http://localhost") yield result def echo(self, x): return self.__echo__(x).next() This raises an AttributeError, the deferred does not have an attribute next() (this is because the deferred is well, a deferred) Again, perhaps I am missing something obvious. Or perhaps this scenario was not anticipated and syntax is getting in the way. However I think the following would be useful in these situations def echo(self, x) @defer.returnAGenerator def __echo__(x): result = yield client.getPage("...") yield result """ the method waits until there is a result """ return __echo__(x).next() and the wrapper (i.e., PyAMF, xmlrpc, etc) is happy. I started to look at defer.inlineCallbacks and its associated methods, such as and _inlineCallbacks, unwindGenerator, and mergeFunctionMetadata. I would like to know if it would make sense to just return a generator and have it behave the way I want. If so, what exactly do I have to do in some variation of _inlineCallbacks to make this so? Thanks, Andrew ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping

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Re: [Twisted-Python] Another inlinecallback question
by Andrew Francis 26 Jan '08

26 Jan '08

Hello Matthias: >User defer.returnValue(result) instead of return. No I previously tried using defer.returnValue(), not expecting it to work, and it did not. The calling function (some method in PyAMF) is expecting a value from the return statement, a return that cannot be set with an argument. Cheers, Andrew ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

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