Mailman 3 September 2005 - Twisted

Re: [Twisted-Python] Re: GUI responsiveness
by Brian Warner 26 Sep '05

26 Sep '05

> Is there a good place to read more about NewPB? Or is it just a matter > of searching the maillist archives and SVN repository? For now, the SVN code and docs are the best source of information: svn://svn.twistedmatrix.com/svn/Twisted/branches/warner/newpb You'll want to look in doc/pb/* and twisted/pb/* . There is a surprising quantity of documentation for newpb, I tried to document everything before implementing it. I've got a few more things to get implemented first, but I'll be merging this stuff into TRUNK sometime soon. I won't promise wire-compatibility for a while yet, but I think it's good enough to be useable already. Connection setup, in particular, is (IMHO) a lot easier than oldpb. cheers, -Brian

2 1

Re: [Twisted-Python] jelly tracebacks
by Brian Warner 25 Sep '05

25 Sep '05

> I just had a grueling experience debugging some > unjellying problem. I wonder, why not make jelly > tracebacks more useful by adding the details of the PB > message that gave rise to them (i.e. which method of > which object was called with which arguments). Any > thoughts? Good idea. I've incorporated this into newpb, where any problem during serialization or unserialization is reported via an exception that has a .where attribute. This .where string reports the location in the object graph that had the problem. In the case of serialization errors during an argument of a method call, you'd get a string with something like: <call-(reqID)-(objID)-(methodname)>.foo If you were to have something unserializable inside a container, the .where string would include the relevant index values: d = {'foo': 12, 'bar': Ephemeral()} l = [1, 2, d] rr.callRemote("doStuff", arg1=5, arg2=l) -> BananaError(where=<call-0-4-doStuff>.arg2[2]['bar']) Likewise, if one of the arguments violates a Schema constraint, the exception should give you enough information to figure out what exactly caused the problem. This occurs on both ends of the wire, so exceptions that occur when serializing the return value can be located too. The same .where technique is used during unserialization, so if someone sends you a serialized instance of a class that you are unaware of (or unwilling to deserialize), or if their value violates your inbound schema, you'll get an exception that has enough detail to help you figure out where exactly the problem was. cheers, -Brian

1 0

Re: [Twisted-Python] unsafe tracebacks in PB
by Brian Warner 25 Sep '05

25 Sep '05

> Just wondering, why is it possible to turn on unsafe > tracebacks only at the server and not at the client? > PB being symmetrical, this discrimination makes it > arbitrarily difficuly to debug PB applications > sometimes. Hey, sorry for the slow response. It *is* possible to set the 'unsafeTracebacks' flag on both ends of the wire. PBServerFactory() takes a constructor argument to set this flag, while PBClientFactory() does not, but you can always set it after the fact: f = PBClientFactory() f.unsafeTracebacks = True I'm more inclined to resolve the asymmetry by removing the argument from PBServerFactory rather than adding it to PBClientFactory. As a debugging thing, I feel it isn't entirely appropriate to have as a constructor argument. However, I don't really feel that strongly about it either way. For the record, I'll describe a little bit more about what exactly this flag does, because there *is* a sense in which unsafe tracebacks can only be enabled on the "server" side of a given method call. The important thing to remember is that there are two different ways to divide the connection into "client" and "server" ends. Suppose you have program A, which has a pb.Referenceable named Alice that implements remote_foo. Likewise, you have program B, which contains a pb.Referenceable named Bob that implements remote_bar. Let us further suppose that program B used PBServerFactory and reactor.listenTCP to make the object Bob available to the world. Program A then used PBClientFactory and reactor.connectTCP to obtain a RemoteReference to Bob (and somehow passed a reference to Alice over to program B at the same time, so that both programs have a RemoteReference to the other's Referenceable). Now, the setting of this "unsafe tracebacks" flag on side A only affects tracebacks being sent *from* side A: that is, for exceptions that occur on side A, during a remote method invocation that was requested by side B. If you consider any given method call to have a "client side" (which requests the call by doing rref.callRemote("foo", args)), and a "server side" (which implements the method remote_foo(self, args)), then the unsafe-tracebacks flag is only relevant for the "server side". In our example, when B does alice.callRemote("foo"), B is the "client" side and A is the "server" side. If an exception occurs inside Alice's remote_foo method, it is the setting of A's clientfactory.unsafeTracebacks flag that determines whether's A's internal state will be exposed to B. On the other hand, when A does bob.callRemote("bar"), B is the "server" side, so it is B's serverfactory.unsafeTracebacks flag that matters. The important point is that the requesting side for any particular method call does not get to ask for an "unsafe traceback": only the owner of the sensitive information (in this case, the stack frames leading up to the exception, and the globals/locals that are in those stack frames) gets to decide whether or not to share it with the outside world. The second usage of the terms "client" and "server" here has to do with which side initiated the TCP connection and which side accepted it. This is how the PBClientFactory and PBServerFactory classes use these terms. Both of these classes have an 'unsafeTracebacks' flag, and if you set it to something non-zero, then any exception-raising methods invoked on that side will send back a full traceback to the other side. The minor asymmetry here (constructor argument versus set-the-flag-later) is just an oversight in the API. hope that's useful, -Brian

1 0

[Twisted-Python] How to send a UDP datagram
by Drake Smith 25 Sep '05

25 Sep '05

Can somebody please show me the Twisted way to send a simple UDP datagram? From the examples, I see how to transport.write in response to receiving a datagram or in response to establishing a UDP "connection". But in my application, I'd like to send datagrams blindly, say, to initiate a heartbeat message or to stream audio samples without acknowledgement via an unconnected UDP socket. I'd also like to do this from a function that is not wrapped inside a Twisted protocol class as such, unless that is contrary to the Twisted approach. I am using Twisted version 2.0.1/Python 2.4 on a Linux box. Thank you.

2 3

[Twisted-Python] RE: [Python-Twisted] How to write a simple telnet client?
by Henning.Ramm＠mediapro-gmbh.de 23 Sep '05

23 Sep '05

>Please look at my posts from 11.08.2005 - What is wrong with this >instance (topic). I have send there a code of my telnet client. I don't >remember what was wrong, but i solve most of problems, so if >you had any >questions e-mail me. I think that my code is what You need. This is a >very simple client and i have developed him. I played around with your code at http://twistedmatrix.com/pipermail/twisted-python/2005-August/011115.html, even if I don't understand polish. ;-) I didn't expect that one must handle control codes (your function reponseFunct), I expected the protocol to handle that for me, but anyway, that was no problem (i.e. you solved it before). And with your code I could even switch off the echo (your next thread). What I don't understand is how to 'inject' some commands and collect their result. What you tried in your "command" function in __main__ can't work, because the protocol has no transport. I don't understand how to get at the Factory's actual protocol instance and its transport. I could 'hardcode' a list of commands in my protocol class, but that would make no sense... Probably I shouldn't use a ClientFactory but something else. Best regards, Henning Hraban Ramm Südkurier Medienhaus / MediaPro Support/Admin/Development Dept.

2 1

[Twisted-Python] Repository for python developers
by Mikhail Kashkin 23 Sep '05

23 Sep '05

Moscow, Russia, September 23th, 2005 We are happy to spread good news about `Key Solutions' <http://keysolutions.ru/>`_ new initiative. We have created a new public repository for python developers. The ulitimate goal of this project is to unite companies and people under the umbrella of Russian-speaking-python (Zope/Plone/Zope3/Twisted/etc) open source programmers community, so that we could jointly push forward new programs and technologies in Russia. The repository powered by `subversion <http://subversion.tigris.org/>`_. **Links**: - `Press release in russian <http://keysolutions.ru/News/subversion>`_ - `Новость на русском <http://keysolutions.ru/News/subversion>`_ - `Subversion <https://svn.keysolutions.ru/community/>`_ About Key Solutions -------------------- Key Solutions is an open source company with primary focus in development of corporative CRM Internet/intranet systems and web-communities. The company promotes and supports Zope, Plone, Asterisk platforms in Russia. To learn more about Key Solutions visit `eng.keysolutions.ru <http://eng.keysolutions.ru/>`_ and `keysolutions.ru <http://keysolutions.ru/>`_ -- Mikhail Kashkin, Key Solutions (http://keysolutions.ru/) Director Zope/Asterisk/Plone - Solutions/Consulting/Support Plone на русском http://plone.org.ru/ Plone Foundation Member (http://plone.org/foundation/members/)

1 0

[Twisted-Python] twisted.internet.serialport
by joy ping 23 Sep '05

23 Sep '05

hi list, i just did a search for a framwork which would be good for a to be written application which controlls serialports over webinterfaces. i found that twisted would be ideal for this. i started to write some code with mod_phyton but as threading+pyserial+apache didn't worked i had a closer look at twisted. it seems cool cause it's async. no real need for threads here. and with twisted-web and livepages some kind of persistance could be achived. but at the end i found not really much documentation especially about twisted.serialport and nevow which i would use as app-server. can someone point me to some docs if they exists beside the the api-docs. thanks zsolt

2 1

[Twisted-Python] internet.TimerSevice in twisted.scripts.twistw
by Maciej Szumocki 22 Sep '05

22 Sep '05

Hello, Just a question that has been bugging me and i can't figure out the answer on my own. Why is there a line like this in python.scripts._twistw runApp: app.startApplication(internet.TimerService(0.1, lambda:None), 0) while there is no such thing in python.scripts.twistd? Is it some Windows-specific workaround i need to worry about if i run my application without using twistd? Maciej Szumocki

2 1

[Twisted-Python] Re: [Python-Twisted] How to write a simple telnet client?
by Michał Tyde 22 Sep '05

22 Sep '05

Please look at my posts from 11.08.2005 - What is wrong with this instance (topic). I have send there a code of my telnet client. I don't remember what was wrong, but i solve most of problems, so if you had any questions e-mail me. I think that my code is what You need. This is a very simple client and i have developed him.

1 0

[Twisted-Python] How to write a simple telnet client?
by Henning.Ramm＠mediapro-gmbh.de 22 Sep '05

22 Sep '05

Hi ho! I need to integrate a simple telnet client into one of my programs to execute a command on an other machine and collect the response. Probably I'm blind, because I didn't find out how to use twisted's telnet protocol for such a client (I know how to setup a server). Could someone please give me a kick? Best regards, Henning Hraban Ramm Südkurier Medienhaus / MediaPro Support/Admin/Development Dept.

1 0