Mailman 3 December 2003 - Twisted

[Twisted-Python] Recovering PB references on broken connection?
by David Bolen 23 Dec '03

23 Dec '03

I've been experimenting with the perspective broker in Twisted 1.1.0 and am wondering? Is there any graceful way to reconnect and continue to use PB references if you temporarily lose a connection due to a network outage? For example, I can envision my application as being a client that connects to a remote application server, and while running may have any number of PB references to that remote application server in various data structures in the client. Should there be a transient network outage such that the TCP session to the server is interrupted, I'd like to be able to reconnect without having to flush all such data in the client. I'm still experimenting, but the docs and some early tests would seem to imply that if the TCP link breaks for any reason then any of my object references can never be used again. Is that in fact true and/or is there any way to avoid such a condition? I was hoping that I could catch network errors in some manner such that I could try to re-establish the PB link, and then permit existing references from the prior connection to continue to function could severely impact a client (or certainly impose a potentially large effort to restore any remote state to newly viable references). What do other perspective broker applications do about being as robust as possible in the presence of transient network conditions? Thanks for any info/suggestions. -- David

2 1

[Twisted-Python] twisted web question
by Greg Lappen 23 Dec '03

23 Dec '03

I am playing with some twisted-web and woven stuff. I noticed that whenever I get an error page, the server no longer handles requests. Is this the intended behavior? Greg

6 9

[Twisted-Python] subclassing ftp
by Douglas Bagnall 23 Dec '03

23 Dec '03

hi all, I'm making a thing which collects webcam images via ftp (the lowest common denominator for webcam software), and sends them off again via the web. I'd quite like to do it without troubling the file system, storing the images as python strings, whilst ignoring all the cd/pwd stuff. Needless to say I don't want to use real system usernames. Is this very sensible or possible? I (happily) don't know much about the ftp protocol, or its twisted implementation. cheers, Douglas Bagnall

2 3

[Twisted-Python] How do I modify sys.path in a .tap file?
by Paul Moore 22 Dec '03

22 Dec '03

I have an application which needs to modify sys.path, in order to pick up its configuration file (written in Python, naturally :-)) But I'm not sure how I do this. Ideally, I'd like to set an option in the tap config file, so I could just do mktap MyApp --confdir .... and be able to use config["confdir"] to set "something" which would be picked up and added to sys.path when I run the tap file with twistd. But I'm not sure how I could do this. Subclassing service.MultiService, so that I could set sys.path in startService(), worked OK, but I'm not sure if that's the best idea. Is there another way of doing this sort of thing, that I'd be better using? Paul. -- This signature intentionally left blank

2 1

[Twisted-Python] Broken link in twistedmatrix.com web site.
by JD 21 Dec '03

21 Dec '03

This page: http://twistedmatrix.com/products/spread In the Jelly section, just a little more then halfway down, has a link titled: "Concern for Pickle" which links to http://www.python.org/doc/current/lib/pickle-sec.html now goes to a non-existant page in the Python web site. I'm most interested in reading this section. Does anyone know where I can get this info? JD

2 1

[Twisted-Python] scheduling a task
by enrico.sirola＠riskmap.it 20 Dec '03

20 Dec '03

Hello, I just wrote my first twisted python application (basically, it's a SOAP server). The application layout is something like the following pseudocode: # validator.py from here class A(service.Service): # .... details omitted ... pass class B(resource.Resource): def __init__(self, service): self.service = service # .... details omitted ... def makeService(config): s = service.MultiService() v = A() soap_server = internet.TCPServer(config['port'], server.Site(B(v))) soap_server.setServiceParent(s) return s # to here # tap.py from here class Options(usage.Options): optParameters = [ ['port', 'p', 8090], ] def makeService(config): return validator.makeService(config) # to here # plugins.tml from here register('server', 'server.tap', description = 'build a server', type = 'tap', tapname = 'server') # to here anyway, i'd like to add the server a task running every 30s. I saw an example using reactor, like the following: reactor.callLater(30, task) now, where must i put this code in order to be run at application bootstrap? I tried putting reactor.callLater into the makeService function, but it seems it's executed during mktap only (am i wrong?)... Thanks very much in advance, enrico -- Enrico Sirola <enrico dot sirola at riskmap dot it>

2 2

[Twisted-Python] SFTP Gateway available
by Fred L. Drake, Jr. 20 Dec '03

20 Dec '03

Zope Corporation has created an SFTP server that uses an FTP server as a back end using Twisted. The code is covered by the Zope Public License (ZPL). I don't expect we'll create a separate downloadable package for SFTP Gateway until January, but it's already available in the public CVS repository on cvs.zope.org. For more information, see the README.txt file in the CVS repository: http://cvs.zope.org/Packages/SFTPGateway/ -Fred -- Fred L. Drake, Jr. <fdrake at acm.org> PythonLabs at Zope Corporation

2 2

[Twisted-Python] Next time we write a protocol implementation
by Itamar Shtull-Trauring 19 Dec '03

19 Dec '03

We should take a look at http://oss.corest.com/projects/impacket.html -- Itamar Shtull-Trauring http://itamarst.org Looking for a job: http://itamarst.org/resume.html

2 1

[Twisted-Python] Broadcasting UDP
by Hegedus, Matthew S 19 Dec '03

19 Dec '03

I am having trouble with UDP broadcasting. self.transport.write(data, (broadcastAddress, port)) yields a socket error 'Permission denied'. It appears the socket is not set up for broadcasting. Upon creation I think it needs something like SO_BROADCAST as an option. Can I get this behavior using Twisted UDP protocols or do I need to do my own socket stuff? Thanks, Matthew Hegedus

2 1

[Twisted-Python] twisted.web performance hacks
by Paul Boehm 18 Dec '03

18 Dec '03

On Thu, Dec 18, 2003 at 12:41:58AM -0500, Itamar Shtull-Trauring wrote: > On Wed, 2003-12-17 at 20:23, Michal Pasternak wrote: > > > Everything works very good right until simultaneous connection number is > > below 40. I just thought it was a hard limit set in the source (DoS > > protecition?) or something similar. If you deny the existence of such limit, > > I'll proceed with examination of the situation. > > No such limit is hardcoded. anyone thought about writing multi-process twisted applications yet? looking at examples/web.py, it would be easy to do reactor.listenTCP(1999, site) for x in xrange(1,5): if os.fork() == 0: break reactor.run() for shared dynamic data you'd of course have to use something along the lines of pb+remotecache, but if i'm not mistaken, for some applications this kind of hack might give a performance edge, especially on multiprocessor machines. in particular twisted.web could improve in benchmarks when being able to emulate classical application behaviour for performance reasons (no shared data between different connection handlers) regards, paul

2 1