Mailman 3 June 2014 - Twisted

[Twisted-Python] Announcing Crossbar.io
by Tobias Oberstein June 12, 2014

June 12, 2014

Hi, this is an early announcement of Crossbar.io, a new application server based on Twisted and Autobahn. Crossbar.io is an open-source application router that allows to build distributed systems out of application components which are loosely coupled and communicate in (soft) real-time. README: https://github.com/crossbario/crossbar#crossbario At it's core, an application router provides generic routing of both calls (for remote procedure calls) and events (for publish & subscribe) which is realized via WAMP, an open WebSocket based communication protocol. Why WAMP?: http://wamp.ws/why/ Technically, Crossbar.io has a multi-process architecture with controller and worker processes, which lets use scale up on multi-core. We also prepared things to add scale-out on multi-node. We've got some early encouraging feedback from developers who think Crossbar.io might get the next Django, MeteorJS or Vert.x: A developer guest post: http://tavendo.com/blog/post/is-crossbar-the-future-of-python-web-apps/ Crossbar.io is an open-source project, and still in the very beginning. Rough edges, stuff breaks, moving fast. If you want to give it a try: https://github.com/crossbario/crossbar/wiki#quick-start We are looking for feedback, help and contributors. It's a big shot project, and to make it take off, we need core hackers and grow a developer community. I know, sounds bold. Sure, and it is. In any case, I'd love to see the Python community get even more ambitious. We can't let the J's of this world take over;) Cheers, /Tobias

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[Twisted-Python] Known bug with twistd log rotation
by Maximilien Riehl June 11, 2014

June 11, 2014

Hi! I'm finding it difficult to get log rotation working cleanly with twistd (if dropping privileges through twistd, which we require). I went through all the docs and also found [1] very helpful, but the problem boils down to the fact that > Implications for Logfile Rotation > > Using the configuration described here, the LOGFILE will be created as > user "root" and group "root", but rotated as user UID and group GID. > If you want rotation to work as advertised it is necessary to put the > LOGFILE in a directory in which UID/GID has permissions to rename files. > and > def rotate(self): > """ > Rotate the file and create a new one. > > If it's not possible to open new logfile, this will fail silently, > and continue logging to old logfile. > """ > if not (os.access(self.directory, os.W_OK) and > os.access(self.path, os.W_OK)): > return (twisted 14.0.0) will never work together. Even if the user twistd runs as is technically able to rename the log file (due to having write permissions on the directory), it will never try to since it can't write to the file. There is a workaround on a comment in [1] but that's a really unnecessary and hacky solution, IMHO. Is this a known bug? I remember running into this issue a year ago or so and IIRC I just gave up. Thanks for any pointers, max [1] http://www.tsheffler.com/blog/?p=526

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[Twisted-Python] Trouble with Record_TXT
by Nahraf34 June 11, 2014

June 11, 2014

Hi all, I am attempting to write a small DNS server that returns custom TXT record when I do: dig -t TXT -p 10053 @127.0.0.1 testdomain.com The code is as follows: ---------- #!/usr/bin/python from twisted.internet import reactor from twisted.names import client, dns, server class DynamicResolver(object): def query(self, query, timeout=None): name = query.name.name # answer = dns.RRHeader( # name = name, # payload = dns.Record_A(address=b'1.2.3.4')) answer = dns.RRHeader( name = name, payload = dns.Record_TXT(data='FirstSecond', ttl=3333)) answers = [answer] authority = [] additional = [] return answers, authority, additional def main(): factory = server.DNSServerFactory( clients = [DynamicResolver()] ) protocol = dns.DNSDatagramProtocol(controller=factory) reactor.listenUDP(10053, protocol) reactor.listenTCP(10053, factory) reactor.run() if __name__ == '__main__': main() ---------- You will notice three lines of code are commented out. They are sample code for an A record that work just fine. But the attempt at Record_TXT fails. I receive the following error when I attempt to perform the dig command: ----------- $ python servlet.py Unhandled Error Traceback (most recent call last): File "/usr/local/lib/python2.7/dist-packages/twisted/names/dns.py", line 2326, in datagramReceived self.controller.messageReceived(m, self, addr) File "/usr/local/lib/python2.7/dist-packages/twisted/names/server.py", line 192, in messageReceived self.handleQuery(message, proto, address) File "/usr/local/lib/python2.7/dist-packages/twisted/names/server.py", line 136, in handleQuery return self.resolver.query(query).addCallback( File "/usr/local/lib/python2.7/dist-packages/twisted/names/common.py", line 73, in query return defer.maybeDeferred(method, query.name.name, timeout) --- <exception caught here> --- File "/usr/local/lib/python2.7/dist-packages/twisted/internet/defer.py", line 139, in maybeDeferred result = f(*args, **kw) File "/usr/local/lib/python2.7/dist-packages/twisted/names/common.py", line 81, in lookupAddress return self._lookup(name, dns.IN, dns.A, timeout) File "/usr/local/lib/python2.7/dist-packages/twisted/names/resolve.py", line 79, in _lookup d = self.resolvers[0].query(q, timeout) File "servlet.py", line 16, in query payload = dns.Record_TXT(data='FirstSecond', ttl=3333)) File "/usr/local/lib/python2.7/dist-packages/twisted/names/dns.py", line 867, in __init__ assert (payload is None) or isinstance(payload, UnknownRecord) or (payload.TYPE == type) exceptions.AssertionError: ----------- I'm a little confused, because I followed the documentation as referenced here: http://twistedmatrix.com/documents/current/api/twisted.names.dns.Record_TXT… Any ideas what this error means and why it is happening? Thank you, Nahraf

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[Twisted-Python] Weekly Bug Summary
by trac＠twistedmatrix.com June 7, 2014

June 7, 2014

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[Twisted-Python] SELECT returns no results without conn.commit()
by Franz Schwartau June 4, 2014

June 4, 2014

Hi! I'm trying to extend ppolicy (http://bimbo.fjfi.cvut.cz/ppolicy) a bit. ppolicy uses the twisted framework. On CentOS 6.5 version 8.2.0 of twisted is installed. I wrote a separate module called LookupSessionDB: http://pastebin.com/u4TMNhpd It looks up some values from a database table. It does some efforts to handle reconnect properly. If called a second time and more the SELECT statement returns no rows (line 138) if "conn.commit()" is missing in line 125. If "conn.commit()" is called after obtaining a database connection "rows = cursor.fetchall()" (line 138) returns the expected results. The module inserting the records calls "conn.commit()" after INSERT. If I execute the same SELECT statement in a separate mysql client the results are displayed. This is quite confusing. Any idea what's going on? Best regards Dirk

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[Twisted-Python] ANN: Crochet 1.3.0 - Use Twisted Anywhere!
by Itamar Turner-Trauring June 2, 2014

June 2, 2014

Crochet is an MIT-licensed library that makes it easier to use Twisted from regular blocking code. Some use cases include: * Easily use Twisted from a blocking framework like Django or Flask. * Write a library that provides a blocking API, but uses Twisted for its implementation. * Port blocking code to Twisted more easily, by keeping a backwards compatibility layer. * Allow normal Twisted programs that use threads to interact with Twisted more cleanly from their threaded parts. For example this can be useful when using Twisted as a WSGI container. This is a bugfix release, recommended for all users of Crochet. Crochet can be downloaded from https://pypi.python.org/pypi/crochet or by running: $ pip install crochet Documentation can be found at http://crochet.readthedocs.org <https://crochet.readthedocs.org/> Bugs and feature requests should be filed at the project https://github.com/itamarst/crochet Here’s an example of a program using Crochet. Notice that you get a completely blocking interface to Twisted and do not need to run the Twisted reactor, the event loop, yourself. #!/usr/bin/python """ Do a DNS lookup using Twisted's APIs. """ from __future__ import print_function # The Twisted code we'll be using: from twisted.names import client from crochet import setup, wait_for setup() # Crochet layer, wrapping Twisted's DNS library in a blocking call. @wait_for(timeout=5.0) def gethostbyname(name): """Lookup the IP of a given hostname. Unlike socket.gethostbyname() which can take an arbitrary amount of time to finish, this function will raise crochet.TimeoutError if more than 5 seconds elapse without an answer being received. """ d = client.lookupAddress(name) d.addCallback(lambda result: result[0][0].payload.dottedQuad()) return d if __name__ == '__main__': # Application code using the public API - notice it works in a normal # blocking manner, with no event loop visible: import sys name = sys.argv[1] ip = gethostbyname(name) print(name, "->", ip) Run on the command line: > $ python blockingdns.py twistedmatrix.com > twistedmatrix.com -> 66.35.39.66

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[Twisted-Python] Auto-Re: Weekly Bug Summary
by 梁国伟 May 31, 2014

May 31, 2014

已收到，感谢您的来信 ---- 北京外国语大学留学生办公室梁国伟

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[Twisted-Python] Weekly Bug Summary
by trac＠twistedmatrix.com May 31, 2014

May 31, 2014

1 0

[Twisted-Python] Auto-Re: Weekly Bug Summary
by 甘肃电大 May 31, 2014

May 31, 2014

您发的邮件收到了!

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