Socket and cycle problem
Hello, I am beginner but so I need help. I have small script for receive data from port 3883, but it print only once. import socket HOST = 'localhost' PORT = 3883 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((HOST, PORT)) data = s.recv(2048) s.close() print 'receive data from server:', `data` So I try to write cycle to this script, like this: import socket HOST = 'localhost' PORT = 3883 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) while 1: s.connect((HOST, PORT)) data = s.recv(2048) s.close() print 'receive data from server:', `data` But Python reporting: Traceback (most recent call last): File "C:\Documents and Settings\poupa\Plocha\TCP3.py", line 7, in s.connect((HOST, PORT)) File "", line 1, in connect File "C:\Python25\lib\socket.py", line 141, in _dummy raise error(EBADF, 'Bad file descriptor') error: (9, 'Bad file descriptor') Where is the mistake? I dont know. thaks for help Petr -- http://mail.python.org/mailman/listinfo/python-list
Re: Socket and cycle problem
On 12 Kvě, 17:54, Jean-Paul Calderone <[EMAIL PROTECTED]> wrote: > On Mon, 12 May 2008 08:34:07 -0700 (PDT), [EMAIL PROTECTED] wrote: > >Hello, > >I am beginner but so I need help. I have small script for receive data > >from port 3883, but it print only once. > > >import socket > > >HOST = 'localhost' > >PORT = 3883 > >s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) > >s.connect((HOST, PORT)) > >data = s.recv(2048) > >s.close() > >print 'receive data from server:', `data` > > >So I try to write cycle to this script, like this: > > >import socket > > >HOST = 'localhost' > >PORT = 3883 > >s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) > >while 1: > >s.connect((HOST, PORT)) > >data = s.recv(2048) > >s.close() > >print 'receive data from server:', `data` > > >But Python reporting: > > >Traceback (most recent call last): > > File "C:\Documents and Settings\poupa\Plocha\TCP3.py", line 7, in > > > >s.connect((HOST, PORT)) > > File "", line 1, in connect > > File "C:\Python25\lib\socket.py", line 141, in _dummy > >raise error(EBADF, 'Bad file descriptor') > >error: (9, 'Bad file descriptor') > > >Where is the mistake? I dont know. > > You cannot reconnect a socket. You need to create a new one for each > connection. It's also almost certainly the case that the way you are > receiving data is incorrect. There is no guarantee that you will get > 2048 bytes from socket.recv(2048). It isn't even guaranteed that all > the bytes written to the socket by the peer will be returned by such > a call. Instead, you need a framing protocol to determine when all > data has been received. For example, you might length prefix the > data, or you might insert a delimiter (or a terminator) at the end. Or > if there is exactly one message to receive, then you should just read > until the recv call returns '', indicating EOF. > > Jean-Paul ok thanks, but I am true greenhorn, so you think that the best way is write new script? Could you send me code if it isnt long, becase I have no idea and unfortunately time as well. Petr Petr -- http://mail.python.org/mailman/listinfo/python-list
Re: Socket and cycle problem
On 12 Kvě, 19:16, Jean-Paul Calderone <[EMAIL PROTECTED]> wrote: > On Mon, 12 May 2008 09:19:48 -0700 (PDT), [EMAIL PROTECTED] wrote: > > > [snip] > > >> >Where is the mistake? I dont know. > > >> You cannot reconnect a socket. You need to create a new one for each > >> connection. It's also almost certainly the case that the way you are > >> receiving data is incorrect. There is no guarantee that you will get > >> 2048 bytes from socket.recv(2048). It isn't even guaranteed that all > >> the bytes written to the socket by the peer will be returned by such > >> a call. Instead, you need a framing protocol to determine when all > >> data has been received. For example, you might length prefix the > >> data, or you might insert a delimiter (or a terminator) at the end. Or > >> if there is exactly one message to receive, then you should just read > >> until the recv call returns '', indicating EOF. > > >> Jean-Paul > > >ok thanks, but I am true greenhorn, so you think that the best way is > >write new script? > >Could you send me code if it isnt long, becase I have no idea and > >unfortunately time as well. > > I'm not sure what you want to happen, so I can't write it for you. I > suggest you start with Twisted instead of the socket module, though, > as Twisted provides a higher-level interface to network programming. > > You can find some introductory documentation about writing clients here: > > http://twistedmatrix.com/projects/core/documentation/howto/clients.html > > Jean-Paul My script send me via 3883 port (VRPN) data, but only once. I need listening this port countinously. So I need make some loop to print data from 3883 port permanent. Data that I recevied looks liek this: receive data from server: 'vrpn: ver. 07.13 0\x00\xe8\x0b\x00\x00' Do you think its necessary to use Twisted? Do you have any ideas how to do it with socket modul? thanks for reply -- http://mail.python.org/mailman/listinfo/python-list
Re: Socket and cycle problem
On 12 Kvě, 21:06, Jean-Paul Calderone <[EMAIL PROTECTED]> wrote:
> On Mon, 12 May 2008 11:16:08 -0700 (PDT), [EMAIL PROTECTED] wrote:
> > [snip]
>
> >My script send me via 3883 port (VRPN) data, but only once. I need
> >listening this port countinously.
> >So I need make some loop to print data from 3883 port permanent.
> >Data that I recevied looks liek this:
>
> >receive data from server: 'vrpn: ver. 07.13 0\x00\xe8\x0b\x00\x00'
>
> I'm not sure if you need to write a server or a client. In your
> original code, you had a client which repeatedly established out-
> bound connections. Here, you say you need to listen on a port.
>
>
>
> >Do you think its necessary to use Twisted? Do you have any ideas how
> >to do it with socket modul?
>
> The basic version is pretty easy either way. However, with Twisted,
> you get cross-platform error handling without any extra effort, and
> you don't have to think about the boring low-level details of BSD
> sockets.
>
> Here's a Twisted server that listens on port 3883 forever and prints
> the data it receives from each connection after the remote side drops
> the connection:
>
> from twisted.internet import reactor
> from twisted.internet.protocol import ServerFactory, Protocol
>
> class PrintingProtocol(Protocol):
> def connectionMade(self):
> """
> When the connection is first established, create a list
> into which to buffer all received data.
> """
> self.received = []
>
> def dataReceived(self, data):
> """
> Whenever any data is received on this connection, add it
> to the buffer.
> """
> self.received.append(data)
>
> def connectionLost(self, reason):
> """
> When the connection is lost, print out the contents of
> the receive buffer.
> """
> print repr("".join(self.received))
>
> # Create a factory which will use our protocol to handle incoming
> # connections.
> factory = ServerFactory()
> factory.protocol = PrintingProtocol
>
> # Listen with it on port 3883
> reactor.listenTCP(3883, factory)
>
> # Start the reactor. Nothing in this program will ever stop the
> # reactor, so it will run and accept connections forever.
> reactor.run()
>
> If you were to use the socket module, then it would look something like this:
>
> from socket import socket
> from errno import EINTR
>
> port = socket()
> port.bind(('', 3883))
> port.listen(5)
> while True:
> try:
> server, clientAddr = port.accept()
> except socket.error, e:
> print "Error accepting client connection", e
> else:
> received = []
> while True:
> try:
> bytes = server.recv(1024 * 16)
> except socket.error, e:
> if e.errno == EINTR:
> continue
> else:
> break
> if not bytes:
> break
> received.append(bytes)
> print repr("".join(received))
>
> Hope this helps,
>
> Jean-Paul
Thanks for code. I am trying both of them, but I am crash to another
problem.
For socket modul example python report:
Traceback (most recent call last):
File "C:\Documents and Settings\poupa\Plocha\listen2.py", line 5, in
port.bind(('', 3883))
File "", line 1, in bind
error: (10048, 'Address already in use')
and for twisted example pythod report:
Traceback (most recent call last):
File "C:\Documents and Settings\poupa\Plocha\listen2twisted.py",
line 8, in -toplevel-
class PrintingProtocol(Protocol):
File "C:\Documents and Settings\poupa\Plocha\listen2twisted.py",
line 28, in PrintingProtocol
print repr("".join(self.received))
NameError: name 'self' is not defined
How can I solve this errors?
(for twisted I instal zope for python, pywin32 and twisted. all for
python 2.4)
--
http://mail.python.org/mailman/listinfo/python-list
listening on TCP port
Hello, is there anybody who has experience with listening on TCP port with python? I am looking for anything codes, tutorials,... . Thanks for any information -- http://mail.python.org/mailman/listinfo/python-list
listen on TCP port
Hello, is it possibble listening on TCP port by python and how? I am trying chilkat but poorly :(. Thanks -- http://mail.python.org/mailman/listinfo/python-list
