On Thu, Oct 30, 2008 at 2:13 PM, gaurav kashyap <[EMAIL PROTECTED]> wrote:
> Dear all,
>
> I have a server program that listens to a particular port and a number
> of client programs that connect to the server.
>
> Now i want to put some data in form of python list in main memory on
> server.Hence whenver a client program is run it connects to the server
> and access the data in main memory.Here the server calls a module that
> processes the data as per the client request and the returns some
> information to the client.
>
> I can create client and server programs using socket programming,but i
> am not able to put the data in shared memory and then access it.
>
> NOTE:I want to put the data in main memory only once(on the server
> using server program) i.e. whenever client connects to the server it
> should only access the data and not create a replica of data already
> loaded in memory.How can this be achieved
This is trivially done with an event-driven framework
such as Twisted or Circuits. I'm the author of circuits (1.0
release coming soon), so here is a circuits based example:
Server code:
<code>
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vim: set sw=3 sts=3 ts=3
"""(Example) Echo Server
A simple Echo Server example that sends back to connected clients
the input the server receieves.
This example demonstrates:
* Basic Component creation.
* Basic Event handling.
* Basic TCP Server
This example makes use of:
* Component
* Event
* Manager
* lib.sockets.TCPServer
"""
from circuits.lib.sockets import TCPServer
from circuits.core import listener, Event, Component, Manager
###
### Components
###
class EchoServer(TCPServer):
def __init__(self, *args, **kwargs):
super(EchoServer, self).__init__(*args, **kwargs)
self.data = [1, 2, 3, 4]
@listener("read")
def onREAD(self, sock, data):
self.write(sock, data)
self.write(sock, "Data: %s" % self.data)
###
### Main
###
def main():
manager = Manager()
server = EchoServer(8000)
manager += server
while True:
try:
manager.flush()
server.poll()
except KeyboardInterrupt:
break
###
### Entry Point
###
if __name__ == "__main__":
main()
</code>
Client code: (I'm just using a basic telnet example here)
<code>
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vim: set sw=3 sts=3 ts=3
"""(Example) Telnet Client
A basic telnet-like clone that connects to remote hosts
via tcp and allows the user to send data to the remote
server.
This example demonstrates:
* Basic Component creation.
* Basic Event handling.
* Basiv Networking
* Basic Request/Response Networking
This example makes use of:
* Component
* Event
* Manager
* lib.sockets.TCPClient
"""
import optparse
from circuits.lib.io import Stdin
from circuits.lib.sockets import TCPClient
from circuits import __version__ as systemVersion
from circuits.core import listener, Event, Component, Manager
USAGE = "%prog [options] host [port]"
VERSION = "%prog v" + systemVersion
###
### Functions
###
def parse_options():
"""parse_options() -> opts, args
Parse any command-line options given returning both
the parsed options and arguments.
"""
parser = optparse.OptionParser(usage=USAGE, version=VERSION)
parser.add_option("-s", "--ssl",
action="store_true", default=False, dest="ssl",
help="Enable Secure Socket Layer (SSL)")
opts, args = parser.parse_args()
if len(args) < 1:
parser.print_help()
raise SystemExit, 1
return opts, args
###
### Components
###
class Telnet(TCPClient):
@listener("connect")
def onCONNECT(self, host, port):
print "Connected to %s" % host
@listener("read")
def onREAD(self, data):
print data.strip()
@listener("stdin:read")
def onINPUT(self, data):
self.write(data)
###
### Main
###
def main():
opts, args = parse_options()
host = args[0]
if len(args) > 1:
port = int(args[1])
else:
port = 23
manager = Manager()
telnet = Telnet()
stdin = Stdin()
manager += stdin
manager += telnet
print "Trying %s..." % host
telnet.open(host, port, ssl=opts.ssl)
while telnet.connected:
try:
manager.flush()
stdin.poll()
telnet.poll()
except KeyboardInterrupt:
break
telnet.close()
###
### Entry Point
###
if __name__ == "__main__":
main()
</code>
Client output:
<paste>
$ ./telnet.py localhost 8000
Trying localhost...
Connected to localhost
test
test
Data: [1, 2, 3, 4]
</paste>
Circuits can be downloaded from:
http://trac.softcircuit.com.au/circuits/
cheers
James
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