[Tutor] Need help with sockets

[James Duffy]

For a part of a program, I need to send a text string to another machine in
a IM style app. I've done this in C# but never in python. The server is in
C# so I just need a client side program that can listen for and display
incoming messages as well as send messages. Ive managed to make a socket and
connect but I don't know how to setup a listen thread and a sender function.
Can someone help? Below is C# code for the listener/send function of my
client that id made. I basically hafta turn this into python. This method
runs inside a thread.

 

 

 

 

void RunClient() 

{

TcpClient myClient; // instantiate TcpClient for sending data to server 

try 

{

Output to screen: Attempting connection\r\n" 

// Step 1: Create TcpClient 

myClient = new TcpClient(); 

// Step 2: Connect to server 

myClient.Connect(address.Text,int.Parse(port.Text)); 

// Step 3: Create a Network Stream associated with TcpClient 

myNetStream = myClient.GetStream();

// Step 4: Create objects for writing and reading across stream 

myWriter = new BinaryWriter(myNetStream); 

myReader = new BinaryReader(myNetStream); 

// loop until server signals termination 

do 

{

// Step 5: Processing phase 

try 

{

// read message from server 

message = myReader.ReadString();

inbound.Text +="\r\n" + message; 

}

// handle exception if error in reading server data 

catch (Exception) 

{

System.Environment.Exit( System.Environment.ExitCode); 

}

} 

while (message != "SERVER>>> TERMINATE"); 

status.Text += "\r\nClosing connection.\r\n"; 

// Step 6: Close connection 

myWriter.Close();

myReader.Close();

myNetStream.Close();

myClient.Close();

Application.Exit(); 

}

// handle exception if error in establishing connection 

Catch (Exception error) 

{

MessageBox.Show(error.ToString()); 

}

}

 

 

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[Tutor] seeking help to a problem w/ sockets

[James Duffy]

I have a problem w/ a file transfer receiver. They way it works is it binds
a port for incoming transfer , when the file transfer is complete. It closes
the connection and the socket, then loops back and restarts the bind and
listen. I have it set so that the socket is reuseable, which is why this
works. However, if the program that is using this function is closed while
listening, it appears that it does not "un-bind" because when the program is
reopened and a listen attepted to start I get a "port already in use" error.
Only a reboot fixes this issue. This code is imported into a main GUI
script. We have it set to execute some cleanup functions on exit, I need a
function that can dig down to the thread the listener is running in, stop
the listen and close the connection and socket. I basically need to get to
the close function and then stop the while loop. Thanks in advance for any
help anyone can give. My code for the listener class follows:

 

class Reciever ( Thread ):   # the reciever class for the test tool, runs as
a separate thread from the main program

 

def __init__( this ):

Thread.__init__( this )



def run(this):

this.process()

 

def bindsock( this ):   # create a new socket, bid the socket to the
port, listen until connection recieved

this.Lport=listen

this.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

this.sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)

this.sock.bind(('',this.Lport))

this.sock.listen(1)

print "Listening on port " +str(this.Lport)

 

def acceptsock( this ): #when connection is incoming, accept the
connection

this.conn, this.addr = this.sock.accept()

 

print 'Got connection from', this.addr



def transfer( this ):   #when connection is full established, begin data
download

global filenumber

print 'Starting media transfer '

 

openfile="XMLrecieved"+str(filenumber)+".xml"

f = open(openfile,"wb") #create and open a new file for writing
incoming data to

while 1:

data = this.conn.recv(1024)   #check for incoming data

if not data: break #if not present, break the loop

f.write(data)   #if data is present, write it to file and
loop back

f.close()  #when loop is broken, close the file

 

print "Got XML file:" + openfile

print 'Closing media transfer'

filenumber = filenumber + 1



def close( this ):  #close all connections and sockets

this.conn.close()

this.sock.close()

 

def process( this ): #this is the loop of the thread, it listens,
receives, closes then repeats until entire program is closed

while 1:

this.bindsock()

this.acceptsock()

this.transfer()

this.close()

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