Here is a simple example of UDP networking with asyncore.
Details:
- UDP is connectionless and “unreliable” meaning you should use sendto( “msg”, (“ip”,port)) and hope the packet arrives at the destination.
- UDP is a good choice when speed is more important than accuracy, UPD is common for first person shooter games.
- Asyncore is used to stop the networking from blocking your program. Call asyncore.loop() to send/receive some packets.
- Use asyncore.loop(count=5) or asyncore.loop(timeout=0) to tune the amount of time spent sending/receiving packets.
Client:
import socket, asyncore
class AsyncoreClientUDP(asyncore.dispatcher):
def __init__(self, server, port):
self.server = server
self.port = port
self.buffer = ""
# Network Connection Magic!
asyncore.dispatcher.__init__(self)
self.create_socket(socket.AF_INET, socket.SOCK_DGRAM)
self.bind( ('', 0) ) # bind to all interfaces and a "random" free port.
print "Connecting..."
# Once a "connection" is made do this stuff.
def handle_connect(self):
print "Connected"
# If a "connection" is closed do this stuff.
def handle_close(self):
self.close()
# If a message has arrived, process it.
def handle_read(self):
data, addr = self.recv(2048)
print data
# Actually sends the message if there was something in the buffer.
def handle_write(self):
if self.buffer != "":
print self.buffer
sent = self.sendto(self.buffer, (self.server, self.port))
self.buffer = self.buffer[sent:]
connection = AsyncoreClientUDP("127.0.0.1",5005) # create the "connection"
while 1:
asyncore.loop(count = 10) # Check for upto 10 packets this call?
connection.buffer += raw_input(" Chat > ") # raw_input (this is a blocking call)Server:
import asyncore, socket
class AsyncoreServerUDP(asyncore.dispatcher):
def __init__(self):
asyncore.dispatcher.__init__(self)
# Bind to port 5005 on all interfaces
self.create_socket(socket.AF_INET, socket.SOCK_DGRAM)
self.bind(('', 5005))
# Even though UDP is connectionless this is called when it binds to a port
def handle_connect(self):
print "Server Started..."
# This is called everytime there is something to read
def handle_read(self):
data, addr = self.recvfrom(2048)
print str(addr)+" >> "+data
# This is called all the time and causes errors if you leave it out.
def handle_write(self):
pass
AsyncoreServerUDP()
asyncore.loop()Notes:
- This simple server only receives packets and prints them, it does not respond to the client or keep track of the client IPs or Ports
- The client does block when it gets to the raw_input() call.
- If you are going to use this code packed into a p3d file you need to use the “-r morepy” flag
I hope someone finds this useful, let me know if you have any questions or if I made any mistakes.
Thanks,
Daniel.
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