o_18ufhmfmq19t513t3lgmn5l1qa8a.pdf

460 CHAPTER 24 ■ PROJECT 5: A VIRTUAL TEA PARTY
Despite the name, it isn’t designed for the type of streaming (continuous) chat application
that we’re working on. (The word “chat” in the name refers to “chat-style” or command-response
protocols.) The good thing about the async_chat class (found in the asynchat module) is that it
hides the most basic socket reading and writing operations: They can be a bit difficult to get
right. All that’s needed to make it work is to override two methods: collect_incoming_data and
found_terminator. The former is called each time a bit of text has been read from the socket,
and the latter is called when a terminator is read. The terminator (in this case) is just a line
break. (You’ll have to tell the async_chat object about that by calling set_terminator as part of
the initialization.)
An updated program, now with a ChatSession class, is shown in Listing 24-4.
Listing 24-4. Server Program with ChatSession Class
from asyncore import dispatcher
from asynchat import async_chat
import socket, asyncore
PORT = 5005
class ChatSession(async_chat):
def __init__(self, sock):
async_chat.__init__(self, sock)
self.set_terminator("\r\n")
self.data = []
def collect_incoming_data(self, data):
self.data.append(data)
def found_terminator(self):
line = ''.join(self.data)
self.data = []
# Do something with the line...
print line
class ChatServer(dispatcher):
def __init__(self, port):
dispatcher.__init__(self)
self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
self.set_reuse_addr()
self.bind(('', port))
self.listen(5)
self.sessions = []