====== socket ======
파이썬의 소켓 프로그래밍을 위한 라이브러리

===== 예제 =====

==== 클라이언트 ====
다음 예제는 google.com의 ip 주소를 알아낸 후 google.com 서버에 80 포트로 접속한다. 그리고 간단히 메시지를 주고 받는다. 웹브라우저 역시 이 예제와 동일한 방식으로 동작한다.

<file python client.py>
#Socket client example in python
 
import socket   #for sockets
import sys  #for exit
 
#create an INET, STREAMing socket
try:
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error:
    print 'Failed to create socket'
    sys.exit()
     
print 'Socket Created'
 
host = 'www.google.com';
port = 80;
 
try:
    remote_ip = socket.gethostbyname( host )
 
except socket.gaierror:
    #could not resolve
    print 'Hostname could not be resolved. Exiting'
    sys.exit()
 
#Connect to remote server
s.connect((remote_ip , port))
 
print 'Socket Connected to ' + host + ' on ip ' + remote_ip
 
#Send some data to remote server
message = "GET / HTTP/1.1\r\n\r\n"
 
try :
    #Set the whole string
    s.sendall(message)
except socket.error:
    #Send failed
    print 'Send failed'
    sys.exit()
 
print 'Message send successfully'
 
#Now receive data
reply = s.recv(4096)
 
print reply

#Close the socket
s.close()
</file>

==== 서버 ====
다음 예제는 8888포트로 바인딩 후 client와의 연결을 기다리고 연결되면 accept 함수 실행 후 핸들링을 위한 쓰레드를 생성한다. 무한루프를 이용하여 계속해서 client 연결 대기와 핸들링을 수행한다.

<file python server.py>
import socket
import sys
from thread import *
 
HOST = ''   # Symbolic name meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port
 
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
 
#Bind socket to local host and port
try:
    s.bind((HOST, PORT))
except socket.error , msg:
    print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
    sys.exit()
     
print 'Socket bind complete'
 
#Start listening on socket
s.listen(10)
print 'Socket now listening'
 
#Function for handling connections. This will be used to create threads
def clientthread(conn):
    #Sending message to connected client
    conn.send('Welcome to the server. Type something and hit enter\n') #send only takes string
     
    #infinite loop so that function do not terminate and thread do not end.
    while True:
         
        #Receiving from client
        data = conn.recv(1024)
        reply = 'OK...' + data
        if not data: 
            break
     
        conn.sendall(reply)
     
    #came out of loop
    conn.close()
 
#now keep talking with the client
while 1:
    #wait to accept a connection - blocking call
    conn, addr = s.accept()
    print 'Connected with ' + addr[0] + ':' + str(addr[1])
     
    #start new thread takes 1st argument as a function name to be run, second is the tuple of arguments to the function.
    start_new_thread(clientthread ,(conn,))
 
s.close()
</file>

===== 참고 =====
  * [[http://www.binarytides.com/python-socket-programming-tutorial/|Python socket – network programming tutorial]] \\