Common lisp sockets

sockets.txt

Source: http://www.huuii.com/people/juan/1301

I want to use sockets under common lisp, so I am going to create a two simple functions the first one serve-socket and the second client-socket, I am going to use usocket library.

- Load the library: 
(ql:quickload "usocket")

- Change to usocket library
(in-package :usocket)

- Create the functions:
 
 (defun server-socket (port)
  "Listening on a port for a message, and print the received message."
  (usocket:with-socket-listener (socket "127.0.0.1" port)
    (loop
       (usocket:with-connected-socket (connection (usocket:socket-accept socket))
     (format t "~a~%" (read-line (usocket:socket-stream connection)))))))


 (defun client-socket (port message)
  "Connect to a server and send a message."
  (usocket:with-client-socket (socket stream "127.0.0.1" port)
    (format stream message)
    (force-output stream))) 

- Test
 
Call the function
USOCKET> (server-socket 9090)

with  netstat -tap linux command we see:
 
tcp        0      0 localhost:9090          0.0.0.0:*               LISTEN      4103/sbcl 

The server is ready! 
 

With other sbcl instance we need to run client socket then:
 
Load the library: 
(ql:quickload "usocket")

Change to usocket library
(in-package :usocket)

call the function 
USOCKET> (client-socket 9090 "Hello world !")
 

The server has :
 
USOCKET> (server-socket 9090)
Hello world !