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#+title: Portal Portable websockets for Common Lisp using [[https://github.com/usocket/usocket][usocket]].

• Install Install with [[https://www.quicklisp.org/beta/][quicklisp]]. #+BEGIN_SRC lisp (ql:quickload 'portal) #+END_SRC
• Use

** Define a Resource Resources are identified by their path in the URL.

A simple echo server. #+BEGIN_SRC lisp (pws:define-resource "/echo" :open (lambda (websocket) (pws:send websocket "Welcome to echo server.")) :message (lambda (websocket message) (sleep 1) (pws:send websocket message) (sleep 1) (pws:send websocket message))) #+END_SRC You can also define :close function and a :error function in case something goes wrong in your other functions. You can't send any more messages after a close has begun.

** Start a Server #+BEGIN_SRC lisp (defparameter server (pws:server 4433)) #+END_SRC

Now connect to =ws://localhost:4433/echo= in a websocket tester and start echoing. You can add a :multi-thread argument to give each client its own thread.

** Close Clients At any point, you can close a client websocket. #+BEGIN_SRC lisp (pws:close websocket) #+END_SRC

** Close Server To stop severing: #+BEGIN_SRC lisp (pws:server-close server) #+END_SRC

It is just a thread!

** Handling Errors These two methods are separate, You can both, neither, or any combination.

*** Custom Handler Function When defining a resource path, you can pass a :error argument with a function that takes the websocket and the condition that occurred. Do whatever you want here. It is called when there is an error in your :open, :message, or :close function.

*** Debugger There is a variable: pws:debug-on-error; when it is non-nil, the debugger will be entered when there is a problem with one of your handler functions. it is bound to t by default.

*** Example Here is another example, this time using the :error function sends the error over the websocket instead of entering the debugger, and the :close just prints to the Lisp console.

#+BEGIN_SRC lisp ;; prevent entering debugger (setq pws:debug-on-error nil)

(pws:define-resource "/err"

:open (lambda (socket)
        (pws:send socket "Welcome to error server."))

:message (lambda (socket message)
           ;; error because message is a string
           (pws:send socket (1+ message)))

:error (lambda (socket condition)
         ;; echo error to websocket
         (pws:send socket condition))

:close (lambda (socket)
         (declare (ignore socket))
         (print "Socket leaving error server.")))

#+END_SRC

• Issues If you find any bugs of have any issues (installing, using, questions, adhering to RFC 6455) use the Github issue tracker.

• Contact If you want to contact me about collaboration, licensing, etc. You can use the email in =portal.asd=.