hunchensocket

2016-10-31

Build Status Hunchensocket - WebSockets for Hunchentoot ==========================================

Hunchensocket is a Common Lisp implementation of WebSockets realized as an extension to Edi Weitz' excellent Hunchentoot web server. Hunchensocket implements a compliant RFC6455 server.

Note that Alexander Kahl, the original author, has desactivated his old version that only supports the drafts of the protocol.

Installation

Hunchensocket is in Quicklisp, so if you have that setup just do (ql:quickload :hunchensocket).

Quicklisp is also good to use the trunk alongside with other dependencies, perhaps to test a new feature or a bugfix:

$ cd ~/Source/Lisp/
$ git clone https://github.com/joaotavora/hunchensocket.git
(push "~/Source/Lisp" ql:*local-project-directories*)
(ql:quickload :hunchensocket) ;; use local hunchensocket and pull
                              ;; dependencies from quicklisp

A chat server in 30 lines

First define classes for rooms and users. Make these subclasses of websocket-resource and websocket-client.

(defpackage :my-chat (:use :cl))
(in-package :my-chat)

(defclass chat-room (hunchensocket:websocket-resource)
  ((name :initarg :name :initform (error "Name this room!") :reader name))
  (:default-initargs :client-class 'user))

(defclass user (hunchensocket:websocket-client)
  ((name :initarg :user-agent :reader name :initform (error "Name this user!"))))

Define a list of rooms. Notice that hunchensocket:*websocket-dispatch-table* works just like hunchentoot:*dispatch-table*, but for websocket specific resources.

(defvar *chat-rooms* (list (make-instance 'chat-room :name "/bongo")
                           (make-instance 'chat-room :name "/fury")))

(defun find-room (request)
  (find (hunchentoot:script-name request) *chat-rooms* :test #'string= :key #'name))

(pushnew 'find-room hunchensocket:*websocket-dispatch-table*)

OK, now a helper function and the dynamics of a chat room.

(defun broadcast (room message &rest args)
  (loop for peer in (hunchensocket:clients room)
        do (hunchensocket:send-text-message peer (apply #'format nil message args))))

(defmethod hunchensocket:client-connected ((room chat-room) user)
  (broadcast room "~a has joined ~a" (name user) (name room)))

(defmethod hunchensocket:client-disconnected ((room chat-room) user)
  (broadcast room "~a has left ~a" (name user) (name room)))

(defmethod hunchensocket:text-message-received ((room chat-room) user message)
  (broadcast room "~a says ~a" (name user) message))  

Finally, start the server. hunchensocket:websocket-acceptor works just like hunchentoot:acceptor, and you can probably also use hunchensocket:websocket-ssl-acceptor.

(defvar *server* (make-instance 'hunchensocket:websocket-acceptor :port 12345))
(hunchentoot:start *server*)

Now open two browser windows on http://www.websocket.org/echo.html, enter ws://localhost:12345/bongo as the host and play around chatting with yourself.

License

See COPYING for license details.

Design

Main sources of inspiration:

  • Original implementation by Alexander Kahl, which cleverly hijacks the Hunchentoot connection after the HTTP response and keeps the connection alive, just like in a Head request.
  • clws's API because it explicitly defines websocket "resources"
  • Hunchentoot's's API because it uses CLOS
Author
capitaomorte <https://github.com/capitaomorte>
License
MIT
Categories
ipc, web, websocket server