Common Lisp/External libraries/Hunchentoot
Hunchentoot is a web application server written in Common Lisp.
Quick start
editInstalling with ASDF
editInstalling Hunchentoot on ASDF-enabled systems. The next command installs Hunchentoot and all dependencies.
(require 'asdf-install)
(asdf-install:install 'hunchentoot)
Generating a simple Web page
edit(asdf:oos 'asdf:load-op :hunchentoot)
(defpackage :testserv
(:use :cl :hunchentoot)
(:export :start-server))
(in-package :testserv)
;; Add a simple prefix dispatcher to the *dispatch-table*
(setq *dispatch-table*
`(,(create-prefix-dispatcher "/hello-world" 'hello-page)))
;; Handler functions either return generated Web pages as strings,
;; or write to the output stream returned by write-headers
(defun hello-page ()
"<html><body>Hello World!</body></html>")
(defun start-server (&key (port 4242))
(start (make-instance 'easy-acceptor :port port)))
Start the server:
(testserv:start-server :port 4242)
The generated image is available on http://localhost:4242/hello-world.
Serving dynamic graphics
editThis example shows how to generate PNG images with Vecto[1] and serve them with Hunchentoot.
First step: load external dependencies
(asdf:oos 'asdf:load-op :hunchentoot)
(asdf:oos 'asdf:load-op :vecto)
Second step: declare a package
(defpackage :testserv
(:use :cl :vecto :hunchentoot)
(:export :start-server))
(in-package :testserv)
Add a simple prefix dispatcher to the *dispatch-table*
:
(setq *dispatch-table*
`(,(create-prefix-dispatcher "/img" 'img-page)))
The img-page
function expects HTTP parameter height
containing an integer value and generates a PNG image height
pixels height. If the parameter is not specified a default value of 150 is used.
(defun img-page ()
(setf (content-type*) "image/png")
(let ((out (send-headers)) ; send-headers returns the output flexi-stream
(bar-height (or (and (parameter "height") (parse-integer (parameter "height")))
150)))
(with-canvas (:width 10 :height bar-height)
(rectangle 0 0 10 bar-height)
(set-gradient-fill 0 0
0 1 1 1
0 bar-height
1 0 0 1)
(fill-and-stroke)
(save-png-stream out)))) ; write the image data to the output stream obtained from send-headers
Start the server:
(testserv:start-server :port 4242)
The generated image is available on http://localhost:4242/img. Try to change the height: http://localhost:4242/img?height=350
References
editSee also
edit- http://weitz.de/hunchentoot/ — Hunchentoot homepage
- http://www.cliki.net/hunchentoot — Common Lisp Wiki entry for Hunchentoot
- LispCast: Writing a simple Reddit clone in Common Lisp