[hunchentoot-devel] Displaying partial output from the handler?

[Pierre THIERRY]

Scribit Andrei Stebakov dies 27/03/2007 hora 10:36:
> Pierre, I am not sure I understood you. Could you give some example of
> what you described?

Sure, here is a file with a complete toy example. Just load the file and
go to the following URI:

http://localhost:8888/step1

After approximately 8 seconds, your browser should show you a second
page, located at:

http://localhost:8888/step2

In the meantime, most browsers should leave the first page visible. I'm
confident this works on most mainstream browsers because the french
national railroad company uses this trick on its online store (that's
where I learned it, by the way, I seem to remember).

I successfully tested this example under SBCL 1.0.0.0 with Linux and
both Firefox and Konqueror.

Visually,
Pierre
-- 
nowhere.man at levallois.eu.org
OpenPGP 0xD9D50D8A
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#|

Copyright (c) 2007 Pierre Thierry <nowhere.man at levallois.eu.org>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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The above copyright notice and this permission notice shall be included in
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THE SOFTWARE.

|#



#| Load and use the needed packages |#

(asdf:oos 'asdf:load-op :hunchentoot)
(asdf:oos 'asdf:load-op :cl-who)

(use-package :hunchentoot)
(use-package :cl-who)


#| Define the two functions that output pages |#

(defun waiter-page (title finished-uri)
  "Return a web page that immediately redirects to another URI"
  (let ((refresh-content (format nil "0;URL=~a" finished-uri)))
    (with-html-output-to-string (out nil :prologue t :indent t)
      (:html
       (:head
	(:title (esc title))
	(:meta :http-equiv "refresh" :content refresh-content))
       (:body
	(:h1 (esc title))
	(:p "Wait. Loooong."))))))

(defun slow-page (message)
  "Return a web page showing a message, but only after waiting some time"
  (sleep 8)
  (with-html-output-to-string (out nil :prologue t :indent t)
    (:html
     (:head
      (:title "Message")
      (:body
       (:h1 "Message")
       (:p (esc message))
       (:hr)
       (:p "Wow. Took time!"))))))


#| Setup the server |#

(push (create-prefix-dispatcher "/step1" (lambda () (waiter-page "Testing two-steps serving" "/step2"))) *dispatch-table*)
(push (create-prefix-dispatcher "/step2" (lambda () (slow-page "It's done"))) *dispatch-table*)
(start-server :port 8888)
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