Richard Newman » holygoat.co.uk » blog

Tue 08 Mar 2005

How Does It Work?

Here's a CL-AJAX version of the ModernMethod tutorial for SAJAX, which does exactly the same thing in PHP (though with a bit less functionality on the server side, as far as I can tell). I've cribbed some of the text to make the similarity as similar as possible. Apologies to ModernMethod, and to my readers for the abysmal <pre> formatting.

Include the library:
```
(asdf:operate 'asdf:load-op :cl-ajax)
```

Initialise it and tell it what functions you wish to export:

;; the function we will be exporting 
;; to JavaScript:
(defexported multiply (x y) (* x y))
;; set the server running:
(install-handler
  (http-listener-handler *listener*)
  (make-instance 'ajax-function-handler)
  *site-url* nil)
(start-listening *listener*)

Setup your HTML (including the JavaScript the library generates)

<html>
  <head>
    <title>Test</title>
    <script>
<!-- 
  here Araneida inserts the results of
  (build-preamble *site-url*)
-->
function set_math_result(result) {
  document.getElementById("z").value = result;
}
function do_the_math() {
  var x, y;
  x = document.getElementById("x").value;
  y = document.getElementById("y").value;
  // The Lisp function (multiply) has been
  // linked to a javascript function named
  // ajax_multiply() with defined args. call it.
  // Also specify if XML will be expected.
  ajax_multiply(x, y, set_math_result, false);
}
    </script>
  </head>
  <body>
    <input type="text"
              name="x" id="x" 
              value="2" size="3">
    *
    <input type="text"
              name="y" id="y"
              value="3" size="3">
    =
    <input type="text"
              name="z" id="z"
              value="" size="3">
    <input type="button" name="check"
              value="Calculate"
      onclick="do_the_math(); return false;">
  </body>
</html>

Thanks to security features in most modern browsers this won't work if you just save it locally — I threw a quick static-file-handler into Araneida to serve the saved HTML, and it worked like a charm:

That's the raw XML response, the form from the original SAJAX example calling into CL-AJAX, and Vim showing the (frankly awful) generated code.

Posted at 2005-03-08 15:57:06 by Richard • Link to How Does It Work?
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