NAME
CGI::Application::Demo::Ajax
- A search engine using CGI::Application, AJAX and JSON
Synopsis
Either:
#!/usr/bin/perl
use CGI::Application::Demo::Ajax;
CGI::Application::Demo::Ajax -> new() -> run();
or:
#!/usr/bin/perl
use strict;
use warnings;
use CGI::Application::Dispatch;
use CGI::Fast;
use FCGI::ProcManager;
# ---------------------
my($proc_manager) = FCGI::ProcManager -> new({processes => 2});
$proc_manager -> pm_manage();
my($cgi);
while ($cgi = CGI::Fast -> new() )
{
$proc_manager -> pm_pre_dispatch();
CGI::Application::Dispatch -> dispatch
(
args_to_new => {QUERY => $cgi},
prefix => 'CGI::Application::Demo',
table =>
[
'' => {app => 'Ajax', rm => 'initialize'},
'/search' => {app => 'Ajax', rm => 'search'},
],
);
$proc_manager -> pm_post_dispatch();
}
Description
CGI::Application::Demo::Ajax
demonstrates how to use CGI::Application
together with AJAX and JSON.
It ships with:
- Two
CGI
instance scripts: ajax.cgi and ajax -
ajax.cgi is a trivial
CGI
script, while ajax is a fancy script usingCGI::Application::Dispatch
andFCGI::ProcManager
. - A text configuration file: .htajax.conf
-
This will be installed into the same directory as Ajax.pm. And that's where Ajax.pm looks for it.
By default, form_action is /cgi-bin/ajax.cgi, so you'll need to edit it to use form_action=/local/ajax.
Also, the default logging directory is /tmp, so this might call for another edit of .htajax.conf.
- A set of
HTML::Template
templates: *.tmpl - This Perl module:
CGI::Application::Demo::Ajax
Distributions
This module is available as a Unix-style distro (*.tgz).
See http://savage.net.au/Perl-modules/html/installing-a-module.html for help on unpacking and installing distros.
Installation
All these assume your doc root is /var/www.
Install YUI
Browse to http://developer.yahoo.com/yui/, download, and unzip into htdocs:
shell>cd /var/www
shell>sudo unzip ~/Desktop/yui_2.7.0b.zip
This creates /var/www/yui, and yui_url in .htajax.conf must match.
Install the module
Install this as you would for any Perl
module:
Unpack the distro, and then either:
perl Build.PL
./Build
./Build test
sudo ./Build install
or:
perl Makefile.PL
make (or dmake)
make test
make install
Install the HTML::Template
files.
shell>cd /var/www
shell>sudo mkdir -p assets/templates/cgi/application/demo/ajax
shell>cp distro's/htdocs/*.tmpl to assets/templates/cgi/application/demo/ajax
Alternately, edit the now installed .htajax.conf, to adjust tmpl_path.
Install the trivial instance script
shell>cp distro's/htdocs/ajax.cgi to /usr/lib/cgi-bin
shell>sudo chmod 755 /usr/lib/cgi-bin/ajax.cgi
Install the fancy instance script
shell>cd /var/www
shell>sudo mkdir local
shell>cp distro's/htdocs/ajax to local
shell>sudo chmod 755 local/ajax
Configure Apache
to use local/ajax
If in fancy mode, add these to httpd.conf:
LoadModule fcgid_module modules/mod_fcgid.so
and:
<Location /local>
SetHandler fcgid-script
Options ExecCGI
Order deny,allow
Deny from all
Allow from 127.0.0.1
</Location>
And restart Apache
.
Start searching
Point your broswer at http://127.0.0.1/cgi-bin/ajax.cgi (trivial script), or http://127.0.0.1/local/ajax (fancy script, nice-and-clean URL).
The Flow of Control
Here's a step-by-step description of what's happening:
- You initialize the process
-
Point your web client at http://127.0.0.1/cgi-bin/ajax.cgi or http://127.0.0.1/local/ajax.
This is equivalent to
CGI::Application::Demo::Ajax -> new() -> run()
.Since there is no run mode input, the code defaults to Ajax.pm's sub initialize(). See sub setup() for details.
- The code assembles the default web page
-
The work is done in Ajax.pm's sub initialize().
This page is sent from the server to the client.
It contains the contents of web.page.tmpl, with both search.js and search.tmpl embedded therein.
Of course, it also contains a minimal set of YUI Javascript files.
- The client accepts the response
-
The default web page is displayed.
- You input a search term
-
The
CGI
form in search.tmpl is set to not submit, but rather to call the Javascript function search_onsubmit(), which lives in search.js.It's actually the copy of this code, now inside web.page.tmpl, now inside your client, which gets executed.
- The
CGI
form is submitted -
Here, Javascript does the submit, in such a way as to also specify a call-back (Javascript) function, search_callback(), which will handle the response from the server.
This function also lives in search.js.
- Ajax.pm runs again
-
This time a run mode was submitted, either as form data or as path info data.
And this means that when using the fancy script, you don't need the line in search.tmp referring to the hidden form variable 'rm', because of the path info '/search' in search_onsubmit().
- sub search() carries out the search.
-
The run mode causes Ajax.pm's sub search() to be the sub which gets executed this time.
It assembles the results, and uses
JSON::XS
to encode them. - The server replies
-
The results of the search are sent to the client.
- The client accepts the response
-
When the client receives the message, these events occur, in this order:
- Control passes to search_callback(), the call-back function
- The data is decoded from JSON to text by a YAHOO.lang.JSON object
- The data is moved into a YAHOO.util.LocalDataSource object
- The data is formatted as it's moved into a YAHOO.widget.DataTable object
This object displays its data automatically. Actually, the object's constructor displays the data, which is why we call new by assigning the object to a Javascript variable, data_table.
Next
It should be obvious that the code in Ajax.pm's sub search() can be extended in any manner, to pass more complex hash refs to the Javascript function search_callback().
This data can then be ignored by the Javascript, or you can extend the responseSchema and column_defs to display it.
Given this framework, extending these data structures is basically effortless.
Author
CGI::Application::Demo::Ajax
was written by Ron Savage <ron@savage.net.au> in 2009.
Home page: http://savage.net.au/index.html
Copyright
Australian copyright (c) 2009, Ron Savage. All Programs of mine are 'OSI Certified Open Source Software'; you can redistribute them and/or modify them under the terms of The Artistic License, a copy of which is available at: http://www.opensource.org/licenses/index.html