How to setup a custom handler ?

[a1ex07]

Hi guys, I'm a newbie in Zen Cart, so I apology for a lame question.
In my store, I want to use ajax for displaying some extra information about products. I'm able to send requests to my handler (websiteroot/my_handler.php), but I also want to access Zen classes, for example, queryFactory, from within my the handler. Is it possible at all ? What files should be included ?
Thanks for your answers.

[kobra]

Don't kmow what exactly your are attempting???

This might assist???
http://www.zen-cart.com/index.php?ma...roducts_id=467

[a1ex07]

@kobra
Thanks for the link, but it's not what I need at the moment. I'll try to illustrate what I want to achieve:
From product listing page I send data to my_handler.php through ajax(this part works, my_handler.php receives everything). Inside this file I want to write, for example

 global $db; 
$db->Execute("some sql code"); 

where $db is an instance of queryFactory. How can I initialize all zen cart stuff? I tried

require_once("includes/application_top.php"); 

, but it worked only if my_handler.php is in the root folder .

[DrByte]

Yes, loading application_top is the right approach.