how to do preprocessing task before node rendering

Hi guys,

Pls forgive me if this question has already been answered, I did lots of googling, but couldn’t fine anything worth. I am pretty new to Drupal and PHP development (2 months of exp, am basically a Java/J2EE guy). Following is what I am trying to do :

When a url like http://server_name/?q=node/[id] is clicked, I want certain preprocessing task to be done before node content is rendered. I have looked into the node.module source code, and I can see a function node_page_view which renders the node content.

sample code snippet is as follows for your reference :

/**
* Menu callback; view a single node.
*/
function node_page_view($node, $cid = NULL) {
drupal_set_title(check_plain($node->title));
return node_show($node, $cid);
}

One *dirty* way to achieve my goal is to write the custom code in the node_page_view function itself. I am sure it will work but at the cost of compromising with the portability of the application. Not an elegant solution ofcourse :-(

I am sure there must be better way of achieving the same in Drupal.

Appreciate if anyone can help me into this.

P.S. I am working on Drupal 5.x

Thanks for your time
Jameel