locating_request_handling_code.md

Locating Request Handling Code

Once the framework responsible for dispatching requests is understood, it is fairly easy to locate the code responsible for performing a certain task in order to modify or extend it. The code that delegates control to the appropriate classes has been written with extensibility in mind; that is, it should rarely need modification.

In order to find the code that handles a specific request, follow these steps:

• Find the name of the Page class in the request URL. This is the second field after index.php; for example, in the following URL:
  • http://www.mylibrary.com/index.php/myjournal/user/profile
• the name of the Page class is UserHandler. (Page classes always end with Handler. Also note the differences in capitalization: in the URL, lowerCamelCase is used; class names are always CamelCase.)
• Find the source code for this Page class in the pages directory of the source tree. In the above example, the source code is in pages/user/UserHandler.inc.php.
• Determine which function is being called by examining the URL. This is the third field after index.php, or, in this case, profile.
• Therefore, the handling code for this request is in the file pages/user/UserHandler.inc.php, in the function profile.