How to understand PHP's URL parsing/routing?

I just inherited a website built in PHP. The main page of www.mysite.com has a href to www.mysite.com/index/35.html somewh开发者_JS百科ere in the page. In the site's root directory and its children there is no document 35.html.

The number 35 is actually an id found in a DB which also holds the html contents of the page.

If I load URL: www.mysite.com/index.php?id=35 the same page loads.

How does PHP know how to automatically convert

/index/35.html

to

/index.php?id=35

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EDIT Based on the answers, I have found a .htaccess file containing rewrite instructions that would explain the functionality.

However, IIS doesn't seem to (or is not configured) know how to use this. (probably because this is an Apache feature?)

So this begs the following question: Is there a way to configure IIS to work with this?

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it will be done usign URL Rewriting using .htaccess - should be in the webroot.

It may look something like:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php [QSA,L]

May have other bits, but what this basically tells apache is to send anything that DOES NOT physically exist to index.php

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It doesn't. There is a mod_rewrite rule that rewrites from /index/foo to /index.php?id=foo, either in a .htaccess file somewhere or in the httpd configuration itself.

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RewriteEngine On
RewriteRule ^index/([\d]+)\.html /index.php?id=$1 [NC,L]

This is off the top of my head. Any browsers trying to load an address starting with index/ has any number ending in .html will be internally redirected to index.php?id= whatever the number is.

Edit: Just saw that your working on IIS. This probably won't work for you. Sorry.

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I think you will be using .htaccess to redirect all requests to index.php. From there You can pass the query string a routing class, which will parse the url and identify the unique ids. In this case we can say like, your routing class will parse the request /index/35.html to indexController, indexAction, id=35. now you can pass this id to the model to get corresponding page contents

NB : Here I a am assuming you are using mvc pattern. Anyway it can be treated in your own way, with the concept remaining the same. Hope this make sence.