URL Shortening Site

Question

I am working on a URL shortening site which uses PHP, MySQL and Apache. General idea of URL shortening as I look at open source projects: user gives a URL link and the system gets ID for that link from database. Then convert the ID X base system (I am using base 36). Then use Apache mod_rewrite and create shortened URL and then redirect. Do all of the URL shortening sites work like that or do some use a different algorithm other than this? And any idea for making a difference from other URL shortening systems?

Answer 1

I think you are quite on the right way.

One thing I would not do like you said, though, is about this part :

then use apache mod_rewrite and create shorten url and then redirect.

I don't think I'd create an Apache RewriteRule, nor use mod_rewrite.

When receiving an short url, like short.com/MYID, Id would :

• decrypt the "MYID" part to the id number in DB
• fetch the URL from database
• just redirect to that URL from some server code (like PHP, using the header function)

A bit like this I guess :

// fetch $urlFull from DB (corresponding to the MYID received in GET)
header('HTTP/1.x 301 Moved Permanently');
header('Location: ' . $urlFull);
die;

(edit) If by mod_rewrite you meant "transform short.com/MYID to short.com/id=MYID", oh, yes, in this case, of course !

I'm using something like this on one of my sites, btw :

RewriteEngine on
RewriteCond %{REQUEST_URI}  !^/index.php
RewriteRule ^(.*)$ /index.php?hash=$1   [L]

Hope this helps :-)

Answer 2

If you want to do something different from other URL shortening sites, figure out a way to make sure the links don't break if your site goes away! I don't know how to do this, I think it's probably impossible...

Answer 3

Just a security note: Do not redirect directly to the site from a shortened url if it's not under your control/domain - have a landing page where the user can see the actual url and decide whether to continue or not...

Answer 4

You can use bit.ly (twitter uses this). There are some APIs which you can use to call and fetch shortened URLs.

Also talk about shortening URLs, you can simply use a table like this

CREATE TABLE `urls` (
  `id` varchar(255) NOT NULL default '',
  `url` text NOT NULL default '',
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Where you can have the id (in base 36 to prevent exhaustion of 32 bit integers) to be the shortened id - http://host/?id

and when you call the URL http://host/?As2dD24B, it will look up the matching ID and URL, then redirects to the URL. simple?

Also keep in mind that you can expand your base 36. I am assuming that your base 36 is: a-z and 0-9. You can add in A-Z (another 26) and other symbols (such as ?,:*&^%$#@).

Answer 5

Being related to the subject... Url Shorteners: Destroying the Web Since 2002