I need to convert a long url into tiny url.

For example in http://tinyurl.com, when you enter www.yahoo.com it makes into tinyurl as http://tinyurl.com/1hm. when you click this link it automatically goes to yahoo.com.

I want to know how this task is done. Did they do it by some algorithms or random number generation.

I searched in cpan, but i couldn't get. So monks, any of you had come across this kind of situation, please tell how to approach this.

Thanks monks for all your valuable time.