I am new here and my english is not the best, so first of all sorry for that

Now my question:
I heard that Twitter would use for twitter.com their own API which all developers can use.
I dont know its true or not, but it sounds good for me to build one API and use it internal and give other people the chance to use a part of it for their own sites like the API of Facebook or Twitter.
So you only have to create one API and this API is maintained as well as the site itself, because you use it for your own site too.

But my problem is how I should use this API on the same server. A Request over cURL or something like that would make no sense for me.
Is there any "best practice" or any good patterns to solve this "problem"?

I hope this is the right place for my question and sorry again for my englisch