A common complaint about OAuth is that it is very difficult to understand, but perhaps some of that confusion is because of an expectation that the abstraction provided by a third-party library will erase the need to understand the steps of an OAuth transaction – it does not. This two-part article demonstrates how how OAuth v1 works by explaining the process of connecting a PHP application to the Twitter API using only a few built-in functions to post a message to a user’s Twitter stream. The example code provided in this article is intended for educational purposes only. It lacks much practical use and error handling, Any real development should take advantage of an existing OAuth library, but after reading this article you’ll have a better understanding of how OAuth works and will be better equipped to troubleshoot any problems that may arise.
See the original post:
PHPMaster: Understanding OAuth – Tweeting from Scratch, Part 1