The thing to remember about questions, answers and comments, though, is that they don't exist in a vacuum. They're created by users, and it's the users that make the site tick. That's why the Stack Exchange API includes a large number of methods designed to let developers access user profiles and timelines, and unearth the relationships between users and their posts. This article will focus primarily on this dimension of the Stack Exchange API, illustrating how to search for users, obtain user profiles and timelines, and retrieve information on a user's questions, answers, comments, badges and tags.

You'll need to get the StackPHP PEAR package to follow along with the code examples (it does some of the hard work for you). He shows how to:

• Grab a list of users ordered by reputation
• Search for usernames matching a string
• Get badge information (in general and for a user)
• Finding a user's activity timeline

Near the end he also includes an example of using the Zend_Paginator component of the Zend Framework to filter down the results to a more manageable size.

The thing about Stack Overflow, though, is that it has a geeky secret of its own. Like many Web 2.0 applications, it exposes its data to the public via the Stack Exchange Web service API, making it possible to develop customized applications that run on top of the base service. This API allows access to a number of important functions, including searching for questions, retrieving answers and comments, accessing user profiles, and working with tags and badges. It's also pretty easy to integrate this API into a PHP application - and this two-part article will show you how!

In part one he introduces you to some of the conventions and tips you'll need to know when reading through the article. He shows how to get and parse a sample response (with json_decode). He also uses the proposed StackPHP PEAR package to make requests for general question information, specific details, tags, comments and search results.