With the recent release of a new Firefox/PHP combination extension, several developers were interested in just how it all worked. One such developer is Terry Chay who has posted about it to his blog today after looking into how it all fits together.

The standard way of debugging in PHP involves just echoing shit to the screen. The fact that PHP is a scripting language makes this an excellent way of debugging on the web. But what happens when doing this breaks your site?

That's where FirePHP comes in - it sends along a special request from your PHP script (as fired off by special code you insert) to include debugging information inside a different part of a "multipart/mixed" message. Terry also includes some of his sample code (including a custom version of the software) that he used to get things working. Check out the screenshot for the results.