Derick Rethans has posted a shootout of a few of the debugging protocols out there, really a comparison between the debugger that Zend is using in its Eclipse PHP IDE and the DBGp package.

He talks about some of the controversy that's surrounded Zend's choice and methods for their debugger and how it compares on various levels to DBGp (the debugger used in Komodo and various other places).

The topics he compares them under include:

• Protocol Communication
• Session Initialization
• Transporting Variables
• Breakpoint Support
• Output Capturing

Under each, there's mentions of how they are supported (or not supported, as the case my be) and what kind of options each has to offer.