Working through many of the concepts and skills needed by intermediate and advanced PHP developers, this book is specifically designed to help good PHP developers become indispensable ones. Topics include debugging, test-driven development, web-based development, advanced object-oriented programming, and web security, and the book also takes an in-depth look at the new PHP Toolkit for IBM i provided by Zend Technologies. Upon completion of this book, readers will be able to use its principles as a basis for architecting complex applications, building web services according to the best standards currently available, significantly reducing the time spent discovering and fixing errors in code, designing architectures that are testable and predictable, building secure applications by protecting against most known attacks, and avoiding and preparing for common performance issues.