Output-oriented Refactoring in PHP-based Dynamic Web Applications

Refactoring is crucial in the development process of traditional programs as well as advanced Web applications. In a dynamic Web application, multiple versions of client code in HTML and JavaScript are dynamically generated from server-side code at run time for different usage scenarios. Toward understanding refactoring for dynamic Web code, we conducted an empirical study on several PHP-based Web applications. We found that Web developers perform a new type of refactoring that is specific to PHP-based dynamic Web code and pertain to output client-side code. After such a refactoring, the server-side code is more compact and modular with less amount of embedded and inline client-side HTML/JS code, or produces more standard-conforming client-side code. However, the corresponding output client-side code of the server code before and after the refactoring provides the same external behavior. We call it output-oriented refactoring. Our finding in the study motivates us to build WebDyn, an automatic tool for dynamicalizing refactorings. When performing on a portion of server-side code (which might contain both PHP and embedded/inline HTML/JS code), WebDyn detects the repeated and varied parts in that code portion and produces dynamic PHP code that creates the same client-side code. Our empirical evaluation on several projects showed WebDyn's accuracy in such automated refactorings.