Web development has made great progress during the last few years. It began as a tedious task that involved using a protocol called Common Gateway Interface (CGI) for interfacing external programs with the web server. The CGI applications used standard I/O facilities available to the C programming language in order to manually parse user input and produce page output. In addition to being difficult to work with, CGI required a separate copy of the program to be launched for each request. This used to quickly overwhelm servers.
Next, scripting languages were introduced to web development, and this inspired developers to create more efficient technologies. Languages such as Perl and PHP quickly made their way into the world of web development. As a result, common web tasks such as cookie handling, session management, and text processing became much easier. Although scripting languages included libraries to deal with day-to-day web-related tasks, they lacked unified frameworks, as libraries were usually disparate in design, usage, and conventions. Therefore, the need for cohesive frameworks arose.
A few years ago, the model-view-controller (MVC) pattern for web-based applications was introduced. This software engineering pattern separates data (model), user interface (view), and data-handling logic (controller) so that one can be changed without affecting the others. The benefits of this pattern are obvious. With it, designers can work on the interface without worrying about data storage or management. Developers are able to program the logic of data handling without getting into the details of presentation. As a result, the MVC pattern quickly found its way into web languages, and serious web developers started to embrace it in preference to previous techniques.
The following diagram illustrates how each of the components of the MVC pattern interacts with each other to serve a user request:
