Programming Jakarta Struts

Why Is Model-View-Controller So Important?

The MVC architectural pattern is not directly related to web applications. In fact, it’s quite common in Smalltalk applications, which generally have nothing to do with the Web.

As we saw in the previous section, the Model 2 approach is concerned with separating responsibilities in web applications. Allowing a JSP page to handle the responsibilities of receiving the request, executing some business logic, and then determining the next view to display can make for an unattractive JSP page, not to mention the maintenance and extensibility problems this entanglement causes. Application development and maintenance are much easier if the different components of a web application have clear and distinct responsibilities.

As an example, say you want to integrate security into your web site. Your first page, in this case, usually is a login screen that collects and validates the username and password. This page then directs the user to another screen that allows her to continue in a secure manner. However, as there is nothing to prevent the user from going directly to a page, each page (in a non-MVC world) needs to be aware of security. This can be accomplished by including a security check on every page, but that can be unwieldy, especially if there are some pages that need to be secure and some that do not. In the MVC world, the security is put inside the controller object. Because the interface to the customer is driven through the controller ...