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原文：
Front end and back end technologies come together to build web applications, but because the World Wide Web has evolved at such a fast pace and because developers need to use a rather large number of technologies to build just a single web application, the result of their work is oftentimes difficult to maintain and fix.
Developers combine HTML code with server side programming languages to create dynamic web pages and applications and this leads to highly entangled and unmaintainable code. Another problem has grown out of the fact that web technologies are increasingly used to build all sorts of complex applications. Microsoft embraces web technologies to encourage developers to build applications for itsrsquo; latest operating system, Windows 8. Also, a lot of frameworks exist that help web developers write applications for mobile devices, like PhoneGap and Appcelerator Titanium. Even more, a mobile operating system is in the works and devices are expect later this year that uses web technologies entirely for the developer API (Mozilla Firefox OS). For these reasons a web application is generally created by a whole team of specialized developers, each working with their favorite technology, like HTML and CSS for the presentation layer, JavaScript for client-side interaction, PHP (or ASP, Java, Python, Pearl, Ruby, etc.) for server-side logic and MySQL (or Oracle Database, Microsoft SQL Server, etc.) for data storage and management.
Each of these specialist needs to work with their colleagues in such a way that their code pieces fit inside the overall design of the application. For example, the client-side (data presentation) developer needs to alter the HTML and CSS code in such a way that he doesnrsquo;t break the server-side developersrsquo; code that resides in the same file. Also, when a database developer alters the schema for an application the server-side developer may need to change a lot of code to make the application work.
The important thing to note here is that there is an acute need to separate presentation from logic and data storage in an application.
There are some application design paradigms and patterns that offer solutions to this problem, but the focus nowadays is on the MVC pattern.
In conducting the research we have used our experience is building web applications with various systems and frameworks and we have tried to identify both strengths and weaknesses of these systems while providing our own view on how these practices could be improved. Studied frameworks and systems include: Symfony, CakePHP, CodeIgniter Zend Framework, Laravel, Fuel PHP, Ruby on Rails and ASP.NET MVC.
The Model
The Model is the part of the system that manages all tasks related to data: validation, session state and control, data source structure (database). The Model greatly reduces the complexity of the code the developer needs to write. The Model layer is responsible with the business logic of an application. It will encapsulate methods to access data (databases, files, etc.) and will make a reusable class library available. Usually a Model is built with data abstraction in mind, validation and authentication.
Moreover, the Model is made up of classes that define the domain of interest. These objects that belong to the domain often times encapsulate data that is stored in databases, but also include code that is used to manipulate this data and enforce business rules.
As a conclusion, the Model mainly handles data access abstraction and validation. The Model holds methods for interaction with different data sources.
We believe in the Thin Model approach, which says that a model should be kept as simple as possible, only encompassing data processing that is strictly tied to the real life object that is modeled. The Thin Model is coupled with a Fat Controller, which houses most of the data processing required by the application. This way, the models become highly reusable between applications and most of a developerrsquo;s work is kept inside controllers
The novelty our Model system brings to the MVC world is a system for versioning control, based on the idea of migrations, that doesnrsquo;t only keep track of data structure but of data itself. The system uses xml files to store data between migrations, making the versioning process for databases an easily accomplishable thing.
The View
The View is responsible with graphical user interface management. This means all forms, buttons, graphic elements and all other HTML elements that are inside the application. Views can also be used to generate RSS content for aggregators or Flash presentations. By separating the design of the application from the logic of the application we greatly reduce the risk of errors showing up when the designer decides to alter the interface of that application by changing a logo or a table. In the same time, the developersrsquo; job is greatly reduced because he no longer needs to see HTML code elements, design elements and graphical elements.
The View layer is what can normally be called web design or templates. It controls the way data is displayed and how the user interacts with it. It also provides ways for data gathering from the users. The technologies that are mainly used in views are HTML, CSS and JavaScript.
As a general rule, a view should never contain elements that belong to application logic, in order to make it easier for the designer to work with it. This means logical blocks should be kept at a minimum.
Most web application frameworks today us
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