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Model-view-controller
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Model–View–Controller (MVC) is an architectural pattern used in software engineering. Successful use of the pattern isolates business logic from user interface considerations, resulting in an application where it is easier to modify either the visual appearance of the application or the underlying business rules without affecting the other. In MVC, the model represents the information (the data) of the application; the view corresponds to elements of the user interface such as text, checkbox items, and so forth; and the controller manages the communication of data and the business rules used to manipulate the data to and from the model.
was first described in 1979 by Trygve Reenskaug, then working on Smalltalk at Xerox PARC.
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Encyclopedia
Model–View–Controller (MVC) is an architectural pattern used in software engineering. Successful use of the pattern isolates business logic from user interface considerations, resulting in an application where it is easier to modify either the visual appearance of the application or the underlying business rules without affecting the other. In MVC, the model represents the information (the data) of the application; the view corresponds to elements of the user interface such as text, checkbox items, and so forth; and the controller manages the communication of data and the business rules used to manipulate the data to and from the model.
History
MVC was first described in 1979 by Trygve Reenskaug, then working on Smalltalk at Xerox PARC. The original implementation is described in depth in the influential paper Applications Programming in Smalltalk-80: How to use Model–View–Controller.
There have been several derivatives of MVC; one of the most known (due to its use by Microsoft) is the Model View Presenter pattern which appeared in the early 1990s and was designed to be an evolution of MVC. However Model–View–Controller still remains very widely used.
In November 2002 the W3C voted to make MVC structures part of their XForms architecture for all future web applications . These specifications will now be integrated directly into the XHTML 2.0 specifications. There are now over 20 vendors that support XForms frameworks with MVC integrated into the application stack.
Pattern description
Model–view–controller is both an architectural pattern and a design pattern, depending on where it is used.
As an architectural pattern
It is common to split an application into separate layers that run on different computers: the presentation/user interface (UI), business logic, and data access. In MVC the presentation layer is further separated into Model, view and controller, resulting in three layers.
MVC is often seen in web applications, where the view is the actual HTML or XHTML page, and the controller is the code that gathers dynamic data and generates the content within the HTML or XHTML. Finally, the model is represented by the actual content, which is often stored in a database or in XML nodes, and the business rules that transform that content based on user actions.
Though MVC comes in different flavors, control flow is generally as follows:
- The user interacts with the user interface in some way (for example, presses a mouse button).
- The controller handles the input event from the user interface, often via a registered handler or callback.
- The controller notifies the model of the user action, possibly resulting in a change in the model's state. (for example, the controller updates the user's shopping cart).
- A view uses the model indirectly to generate an appropriate user interface (for example, the view lists the shopping cart's contents). The view gets its own data from the model. The model and controller have no direct knowledge of the view.
- The user interface waits for further user interactions, which restarts the cycle.
Some implementations such as the W3C XForms also use the concept of a dependency graph to automate the updating of views when data in the model changes.
By decoupling models and views, MVC helps to reduce the complexity in architectural design and to increase flexibility and reuse of code.
As a design pattern
MVC encompasses more of the architecture of an application than is typical for a design pattern.
Model
- Is the
domain-specific representation of the information on which the application operates. Domain logic adds meaning to raw data (for example, calculating whether today is the user's birthday, or the totals, taxes, and shipping charges for shopping cart items). Many applications use a persistent storage mechanism (such as a database) to store data. MVC does not specifically mention the data access layer because it is understood to be underneath or encapsulated by the model.
View
- Renders the model into a form suitable for interaction, typically a user interface element. Multiple views can exist for a single model for different purposes.
Controller
- Processes and responds to events (typically user actions) and may indirectly invoke changes on the model.
Selected frameworks
GUI frameworks
Java: Java Swing
Java Swing is different from the other frameworks in that it supports two MVC patterns:
Model
- Frame level model—Like other frameworks, the design of the real model is usually left to the developer.
- Control level model—Swing also supports models on the level of controls (elements of the graphical user interface). Unlike other frameworks, Swing exposes the internal storage of each control as a model.
View
- The view is represented by a class that inherits from Component.
Controller
- Java Swing doesn't use a single controller. Because its event model is based on interfaces, it is common to create an anonymous action class for each event. In fact, the real controller is in a separate thread, the Event dispatching thread. It catches and propagates the events to the view and model.
Combined frameworks
Simple Version using only Java Servlets and JavaServer Pages from Java EE:
Model
- The model is a collection of Java classes that forms a software application intended to store, and optionally move, data. There is a single front end class that can communicate with any user interface (for example: a console, a graphical user interface, or a web application).
View
- The view is represented by JavaServer Page, with data being transported to the page in the HttpServletRequest or HttpSession.
Controller
- The controller servlet communicates with the front end of the model and loads the HttpServletRequest or HttpSession with appropriate data, before forwarding the HttpServletRequest and Response to the JSP using a RequestDispatcher.
The Servlet is a Java class, and it communicates and interacts with the model but does not need to generate HTML or XHTML output; the JSPs do not have to communicate with the model because the Servlet provides them with the information—they can concentrate on creating output.
Unlike the other frameworks, Java EE defines a pattern for model objects.
Model
- The model is commonly represented by entity beans, although the model can be created by a servlet using a business object framework such as Spring.
View
- The view in a Java EE application may be represented by a JavaServer Page, which may be currently implemented using JavaServer Faces Technology (JSF). Alternatively, the code to generate the view may be part of a servlet.
Controller
- The controller in a Java EE application may be represented by a servlet, which may be currently implemented using JavaServer Faces (JSF).
XForms
XForms is an XML format for the specification of a data processing model for XML data and user interface(s) for the XML data, such as web forms.
Model
XForms stores the Model as XML elements in the browser. They are usually placed in the non-visible
View
The Views are XForms controls for screen elements and can be placed directly in the visible section of web page. They are usually placed in the
The model and views are bound together using reference or binding statements. These binding statements are used by the XForms dependency graph to ensure that the correct views are updated when data in the model changes. This means that forms developers do not need to be able to understand either the push or pull models of event processing.
Controller
All mouse events are processed by XForms controls and XML events are dispatched.
Implementations of MVC as GUI frameworks
Smalltalk's MVC implementation inspired many other GUI frameworks, such as the following:
Implementations of MVC as web-based frameworks
In the design of web applications, MVC is implemented by web template systems as "View for web" component.
MVC is typically implemented as a "Model 2" architecture in Sun parlance. Model2 focuses on efficiently handling and dispatching full page form posts and reconstructing the full page via a front controller. Complex web applications continue to be more difficult to design than traditional applications because of this "full page" effect. More recently AJAX driven frameworks that focus on firing focused UI events at specific UI Components on the page are emerging. This is causing MVC to be revisited for web application development using traditional desktop programming techniques.
.NET
MVC in ASP.net 2.0 below link
- PureMVC Framework for Actionscript.
- ASP Xtreme Evolution (AXE)
- Mach-II A framework that focuses on trying to ease software development and maintenance
- Model-Glue Through a simple implementation of Implicit Invocation and Model–View–Controller, they allow applications to be well organized without sacrificing flexibility.
- Fusebox Fusebox does not force the Model–View–Controller (MVC) pattern or Object-Oriented Programming (OOP) on the developer. However, either or both of these development approaches can be used with Fusebox.
- PureMVC Framework for ColdFusion
- Coldbox is an event-driven conventions based MVC ColdFusion Framework with an extensive array of patterns for its operations such as Factories, Helpers, Workers, etc.
- is a MVC framework with built in authentication, redirecting, and URL routing.
Flex
- Cairngorm one of the primary open source frameworks for application architecture in Adobe Flex.
- Mate Architectural framework for Flex development.
Java
MVC web application frameworks:
JavaScript
MVC web application frameworks:
ABAP Objects
Informix 4GL
- Informix 4GL MVC models to use for Informix 4GL report and form creation
- EGL — IBM's EGL MVC Implementation
Lua
Perl
- Catalyst An MVC-based avant-garde web framework.
- Maypole A useful perl MVC framework
- Gantry An MVC framework similar to django
- Jifty the "one true way" for MVC
- CGIApplication Another MVC Web Framework
- MasonXMiniMVC MVC Framework
- Solstice Based on the MVC programming paradigm,
PHP
- Akelos PHP Framework a Ruby on Rails port to PHP4/5.
- CakePHP webapplication framework modeled after the concepts of Ruby on Rails.
- CodeIgniter A PHP MVC framework.
- A PHP MVC framework and CMS platform.
- Drupal A Content Management System utilizing the MVC framework.
- FUSE A powerful but easy-to-use PHP 5 Framework for MVC development modeled after the concepts of Ruby on Rails.
- Jelix (web framework)
- Jaws is a Framework and Content Management System for building dynamic web sites.
- Joomla v1.5.x is an open source Content Management System that employs the MVC model for its extensions, called components and modules.
- Kohana is an open source MVC oriented framework, originally forked from CodeIgniter.
- LISA MVC is an open source object oriented web application framework.
- Micro CMS Open Source (LGPL) MVC framework and nice and simple CMS in one
- A lightweight open-source PHP5 library featuring a simple MVC routing framework.
- Odin Assemble Small footprint PHP based MVC Framework.
- Orinoco Framework is a full-stack yet lightweight framework written in PHP5. It implements the Model 2 design paradigm.
- PHPonTrax A PHP 5 MVC framework modeled after Ruby on Rails.
- phpXCore A MVC design pattern based PHP content management framework compatible with PHP4 and PHP5.
- Prado A PHP 5 MVC framework modeled after ASP.NET web forms.
- Qcodo is an open-source PHP 5 web application framework
- SilverStripe contains a fully fledged PHP 5.2 ORM/MVC Framework focused on building websites. Much like Ruby on Rails.
- Solar
- Switch board (framework) with Routing PHP 5 MVC Framework with Routing.
- Symfony Framework PHP 5 MVC Framework modeled after the concepts of Ruby on Rails.
- Yii PHP Framework A PHP 5-based MVC framework.
- Zend Framework A PHP 5-based MVC framework modeled after the concepts of Ruby on Rails.
- ZNF PHP5 MVC framework for enterprise web applications
- Zoop Framework A Mature PHP 4/5 MVC framework.
- PureMVC Framework for PHP
Python
- Django A complete Python web application framework. Django prefers to call its MVC implementation
MTV, for Model-Template-View. Enthought The Enthought Tool Suite brings the Model–view–controller mindset to scientific GUI's and visualizationPylons—Python Web FrameworkTurboGears for Pythonweb2py A scalable full-stack enterprise level Python agile web development framework with support for highly flexible and rapid database-driven web application development. Zope Content Management Framework PureMVC Framework for Python
Ruby
Smalltalk
XML
- XForms—XForms has an integrated Model–view–controller architecture with an integral dependency graph that frees the programmer from specifically having to perform either push or pull operations.
See also
External links
- CodeProject article.
- by Martin Fowler.
- Microsoft's Scott Guthrie on .NET MVC
- Scott Hanselman builds an application step-by-step using the first CTP of the ASP.NET MVC Framework in this Introductory Video*Greer, Derek. "", Ctrl-Shift-B, 2007.
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