Model–view–controller (MVC) is a software design pattern commonly used for developing user interfaces that divide the related program logic into three interconnected elements. This is done to separate internal representations of information from the ways information is presented to and accepted from the user.
Traditionally used for desktop graphical user interfaces (GUIs), this pattern became popular for designing web applications. Popular programming languages have MVC frameworks that facilitate implementation of the pattern.
One of the seminal insights in the early development of graphical user interfaces, MVC became one of the first approaches to describe and implement software constructs in terms of their responsibilities.
Trygve Reenskaug introduced MVC into Smalltalk-79 while visiting the Xerox Palo Alto Research Center (PARC) in the 1970s. In the 1980s, Jim Althoff and others implemented a version of MVC for the Smalltalk-80 class library. Only later did a 1988 article in The Journal of Object Technology (JOT) express MVC as a general concept.
The MVC pattern subsequently evolved, giving rise to variants such as hierarchical model–view–controller (HMVC), model–view–adapter (MVA), model–view–presenter (MVP), model–view–viewmodel (MVVM), and others that adapted MVC to different contexts.
The use of the MVC pattern in web applications grew after the introduction of NeXT's WebObjects in 1996, which was originally written in Objective-C (that borrowed heavily from Smalltalk) and helped enforce MVC principles. Later, the MVC pattern became popular with Java developers when WebObjects was ported to Java. Later frameworks for Java, such as Spring (released in October 2002), continued the strong bond between Java and MVC. The introduction of the frameworks Django (July 2005, for Python) and Rails (December 2005, for Ruby), both of which had a strong emphasis on rapid deployment, increased MVC's popularity outside the traditional enterprise environment in which it has long been popular.
- The central component of the pattern. It is the application's dynamic data structure, independent of the user interface. It directly manages the data, logic and rules of the application.
- Any representation of information such as a chart, diagram or table. Multiple views of the same information are possible, such as a bar chart for management and a tabular view for accountants.
- Accepts input and converts it to commands for the model or view.
In addition to dividing the application into these components, the model–view–controller design defines the interactions between them.
- The model is responsible for managing the data of the application. It receives user input from the controller.
- The view renders presentation of the model in a particular format.
- The controller responds to the user input and performs interactions on the data model objects. The controller receives the input, optionally validates it and then passes the input to the model.
As with other software patterns, MVC expresses the "core of the solution" to a problem while allowing it to be adapted for each system. Particular MVC designs can vary significantly from the traditional description here.
As Alan Kay wrote in 2003 the original motivation behind the MVC was to allow creation of a graphical interface for any object. That was outlined in detail in Richard Pawson's book called "Naked Objects".
Use in web applications
Although originally developed for desktop computing, MVC has been widely adopted as a design for World Wide Web applications in major programming languages. Several web frameworks have been created that enforce the pattern. These software frameworks vary in their interpretations, mainly in the way that the MVC responsibilities are divided between the client and server.
Some web MVC frameworks take a thin client approach that places almost the entire model, view and controller logic on the server. In this approach, the client sends either hyperlink requests or form submissions to the controller and then receives a complete and updated web page (or other document) from the view; the model exists entirely on the server.
- Multitier architecture
- Hierarchical model–view–controller
- Entity-Control-Boundary pattern
- Observer pattern
- Separation of concerns
- Strategy pattern
- Reenskaug, Trygve; Coplien, James O. (20 March 2009). "The DCI Architecture: A New Vision of Object-Oriented Programming". Artima Developer. Archived from the original (html) on 23 March 2009. Retrieved 3 August 2019.
More deeply, the framework exists to separate the representation of information from user interaction.
- Burbeck (1992): "... the user input, the modeling of the external world, and the visual feedback to the user are explicitly separated and handled by three types of object."
- Davis, Ian. "What Are The Benefits of MVC?". Internet Alchemy. Retrieved 2016-11-29.
- Model–View–Controller History. C2.com (2012-05-11). Retrieved on 2013-12-09.
- Notes and Historical documents from Trygve Reenskaug, inventor of MVC.
- "A note on DynaBook requirements", Trygve Reenskaug, 22 March 1979, SysReq.pdf.
- Krasner, Glenn E.; Pope, Stephen T. (Aug–Sep 1988). "A cookbook for using the model–view controller user interface paradigm in Smalltalk-80". The Journal of Object Technology. SIGS Publications. 1 (3): 26–49. Also published as "A Description of the Model–View–Controller User Interface Paradigm in the Smalltalk-80 System" (Report), ParcPlace Systems; Retrieved 2012-06-05.
- The evolution of MVC and other UI architectures from Martin Fowler.
- Burbeck, Steve (1992) Applications Programming in Smalltalk-80:How to use Model–View–Controller (MVC)
- Simple Example of MVC (Model–View–Controller) Architectural Pattern for Abstraction
- Buschmann, Frank (1996) Pattern-Oriented Software Architecture.
- Gamma, Erich et al. (1994) Design Patterns
- Moore, Dana et al. (2007) Professional Rich Internet Applications: Ajax and Beyond: "Since the origin of MVC, there have been many interpretations of the pattern. The concept has been adapted and applied in very different ways to a wide variety of systems and architectures."
- Alan Kay (23 May 2003). "is squeak really object oriented ?". Squeak Foundation mailing list. Retrieved 26 October 2021.
- Leff, Avraham; Rayfield, James T. (September 2001). Web-Application Development Using the Model/View/Controller Design Pattern. IEEE Enterprise Distributed Object Computing Conference. pp. 118–127.
|Wikibooks has a book on the topic of: Computer Science Design Patterns/Model–view–controller|