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Model-View-Controller

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MVC: Model-View-Controller

CONTROLLER:

  • receives user input and interprets it
  • updates the Model based on user actions
  • selects and displays the appropriate View
  • doesn’t have to worry about handling data logic, just tells model what to do
  • eg. in a bookstore application, controller handles actions such as searching for book, adding book to cart, or checking out

VIEW:

  • renders data to the user in a specific format
  • displays the user interface elements
  • updates the display when the model changes
  • created by the data which is collected by the model but this data isn’t taken directly, instead only through controller
  • eg. view displays the list of books, book details, provides input fields for searching or filtering books

MODEL:

  • manages data: CRUD operations
  • enforces business rules
  • notifies the view and controller of state changes
  • can add / retrieve data from the database
  • responds to the controller’s request because the controller can’t interact with the database by itself
  • eg. model handles data related to books, such as book title, author, price and stock level

Example:

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Design Principles:

  1. Divide and conquer.
    • The three components can be somewhat independently designed.
  2. Increase cohesion.
    • The components have stronger layer cohesion than if the view and controller were together in a single UI layer.
  3. Reduce coupling.
    • The communication channels between the three components are minimal and easy to find.
  4. Increase reuse.
    • The view and controller normally make extensive use of reusable components for various kinds of UI controls. The UI, however, will become application-specific, therefore it will not be easily reusable.
  5. Design for flexibility.
    • It is usually quite easy to change the UI by changing the view, the controller, or both.
AdvantagesDisadvantages
Codes are easy to maintain and they can be extended easily.It is difficult to read, change, test, and reuse this model
The MVC model component can be tested separately.It is not suitable for building small applications.
The components of MVC can be developed simultaneously.The inefficiency of data access in view.
It reduces complexity by dividing an application into three units. Model, view, and controller.The framework navigation can be complex as it introduces new layers of abstraction which requires users to adapt to the decomposition criteria of MVC.
It supports Test Driven Development (TDD).Increased complexity and Inefficiency of data
It works well for Web apps that are supported by large teams of web designers and developers.
This architecture helps to test components independently as all classes and objects are independent of each other
Search Engine Optimization (SEO) Friendly.

Graph View