Working of the MVC framework with an example

Let’s imagine an end-user sends a request to a server to get a list of students studying in a class. The server would then send that request to that particular controller that handles students. That controller would then request the model that handles students to return a list of all students studying in a class.

The model would query the database for the list of all students and then return that list back to the controller. If the response back from the model was successful, then the controller would ask the view associated with students to return a presentation of the list of students. This view would take the list of students from the controller and render the list into HTML that can be used by the browser.

The controller would then take that presentation and returns it back to the user. Thus ending the request. If earlier the model returned an error, the controller would handle that error by asking the view that handles errors to render a presentation for that particular error. That error presentation would then be returned to the user instead of the student list presentation.

As we can see from the above example, the model handles all of the data. The view handles all of the presentations and the controller just tells the model and view of what to do. This is the basic architecture and working of the MVC framework.

The MVC architectural pattern allows us to adhere to the following 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. 

Advantages of MVC:

• Codes are easy to maintain and they can be extended easily.
• The MVC model component can be tested separately.
• The components of MVC can be developed simultaneously.
• It reduces complexity by dividing an application into three units. Model, view, and controller.
• It supports Test Driven Development (TDD).
• 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.

Disadvantages of MVC:

• It is difficult to read, change, test, and reuse this model
• It is not suitable for building small applications.
• The inefficiency of data access in view.
• The framework navigation can be complex as it introduces new layers of abstraction which requires users to adapt to the decomposition criteria of MVC.
• Increased complexity and Inefficiency of data

Over the last few years, websites have shifted from simple HTML pages with a bit of CSS to incredibly complex applications with thousands of developers working on them at the same time. To work with these complex web applications developers use different design patterns to lay out their projects, to make the code less complex and easier to work with. The most popular of these patterns is MVC also known as Model View Controller.