What Is MVC and Why Do We Use MVC?

Let’s start with Windows background, about Microsoft at the start. Microsoft introduced it with the word visual and Microsoft wanted the same success story as Windows used in programming a lot of languages like COBOL, C++, and DB’S. All these languages do not have any Visual effect, so if you want to fix a button in C++, actually you have to write the code for it. Thus, Microsoft ventured something called Visual programming or RAD programming (Rapid App development), so they set that for this, rather than programmer code for this, so for creating a window Microsoft introduced tool box. Due to this, they launched Visual Studio and again in programming language, Microsoft got success. At that time, power builder was to be completely replaced by VB, like VC++ was replaced by C++ and VF (Visual FoxPro) almost killed it and it replaced DB so Microsoft achieved success.

The RAD programming is great but it leads to some issues -- the issue is at the backend of the code. In other words, when the programmers drag and drop, the code is generated in partial class. Let's discus some of the drags of this RAD programming:

If user sends an action, what happens in the page life cycle is that the life cycle just calls a complex structure, and the page loads the page in, and you know what other kind of life cycles get executed, and then runs the required event. Now it’s a really complicated method. What should happen is this is a required event, not one that runs other events. So what happened in this scenario when the end user sends a request as an action is it then goes to the View first, and again runs a complicated life cycle. In other words, you go to the complicated life cycle, but the logical approach should be to go to action directory; that means once the user sends the action request it should actually map to a method inside the program, and the method gets invoked, runs all the necessary logic for the action, and then it's invoked the required view and that would actually happen in MVC.

So the connected problem for selecting bad architecture was that the behind code was not reusable so the RAD architecture is not usable but in MVC we can code reusable code again and again.

Mostly the web pages are on HTML but in case of xml if your application is communicating with languages like JavaScript, probably its sends it to Jason then you would like to invoke the action but the action can have different kinds of response types depending on the situation.

So Web Forms is a View based architecture -- always view has been decided but in the case of MVC what happened is it first hits to controller so the possibility of combining is more in the case of MVC but not in the case of Web Forms. Why? Because the view always fixed.

We have easy way of unit testing in MVC, which is the option of a Unit test after creating a new project but in the web it would quite difficult to handle.

So the solution of these problem is the simple structures, just MVC in this diagram, the first line shows RAD or WEB FORMS architecture which will be in the form of aspx which is divided into two parts -- one is view and the other is behind code which is called the middle layer, which has the business logic and this logic calls the DAL data access layer. The problem is the first time it comes in the view. But in MVC its behind code is controller and first receives the request and then sends to the view and model as mentioned in the diagram.