Where can I find a dead-simple explanation of MVC?

Question

At my company we\'re about to build a new site using ASP.NET MVC. My boss (marketing guy) would like to know some more about the technology so I\'ve tried to find a really g

Answer 1

Craig Strong has a pretty nice article about MVC in general and how to explain its benefits to business. Check it out here: Updated link.

Define MVC in layman’s terms

Remember you’re technically minded and close to the code. MVC to you is as clear as day, but saying to the business ‘Model, View, Contoller’ could give them the impression that you are suffering from some form tourette syndrome. MVC won’t mean much to the business even after you define them in relation to the code. To get the business to understand why this is the answer and least of all what it is, can be more of a task than expected in my experience. Even some fellow developers have difficulty understanding this on occasion.

To get the listener to understand what MVC is and why it works what I have tried in the pass is to apply MVC to a different industries where the listeners have had more involvement. An example that has worked for me in the past in a comparison to the property or even the vehicles. Most people have had dealing’s with builders, carpenters, plumbers, electricians or have watched the flood of property shows on the TV. This experience is a good platform to use and to explain why separation such as MVC works. I know you’re probably thinking that won’t work as it’s not the same as in software, but remember you’re not trying to train the business to become developers or have an in depth understanding of MVC, simply explaining to them that separation in production is required and that’s what an MVC structure offers.

To give an example of how you could describe this I have very briefly explained how separation works in property. Keep in mind this is focused on using the system not developing which could be a completely different angle of explanation.

View

The view in MVC is the presentation layer. This is what the end user of a product will see and interact with. A system can have multiple views of all different types ranging from command line output to rendered HTML. The view doesn’t consist of business logic in most clear designs. The interface is fit for purpose and is the area of interaction. Therefore you could simply output HTML for consumers to interact with or output SOAP/XML for businesses to interact with. Both use the same business logic behind the system otherwise known as the models and controllers.

In the world of property you could think of the view as the interior of a property or the outer layer of a property that the inhabitants interact with. The interior can be customised for purpose and the same property can have many different types of tenants. For example a property of a particular design could contain residential dwellings. The same internal space could easily be used as office space, where although in the same property has a different purpose. However the property structure is the same. Therefore the environment in which the users interact does not interfere with the structure of the building.

Controllers

The controller is where the magic happens and defines the business application logic. This could be where the user has sent a response from the view, then this response is used to process the internal workings of the request and processes the response back to the user. Taking a typical response where a user has requested to buy a book. The controller has the user id, payment details, shipping address and item choice. These elements are then processed through the business logic to complete a purchase. The data is passed through the system into the model layer and eventually after the entire request satisfies the business definitions, the order is constructed and the user receives their item.

If we compare this to a property, we could compare the ordering of a book online to turning on a light switch. A tenant will flick the switch to on just like ordering a book. The switch itself is an element in the view layer which sends the request to the controller just like clicking a checkout button on a web site. The business logic in this case is what the electrician installed and are embedded within the property designs. The switch is flicked, which completes the circuit. Electricity runs through all the wires including the fuse box straight through to the light bulb. Just like the user receiving a book, in this case the tenant receives light. The whole process behind the scenes involving the electricity cabling is not visible to the the tenant. They simply interact with the switch within the space and from there the controller handles the request.

Models

The models in MVC are the bottom most layer and handle the core logic of the system. In most cases this could be seen as the layer that interacts with the data source. In systems using MVC, the controller will pass information to the model in order to store and retrieve data. Following on from the example above controller definition, this is where the order details are stored. Additional data such as stock levels, physical location of product of the book amongst many things are all stored here. If that was the last book in stock ordered, the next request for this item may check if it’s available and disallow the order as the item is no longer available.

Sticking with our example of turning on a light switch, this level in our structure could be the electricity supply. When the tenant flicks the switch, the internal circuit must request electricity to power the request which is similar when the user requested data from the database, as in data is needed to process a request. If the dwelling isn’t connected to an electric supply, it cannot complete the process. Business benefits from using MVC

After you get the message across explaining what MVC is, you will then have to see what benefits can be obtained from it. I’m not going to go into a huge amount of detail here are I’m sure you can apply benefits more accurately which are directly related to you actual situation. To list just some of the common benefits of an MVC based system here are a few examples:

• Different skill levels can work on different system levels. For example designers can work on the interface (View) with very little development knowledge and developers can work on the business logic (Controller) with very little concern for the design level. Then they simply integrate together on completion.
• As a result of the above separation projects can be managed easier and quicker. The designer can start the interfaces before the developer and vice versa. This development process can be parallel as opposed to being sequential therefore reducing development time.
• Easy to have multiple view types using the same business logic.
• Clear route through the system. You clearly know where there different levels of the system are. With a clear route of the system, logic can be shared and improved. This has added security benefits as you clearly know the permitted route from the data to the user and can have clear security checks along the route.
• Each layer is responsible for itself. (Relates to point 1) This means that you can have clean file structure which can be maintained and managed much easier and quicker than a tightly couple system where you may have lots of duplicate logic.
• Having a clear structure means development will be more transparent which should result in reduced development time, maintenance problems and release cycles if applied properly.

Answer 2

I wouldn't try to explain the technology to him, I'd try to explain what the MVC architectural principle is all about.

MVC was designed to separate concerns. Plain and simple. Explain to him that when you build anything that what you're building can be classified in two different categories: what the business need is (the domain), and everything else.

MVC separates the Domain from the everything else by introducing layers to separate out the concerns. M is for Model, which is your domain. V is for View, which is the visible part to him, what he sees. C is for Controller, the part that controls what is going on in between the Domain and the View.

Answer 3

The marketing guy would just be interested in the "V" part, the View. Depending on how you design things, the View would just be basic HTML/CSS "templates" that the marketing person could modify. Technically without breaking anything.

Ideally the Model (database) and Controller (logic) shouldn't care if the View (presentation) is XML, HTML, text, etc. The marketing person shouldn't care what the Model and Controller do, except for requesting additional functionality.

Going further with the "ideal", you should technically be able to replace ASP with PHP, Java, Ruby, etc as the Controller without touching the Model or View.

Answer 4

Imagine a control room in a factory, the model is the machine itself, the monitoring equipment is the view and the instrument panel is the controller. You could have several different control rooms for the same machine and changes in the controls in one control room would reflect on the monitors in all control rooms.

The point is that you should only model once and then view or control however is most convenient.

Answer 5

You can very easily do this, that is if you understand marking speak. I dont but I imagine it would go something like this...

This should be use. MVC (if done right) will allow you to decouple the UI from the data (model) and control of the UI (controler). This will allow the UI to be more flexible which will in turn allow to better market it self faster.

Answer 6

M-V-C Think of it as: "Order Details (including Customer & Employee info)", "HTML/ASP Form (to display the OrderDetails)" and "Order details service class (having methods to SaveOrderDetails, GetOrderDetails etc.).

The Model (Data Class e.g. OrderDetails)

1. The data you want to Display

The Controller (Service class)

1. Knows about the Model (Order Details)
2. Has methods to manage the Model
3. And as such can be unit tested Its Single Responsibility is to manage the OrderDetails CRUD operations.
4. It knows NOTHING about the View

The View (ASP Page)

1. Displays the Model (OrderDetail's ViewData).
2. It has to know about the Model's structure so it can correctly display the data to the users on screen.
3. The View's structure (style, layout, HTML etc., locale) can be changed at anytime without it changing anything in the application's functionality.
4. And as such, many Views can display the same Model in many different ways.
5. In multi-tenant web applications, Customer specific Views can be stored in a database table and displayed based on Customer information