Layering an ASP.NET MVC Web Application

Question

When I develop a WinForms or WebForms app, I create a solution and add multiple projects. The BOL project is a class library for business objects, there's a SQL and a DAL project for ADO.NET related stuff, I have a Utilities project which contains classes for stuff like validation and whatnot. Now the presentation layer which I usually call the GUI contains the forms. The forms work directly with the BOL, which connects to the SQL which connects to the DAL, etc...

I'm sure you all know this already so here's where I get confused. In working with MVC, projects I see all contain this type of functionality but are all in one project, just separated into folders. I looked at the Nerd Dinner application and even that is all in the one project. The end result is a single DLL to handle it all. Is this a good idea, or do you guys separate the pieces into different projects? Usually one DLL has to go through another DLL before it can reach the data access DLL type of thing. Maybe I'm just confused on the whole concept.

Answer 1

You can always seperate this logical layers into seperate physical layers (projects). You can create a seperate project for your Entities, one for your Data Access code etc..

Here is the structure i did for one of my receny project

1) UI : The standard MVC Project with UI related stuff. Controllers and Views and Relevant CSS stuff & Scripts.

2) Entities : The class library Project. My Business entities are here. These are just POCO's which represent my domain modal ( I use this for the CodeFirst Database generation).

3) Data Access : The class library Project. I have my Data Access code here. Repositary, Interfaces and my DBContext class as well.

4) Test : My Unit Tests are in this project.

UI Project has a reference to my Entities and My Data Access Project.

Data Access Project has a reference to my Entities because my Repositary method returns objects.

I have few ViewModel classes also inside my UI project ViewModels folder. I use this for some screens where i have to show data from multiple domain objects. I have a mapping/service class which maps the domain object to view model object. If your project is bifg, you may keep this as a serperate project under the same solution.

The solution looks like this. (This is an open source project i am working on)