Area vs Class Library: How distinct they purposes are?

Question

Hello,

To make a projet manageable, we break it into sub-projets (class libraries in C#, for instance). Now, in ASP.NET MVC 2, we do have Areas. I'd like to know if Areas have or can serve the same purposes as class libraries? It looks like both are meant to make a project manageable...

Personaly, I'm about to write something bigger. I don't know which way to go: Area vs class library...both?

Thanks for helping

Answer 1

At the most basic level your comparing how C# is compiled into a specific framework feature.

Areas are simply built in routing/finding/searching customizations against so you can separate your app into different folders. You could provide your MVC application with a VirtualPathProvider and use views embedded in class libraries to segment your application but it isn't the standard way of organizing things.

Answer 2

Making a project manageable is really not the point of areas nor class libraries, though they do have that effect when used well.

Generally, the purpose of a class library is more about creating a stand-alone library of code that all serves some inter-related purpose. The point is really that a well used class library represents a collection of code that is maintained, developed, and distributed as a single unit. The big key is the distribution though, since class libraries can be distributed and used in many applications. It is usually a waste of time to split code out into class libraries if those libraries are never distributed, maintained, or developed independently. If they exist just to organize and group code that is otherwise dependent on other code in other libraries then you may be making your code less manageable in the long run; namespaces and folders alone can serve the purpose of keeping code grouped, organized, and manageable.

Areas in MVC are a tad different. Their purpose is to partition large web applications into semi-independent segments that are all hosted in a single project (and thus are part of the same class library; an MVC app is just a fancy kind of class library). So the entire purpose of areas tends to be responsibility. The biggest advantage of areas is that they are useful to split large applications into sections that are maintained and developed by separate teams of developers; or into sections that have widely different infrastructure requirements from other sections of the application.

So in terms of manageability alone, areas are a good idea if your MVC app is large and has distinct functional sections. Class libraries can only be justified if there are other benefits aside from code manageability.