ASP.NET MVC Three Tier - what's everyone else doing?

Question

When I start work on a new web application I tend to reach for the same tried & tested architecture of ASP.NET MVC, BLL (consisting of a set of services that contain all business logic) and a DAL (consisting of a set of repositories that facilitate the unit of work pattern over something like EF/*Linq to SQL*).

The controllers talk only to services, the services only to repositories and other services. At the service layer are where models are defined and these are used as input/output to/from the controllers.

My question is: what are others doing? I'm interested in knowing if people are doing anything different in the context of an ASP.NET MVC web application. For instance, there are concepts like CQRS and Domain Events. Is anyone using these to solve a problem with the method I've described above?

This question is mainly a source of attempting to discover what I don't know I don't know. I hope it's not too vague, but I think it's important to see what others are doing to evaluate your own methods.

Answer 1

We're basically doing what you're doing, except that we consider our repository interfaces to be services (they are defined in the business layer), and therefore our controllers often access them directly. An IoC container takes care of injecting the correct repository implementation via constructor injection. So the data layer depends on the business layer, and is in charge of implementing the repositories, while the business layer just assumes that all the repositories it has defined will be available at runtime.

We've further divided our product up into different modules of functionality. Some of the modules depend on one another (for example, everything depends on our core functionality, and most of the other modules depend on the web portal module), but keeping them in separate dlls helps us to avoid making these modules be too tightly coupled. The system can therefore only load the DLLs for the modules that a given client has paid for. We plan to use an event bus with events defined in the core module to allow the modules to communicate via a publish/subscribe model.

Answer 2

I am using CQRS with MVC. Its nice. You still use the MVC pattern, but in the controller I use the command pattern for the write, and just pure NHibernate Linq for the read... also some SolrNet for the read. :-)