What's wrong with this ASP.net MVC system design?

Question

I have a ASP.Net MVC 3 photo gallery, which is designed in this way:

Data Repositories(IImageRepoSitory, ITagRepository etc)
      |
   Services (IGalleryService, IWebService etc)
      |
  Web Application

Which I use Ninject to inject the required Services and repositories into the web application.

Before I use actual database, I used a simple ArrayList (and JSON serialization) as my presistent logic (That will be JsonImageRepository/JSonTagRepository) which works perfectly fine. But later on, I moved to EF4 CTP5 (Code First), and many problems appeared. Basically, I injected those repositories and services as Singleton (which declared in Global.asax.cs), but when I have several threads that access the repositories, it saids:

Data Connection is closed.

I changed to something like Thread Mode or Request Mode in Ninject but various exception raised (regarding to multiple instances of context, so I think Singleton should be the only option).

Is there anything wrong with the design? or how should I configure those components?

Answer 1

Normally, repository access should be in request scope (at least the ones that change data). I recommend looking at bob's blog posts about a repository pattern implementation using Ninject and NHibernate. It should be pretty much the same for EF4:

http://blog.bobcravens.com/2010/06/the-repository-pattern-with-linq-to-fluent-nhibernate-and-mysql/

http://blog.bobcravens.com/2010/07/using-nhibernate-in-asp-net-mvc/

http://blog.bobcravens.com/2010/09/the-repository-pattern-part-2/

I planned adding this to the sample application in near future.