Question

I have a large existing solution with multiple tiers that uses CastleWindsor as a DI framework for the newer layers/projects. I am currently trying to implement some new functionality in a layer/project that has no previous DI in place but I keep getting “circular refernce” problems.

Given a solution like this…

• MyCompany.Core – includes CastleWindsorConfiguration
• MyCompany.BusinessLayer – includes entities & business logic
• MyCompany.Data – includes NHibernate mapping & repositories
• MyCompany.Emails – existsing non DI functionality to complement the BusinessLayer
• MyCompany.Web – Web app fron end/display

In reality there are actually quite a few BusinessLayer supplimentry projects/layers

I cannot add a reference to MyCompany.Core in MyCompany.Emails because the CastleWindsor container in Core references the Emails project so it can be configured/mapped with the following…

_windsorContainer.Register(Component.For<IEMailPoolHandler>().ImplementedBy(typeof(EMailPoolHandler)).LifeStyle.PerWebRequest);

But I then need to resolve this dependency in the Emails project with something like the following…

private IEMailPoolHandler EMailPoolHandler
{
    get
    {
        return MyCompany.Core.WindsorContainer.Resolve<IEMailPoolHandler>();
    }
}

And here I get the circular reference error. Basically I cant reference Core because it references Emails.

So, the question really is, what is the best way to handle this kind of situation and where should I have my CastleWindsor Container? Or is it ok to have more than one? For example one in each project?

Answer 1

You should put it in the .Web project. I believe it’s the project that is the actual application -controls lifetime and overall configuration – that should configure, instantiate and resolve from the container.

Then you should – if at all possible – inject (ctor or setter, automatically or manually) either the EmailPoolHandler or an EmailPoolHandlerFactory into the classes in the Email project, not access the container from there.