How to configure simple injector container and lifestylse in a MVC web app with WebAPI, WCF, SignalR and Background Task

Question

The simple injector documentation provides great examples on how to setup the container for WebRequest, Web API, WCF, ... but the examples are specific to one technology/lifest

Answer 1

Usually you don't need to have one container per lifestyle; In general you want to have one container instance per AppDomain. However, mixing Web API in the same project with MVC is from an architectural point of view a horrible idea IMO (as explained here, here, and here). So in case you are separating those parts into their own architectural blocks, you will already have less problems already.

But in case you are running MVC and Web API in the same project, this basically means that you will always be using Web API. The WebApiRequestLifestyle was explicitly built to work:

well both inside and outside of IIS. i.e. It can function in a self-hosted Web API project where there is no HttpContext.Current. (source)

In general, it is safe to use the WebRequestLifestyle in case you are only running in IIS when you have no intention to spin of parallel operations using ConfigureAwait(false) (which should be really rare IMO) as explained here.

So in the case you are still mixing Web API with MVC in the same project, there's no reason to use a hybrid lifestyle; you can simply use the same lifestyle. For doing background processing you might however need to build a hybrid lifestyle, but it every scenario needs a different hybrid. However, hybrids can be stacked up and you can easily create a 'triple lifestyle' if needed.

Since you want to do background processing with SignalR, you need to decide in what type of scoped lifestyle to run those background operations. The most obvious lifestyle is the LifetimeScopeLifestyle and this means you should make your scoped registrations using the following scoped lifestyle:

var hybridLifestyle = Lifestyle.CreateHybrid(
    lifestyleSelector: () => HttpContext.Current != null,
    trueLifestyle: new WebRequestLifestyle(),
    falseLifestyle: new LifetimeScopeLifestyle());

A lifetime scope however needs to be started explicitly (as were the web request scope gets started implicitly for you if you include the SimpleInjector.Integration.Web.dll in your web application). How to do this depends on your design, but this q/a about SignalR might point you in the right direction.