How to find out if the current application is an ASP.NET web app

Question

From a managed class library, I\'d like to find out whether the currently executing application is an ASP.NET web application (web forms or MVC) or not.

I have seen diff

Answer 1

Potentially Not reliable. MSDN implies that this will always return a new object if one does not exist already. Thus there are technically times where you can call it and have one not exist before it is called.

    System.Web.Hosting.HostingEnvironment.IsHosted == true

All web environments need a context. What handler is inside that context is what tells you the type of web environment. (MvcHandler for example). Note this can be different types of handlers for the same environment - You can run MVC and web forms together for example. It just depends on what is currently being served and the pipeline it is using.

    System.Web.HttpContext.Current != null

All web apps need an application ID. It is unique and does not change as application pools are restarted.

    System.Web.HttpRuntime.AppDomainAppId != null

I've never seen this, though just logically I can imagine a time where the cache is not used and thus wouldn't be reliable.

    System.Web.HttpRuntime.Cache != null

You're right.

checking for a web.config file (note: I don't think this is reliable)

I use something of this sort within a library. I've found it reliable.

         Page page = (HttpContext.Current != null && HttpContext.Current.Handler != null) ? HttpContext.Current.Handler as Page : null;
         if (HttpRuntime.AppDomainAppId != null && page != null)
         {
            //I'm a web forms application
         }
         else if (HttpRuntime.AppDomainAppId != null && page == null && HttpContext.Current != null) { throw new InvalidOperationException("I'm an MVC application"); }
         else throw new InvalidOperationException("Im not ASP.Net web");