How to check if an IHttpHandler is loaded?

Question

I have a global.asax and I would like to check in the Application_Start method if a IHttpHandler with a certain name is registered. How can I do this?

_{The handler can be declared in the apps own web.config or one of another virtual parent directories or the machine.config.}

Answer 1

I'm not aware of a public method to do what you're asking for.

I think the code you want is either HttpContext.Current.ApplicationInstance.GetHandlerMapping(), .MapHttpHandler() or .MapIntegratedHttpHandler(), but they are private or internal methods. However, you should be able to use reflection to call them.

An alternative would be some trial-and-error type testing (try to request a target that should be routed to the expected handler, and see what happens in several place, such as in the MapRequestHandler event in an HttpModule -- but I think Application_Start is too early for that.

Answer 2

Read the web.config file using WebConfigurationManager.OpenWebConfiguration method. Due to ASP.NET Configuration File Hierarchy and Inheritance all these configuration sections which are added in machine.config are available to your web-app so you need to read local web.config.

Configuration config = WebConfigurationManager.OpenWebConfiguration("~/web.config");
HttpHandlersSection section = (HttpHandlersSection)config.GetSection("system.web/httpHandlers");

GridView1.DataSource = section.Handlers;
GridView1.DataBind();