Execution Order for the ApiController

Question

Is there something like this for the common method order?

http://blogs.msdn.com/cfs-filesystemfile.ashx/__key/communityserver-blogs-components-weblogfiles/00-00-01-46-38-WebApiStackDiagramsNew/6428.ASP.NET_5F00_MVC4_5F00_WebAPI_5F00_StackDiagram_5F00_Future.jpg

My Web Api solution has now a new order in the execution of some methods since I upgraded from Beta/RC version to RTM version. (Its not the reverse order of message handler execution)

Earlier this method of the APIControllers was called:

protected override void Initialize(System.Web.Http.Controllers.HttpControllerContext controllerContext)
{
}

Before the filtermethods of my AuthorizationFilter

public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)
{
}

After RTM the OnAuthorization is called before Initialize(). Are there some informations about the execution order of the ApiController methods and the changes after RTM release?

Answer 1

Assuming the request goes into the ApiController scope, the operation order is as below:

• The ExecuteAsync method of the ApiController is invoked.
• The Initialize method of the ApiController is invoked.
• The registered Action Selector is retrieved.
• The SelectAction method of the registered action selector is invoked. If only one action method is matched, the pipeline continues.
• All registered Filters for the selected action is retrieved.
• The Authorization Filters are called. The authorization filter can decide either to let the pipeline to continue executing or to terminate the pipeline.
• If Authorization Filters didn't terminate the request, action parameter bindings are performed.
• ApiController.ModelState is set.
• Action Filters are invoked. The Action Filters can decide either to let the pipeline to continue executing or terminate the pipeline.
• If Action Filters didn't terminate the request, registered Action Invoker is retrieved.
• The InvokeActionAsync method of the registered Action Invoker is called to invoked the selected action method.
• Note: If any exception occurs from the execution of the Authorization Filters to the execution of the action method, the exception filters are be called.

There are a few more things which happen in between but this is very close to a complete view. Check out the ApiController source code for more information.