ASP.NET MVC 2 beta Asynchronous RenderAction

Question

Background:

http://www.hanselman.com/blog/HanselminutesPodcast188ASPNETMVC2BetaWithPhilHaack.aspx

Start from 27:15,RenderAction has been discussed at 28:43 that a RenderAction will not be part of Asynchronocity as an asyncronous action method called.

(Let's say your home portal index action calling 1.GetNews 2.GetWeather 3.GetStock asynchronously.You have have a RenderAction displaying user recent posts on the same view. (GetUserRecentPosts))

Questions

What if RenderActions themselves are asynchronous ?

Would GetUserRecentPosts be called only after home index completed its action even though?

Should RenderActions be rendered asynchronously on a view by default?

Answer 1

I don't think you can do this successfully. The point where you could benefit from asynch processing has already passed when your views start rendering. The MVC pipeline that sets up the begin/end methods has already completed and the View has no way to get back into it on the same request. Seems like you may be stuck with synchronous processing OR devise some way to retrieve all your data up front and cache it in TempData or something for rendering.

Answer 2

Lift framework in Scala is probably the only one that I am aware of that has parallel partial actions which will not block the rendering of the main content but will use Comet-push to deliver partial view content for those blocks which may take a while to get data for.

to use it, just wrap a block in your view inside a parallel node

<lift:parallel>
     //this is where Html.RenderAction("GottaFetchNetworkDataFromSomewhereView");
    //this is where Html.RenderAction("GottaFetchNetworkDataFromSomewhereView2");
  // would go
</lift:parallel>

Lift will also take care of connection starvation of your page to manage http requests in the appropriate manner so that browser pushes are not "waiting 'round".

Unfortunately, ASP.NET MVC has poor Comet support. There's not much outside of Asynchronous Controllers, which is an improvement but not as elegant as, say, Akka's framework suspend() method for long-polling.