Question

in my ASP.NET MVC3 Project, I’ve got an action which runs a certain amount of time.
It would be nice, if it could send partial responses back to the view.
The goal would be to show the user some progress-information.
Has anybody a clue how to make that work?

I did a try with some direct output to the response, but it’s not being sent to the client in parts but all on one block:

[HttpPost]
public string DoTimeConsumingThings(int someId)
{
   for (int i = 0; i < 10; i++)
   {
      this.Response.Write(i.ToString());
      this.Response.Flush();
      Thread.Sleep(500); // Simulate time-consuming action
   }
   return "Done";
}

In the view:

@Ajax.ActionLink("TestLink", "Create", new AjaxOptions() 
  { HttpMethod = "POST", UpdateTargetId="ProgressTarget" })<br />

<div id="ProgressTarget"></div>

Can anybody help me making progressive action-results?
Thanks!!

Answer 1

Here’s how you could implement this: start by defining some class which will hold the state of the long running operation -> you will need properties such as the id, progress, result, … Then you will need two controller actions: one which will start the task and another one which will return the progress. The Start action will spawn a new thread to execute the long running operation and return immediately. Once a task is started you could store the state of this operation into some common storage such as the Application given the task id.

The second controller action would be passed the task id and it will query the Application to fetch the progress of the given task. During that time the background thread will execute and every time it progresses it will update the progress of the task in the Application.

The last part is the client: you could poll the progress controller action at regular intervals using AJAX and update the progress.