asp.net AJAX客户端调用服务器上的低异步进程的最佳实践

I have a service that performs a slow task, when its finished I want to update the client using AJAX with the result of the task. In my client I call the task many times to update a grid of results. For the purposes of understanding, its a connection tester that loops through a list of connections to see if they are alive.I have a service that performs a slow task, whe