When an Ajax callback is made from a Grid or UX component, the server-side code executes synchronously. The client will wait for a response from the server. This response is typically sent when the server-side code completes. However, the browser will only wait a certain amount of time for the server to send a response. If the server-side code takes a long time to execute, the browser will likely have stopped listening (i.e. the Ajax request will time out) for a response. Furthermore on IIS (which includes Alpha Cloud), as soon as the browser stops listening for a response the server will stop executing the server-side code.

Because of all of the above, it is not appropriate to execute 'long-running' server-side code in an Ajax callback, unless the code can be run asynchronously.

In this video we show how you can run Xbasic code asynchronously in an Ajax callback. We also show how you can make periodic callbacks to the server to get the status of the asynchronous Xbasic.