How does UpdatePanel work?

Question

What is updated when the update starts? What goes to the server? What is coming back?

I had the impression that only the contents of the panel were transferred to the server and back (without touching anything on the page outside the panel), but I am experiencing strange results, perhaps because I really do not understand how this works.

Can someone give an easy explanation of exactly how it works?

Answer 1

What is generated is submitting the form via AJAX, which basically means XML HTTP in the browser. When it hits the server, the server sees it as an AJAX call and sends a request to the correct method.

As for exactly what is submitted, this is all that the submit form submits, which may well be information outside of the UpdatePanel. and then finds out what to work with and sends a response.

It’s good and good as a theory, but you are dealing with problems, not theory. What strangeness do you feel? If you can post, we can focus on the details of the problem.

Answer 2

A message that is sent to the server contains almost all information about the message, including viewstate. The difference is that it actually goes back to the browser. To process the request, a full page is created, if anything is updated outside the update panel, then you may get some ugly errors.

Update 1: this is different from other ajax approaches that only send a bit of necessary information and don't use viewstate, i.e. ajax autocompleteextender ajax management toolkit - look for json, ajax requests, and other related information.

This may work for you, but you are right to understand what is happening the way you need it, when it is only suitable for other solutions.