Waiting Screen (Like this Forum) - How?

[eluser]Multisnet[/eluser]
Hello,

I'm developing a web application and I would like if someone could explain me the logic behind implementing a waiting screen in CI (like this forum).

Thank You!
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I want to display a waiting screen for my application users. For example, when they submit the registration form the application access to a web service, it usually takes a while to do the validation, so I would like to show the waiting screen and then if validation fails go back to form, otherwise it should go to another screen.

Could someone explain how to implement this? I've been thinking about this but I can't reach any conclusion...

Thanks in advance...