I am looking at a scenario where I have multiple text boxes on a form, and as each one is given a value, I want to hand off the value to the server and return one or more parameters. Example: This is going to be used to check a persons information against the database to see if it is likely that they already exist. As the user completes more information, the success of identifying the duplicate user increases. At some point I want to be aware that it is a duplicate and present the user with a warning.

 Any ideas on where to start with this? I looked at the control tookkit, but I don't think anything in it is going to provide this kind of functionality. I probably need to look much more at the framework, but one question I have is how would I register multiple controls with this? Or is it possible to just write some client side code that will interact with the ajax control? Any suggestions are appreciated!