Returning variables from asp

Hi,

Is it possible to return server side variable values to an html page which a user is viewing?

For example:

User opens the html page which contains a tree view like structure. The user clicks one of the branches, and an asp file is called. Instead of the asp being returned, only a set of output variables are returned. The html page is not replaced, but the variables returned by the asp are used to add to the existing html.

The user does not need to wait for all the graphics to be reloaded and page redisplayed. This also eliminates the task of recalculating the tree. Also saves processing large amount of unwanted data.

Best way to do *THAT* is XML.

Do the tree client side in jscript...

Thanks guys. Found the "best way" though. Its actually using Remote Scripting. Search msdn, it gives you what you need to know.