On-the-fly server interaction without postback

[Hardik Shah]

Hi,

I was looking for ways to interact with server for an ASP.net app.
(on-the-fly server validation and return some values) without doing
postback. I found some ways on the forum to achieve this, but am not
sure which would be the best with regards to performance. The app.
doesn't care for other browsers/versions as long as it works for IE
6.x. Here are few methods I found:

a. Using hidden frame or iframe. Document explaining this is
http://www.dotnetjunkies.com/Tutoria...1&ForumID=4201

b. Using XMLHttp to post/fetch XML data.

c. Using WebService Behavior.
For WebService Behavior, I saw this link on MSDN saying its no longer
supported: http://msdn.microsoft.com/downloads/...ce/default.asp

Couple of questions:
1. Which of the above would be the best way to go with regards to
performance?
2. As WebService Behavior is now not supported by MS, should I not
consider it as an option? Is there an alternative to it?

I would also be glad to know any other better ways to achieve this.

TIA!
Hardik