Why treat them as mutually exclusive things?  Use MS AJAX for the communication layer, where it's strongest, and use YUI (or another presentational framework) for your client side chrome. 

hello.

yes, I agree with gt1329a (man, what's your name? I'm assuming it's not gt..., right? :) )

As much as I use this user name, I should probably just change it to gt, but my name's Dave.

Hi gt1329a

I was reading we should not mix AJAX.NET and YUI library. Both libraries provides communication library. So will not able to identify the exact problem.

I haven't had any trouble mixing ASP.NET AJAX with other AJAX frameworks that also provide communication functions.  I use jQuery for presentation in almost all of my ASP.NET AJAX sites.

Have you ever use AJAX.NET and YUI in same applicaton.

Yeah.  I didn't run into any trouble. 

 Did you implement AJAX.Net and YUI on same page? I tried with one sample I was getting error in page post back. I was not able to resolve the problem.  I removed AJAX.Net from that page and application then it was working fine. Even I was reading a post on the same line. Please see the link. http://forums.asp.net/p/1047608/1473125.aspx#1473125

Yes.  I believe I just made sure not to include the connection.js library from YUI.  It wasn't necessary for the UI effects that I used.  It and ASP.NET AJAX both trapping the XmlHttpRequest status changes is probably what would cause trouble using them together.

I've since moved on to mainly using jQuery for client side effects, so I'm not sure if more recent changes to YUI have made it harder to integrate.  It should work fine though, as long as you're just using DOM effects. 

I am agreeing with you that we should not mix AJAX.Net and connection manager. I was also facing the same problem.

We can use YUI for Dom effects and for rich UI. And for asynchronous call we can use Ajax.Net framework. It will give us a optimum solution.

The only drawback I can think is the performance issue. We might end up downloading js files from both libraries. It will affect performance. We can always add expiry tag in our page to come around this problem.

 Hi guys,

 Nice to see you're interested in YUI. I have recently started to play around with YUI, and ended up writing some web controls for ASP.NET which use YUI on client side.

So far, I didn't had  any conflicts between them. If you're curious, you can checkout the control at http://www.yui-asp.net

Hope this helps,

Raul