Lately I was trying to get data back from response once the Ajax Call is complete. There were few examples and i couldnt find them conclusive enough. Here is the snippet of MVC Portlet in Liferay 6. In this example i am sending a AJAX request with parameters and then getting few parameter back from response using Alloy UI Ajax Call.
view.jsp
Following is the code, from the JSP file which makes an AJAX Call.
Alloy UI Call, JSP Snippet
MVC Portlet Class
Following is the code from MVC Portlet.
MVC Portlet Serve Resource Method
Feel free to email me or comment for further questions.
– Thanks
Arvind Mishra
Knowledge Share 
I tried this example in Firefox and IE. It’s working in Firefox and IE8. But not in IE7. I have to make AUI ajax in IE 7. Is it supported.
Thank you, it helped me a lot.