Allow the user to specify the source of the XmlHttpObject.  Ex: IsUserAvailable.aspx which produces XML or plaintext.

 

Allow the user to specify to use an ASP.NET event to return the XmlHttpObject.  Ex: TextChanged += “IsUserAvailable_TextChanged”

 

Must be able to return:

            DataSet

            DataReader

XmlReader

            Scalar (object)

 

Must be degradable.  If browser does not support XmlHttpObject, the javascript will either do nothing (no errors) or revert to server side post backs.