Ajax.NET Professional (AjaxPro) is one of the first AJAX frameworks available for Microsoft ASP.NET and is working with .NET 1.1 and 2.0.
The framework will create proxy classes that are used on client-side JavaScript to invoke methods on the web server with full data type support working on all common web browsers including mobile devices. Return your own classes, structures, DataSets, enums,... as you are doing directly in .NET.