RadControls for ASP.NET AJAX is Telerik’s next-generation ASP.NET UI control suite. Just as ASP.NET AJAX is the future of ASP.NET, RadControls for ASP.NET AJAX represents the future direction of the Telerik web development tools and aims to deliver unmatched richness, reliability and productivity.

RadControls for ASP.NET AJAX offers much more than just support for the “AJAX” part of ASP.NET AJAX. Telerik has been a pioneer in the AJAX space since 2004 and was the first major component vendor to provide ASP.NET AJAX compatibility for its product line. RadControls for ASP.NET AJAX goes a step further. It is entirely built on top of the ASP.NET AJAX framework allowing developers to fully leverage the widely supported client-oriented programming model introduced by Microsoft.

RadControls for ASP.NET is the predecessor of RadControls for ASP.NET AJAX. The suite supports .NET 1.x and 2.0 and works independently from Microsoft ASP.NET AJAX.

RadControls for ASP.NET AJAX includes all controls from the RadControls for ASP.NET suite (with the exception of RadRotator, which will be added in Q2 2008). The new RadControls for ASP.NET AJAX suite also includes 3 new controls which are not available in RadControls for ASP.NET -  RadScheduler, RadColorPicker, and RadSlider as well as other utilities like RadScriptManager, RadStyleSheetManager and FormDecorator for skinnable buttons, checkboxes and radio buttons.

• New client-side features, which are based on the underlying ASP.NET AJAX framework
• Faster performance due to the on-demand loading of scripts 
• Simpler deployment as all controls are now shipped in a single assembly 
• Unified programming model; learn one control and know them all 
• Built on top of the industry-standard Microsoft ASP.NET AJAX framework 
• Minimized memory leaks 
• Common skins for all controls 
• More controls, including tools that were never available in RadControls for ASP.NET, such as RadScheduler, RadColorPicker and RadSlider

RadControls for ASP.NET AJAX builds on top of ASP.NET AJAX (System.Web.Extensions), so you will need to have ASP.NET AJAX installed and correctly configured for your application to use the new Telerik controls. If you are using Visual Studio 2008 and ASP.NET 3.5, System.Web.Extensions is already available on your machine. If you are using Visual Studio 2005 and ASP.NET 2.0, you need a separate install of System.Web.Extensions.

Even if you do not need Ajax capabilities in your project, you do need the ASP.NET AJAX client libraries. You can safely add ASP.NET AJAX to an existing application and not expect any major issues.

Please, note that RadControls for ASP.NET AJAX are not backwards compatible with RadControls for ASP.NET.
While for some products, such as RadAjax, the transition is going to be painless (see RadAjax for ASP.NET vs RadAjax for ASP.NET AJAX), for other products, the migration will be more difficult due to the new architecture, use of single assembly, new API, and other changes introduced in RadControls for ASP.NET AJAX. 
For every control we have a help topic dedicated to the upgrade from ASP.NET to ASP.NET AJAX version and the changes in the respective APIs.  For example, this is the topic for RadGrid: 
http://www.telerik.com/help/radcontrols/prometheus/?grdMigrationToPrometheus.html

RadControls for ASP.NET AJAX represents a new generation of ASP.NET controls that will carry developers into the future of web standards and experiences. As such, there are a number of differences from the current RadControls for ASP.NET:  

• RadControls for ASP.NET AJAX controls use a single assembly and shared scripts, whereas each control in RadControls for ASP.NET has its own assembly, scripts, resource file, etc. These shared resources and the simplified single assembly approach should make the controls easier to work with 
• RadControls for ASP.NET AJAX builds on top of ASP.NET AJAX and the client-side model of the controls is based on the framework, whereas in RadControls for ASP.NET Telerik is using its custom implementation 
• RadControls for ASP.NET support .NET 1.x and 2.0, whereas RadControls for ASP.NET AJAX controls target .NET 2.0 and higher
• RadControls for ASP.NET AJAX controls require ASP.NET AJAX (Sytem.Web.Extensions) in the application whereas RadControls for ASP.NET work independently of Microsoft’s framework.

As with any technology decision, there are pros and cons to the single assembly approach.
The biggest con is that RadControls for ASP.NET AJAX users will need to simultaneously upgrade all UI controls when they move on from one version to another as the .NET Framework does not allow two versions of an assembly to co-exist in a project. In case there is no backwards compatibility from release to release, developers will have problems in the upgrade process. However, we are fully aware of this fact and have made it our paramount priority to make upgrades painless.
The advantages of the single assembly outweigh by far this single issue:

• First, and foremost, the single assembly approach will force us to be much more careful when introducing changes to the controls as even the slightest backwards compatibility issue will affect customers
• The single-assembly architecture will result in much lighter and faster controls, since much of the client-side code will be shared
• RadControls for ASP.NET AJAX APIs will be consistent from control to control 
• A single assembly will also help the dev teams ensure to a greater level that all controls "play nice" together and avoid some of the issues with conflicting controls that have been experienced in the past 
• There will be tight integration between the controls and as they are all based on the same framework, RadControls for ASP.NET AJAX will know about each other and you will have to write less code to hook them up
• The new approach will allow the Telerik team to roll-out new products and features faster. It would be impossible to do the things we’ve planned without having a single assembly and sharing and re-using code
• Having a single assembly will make deployment much simpler

Our goal is to deliver a next-generation experience with RadControls for ASP.NET AJAX, both to developers and to end-users: we want to provide you with UI controls that deliver both desktop capabilities and desktop performance. With RadControls for ASP.NET AJAX we hope that Telerik will be able to deliver controls that are more efficient, easier to use (from a developer perspective), and of even higher quality.

Unfortunately, this will not be possible. The RadControls for ASP.NET AJAX controls are all part of a single assembly and the .NET Framework does not allow different versions of the same assembly to co-exist in the same application. When moving from Q3 2007 to Q1 2008, for example, you will need to update all controls.

The introduction of the RadControls for ASP.NET AJAX controls will not affect Telerik’s support for the existing RadControls for ASP.NET. They will be fully supported through at least 2010, after which only “extended support” for the RadControls for ASP.NET will be offered.

Although new controls will be only added to RadControls for ASP.NET AJAX, all existing controls will continue to be enhanced with minor updates. The new releases of the classic ASP.NET controls will not be mirror versions of their RadControls for ASP.NET AJAX counterparts, as there are features which will be very hard or impossible to implement due to the underlying architectural differences in the two UI suites. You can review the product lifecycle scheme here: http://www.telerik.com/products/lifecycle.aspx

We know that large projects do not have the luxury of quickly adopting a new control suite or product framework. We are committed to offering support for existing RadControls for ASP.NET and helping you make plans to transition your projects over the next 2 years.

Our recommendation is to use RadControls for ASP.NET AJAX for all new applications. All controls in the suite are with production quality and you will be able to take advantage of the unique new features and performance optimizations.

We would like to note that we are open to changes based on the feedback we get from the community. Our #1 goal is to serve you well and we will act according to the needs of the greater part of the community.

Yes, you can. We have designed and tested the ASP.NET AJAX Prometheus controls to work with RadControls for ASP.NET and have not encountered any issues running them together in a wide variety of scenarios.

We know that not all projects have the luxury of updating their UI components, so rest assured that Telerik will continue our dedication to supporting RadControls for ASP.NET until the end of 2010.

If you have a RadControls for ASP.NET Subscription License with a valid subscription term, you will receive a complimentary license for RadControls for ASP.NET AJAX. You can download the latest version of the suite from your Client.NET account -> My Licenses-> My Purchases.
If you have a RadControls for ASP.NET Developer License (without Subscription) and would like to receive RadControls for ASP.NET AJAX, please contact sales@telerik.com for an upgrade offer.