Exploring ASP.NET & Web Development
AJAX 4.0
More than a Work in Progress
By Don Kiely
ASP.NET AJAX started life as an add-on to Visual Studio 2005 and ASP.NET 2.0. Since then it hasn t changed all that much as Microsoft focused on getting Visual Studio 2008, ASP.NET 3.5, and service pack 1 out the door. AJAX became integrated with Visual Studio in the latest release, but there wasn t much new to explore.
That doesn t mean that AJAX has languished or grown stale. Now that Microsoft has released a slew of ASP.NET enhancements, AJAX is getting some major attention in preparation for an out of band update. That means you ll soon see new AJAX features once again released separately from a major framework or Visual Studio update. Last week the company released preview 3 of AJAX 4.0, and there are a lot of goodies to explore and salivate over, waiting for them to mature enough for production use.
The biggest new feature is the ability to integrate with various data sources, making it easier to update pages from Web services and ADO.NET data services, in a variety of formats. These data service features enable a data-driven user interface using new declarative AJAX templates. Combined with the ability to attach data objects to propertyChanged event handlers, you ll be able to create rich data applications that rival, and sometimes exceed, Windows Forms applications.
Microsoft describes the features in the release as providing a client-side data story that rivals data binding in other Windows development technologies. The main implementation is in a new script library, MicrosoftAjaxAdoNet.js, which supports all data maintenance operations in ADO.NET, with support for optimistic concurrency. This preview supports read-only integration of data sources with the DataView control; read-write will come in a future preview. An interesting feature that I have yet to play with is a command bubbling model with support for custom commands and item selection to better support master-detail scenarios.
AJAX templates, supported in the new MicrosoftAjaxTemplates.js script library, provide support for creating data-driven user interfaces with little or no JavaScript code. I always chuckle a bit when I read something from Microsoft about little or no code, since it is generally an ideal that we haven t seen or met yet. But the JavaScript libraries in AJAX do dramatically reduce the need for custom script, no doubt about that. And being able to declaratively create data applications will simplify page development. There is rich support for attaching an AJAX DataView control to an HTML container element for the dynamic user interface.
AJAX 4.0 is most certainly a work in progress, but if you use AJAX in production Web sites it is worthwhile to spend some time exploring preview 3 and the roadmap to see what is coming in the months ahead. I ll be presenting a session about AJAX 4.0 at DevTeach in Montreal this December, and at Quebec City .NET community that same week, so be sure to stop by to say hi if you re there.
Resources
http://quickstarts.asp.net/previews/ajax/default.aspx
The main source of information for the new release. Here you ll find high-level information about the latest AJAX 4.0 release, tutorials, and links to the CodePlex download page. This site serves, at the moment, as the complete set of documentation for the preview release, including an API reference for the Templates API and the features used to integrate with ADO.NET Data Services.
http://www.codeplex.com/aspnet/Wiki/View.aspx?title=AJAX
Download page for AJAX 4.0, preview 3. Take a look at the roadmap so you have a feel for what else is coming. Note that this is a shared site for a variety of ASP.NET previews, including MVC, dynamic data, and Web forms, so don t get confused if you surf around and see other technologies.
Don Kiely, MVP, MCSD, is a senior technology consultant, building custom applications as well as providing business and technology consulting services. His development work involves tools such as SQL Server, Visual Basic, C#, ASP.NET, and Microsoft Office. He writes regularly for several trade journals, and trains developers in database and .NET technologies. You can reach Don at mailto:[email protected] and read his blog at http://www.sqljunkies.com/weblog/donkiely/.
