Professional DevExpress™ ASP.NET Controls

Chapter 11. Asynchronous Computing for ASP.NET

Asynchronous programming is essentially client-side programming of functionality that doesn't complete immediately (synchronously, in other words) but that is completed some time later. The application is notified, usually through an event, that processing has completed. During the time between firing off the processing request and getting the completed response, the application doesn't block, and the user can continue to interact with it.

This asynchronous behavior is provided with ASP.NET in a couple of ways.

• The first is very simple: a timer that ticks at regular intervals, with each tick resulting in an event being triggered. Here there is no processing per se, just the requirement that the application be notified of every tick.

• The second is more complex and broader in scope: Asynchronous JavaScript and XML (Ajax) and callbacks. The X in Ajax has become less of a requirement these days with simple strings or JSON packets becoming more prevalent.

Ajax is the underlying technology that provides the ability to update part of a Web page from server-provided data without refreshing it all. Using it gives you the opportunity to provide Rich Internet Application (RIA) features in your application.

Ajax has been available officially for ASP.NET since the beginning of 2007, and since that time third-party vendors have been Ajaxifying (if there is such a verb) their ASP.NET controls to give them the ability to perform RIA-type services in Web ...