Ajax update panel image while updating
The element can be used to trigger a partial page render, but one that requires a full round-trip to the server.
Click the Update This Panel button, and notice the top Update Panel will be updated with the current server time.With it, we can observe which controls are intended to cause AJAX postbacks.For example, let's add two additional controls to the page, leaving one control outside of the Update Panels entirely, and leaving one within an Update Panel.For instance, consider a Check Box control; examine the class disassembly in . The interception of the form's submission, then, allows ASP.NET AJAX to be injected into the page nonintrusively, helping to avoid any potential breaking changes that might occur by utilizing a possibly-imprecise string replacement.This whitepaper is based on the Beta 2 release of the . Remember that Pages are stateless, and so you should re-register these controls every time they are created.
Automatic child trigger inclusion can also be disabled (so that child controls that create postbacks do not automatically trigger partial renders) by setting the property to false.
The check box should not cause an AJAX update, but the drop-down list should, even though it is not housed within an Update Panel.
(Click to view full-size image) As is apparent in the above screen shot, the most-recent button to be clicked was the right button Update This Panel, which updated the top time independent of the bottom time.
However, its server-side processing model has several drawbacks inherent in the technology, many of which can be addressed by the new features included in the Microsoft ASP. These extensions enable many new rich client features, including partial rendering of pages without requiring a full page refresh, the ability to access Web Services via client script (including the ASP. This whitepaper also assumes that you will be working with Visual Studio 2008, not Visual Web Developer Express, and will provide walkthroughs according to the user interface of Visual Studio (although code listings will be entirely compatible regardless of development environment).
NET profiling API), and an extensive client-side API designed to mirror many of the control schemes seen in the ASP. This whitepaper examines the XML Triggers functionality of the ASP. XML Triggers give granular control over the components that can cause partial rendering for specific Update Panel controls. NET AJAX Extensions, previously an add-on assembly targeted at ASP. Triggers for a given Update Panel, by default, automatically include any child controls that invoke a postback, including (for example) Text Box controls that have their event.
We will add a Check Box control within the upper Update Panel, and drop a Drop Down List with a number of colors defined within the list.