Asynchronous Command Controls for webMethods CAF Applications

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To incorporate Ajax (Asynchronous JavaScript and XML) into your webMethods CAF applications, use the asynchronous command controls. The following describes the asynchronous command controls available in the webMethods Designer Palette view.
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Async Command Button
Use to add a button to your user interface that, when clicked, asynchronously performs a server-side action. Use when you do not need the application to refresh the entire user interface in response to the user action and when you want to continue to allow users to use controls in the user interface.
When the user clicks the button, the webMethods CAF JavaScript in the Web browser client makes an asynchronous request to the server‑side CAF JSF engine to handle the request.
Note that while the request is being processed the user can even continue to click the button again, which will create another request. In this situation, the CAF JSF engine would asynchronously process the subsequent request.
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Async Command Icon
Use to add an image to your user interface that, when clicked, asynchronously performs a server-side action. This asynchronous command works identically to the Async Command Button except that the user interface includes an image rather than a button. Use when you do not need the application to refresh the entire user interface in response to the user action and when you want to continue to allow users to use controls in the user interface.
When the user clicks the image, the CAF JavaScript makes an asynchronous request to the CAF JSF engine to handle the request.
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Async Command Interval
Use to add a script to your client that executes on a timed interval to asynchronously invoke a server‑side action. The typical used of this asynchronous command is to refresh the data on the screen by periodically polling the server for the latest data.
At the specified intervals, the CAF JavaScript makes an asynchronous request to the CAF JSF engine to perform the actions specified in the script.
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Async Command Link
Use to add a hyptertext link to your user interface that, when clicked, asynchronously performs a server-side action. Use when you do not need the application to refresh the entire user interface in response to the user action and when you want to continue to allow users to use controls in the user interface.
When the user clicks the link, the CAF JavaScript makes an asynchronous request to the CAF JSF engine to handle the request.
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Async Hidden Command
Use to add a script to your client that is invoked by other code in the client to asynchronously invoke a server‑side action.
For example, the user interface might contain a drop-down list. Rather than including an Async Command Button that you require the user to click after making a selection from the drop‑down list, use an Async Hidden Command. You can add a RaiseOnChange control so that the Async Hidden Command is invoked each time the drop-down list changes.
When an Async Hidden Command is invoked by other client code, the CAF JavaScript makes an asynchronous request to the CAF JSF engine to handle the request.
To bind one of the asynchronous command controls to a server‑side action, you specify a binding expression on the Properties view for the control to bind the control to a managed bean.
Asynchronous Command Controls vs. Standard Command Controls
The following table compares the characteristics of asynchronous command controls to those of standard command controls.
 
Asynchronous Command Controls
   
Synchronous Command Controls
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The requests to the server are asynchronous allowing client‑side interaction with the user interface to continue.
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The communication with the server is performed using the XMLHttpRequest JavaScript class.
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You control the user interface elements that are refreshed. You can refresh some, none, or all of the user interface.
   
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The requests to the server are synchronous; when a request is initiated, the client‑side interaction waits until the server responds.
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The communication with the server is performed using a standard HTTP form post.
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The entire page is always refreshed.