Developer's Guide

0 THE VOICE FOUNDATION CLASSES VOICEXML PROGRAMMING GUIDE

FOR CISCO UNIFIED CUSTOMER VOICE PORTAL RELEASE 4.0(1)

VPreference pref = ved.getPreference();

VForm form = VForm.getNew(pref, "start");

Here, the VPreference object is obtained from the VoiceElementData object passed as input to

a voice element. It is used to create a VForm object. Assuming the application is using the voice

browser Foo, that choice is reflected in the VPreference object and therefore the getNew factory

method returns a VFormFoo object, which is automatically downcasted to a VForm object. The

developer then uses the form object as desired.

This ability to treat all objects returned as a root VFC object is not available when the developer

wishes to use functionality that exists either in a particular version of VoiceXML or a particular

voice browser. The developer must understand that doing so would prevent their code from

functioning on all voice browsers. In this case, the developer simply treats the return of the

factory method as a class higher in the class hierarchy (VFormV2 or VFormFoo in the example in

Figure 15-1).

The following Java code demonstrates this:

VGrammar myGrammar = VGrammar.getNew(pref);

((VGrammarV2) myGrammar).setMaxage(1000);

The setMaxage method exists only in the VGrammarV2 class since this is a feature that exists only

in VoiceXML 2.0. To call this method, one must first upcast the previously downcasted object

back to VGrammarV2. If this is not done, an exception will be thrown indicating that VGrammar

does not have a method named setMaxage. Also note that if the user in VoiceXML Studio chose

a voice browser that was compatible with VoiceXML 1.0 only, a runtime exception would be

thrown when this code is encountered because that browser would be unable to understand

VoiceXML referring to maxage.

VFC Classes

The following lists all the VFC classes (with full package names) and briefly explains what they

are responsible for. The Javadocs for Cisco Unified Customer Voice Portal for the VFCs provide

significantly more detail about the classes, their methods, and how they are used.

com.audium.core.vfc.util.VMain. This object is the container for a complete VoiceXML

document. It includes methods for managing information about the page such as the meta

tags, the doc type, and the value to put in the

<vxml> tag’s xml:lang attribute. It includes

methods for adding document-scope data such as links, variables, and VoiceXML properties.

VForm objects are added to this object to create the VoiceXML page. Unified CVP

VoiceXML Server uses the

VMain object to handle the printing of the VoiceXML page.

Voice elements receive an instantiated VMain object as input and the developer need only

worry about filling the object with the appropriate content.

com.audium.core.vfc.form.VForm. This class is a container for all the content in a VoiceXML

page not handled by the VMain class. It is a direct mapping of the <form> tag, though it also

produces other form-level tags such as <var> or <filled>.