Cisco Cisco Customer Voice Portal 8.0(1) Entwickleranleitung

0

 

T

HE 

V

OICE 

F

OUNDATION 

C

LASSES

 

 

V

OICE

XML

 

P

ROGRAMMING 

G

UIDE 

 

 

 

FOR 

C

ISCO 

U

NIFIED 

C

USTOMER 

V

OICE 

P

ORTAL 

R

ELEASE 

4.0(1) 

 

 

 

76

 

and version 2.0, and the similarities are encapsulated in a common base class. Figure 15-1 shows 
this graphically with the 

VForm

 class. The main 

VForm

 class extends the 

VRoot

 class and is itself 

extended by 

VFormV1

 and 

VFormV2

, representing VoiceXML 1.0 and 2.0 compliance. Luckily, 

there are only a few differences between these versions, so the developer can still do most coding 
to the base 

VForm

 class. The Gateway Adapters introduce VFCs that extend 

VFormV1

 or 

VFormV2

 

depending on whether the voice browser it supports is compatible with VoiceXML 1.0 or 2.0. 

 

The last concept is that VFC objects are not instantiated using the 

new

 keyword. A static factory 

method named 

getNew

 is used instead. The reason for this is related to the abstraction of the 

voice browser differences. As mentioned previously, a developer need only code using the base 
VFC classes. At runtime, the factory methods used to instantiate VFC classes actually returns the 
appropriate voice browser-specific VFC (for example, 

VFormFoo

But since the developer treats the return object as the base VFC, that object is downcasted. This 
is the heart of the VFC abstraction design. Since all VFC derivative classes extend their base 
VFCs, a developer need only code to the base VFCs and that automatically makes their code 
compatible with any voice browser represented by a Gateway Adapter. 

In order to identify which voice browser VFC to return, every factory method must include as its 
first argument an instance of 

VPreference

. 

VPreference

, while a VFC class, does not match to 

a VoiceXML tag, it is used instead to hold preferences made by the user in Unified CVP 
VoiceXML Studio for the application, such as the voice browser and default audio path. By 
passing this object to all factory methods, the appropriate object can be returned. The 

VPreference

 instance is automatically created for the developer and made available through the 

Session API passed to voice elements, hotevents, or call end classes. 

The following Java code demonstrates the concepts described above: