Digital Signal Processing Reference
In-Depth Information
Figure 5-6.
Grammar compilation using corpus.
5.
SWITCHING EXTERNAL/INTERNAL
APPLICATIONS
In car telematics systems, communication between the server and the
client can be unstable. The system must exhibit robust behavior when a
communication channel is suddenly disconnected without warning. The
VoiceXML specification includes an “error.badfetch” event, which signals
that an error occurred when fetching a requested document. Our VoiceXML
documents therefore include event handlers for “error.badfetch” that switch
dialog control to a local, compact dialog management application residing on
the client side. For example, if the dialog is about traffic guidance, the
internal application may know the route from the current position to the
desired destination, but it will not have access to dynamic (real-time)
information such as current traffic conditions. If the user asks about traffic
conditions in the absence of an established communication channel, the
system would reply “I'm sorry. Currently I can't access that information.” The
local dialog manager will enter a wait state, and poll the remote server
