Digital Signal Processing Reference
In-Depth Information
periodically in an attempt to re-establish the communication channel until it is
forced to proceed to the next dialog task by the user's command.
It is also possible to store the complete DM application on the client side
if the application does not require any dynamic information. For example,
voice control of the vehicle air conditioner can be achieved on the client side
with no need for server-side dialog management. By using client-side
applications for such small tasks, we can reduce bandwidth utilization
between the client and the server.
As described in Section 2, client-side applications can use the “back door”
of the VoiceXML Interpreter to communicate with it asynchronously. This
mechanism can be utilized if we want the system to interrupt a local (client-
side) dialog as soon as it re-establishes a network connection with the remote
server. However, it is also possible to implement substantial client-side
applications simply by storing and accessing static VoiceXML documents
within the client.
INITIAL PROTOTYPE SYSTEM
6.
We have developed an initial prototype system that is integrated with the
ScenarioXML and DialogXML compilers. Control of the dialog flow using
grammars and lexicons as described in Section 4 has also been implemented;
automatic grammar compilation from a corpus is currently being evaluated in
a separate prototype system. The task switching described in Section 5 is also
being tested in a separate prototype.
The initial prototype system was modified to communicate with an
internal GPS module, as described in Section 2. Figure 5-7 shows a schematic
diagram for the initial prototype system; the data flow sequence for a typical
route guidance dialog is illustrated in detail. The GPS simulator, which
provides functionality equivalent to a GPS module in a vehicle, plays the role
of internal application as described in Fig. 5-1. The Route Planner is an
example of an external database or information service, but it was
implemented on the client side in the prototype because it requires frequent
communication with the GPS simulator.
In this system, the user first asks the VoiceXML Interpreter to send an
HTTP request, which includes the current position given by the GPS
simulator and the destination given by the user's voice command. When the
Dialog Manager receives the request, it asks the Route Planner how to get to
the desired destination. The Route Planner provides directions in the form of a
set of sentences, each of which is to be delivered to the user at a
predetermined landmark point (e.g. intersection). Landmark point information
