Review: Telera DeVXchange (Part II)

Monday Dec 9th 2002 by Hitesh Seth
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This week we will focus on some of the advanced features of the Studio, including the grammar verifier, outbound calling and a number of VoiceXML extensions that Telera has made around call-control. We'll also take a brief look at AppCenter, the DeVXchange application development tool for developing dynamic VoiceXML applications. 

In the first part of this review we took a look at the basic features of Telera DeVXchange CodeCenter, a hosted VoiceXML development environment. This week we will focus on some of the advanced features of the Studio, including the grammar verifier, outbound calling and a number of VoiceXML extensions that Telera has made around call-control. We'll also take a brief look at AppCenter, the DeVXchange application development tool for developing dynamic VoiceXML applications. 

Grammar Verifier

The philosophy of the Grammar Verifier tool is simple, given a grammar (either through the included scratchpad or through a URL). It validates the grammar and lets the user know if there were any errors. The Grammar verifier supports Nuance GSL style as well as the W3C XML-based grammar specification. A feature that would be nice to have (and that I would expect in future releases of CodeCenter) would be a tool which can generate GSL/XML grammars based on a set of input criteria.

Another tool available to premium CodeCenter users is the "Grammar Manager". The Grammar Manager is a web-based interface for deploying and managing grammar packages on speech recognition platforms. It stores grammars in a pre-compiled format so that they can be readily used within applications.

Outbound Notification

The idea of outbound notification (a server-side application initiates a call to an end-user and starts a VoiceXML session) has created a whole new set of application scenarios for VoiceXML. Similar to the concept of wake-up calls, using the concept we can actually build complex alert-based systems. For instance, it could alert the plant manager when a particular raw material goes down a specified limit. And because it is an interactive VoiceXML application and not just a recorded message, the plant manager can actually interact with the system to find the best supplier and actually order the product as well. 

Outbound Notification is invoked through a URL, with the following syntax:

http://codecenter.telera.com/Outbound/outbound.asp?
notifyprocess=sap
&servicetype=notify&requesttype=new&custid=TeleraOBN&
appid=CodeCenter_OBN&token=100&maxretries=5&timetolive=5
&outboundno=7324335603&failureurl= http://www.hiteshseth.com/failure.vxml
?token=100&url=http://www.hiteshseth.com/Application.vxml
&login=1234&pin=1234

The key parameters of the Notification URL include

token User data that needs to be passed to the application.
outboundno The number to be called
failureurl URL of the application that you would like to start when the call is not-successful.
url URL of the application that you would like to start when the URL is not available.
login CodeCenter Login
pin CodeCenter PIN

AppBuilder

AppBuilder is a desktop-based Visual VoiceXML server-side application generation environment. If you have worked in the world of IVR applications, you would find this tool very similar. The focus of the tool is not really to provide a rich VoiceXML-based editor environment, but rather to generate the underlying dynamic scripting code in VoiceXML 1.0. Based on the environment selection, AppBuilder generates dynamic server-side code in Java Server Pages (JSP) or Active Server Pages (ASP).

The figure below shows a simple menu-based dialog built using the visual tool. The bottom window shows the VoiceXML dynamically generated. AppBuilder runs on top of Windows NT/2000 platforms and requires either Microsoft Internet Information Server 4.0/5.0 and/or a JSP/Servlet engine such as Apache Tomcat (included with the installation). 

Telera Extensions

To enable development of better call-control features (over and above the basic functionality that is supported by VoiceXML platform), the Telera Voice platform has created a number of extensions. The table below lists the various extensions and their functionality.

Call Control Elements Description
ALERT_LEG Alerting a  call-leg and direct it to a specified URL
BRIDGE_CALL Bridges the current call with another call
CREATE_LEG_AND_DIAL Enables a voice application to make outbound calls. This provides enhanced functionality over VoiceXML's <transfer> element 
END_SESSION Destroys all legs of the session
HANGUP_AND_DESTROY_LEG Terminates the call
LEG_WAIT Puts the executing VoiceXML interpreter in the wait stage
QUEUE_CALL Puts the call on hold
REXFER Transfers the call from one call-center agent to another
SCRIPT_RESULT Returns the results of a script execution
SET Provides a state management mechanism to otherwise stateless voice applications
UBRIDGE_CALL Breaks the bridge between the specified legs of the call

Let's look at the functionality of one of extensions by taking a look at an example. The example below shows an interactive voice application that is allowing the user to say "Customer Service" in order to be connected to a customer service representative. The CREATE_LEG_AND_DIAL element connects the caller with the agent specified in the TELNUM attribute. The IVRURL specifies the document to execute for the second leg once the call has been connected. Using these extensions it is actually possible for the application to "whisper" information about the caller to the agent before bridging the call.

Conclusion

Overall, I believe CodeCenter has the necessary toolsets for a useful VoiceXML development platform, with the key being support for the VoiceXML 2.0, call tracer, grammar verifier/manager and outbound notification. The extensions are definitely interesting and provide a lot of added functionality on-top of VoiceXML, but should probably evolve through support of a standard such as CCXML. AppBuilder has a lot of potential for being a server-side dynamic VoiceXML application tool, however, it does need to be upgraded to support VoiceXML 2.0 and CCXML.

Resources

About Hitesh Seth

A freelance author and known speaker, Hitesh is a columnist on VoiceXML technology and regularly writes for technology publications including Java Developer's Journal, Web Services Journal, XML Journal and The Computer Bulletin on emerging technology topics such as J2EE, Microsoft .NET, XML, Wireless Computing, Speech Applications, Web Services & Enterprise/B2B Integration. He is the conference chair for VoiceXML Planet Conference & Expo. Hitesh received his Bachelors Degree from the Indian Institute of Technology Kanpur (IITK), India. Feel free to email any comments or suggestions about the articles featured in this column at hks@hiteshseth.com.

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