CONTENTS Introduction History Usage Sample Program VoiceXML Inputs Goals of VoiceXML Advantages of VoiceXML Conclusion
Introduction VoiceXML (VXML) is the W3Cs standard XML format for specifying interactive voice dialogues between a human and a computer. It allows voice applications to be developed and deployed in an analogous way to HTML for visual applications. Just as HTML documents are interpreted by a visual web browser, VoiceXML documents are interpreted by a voice browser.
Welcome to voice portal query A common architecture is to deploy banks of voice browsers attached to the Public Switched Telephone Network (PSTN) to allow users to interact with voice applications over the telephone.
History AT&T,IBM, Lucent, and Motorola formed the VoiceXML Forum in March 1999, in order to develop a standard markup language for specifying voice dialogs. In March 2000 they published VoiceXML 1.0 The W3C produced version of VoiceXML 2.0, which reached the final recommendation stage in March 2004.
Usage Many commercial VoiceXML applications have been deployed, processing millions of telephone calls per day. These applications include: order inquiry, package tracking, driving directions, emergency notification, flight tracking, voice access to email, audio news magazines, voice dialing etc.
Sample programVoiceXML has tags that instruct the voice browser toprovide speech synthesis, automatic speech recognition, dialogmanagement, and audio playback.The following is an example of a VoiceXML document: <vxml version="2.0" xmlns="http://www.w3.org/2001/vxml"> <form> <block> <prompt> Hello world! </prompt> </block> </form> </vxml>
When interpreted by a VoiceXMLinterpreter this will output "Hello world"with synthesized speech. Typically, HTTP is used as the transport protocol for fetching VoiceXML pages. Some applications may use static VoiceXML pages, while others rely on dynamic VoiceXML page generation using an application server like tomcat, web logic.
Sample program:<?xml version="1.0" encoding="UTF-8"?><vxml version="2.1"> <form id="MainMenu"><field name="instrument"><prompt>What is your favorite musical instrument?</prompt><grammar > [guitar mandolin dobro (violin fiddle) banjo] </grammar><noinput> Did you say something? I didnt hear you.<reprompt /></noinput><nomatch> I suppose thats OK, but its not on my top five. Want to try again?<reprompt /></nomatch></field>
<filled namelist="instrument"><if cond="instrument == guitar"> <prompt>Thats right! Hang up and go practice.</prompt><elseif cond="instrument == mandolin" /> <prompt>Nice... and only four strings to keep in tune.</prompt><elseif cond="instrument == dobro" /> <prompt>Boy, thats no fun to learn, is it?</prompt><elseif cond="instrument == violin" /> <prompt>We call that a fiddle, Mr. Fancy Pants.</prompt><elseif cond="instrument == fiddle" /> <prompt>Does playing classical music on a fiddle make it a violin?</prompt><elseif cond="instrument == banjo" /> <prompt>Wow, I hope you live alone.</prompt></if></filled></form></vxml>
Playing a Sound The Audio Element Must be contained with a block: <block> <audio src="ui/welcome.wav"> Welcome </audio> </block>
Voice XML InputsVoice XML accepts: Touch tone key Speech There is a difference between voice recognition and Voice XML. Personal voice recognition systems allow for wide grammar, but restrict the number of users. Voice XML restricts the grammar, but allows for a wide number of users.
Goals of voicexml Minimizes client/server interactions by specifying multiple interactions per document. Separates user interaction code (in VoiceXML) from service logic (e.g. scripts). Promotes service portability across implementation platforms. Is easy to use for simple interactions, and yet provides language features to support complex dialogs.
Advantages of Voice XML Allows for the easy implementation of voice interfaces VoiceXML supports playback of prerecorded audio files Runs on existing web infrastructure
ConclusionVoicexml has become a standard: All-in-one solutions available Reduces dialogue system development time Additional functions can be easily implemented Develop our own dialogue system with free VoiceXML browser