The popularity of VoiceXML 2.0 spurred the development of numerous voice browser implementations early in the specification process. VoiceXML 2.0 has been phenomenally successful in enabling the rapid development and deployment of voice applications that handle millions of phone calls every day. The broad implementation experience of VoiceXML 2.0 has led to the development of additional, innovative features that help developers build even more powerful voice-activated services.
While it was too late to incorporate these additional features into VoiceXML 2.0, the purpose of the VoiceXML 2.1 specification is to formally specify the most widely supported among these features to ensure their portability between platforms and at the same time maintain complete backwards-compatibility with VoiceXML 2.0.
The features specified in VoiceXML 2.1 include:
- Allowing grammars to be referenced dynamically via a srcexpr attribute on the <grammar> element.
- Allowing scripts to be referenced dynamically via a srcexpr attribute on the <script> element.
- Enabling the precise detection of where a barge-in occurred during prompt playback by reflecting <mark> element information into ECMAScript.
- Enabling XML documents to be fetched without requiring a dialog transition through the use of the new <data> element. The XML document is reflected into ECMAScript via the W3C Document Object Model.
- Allowing prompts to be concatenated dynamically through the new <foreach> element.
- Enabling the capture and reflection of user utterances during speech recognition through the ‘recordutterance’ property.
- Improving integration with the interpreter context such as a CCXML interpreter by exposing a namelist attribute on the <disconnect> element.
- Extending call transfer capabilities by adding a type attribute to the <transfer> element.
Examples demonstrating each of these features can be found in the VoiceXML 2.1 specification at http://www.w3.org/TR/voicexml21/. In addition, you find in-depth tutorials on each of the VoiceXML 2.1 features in Rob Marchand’s ‘First Words’ column on the VoiceXML Review Web Site:
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