Early Adopter VoiceXML
There is a reason why Wrox has deemed this title as part of their Early Adopter series: The book, like the current state of VoiceXML, is not quite there yet for the typical developer to consider. While the attempt to capture the enthusiasm for the potential of this syntax and its conjunctive technology is appreciable, disclaimers of costly installations and weak implementations to the 1.0 specification unintentionally discourage all but the most adventurous of programmers from spending a lot of time with the current state of VoiceXML.
Like many standards, VoiceXML is an amalgamation of proprietary specifications developed by competing companies. These competitors discovered that for their industries to benefit from their work they would have to come together and agree on a common language. AT&T, Motorola, IBM, Lucent, and others have submitted their own specifications into the Internet-enabled Interactive Voice Response (IVR) soup and cooked up a syntax that provides a foundation for future, Web-enabled IVR applications to be constructed. The only problem with any young 1.0 specification is that they often leave room for implementation interpretation, which explains why, like competing Web browsers, the voice gateway providers recommended in the book each have their own, occasionally incompatible interpretations and proprietary extensions of the VoiceXML 1.0 parser. Developers can only hope that the 2.0 standard will correct past omissions.
As for the book itself, it may be of value to developers being introduced to VoiceXML for the first time, since there are very few other books published on the nascent subject. However, as is often the case with books written by multiple authors and pushed out to the market as quickly as possible, there is some redundancy in the content. Additionally, the book reads like it is a collection of essays and examples on the subject rather than a single cohesive work. Examples range from using the VoiceXML with ASP, Java, PHP, and XSLT, leaving it up to the reader to decide what fragments of code are most useful for their own applications.
The heart of the book is the two chapters and appendix on VoiceXML syntax. Because there are not a lot of attributes in VoiceXML, these sections are relatively small but they still do the job of communicating the key meanings of each tag. That leaves the remainder of the book to discuss configuration and implementation details, capped with an interesting but brief final chapter on future scenarios using VoiceXML. In the end, the book is too expensive to justify its momentary coverage of the subject. Perhaps if this were an affordable pocket guide instead, the value of its content would have been worth considering. For now, only true early adopters ready to spend the money for that labeled privilege need apply.
Early Adopter VoiceXML by Stephen Breitenbach, Tyler Burd, Nirmal Chidambaram, Eve Astrid Andersson, Xiaofei Tang, Paul Houle, Daniel Newsome, and Xiaolan Zhu; Wrox Press, http://www.wrox.com.
Cover Price: US$34.99