If one calls the first available VoiceXML book the best, one can also call it the worst. Bod Edgar is an expert in computer telephony, but what can you expect to learn about VoiceXML, the language for the Voice Web, from someone who "had little experience of Internet technologies" and "decided to learn about HTTP, HTML" by the summer of 2000, and who doesn't seem to have created any practical VoiceXML applications? He states that one critical decision to be made in writing the book was which VoiceXML version to cover. Oddly, he chose VoiceXML 2.0. Then you realize how convenient that is - he actually revealed it himself: "there were no VoiceXML 2.0 browsers available for me in developing and testing example code." The fact is there were already at least three commercially available VoiceXML 1.0 browsers at the time of his writing (January 2001) for him to develop and test code: cafe.bevocal.com, studio.tellme.com, and developer.voicegenie.com. The next question is: does VoiceXML 1.0 lack many important features in VoiceXML 2.0? No, with strong integration with Web server technologies, applications built on VoiceXML 1.0 can do a lot! Yes, nobody supports VoiceXML 2.0 yet, as it's still an early draft. But many support VoiceXML 1.0, an already powerful language if you know how to build advanced VoiceXML application using web server technologies and some important VoiceXML elements such as <subdialog> and <object>, which he didn't give appropriate coverage at all. He says "A subdialog is a form which is called from another form and returns", where in fact, a subdialog can invoke either a form on the current page or more importantly, another VoiceXML document, which can be dynamically generated by your web application. Again, because the author's inexperience with Internet technologies, you miss great opportunities in learning how to integrate VoiceXML with your web applications.
What further bothers me are mistakes in the book such as "The VoiceXML 1.0 standard was published on March 7th, 2000" - the fact is VoiceXML 1.0 was submitted to and acknowledged by the W3C on that day, and is still on the standardization process now - and that the title for the classic "Hello, World" application is "Hello, Web" - which reminds of the professor George Polya describes: he says A, writes B, thinks C, and the correct answer is D.
Even if you just want to get some basic introduction to the language itself, you'll gain a lot more reading those online documentaion from sites offering VoiceXML browsers. If you want to get serious about VoiceXML and build real-world VoiceXML applications, wait or look elsewhere. This book will make you feel very disappointed.
