Voice XML provides a framework with scoping rules for building complex, modular applications around grammars and events. Based on a hierarchy of fields, forms, documents and applications, a developer can control the visibility of grammars, variables, events and properties.
The ability to define application-specific events and throw them up the hierarchy stack enables developers to define behaviors that will be the same across multiple documents and forms. The deeper we get into Voice XML, the more we see its resemblance to full-fledged, modern programming languages.
In our next and final article in the series, we’ll look at how Voice XML can be used to augment the delivery of server-based web services.