Markup languages are used to both format and annotate commands in ways that makes them visibly distinguishable from text. Markup languages can serve to specify how data will be both presented and executed. According to Wikipedia:
“Some markup languages, like HTML have presentation semantics, meaning their specification prescribes how the structured data is to be presented, but other markup languages, like XML, have no predefined semantics.” (1)
HTML is the coding language of the Internet and is primarily used for authoring web pages that can be processed and decoded by web browsers. VoiceXML is a language that is designed to allow applications to interact with both humans and computers telephonically. VoiceXML is based on XML, but instead of web formatting, VXML allows for the building and maintenance of call flows incorporating various interactive voice response features.
VoiceXML is similar to HTML in that they are both markup languages that allow for data processing by browsers (either web or voice). Each language is similar in terms of web architecture, which defines the design and setup of websites or call flows. Both languages are generated by web servers, and rely on client-server web architecture to structure their transmissions. Client-server web architecture distributes tasks and workloads between the servers and those making the service requests (clients).
Additionally, VoiceXML is similar to HTML in that both run on four-tiered architecture systems combining data, business logic servers, application servers, and the actual markup language platform. If a developer knows how to program in HTML or XML, they can very easily program in VoiceXML as well.
However, the functionality of VoiceXML and HTML is completely different. HTML describes the layout of a page, including its aesthetics and purpose. There are multiple paths that can be executed while interfacing with web pages, whereas VXML follows a single path that takes you through a call flow, and on this path you are either hearing or entering/saying something.
(1) “Markup Language,” Wikipedia, the Free Encyclopedia, accessed April 20, 2011, http://en.wikipedia.org/wiki/Markup_languages.
