STM Blog —
May 21, 2008 @ 10:16 am 
SCXML, or the “State Chart extensible Markup Language” provides a generic state-machine based execution environment based on CCXML and Harel State Tables. The fourth Working Draft of SCXMLhas been published at:
The main differences from the previous draft are:
1. the modularization of the language,
2. the introduction of profiles and
3. a revision of the algorithm for document interpretation.
The document as a whole has changed significantly and the W3C Voice Browser Working Group welcomes review. Please send comments to www-voice@w3.org
Jim Larson
Co-chair, W3C Voice Browser Working Group
Q) Dammit, Jim, what is this?
A) State charts are a used by software developers to specify the “flow of control.” State charts can be though of as a type of flow chart that describes the order and sequence of things that happen during the execution of an application. Basically, a state chart consists of “states” and “transitions”. Think of “state” as a something that the the application does, and a “transition” as the rules for moving from one position to another.
State charts were originally developed by the mathematician David Harel and is included in the Universal Modeling Language (UML). State charts offer a clean and well-thought out semantics for sophisticated flow control constructs such as sequential, conditional, and parallel flow control. State chart have been defined as a graphical specification language, however, and hence do not have an XML representation. The goal of this document is to combine Harel semantics with an XML syntax.
We expect that the SCXML notation specified in this document will be used to specify the flow control of multimodal and speech only applications. The notation may also be used to specify flow control for other types of applications.