SCXML

["Jacques R. Durand" <JDurand@us.fujitsu.com>]

From the OASIS XML news below:

 

We need to have a look at SCXML, just recently submitted to W3C.

 

My first quick assessment:

 

- it would allow to execute "Labelled Transition Systems" that we also consider in scope of eTSM.

Though it is definitely more focused than eTSM on state machine programming (concept of "state" is central)

- SCXML could be positioned as an intermediate language for higher level languages the execution

of which can be seen as a state machine with well-identified states (not too fine-grained), e.g. a workflow.

- The notion of "Event" seems rather abstract. But there is reference to a CCXML event notation that we may want to look at.

- The event handling in SCXML is geared to control of state transitions, while eTSM it is a more general script language intended to detecting event patterns, and reacting to these to compute related metrics and properties (for which state transition model is not quite appropriate or cumbersome).

- notion of concurrent processing is supported.

- There is an XPath profile.

 

Lets put this on the agenda of next call.

 

-jacques

 

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State Chart XML (SCXML): State Machine Notation for Control Abstraction Jim Barnett, Rahul Akolkar, RJ Auburn (et al, eds), W3C Technical Report

W3C announced the publication of a revised draft of the SCXML specifcation, updating the WD of 2009-05-07. The "State Chart XML (SCXML): State Machine Notation for Control Abstraction" document is the sixth Public Working Draft of SCXML, published on 29-October,2009 for review by W3C Members and other interested parties, and has been developed by the Voice Browser Working Group as part of the W3C Voice Browser Activity.

State Chart XML (SCXML) is a general-purpose event-based state machine language that can be used in many ways, including: (1) As a high-level dialog language controlling VoiceXML 3.0's encapsulated speech modules;

(2) As a voice application metalanguage, where in addition to VoiceXML 3.0 functionality, it may also control database access and business logic modules; (3) As a multimodal control language in the MultiModal Interaction framework, combining VoiceXML 3.0 dialogs with dialogs in other modalities including keyboard and mouse, ink, vision, haptics, etc; it may also control combined modalities such as lipreading [combined speech recognition and vision] speech input with keyboard as fallback, and multiple keyboards for multi-user editing; (4) As the state machine framework for a future version of CCXML; (5) As an extended call center management language, combining CCXML call control functionality with computer-telephony integration for call centers that integrate telephone calls with computer screen pops, as well as other types of message exchange such as chats, instant messaging... (6) As a general process control language in other contexts not involving speech processing...

SCXML combines concepts from CCXML and Harel State Tables. 'Voice Browser Call Control: CCXML Version 1.0' is an event-based state machine language designed to support call control features in Voice Applications, specifically including VoiceXML but not limited to it. The CCXML 1.0 specification defines both a state machine and event handing syntax and a standardized set of call control elements... The goal of this document is to combine Harel semantics with an XML syntax that is a logical extension of CCXML's state and event notation...

SCXML is defined in terms of modules, which define logical units of functionality. Modules are customized and combined into profiles, each of which can be thought of as defining a variant of the language. This modularity allows implementations flexibility in selecting the features that they want to support. It is particularly intended to allow them the choice of which data manipulation language (e.g., ECMAScript, XPath) to embed..."

http://www.w3.org/TR/2009/WD-scxml-20091029/

See also the color-coded diff marked version: http://www.w3.org/TR/2009/WD-scxml-20091029/diff.html