SCXML Web Laboratory

SCXML Web Laboratory is a web interface to a prototype implementation of State Chart XML (SCXML). For an immediate demonstration of what the program does, click the Run button in the frame to the left. Then perhaps try some of the other examples from the menu on the top. Note that you may actually edit the sources and/or the event strings before you click Run. This is the main purpose of SCXML Web Laboratory: To allow people to get a feeling for what SCXML is all about, and to elicit feedback in order that we can improve our implementation!

Never heard about SCXML? Unfortunately, this is not the place to introduce SCXML as such. Instead, we refer the interested visitor to the documents listed in the bibliography.

Synergy SCXML v. 0.7

Synergy is the name of a dialogue system research platform that we are developing in a project of ours, and Synergy SCXML is an explorative implementation of SCXML in the Oz programming language - the language that we tend to use a lot in our projects.

We hope that our implementation of SCXML will provide us with flexible means to explore the Data-Flow-Presentation (DFP) framework recently proposed by the W3C. The choice of Oz as implementation language means that we can keep the codebase conveniently small (version 0.7 consists of less than 1,500 lines of code half of which is reusable library code). A small codebase together with what Oz has to offer in the form of dataflow concurrency, logic programming, constraint-programming, network transparent distribution. etc., means we will be able to explore advanced concepts very quickly.

Also, since we use Oz as our datamodel access/scripting language our SCXML developers will have at their disposal something far more powerful than Javascript or anything like it.

Limitations in version 0.7

Well, there is probably more than we realize ourselves... but for a start:

• Some SCXML elements have not yet been implemented at all:
1. <param>
2. <finalize>
3. <anchor>
• Others have not been completely implemented:
1. <datamodel> - restricted model, based on Oz.
2. <send> - supports only the 'event' and the 'delay' attributes.
• Various discrepancies between our implementation and the specs:
1. The value of the name attribute in <data> must be a capitalized string. Reason: Oz variable names start with a capital letter.
2. The name of the eventdata variable is "Eventdata" (rather than "_eventdata"). Oz does not allow variable names starting with an underscore.

Changes

• 070302 First release - v. 0.3
• 070305 Added simple datamodel + things related to that. More examples. Better error handling.
• 070312 First implementation of <invoke>. Added more examples. Bumped version up to 0.6.
• 070324 Fixed a few bugs. Added more examples. Bumped version up to 0.7.
• 070403 Fixed a major bug. Added more examples.
• 070413 Added a (non-standard) <script> element. Added more examples.

Acknowledgements

Torbjörn Lager wrote this particular version, based on discussions with Fredrik Kronlid and based on a previous version written by Fredrik Kronlid and Torbjörn Lager.

Availability

The source code will be made available as soon as we've cleaned it up a bit.

Contact

We'll appreciate your feedback! Please write to the Synergy Team.

Bibliography

Here is a short list of links to relevant material:

1. Jim Barnett, "An Introduction to SCXML" - http://www.voicexmlreview.org/Aug2005/features/scxml_for_voicexmlreview.html
2. "State Chart XML (SCXML): State Machine Notation for Control Abstraction,” http://www.w3.org/TR/scxml/
3. "The Voice Browser DFP Framework," http://www.w3.org/Voice/20.7/DFP
4. Harel, David, “Statecharts: A Visual Formalism for Complex Systems,” http://www.wisdom.weizmann.ac.il/~dharel/SCANNED.PAPERS/Statecharts.pdf
5. W3C Voice Browser Working Group Web site http://www.w3.org/voice