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Unique ids for transitions

From: Gavin Kistner <phrogz@me.com>
Date: Thu, 31 Jan 2013 23:40:54 +0000 (GMT)
To: www-voice@w3.org, www-voice@w3.org
Message-id: <7a5f64b3-5af7-4a11-bbc4-8d1b2db12f34@me.com>
Transitions currently do not specify the presence of an id="..." attribute. As any pair of states can have n transitions anchored at both ends, even with the same event(s), the only way to uniquely talk about a particular transition (to any sort of an external system) is to fully describe it. Contrast this with a state, which can be uniquely identified with a short id string.

This causes no problem for the runtime itself. However, for external tools working with an SCXML document this can be annoying. I'm thinking specifically of a visual runtime debugger for a state machine. For example, consider the scxmlgui tool[1]. It has a simple network protocol for highlighting/unhighlighting either states or transitions. The states are referred to by id. The transitions are referred to by source/target state ids, which clearly does not uniquely reference a specific transition in all cases.

It will be trivial to add a namespaced attribute to transitions to track this, but I would feel cleaner if this were in the spec itself. Any chance of having an a non-required id (ID) attribute spec'd on <transition> elements?

[1] https://code.google.com/p/scxmlgui/ 
Received on Thursday, 31 January 2013 23:42:26 UTC

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