Heiko, Please prefix email subjects since this mailing list is shared by all of Commons. I've added the [scxml] prefix to the subject for this thread. Onto your question ...
On 3/17/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > Hi, > > is it possible to declare a data model like defined in W3C Working Draft? I > tried it but I got a warning for undefined variable (UNDEFINED_VARIABLE (X > = null):). > <snip/> Not yet. Though incidentally, I just started working on the <datamodel> section [1] which was added as part of the latest SCXML WD (24 Jan '06). Given your nudge, I'll try to push some of it out into the nightlies early next week. > <?xml version="1.0" encoding="us-ascii"?> > <scxml version="1.0" xmlns="http://www.w3.org/2005/07/scxml";> > <datamodel> > <data name="X" expr="2"/> > </datamodel> > <snap/> The usage above, though quite correct, is really the degenerate case where your XML data tree has collapsed into a single leaf node. For such usages, you can simply use the <var> element (which is used to create similar "scratch space" variables) inside the pertinent <onentry> to define the variable with an appropriate initial value and do away with the UNDEFINED_VARIABLE callback on the ErrorReporter (as well as the <datamodel> -- again, for such degenerate usages). The data element is really meant to hold XML data trees such as: <data name="ticket"> <origin/> <destination/> <!-- default values for trip and class --> <trip>round</trip> <class>economy</class> <meal/> <!-- and so on --> </data> A <datamodel> can contain more than one of these. Moreover, the datamodel can be distributed across the SCXML document, and scoping rules apply to these <data> once they start appearing as children of <datamodel>s within <state>s. Furthermore, these XML data trees can now be transported via the EventDispatcher (<send>) or the Invoker (<invoke> from the latest SCXML WD, soon to come to Commons SCXML) to any related, even external process. Finally, one may think of distributed datamodels as task completion goals, possibly bubbling up and co-operating to fulfill some supertask defined at document root. These are powerful constructs, IMO. We only have the beginnings of SCXML usecases available [2]. -Rahul [1] http://www.w3.org/TR/scxml/#data [2] http://jakarta.apache.org/commons/sandbox/scxml/usecases.html > > </scxml> > > Regards, > > Heiko > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
