RE: SCXML: the src attribute of invoke, invokeid targeting

  I'll address your third question here.  I'll reply to the other two
once we've had a chance to discuss them in the group.  

The mechanisms of <invoke> are intended to be platform-specific so there
is no requirement for interoperability.  <send> is intended to be
interoperable (hence the definition of the Event I/O Processor).  If you
look at section 6.4.4, there are enough details of the semantics of
<invoke> specified so that it probably wouldn't be too much work to
figure out how to invoke another SCXML processor, as long as it provided
a bit of details on its internals,  but it would require extra work.
<send>, on the other hand, with the BasicHTTP EventI/O processor, should
be interoperable out of the box (as long as the other processor supports
BasicHTTP).  We haven't decided whether to _require_ support for the
BasicHTTP EventI/O processor.  It seems to us that most platforms will
support it, but there could be applications, such as embedded devices,
where it didn't make sense.

- Jim Barnett

-----Original Message-----
From: [] On
Behalf Of Johan Roxendal
Sent: Saturday, January 15, 2011 5:08 AM
Subject: SCXML: the src attribute of invoke, invokeid targeting


thanks for the help with my previous issues. there is, however, more
where those came from ;)

there seems to be some conflicting information about with which syntax
to target invoked processes with send elements. in  the format #_invokeid is
suggested, but it's unclear whether the underscore should be included or
not. in the preferred approach
is #_invoke_invokeid. 

in my implementation, <invoke id="i" /> can be reached through <send
target="#i" />. simple enough, but it'd be good to know how it _should_

invoked scxml documents (linked to using the src attribute) could be
fetched either asynchronously or synchronously. the standard offers no
hints, so I assume you prefer the synchronous approach (which is fine
for languages such as Python but not as fun in event-driven languages
such as Actionscript). do you intend to leave the synchronicity of the
src attribute open or will that be clarified in the standard? 

The scxml invoke type seems specifically for invoking external
_documents_. are there any plans for invoking external SCXML processors
(i.e documents that are being executed) as well, or is the preferred
method of communication <send> with type scxml and target and
http-enabled location? I ask, of course, because I've come across a need
for invoking external processors and my implementation won't be
compatible with any other processor than PySCXML as things now stand. 

thanks for your time,
Johan Roxendal

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Received on Monday, 17 January 2011 15:40:36 UTC