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

From: Jim Barnett <Jim.Barnett@alcatel-lucent.com>
Date: Mon, 17 Jan 2011 07:39:52 -0800
Message-ID: <E17CAD772E76C742B645BD4DC602CD8103CB896F@NAHALD.us.int.genesyslab.com>
To: "Johan Roxendal" <johan@roxendal.com>, <www-voice@w3.org>
Johan,
  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: www-voice-request@w3.org [mailto:www-voice-request@w3.org] On
Behalf Of Johan Roxendal
Sent: Saturday, January 15, 2011 5:08 AM
To: www-voice@w3.org
Subject: SCXML: the src attribute of invoke, invokeid targeting

hi,

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

Q1:
there seems to be some conflicting information about with which syntax
to target invoked processes with send elements. in
http://www.w3.org/TR/scxml/#DataSharing  the format #_invokeid is
suggested, but it's unclear whether the underscore should be included or
not. in http://www.w3.org/TR/scxml/#SendTargets 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_
be. 

Q2:
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? 

Q3:
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
http://code.google.com/p/pyscxml

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

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