Subject: RE: [Sipping] VoiceXML Dialog Servers

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 19 Sep 2001 00:01:18 -0400

> -----Original Message-----
> From: Paul Kyzivat [mailto:[email-masked]]
> Sent: Friday, September 14, 2001 11:19 AM
> To: Michael Hammer
> Cc: [email-masked]
> Subject: Re: [Sipping] VoiceXML Dialog Servers
> 
> 
> Michael,
> 
> I will take a crack at your first question:
> 
> Michael Hammer wrote:
> > 
> > The description on page 7 implies that there can be many 
> servers running
> > VSML interpreters simultaneously under the feature 
> interaction control of
> > the application server.  In 4.2 the effect of the BYE seems 
> to be local to
> > the application server. (?)  Shouldn't this also indicate that the
> > application server has the responsibility to send BYE to 
> all other servers
> > related to that caller, so they can exit abnormally from 
> any active or
> > suspended scripts?  Cleaning up these stateful machines could avoid
> > accumulation of hung scripts.
> 
> 
> The AS is acting as a 3pcc, coordinating call control for multiple
> related calls. It receives the BYE from any of them, and is 
> responsible
> for doing the right thing, whatever that might be. In the example, the
> AS has preempted the call to the stock service in order to 
> give focus to
> the notification service. When the AS receives a BYE from
> thenotification service , it knows that the right thing to do 
> is resume
> the stock service. However, if it received a BYE from the user, the
> right thing to do would be to send BYEs to both the stock service and
> the notification service.
> 

There is not so much depth to what 4.2 is saying. The error in this section
is the use of the word "caller". Really what this is trying to say is that
when the vxml interpreter context gets a BYE, it throws a
telephone.disconnect event to the interpreter. "caller" in this case, is the
3pcc controller, NOT the end user. 4.2 is not trying to dictate any rules
about how feature composition and interaction is done. I'll change to
reflect this.

Michael Hammer wrote:
> Second, when suspending the script, it appears that the 
> script has the job 
> of deciding when to "finish its sentence" (at an appropriate 
> checkpoint) 
> and reply to the re-Invite which suspends it, prior to the 
> application 
> server giving the go-ahead to the second server.  Are there 
> any guidelines 
> to how verbose an server can be?  Is there a way to interrupt 
> one that is?

This bit is really something that the voice browser group in w3c has to
figure out. They are actively debating this stuff right now. 

> 
> Third, there is no Security section to this document. 

-00 syndrome.

> It 
> appears to be 
> anticipated that the dialog server will download scripts from the 
> application server which is trusted.  Is it conceivable that 
> the scripts 
> are from third-party sources, even the user? 

Absolutely. It depends on the application.

> Is that out of 
> scope for this 
> document?

Where the VXML scripts come from is most definitely out of scope for this,
or any other standards document. The app components architecture merely
argues that there is benefit to getting them from the AS.

-Jonathan R.

---
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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