Subject: RE: [Megaco] Sequential Signal List Interrupted by an Event

From: "Kevin Boyle" <[email-masked]>
Date: Fri, 16 Jul 2004 09:53:22 -0400

A sequential signal list is treated as if it were a single atomic signal.
In the case you describe, the signal list halts at the time of event
detection, so S1 is clipped and S2 is never started.

Note that in the absence of a signal list, signals play simultaneously, so
any signal that is not active will have already terminated on its own.

Kevin

-----Original Message-----
From: Juergen Stoetzer [mailto:[email-masked]] 
Sent: Friday, July 16, 2004 8:09 AM
To: [email-masked]
Subject: [Megaco] Sequential Signal List Interrupted by an Event

Hello,

According to Section 7.1.9 of H.248.1 recognition of an event causes any
active signal to stop unless the KeepActive flag is set for that event. More
specifically, it is said that "... event recognition may cause currently
active signals to stop, ..." and "Normally, recognition of an event shall
cause any active signals to stop."

In both places "active signals" are mentioned.
My question is how this should be applied to sequential signal lists.

Let's assume the corresponding termination has an active Signals descriptor
containing a sequential signal list of two timeout signals S1 and S2.
Let's further assume an event (without set KeepActive flag) occurs while the
first timeout signal S1 is still playing.
It seems to be clear that that currently playing first signal S1 has to be
stopped.

But what about the not yet started second signal S2?
Should this be started at that point anyhow?
Or should it rather be omitted?

More generally, should recognition of an event only cause currently, at that
very point in time active signals to stop without influencing possibly
present not yet started signals in sequential signal lists?
Or should recognition of an event not only cause "currently active"
signals to stop but should rather cause the whole signals descriptor to
become "inactive" (as if replaced with an empty signals descriptor)?

Thanks a lot in advance for comments and ideas on this!

Best Regards,
Juergen Stoetzer

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From: "Kevin Boyle" <[email-masked]>
Date: Mon, 19 Jul 2004 11:39:23 -0400

Stop sending to megaco-bounces.  That is an admin interface to help weed out
spam.

The event reporting would occur AFTER the signal is stopped, not before.

You are talking about actual physical steps an MG might take to replace a
signals descriptor.  From a protocol point of view, however, a embedded
signals descriptor replaces the existing descriptor in a single step.
Speaking from the higher level view of the protocol:

1) The signals descriptor is replaced, halting any signals that are not
present in the new signals descriptor with the KA flag.
2) Notifications for any requested complete signals are sent.

As far as detection of an event, the signals descriptor is not replaced.
The signals are just halted (if the event does not contain the KA flag),
with the subsequent event notification for requested signal completion
following thereafter.

Kevin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: Monday, July 19, 2004 12:34 AM
To: Boyle, Kevin [NCRTP:3Z40:EXCH]
Cc: Juergen Stoetzer; [email-masked]; [email-masked]
Subject: RE: [Megaco] Sequential Signal List Interrupted by an Event

Hi
      ACTIVE is the keyword there. Even if there is a embedded signal
descriptor, the currently ACTIVE signal descriptor has to be removed first
and then the embedded signal descriptor gets applied. So the logical steps
in handling a Event indication would be:
1) Report the Event to the Call Agent if the signal completion is armed.
2) Stop the signals thereby disabling the currently active signal
descriptor.
3) If there are any embedded descriptors present then activate them. In the
embedded case, the currently active signal descriptor is infact replaced by
the non-empty embedded signal descriptor.

regards
B Venkat S.R Swamy
Hughes Software Systems
Phone:  +91-124-2455555 Extn 3620
Fax: +91-124-2455345
web: www.hssworld.com

             "Kevin Boyle"                                                 
             <kboyle@nortelnet                                             
             works.com>                                                 To 
             Sent by:                  B Venkat S.R Swamy/HSS@HSS, Juergen 
             megaco-bounces@ie         Stoetzer <[email-masked]>    
             tf.org                                                     cc 
                                       [email-masked]                     
                                                                   Subject 
             07/16/2004 07:24          RE: [Megaco] Sequential Signal List 
             PM                        Interrupted by an Event             

                                                                           

Be careful here.  There is a subtle distinction between active signals and
the Signals descriptor.  I disagree with the idea that an event without a KA
flag is an implied embedded empty signals descriptor, since there may very
well be an embedded signals descriptor on the event.  The signals descriptor
itself is not being replaced -- the atomic signals themselves are stopping.

Kevin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Friday, July 16, 2004 8:34 AM
To: Juergen Stoetzer
Cc: [email-masked]; [email-masked]
Subject: Re: [Megaco] Sequential Signal List Interrupted by an Event

Hi
      An Event recognition without KeepActive flag  causes the currently
active signal descriptor to be disabled irrespective of the status of the
individual signals in the signal descriptor as if an embedded empty signal
descriptor got invoked.

Regards
B Venkat S.R Swamy
Hughes Software Systems
Phone:  +91-124-2455555 Extn 3620
Fax: +91-124-2455345
web: www.hssworld.com

             Juergen Stoetzer
             <J.Stoetzer@alcat
             el.de>                                                     To
             Sent by:                  [email-masked]
             megaco-bounces@ie                                          cc
             tf.org
                                                                   Subject
                                       [Megaco] Sequential Signal List
             07/16/2004 05:39          Interrupted by an Event
             PM

Hello,

active signal to stop unless the KeepActive flag is set for that event.
More

Best Regards,
Juergen Stoetzer