Subject: [Megaco] Event descriptor handling for static logic interfaces like CAS

From: Thomas Voith <[email-masked]>
Date: Wed, 01 Oct 2003 13:52:14 +0200

Dear list-members,

H.248.26 and in H.248.ICAS I miss a feature, which has been used
already for On-Hook, Off-Hook  the 'strict' parameter.

All interfaces, which have static states, should implement such
a mechanism.

The problem is that the EventsDescriptor EventBufferDescriptor or an
embedded EventsDescriptor may discard events, if the newly received or
replacing Event Descriptor does not match the event.

In the Megaco Secnarios, always just the good case is shown.

e.g. a static interface with 4 logical incoming events ( S1,S2,S3,S4)
would then set the EventsDescripror like:

MGC guess the MG is in state i1, no Notify will be sent by MG, when
state of interface is still i1.

Events { S1{strict="exact"},S2{strict="state"},S3{strict="state"},S4{strict="state"} }

( Note: in case "state" is the default, then EventsDescriptor could be shorter)

The events descriptor remains active, after Notification is sent.
The strict parameter avoids unnecessary Notifications for the already by MGC known state.

This mechanism would be very simple and avoids lost of any events, which is strong
required for signalling interfaces on MG transferred via H.248 to an MGC.

For a better illustration I have attached a Excel-File containing a simple scenario.

So my question/proposal is:

- Is it possible to extend the existing static state interfacepackages like H.248.26 with this
  strict feature?
- If not, can I get this functionality otherwise ?

Kind regards

Thomas Voith

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