Subject: [Atoca] Summary of "Requirement D2: Large Audience" Discussion

From: Hannes Tschofenig <[email-masked]>
Date: Sun, 27 Feb 2011 12:11:07 +0200

Hi all, 

thank you for your feedback on the long thread regarding the large audience requirement. 

Your feedback went in various directions, some of them were not related to the initial question. 

The initial question was about the refinement of the currently provided text that does not further specify a **number** for large audience. 

Two suggestions were made to deal with this issue: 

1) Talk about broadcast

2) Segment the numbers into groups depending on the likely number of recipients. 

Both approaches sound fine to me but I believe the former might be more appropriate because it points to the different architectural variants currently described in the document. 

I believe that this would be a good discussion topic for the upcoming IETF meeting. In particular, it would be interesting to discuss what tools we have in SIP to deal with the fulfillment of some of these requirements.  

The discussion then went on and lot of focus was spent on the "acknowledgment" messages that a receiver may sent as a confirmation of an alert delivery. 
There, a number of issues were raised, such as 
* At what layer does the ack happen? (e.g., SIP 200 OK, transport layer, application layer ack)
* Is the ack useful for cases were the alert message it targeted to a specific set of receivers rather than broadcasted? 
* Are we bound to the capabilities of the underlying communication infrastructure? 
* What are the scalability constraints? 
* Is an aggregation mechanism for acks useful? 

Ciao
Hannes