Group Termination without Explicit Timing Parameters

[Tom Rutt <tom@coastin.com>]

The problem case for group autotermination, based on a 
MaxExpiryTimeOfMessagesReceivedInGroup
was when the sender had a later message with smaller expiry time than an 
earlier message in
the sequence.

Ordered example 3

GroupExpiryTime 8:00pm

1 – exp4pm (start) sent at 0 pm –

2 – exp8pm (continue) sent at 0 pm –

3 – exp 4pm (end) sent at 0 pm

receive 1 - at 1pm ack, derived get=4pm then make avialable to user -

recieve 3 – 1.05 pm then ack – derived get=4pm, and buffered (not made 
available yet, waiting for 2

8pm – group terminated, 3 removed from messageOrder queue, will not be 
made available to use.

8pm – terminate new sequence, remove 2 from buffer will not be made 
available to user.

receive 2 – at 9:00 PM – expired, not acked and do not start new sequence.

One solution is to have the protocol disallow this from the sender:

"The ExpiryTime for each message in a group sequence MUST be greater or 
equal to the
expiryTime for all preceeding messages in that group."

We already require that they be less than or equal to the 
groupExpiryTime when it is present, The above rule could be the 
corresponding validity check for the case when there is no groupExpiry 
Time or idleInterval specified by the sender.

Tom Rutt



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Tom Rutt		email: tom@coastin.com; trutt@fsw.fujitsu.com
Tel: +1 732 801 5744          Fax: +1 732 774 5133