Subject: Re: T13) Transactions - allowing optional commands

From: Christian Huitema <[email-masked]>
Date: Mon, 23 Aug 1999 11:27:57 -0400

At 09:47 AM 8/23/99 -0400, Tom-PT Taylor wrote:

>Regarding (3): we have a choice between the command, the action, or the
>message as the unit of acknowledgement.  Whichever we use has to be uniquely
>identifiable in the response.  This doesn't introduce anything new in
>principle.  We also have to bear in mind the different lengths of time that
>different commands may take to execute.  The unit of acknowledgement affects
>message volumes and what records the issuer of a command has to maintain.
>There's a tradeoff here: smaller acknowledgement units may mean increased
>acknowledgement message volume, but the command issuer can release records
>sooner.

The "all or nothing" is very much related to the acknowledgement/response
strategy. Let's but it this way: the concept of transaction does not make a
whole lot of sense if they are not atomic.  If they are atomic, then you
have to get a single acknowledgement per transaction, and all of the
transaction's command have to terminate at the same time. There is no way,
for example, to say that the addition of termination 1 is complete, but
that the addition of termination 2 is still in progress.

Maybe we should go back to the original MGCP design, remove the transaction
layer, and simply have atomic commands. That means that each command should
have its own "transaction-id", however you call it.
Christian Huitema

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From: John Segers <[email-masked]>
Date: Mon, 23 Aug 1999 18:20:41 +0200

One thing that the Transaction concept adds is ordered execution of the
commands it contains. Even if a Transaction is not atomic, it can be
acknowledged by one Accept or Reject.  Accept indicates that all
commands in the Transaction have been executed successfully; Reject
indicates that not all have been executed successfully and it specifies
which command caused an error.

BTW, I agree that "Transaction" is not a very good name for something
that is not atomic.

John

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