Subject: RE: Error in transaction reply.

From: [email-masked]
Date: Thu, 3 May 2001 21:09:51 +0530

Hello,
     There could be an alternative to
"Of course, you could get a syntax error on a transactionAck!  I think we can
either ignore that possibility, or allow the Ack the other way.  I'd vote
the former."
The MG at this point just needs to know whether the MGC has processed the
response or not. Thus it needs to know only the transaction id for the response
which had failed. So the transactionAck with error descriptor could be replaced
with a subtractTransaction which contains just the transaction id. If the MG
understands the subtractTransaction token and the transaction id, it could undo
the changes. If it fails to decode the token or the transaction id, anyhow a
message level error should be generated in which case the action for handling a
message level error would come into action.

                                         Regards,
                                         R. Ezhirpavai

"Rosen, Brian" <[email-masked]> on 05/03/2001 06:48:17 PM

To:   "[email-masked]'" <[email-masked]>, R Ezhirpavai/HSS@HSS
cc:   Madhu Babu Brahmanapally <[email-masked]>, "'megaco mail list'"
      <[email-masked]>

Subject:  RE: Error in transaction reply.

I'm beginning to think that maybe we ought to do something about this.

First of all, every one of these discussions around syntax errors often
misses
a real important point
    There is basically no recovery possible for the error
This is because there is no way either end is going to change the SYNTAX
of the message it sends as a result of an error.  It's going to take the
offending
programmer to do that (20 lashes with a wet noodle please).  Your only
real recourse is:
    Don't do whatever caused that problem to happen, until the software is
fixed

Now, having said that, real systems often have problems and vendors need
a way to figure out what happened and even customers need a way to figure
out that something wrong happened so they at least have a shot at a
workaround.

The best solution I can come up with is a real change to the protocol, and
I'm not
at all wild about proposing something that actually changes things, but here
goes:

Send a TransactionAck (even if you are using a reliable transport) with an
error
message.

Of course, you could get a syntax error on a transactionAck!  I think we can
either ignore that possibility, or allow the Ack the other way.  I'd vote
the former.

Brian

-----Original Message-----
From: Titty Thomas [mailto:[email-masked]]
Sent: Wednesday, May 02, 2001 11:39 PM
To: [email-masked]
Cc: Madhu Babu Brahmanapally; [email-masked]; 'megaco mail list'
Subject: Re: Error in transaction reply.

Hi ,

    In this case one of the options can be to audit the MG and find out its
state.

Regards,
-- Titty

[email-masked] wrote:

Hello Madhu,
     If the MGC assumes that the transaction response containing a parse
error
is a transaction reply with error, then this would lead to discrepancy
between
the states of MG and MGC. The MGC would assume that the MG has not processed
the
request whereas the MG would have processed the request and would have
possibly
changed the termination state.

                                         Regards,
                                         R. Ezhirpavai

"Madhu Babu Brahmanapally" <[email-masked]> on 05/02/2001 07:09:47 PM

To:   [email-masked], "'megaco mail list'" <[email-masked]>
cc:    (bcc: R Ezhirpavai/HSS)

Subject:  RE: Error in transaction reply.

Hi Titty,

In normal circumstances, even if the MGC retransmit its transaction-request
the same transaction response is received from MG. IMO the MGC can treat the

error transaction response as error response from MG.
Regards
Madhubabu

 -----Original Message-----
From: [email-masked]
[ mailto:[email-masked]
<mailto:[email-masked]> ]On Behalf Of Titty Thomas
Sent: Wednesday, May 02, 2001 12:04 AM
To: megaco mail list
Subject: Error in transaction reply.

  Hi all,

      If there is an error in transaction reply, what will the receiver of
the reply do. How
  can he report back to the sender that the reply was an error. And what
will happen if

  the reply had some values chosen by the sender (eg. reply for a command
with $ ) and the

  value is in error.

  Regards,

  - Titty

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From: Christian Groves <[email-masked]>
Date: Fri, 04 May 2001 14:29:13 +1000

I think Brian has a valid point. If you have a syntax error you can't
recover - there's something fundamentally wrong with the stack.
Depending where the actual syntax error is you may not even be able to
send anything sensible back. The side that detects the error in a
transaction reply should notify the appropriate O&M systems. As Brian
points out what happens if the ack has an error.

Christian