RE: [bt-spec] Issue 15 - Negative reply to BEGIN

[Sanjay Dalal <sanjay@bea.com>]

>I suppose one could use a qualifier on FAULT to point to the message / parameter that caused the problem.

 

>>Since we can potentially compound many different messages and not just BEGIN/CONTEXT, I would suggest that we need some general mechanism that allows users to determine exactly where the error occurred.

 

I agree on having a general mechanism to determine where and what exactly happened in case of faults with compound messages. Reference mechanism will be needed especially for FAULTs in compound messages.

 

Also, do we describe what should happen if fault occurs for 2nd out of 3-related-message group compound message? Should actions of the whole group be reversed or only of the failed message? Compound messages are processed in order. That means, if 2nd message fails, 3rd message is never processed. However, what about the effects of the 1st message? Should it be reversed? This is even difficult if an application message is present in that group. Is the effect of compound message group atomic? I think not. So, it seems failures in Compound Messages deserve a paragraph or two in "Failure Recovery" section to address all such questions.

 

sanjay

-----Original Message-----
From: Mark Little [mailto:mark_little@hp.com]
Sent: Friday, January 25, 2002 4:54 AM
To: Tony Fletcher; BT - spec
Subject: Re: [bt-spec] Issue 15 - Negative reply to BEGIN

 

I guess that the spec is not very heavy at present on error reporting - it takes a relatively light, but probably adequate, touch. 

I think as far as error reporting is concerned "adequate" is not good enough in a distributed system. It's hard enough to track down problems locally without having to factor in remoteness.

 

 I think that what you are highlighting is actually a problem when you have more than one BTP message travelling together - which one does a FAULT message in reply refer to?  I suppose one could use a qualifier on FAULT to point to the message / parameter that caused the problem.

 

With regards to BEGIN, would you like to propose some text for us to consider?

Since we can potentially compound many different messages and not just BEGIN/CONTEXT, I would suggest that we need some general mechanism that allows users to determine exactly where the error occurred. However, specifically for BEGIN I'd suggest adding text along the lines of "If BEGIN is accompanied by a CONTEXT then the additional FAULT of WrongState may be returned."

 

Mark.

 

----------------------------------------------
Dr. Mark Little, Distinguished Engineer,
Transactions Architect, HP Arjuna Labs
Email: mark_little@hp.com
Phone: +44 191 2606216
Fax  : +44 191 2606250