addParticipant optimization

[Mark Little <mark.little@arjuna.com>]

In order to try to move this forward, here's another go at some proposed 
text for optimizing the addParticipant messages. This has been 
repositioned to be within WS-CF, rather than WS-ACID. I'd like to get to 
the point where we could have some concerete proposal for vote at the 
telecon on Monday.

"A service that receives a WS-CF context on an application request 
SHOULD enlist participants with the corresponding activity group if the 
operation execution semantic for the activity requires enlistment. The 
Referencing Specification or implementation MAY decide to use the 
following protocol to optimize remote registration invocations.

Rather than register participants directly, the wscf:addParticipants 
messages MAY be delayed and retained by the Registering Service until 
the response to the original invocation is sent; in which case a 
wscf:AddParticipants SOAP header element, which contains the individual 
wscf:addParticipants messages is propagated back with the response. 
[Editor's note: this element MUST have SOAP:mustUnderstand defined to be 
true.]

If a receiver of a response obtains this SOAP header it MUST be able to 
perform the enlistments or, if it does not support this optimization, 
send back a wscf:CannotOptimizeEnlistment fault code message.  In the 
case of failures (e.g., delivery failure of the application response), 
it is up to Referencing Specifications as to the appropriate action to 
take, e.g., in the case of an ACID transaction implementation, any 
associated transaction MUST be forced to roll back. An implementation 
MAY retry transient registration failures.

When using this optimization, the Registering Service MUST still see a 
wscf:participantAdded message in order to be compliant with WS-CF. How 
that message is produced is up to the Referencing Specification or 
implementation. For example, when used in conjunction with ACID 
transactions, an implementation MAY require this to be tied into the 
notion of checked transaction semantics."

Mark.

-- 
Mark Little
Chief Architect
Arjuna Technologies Ltd
www.arjuna.com