Re: [ws-rx] PR035, PR009, PR020: DA defs

[Matthew Lovett <MLOVETT@uk.ibm.com>]

Hi all,

Following on from the discussion about using "deliver" rather than 
"process to conclusion", here are some definitions that Peter and I have 
worked on. We believe these definitions help define the end-to-end DA, as 
they include the RMS behaviour.

--

wsrmp:DeliveryAssurance

When applied to an RM Destination, this element defines a policy assertion 
that identifies a requirement on RM Sources. Any RM Source that transmits 
messages to this RM Destination SHOULD conform to the requirement 
expressed by this assertion. Conversely, when it is applied to an RM 
Source this assertion identifies a requirement on RM Destinations. Any RM 
Destination that receives messages from this RM Source SHOULD conform to 
the requirement expressed by this assertion.

wsrmp:AtLeastOnce

Each message is to be delivered at least once. The requirement on an RM 
Source is that it SHOULD retry transmission of every message sent by the 
Application Source until it receives an acknowledgement from the RM 
Destination. The requirement on the RM Destination is that it SHOULD retry 
delivery to the Application Destination of every message that it accepts 
from the RM Source. There is no requirement for the RM Destination to 
apply duplicate message filtering.

wsrmp:AtMostOnce

Each message is to be delivered at most once. The RM Source MAY retry 
transmission of unacknowledged messages, but is NOT REQUIRED to do so. The 
requirement on the RM Destination is that it MUST filter out duplicate 
messages, i.e. that it MUST NOT redeliver any message.

wsrmp:ExactlyOnce

Each message is to be delivered exactly once. The requirement on an RM 
Source is that it SHOULD retry transmission of every message sent by the 
Application Source until it receives an acknowledgement from the RM 
Destination. The requirement on the RM Destination is that it MUST filter 
out duplicate messages, i.e. that it MUST NOT redeliver any message.

--

Some additional comments:

Doug pointed out that we talk about the RMS and RMD here, but that the 
wsrmp spec doesn't quite call out where the RMS and RMD are. For example, 
if a WSDL output message is decorated with the RM assertion + a DA, we 
would expect the server-side RMS to exist and do it's part, and similarly 
the client side RMD has a role to play. I think that this is a separate 
issue, and needs a bit of discussion, but the text for the DAs should be 
ok however we resolve that.

Jacques: I hoped to get this out to you earlier so you could see our 
thought process, but I'm running out of time before the call. I'm sorry 
that time got away from me!

Thanks

Matt