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Subject: Formal proposal for issue i020
All, Here's a formal proposed resolution to issue i020 [1]. Rationale: The Delivery Assurance semantic applies to the "contract" between the logical RMD and AD, and the RMS and AS roles. It does not apply to the protocol as seen "on the wire". For example, if the InOrder DA were to be manifested on the wire, it would mean that the RMS could transmit but a single message at a time. It must await receipt of a SequenceAcknowledgement from the RMD acknowledging receipt of that transmitted message -- retransmitting that same message ad nauseum until such time as it has been acknowledged before proceeding to attempt transmission of the next in-order message in the sequence. That would be pathetic. That was clearly not the intent of the specification authors. The same applies to the AtMostOnce and ExactlyOnce DA. It is manifested between the RMD and AD, and/or between the RMS and AS roles, not between the RMS and RMD. The protocol itself is described as an "AtLeastOnce" protocol as manifested on the wire, meaning that each message MUST be transmitted at least once, and that each message MUST be acknowledged or retransmitted until such time as it has been acknowledged, or the Sequence is prematurely terminated. However, the DA does not apply to the protocol. Possibly, that is where the confusion lies. An RMD would effect an AtLeastOnce DA by passing received messages to the AD, possibly without bothering to perform duplicate detection. Proposed change/clarification: At line 162 of the WS-ReliableMessaging spec, delete the following paragraph: WS-ReliableMessaging provides an interoperable protocol that a Reliable Messaging (RM) Source and Reliable Messaging (RM) Destination use to provide Application Source and Destination a guarantee that a message that is sent will be delivered. The guarantee is specified as a delivery assurance. The protocol supports the endpoints in providing these delivery assurances. It is the responsibility of the RM Source and RM Destination to fulfill the delivery assurances, or raise an error. The protocol defined here allows endpoints to meet this guarantee for the delivery assurances defined below. and replace it with the following text: The WS-ReliableMessaging specification defines an interoperable protocol that enables a Reliable Messaging (RM) Source and Reliable Messaging (RM) Destination to ensure that each message transmitted by the RM Source is successfully received by an RM Destination, or barring successful receipt, that an RM Source can, except in the most extreem circumstances, accurately determine the disposition of each message transmitted as perceived by the RM Destination, so as to resolve any in-doubt status. The protocol allows the RM Source and RM Destination to provide their respective Application Source and Application Destination a guarantee that a message that is sent by an Application Source will be delivered to the Application Destination. This guarantee is specified as a delivery assurance. It is the responsibility of the RM Source and RM Destination to fulfill the delivery assurances on behalf of their respective Application counterparts, or raise an error. The protocol defined here allows endpoints to meet this guarantee for the delivery assurances defined below. However, the means by which these delivery assurances are manifested by either the RM Source or RM Destination roles is an implementation concern, and is out of scope of this specification. [1] http://www.oasis-open.org/committees/download.php/14329/ReliableMessagin#i020 Cheers, Christopher Ferris STSM, Emerging e-business Industry Architecture email: chrisfer@us.ibm.com blog: http://webpages.charter.net/chrisfer/blog.html phone: +1 508 377 9295
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