[i006] Two facets of issue i006...

[Jacques Durand <JDurand@us.fujitsu.com>]

Title: [i006] Two facets of issue i006...

I believe there are (at least...) two aspects in what Tom has raised:

(a) In case it is possible an RM Destination may have to deal with
Several delivery assurance (DA) policies concurrently then it must be able to discriminate which one applies to a received message without having to peek inside the message at something else than Sequence ID. In other words, the sequence # used by the Source would determine the DA used.

Yes that hinges on issue i008, but not exclusively: we first need to decide if we consider use cases where a Source willingly declines using DA offered by Destination (e.g. due to overhead). Also is there a requirement that an RM Source be always  assigned to a single WS port?

(b) *In general*, both RM Source and RM Destination have their behavior affected by the use of a delivery assurance. This is true for atLeastOnce, and also InOrder (where RM Source must first ensure it transmits messages in the order the Application sent them), with the exception of AtMostOnce where the Source has nothing to do. Consequently each side must know which DA applies when using a sequence, and currently there is no way to communicate this association <DA - sequence> to the other party (regardless of which party made this association).

Does this clarify the point, Tom?

Jacques

-----Original Message-----
From: Tom Rutt2
Sent: Thursday, July 14, 2005 12:19 PM
To: wsrx
Subject: [ws-rx] Discussion on Issue i006

This email is intended to start discussion on the ws-rx issue i006

I006 - Source based delivery QoS policy assertion
http://lists.oasis-open.org/archives/ws-rx/200506/msg00055.html

Here is a more precise statement about the real issue at the core of i006

"How does the RM Destination know which level of Delivery assurance to
associate with a received message?"

We can't just discard this question as only relevant to the
implementation space, especially if the assumptions below are valid:

- I expect an RM Destination to handle concurrently several sequences
associated with different delivery assurances (DA) (driven by different
WS operation requirements, e.g. InOrder or not, but also by SLA
requirements, given the cost / overhead of RM)
- Even if we assume that some DA is statically assigned to an endpoint,
a layered implementation (see discussion below) of the RM destination
component should not have to peak inside the message body or other
headers to figure the DA. RM Header data such as Sequence ID should be
sufficient.
- Assuming all messages within a sequence as associated with the same
delivery assurance (DA) (assumed in WS-RM Policy), it is not clear how
the RM Destination associates a new sequence ID with a DA, when
answering a SequenceCreation request from the Source.

The following discussion items make a more detailed case for the above
assumptions.