HI Again:
What I'm trying to say is that there is no "implicit message"... the agreement factory is the agreement responder in this picture (for AI=MI in your terminology). It is one entity and we really should not say anything about the internal implementation structure.
I totally agree..
I should have labeled the "agreement factory" in steps (3) and (4) as "renegotiated agreement factory" since we really haven't stated whether these would be separate port types. But it was my intention that these factories be interfaces to the same responder entity for the AI=MI case.
I am worried about this ""renegotiated agreement factory" with the role of the original agreement factory . Can they be completely differnent? Best Regards Toshi ----- Toshiyuki Nakata 中田 登志之 Executive Chief Engineer, Central Research Lab. NEC 1753, Shimonumabe, Nakahara-Ku, Kawasaki,Kanagawa 211-8666,Japan Tel +81-44-431-7653 (NEC Internal 22-60035) Fax +81-44-431-7609 (NEC Internal 22-60509)
-----Original Message----- From: Karl Czajkowski [mailto:karlcz@univaud.com] Sent: Saturday, March 01, 2008 3:09 PM To: Toshiyuki Nakata Cc: graap-wg@gridforum.org Subject: Re: [GRAAP-WG] Re-negotiation Protocol Proposal
On Mar 01, Toshiyuki Nakata modulated:
Hi Again:
I wouldn't say slide 7 captures my comment. My endpoint rendering doesn't imply a third entity, just that the responder entity is rendered with multiple endpoints to allow a more general scenario such as renegotiation that could combine multiple agreements (something you couldn't do if the preceding agreement is always implied like the "this" pointer in a simple object system):
1. agreement initiator sends offer to agreement factory
2. agreement factory sends accept (sync or async reply)
... repeat 1-2 for multiple agreements...
3. renegotiation initiator sends offer to agreement factory
4. agreement factory sends accept (sync or async reply)
These are somethngs I can guess and feel provide an elegant solution, but I feel that the implicit messages needed here between the Agreement Responder and the Agreement Factory would needed to be spelt out or (My guess) would always, fail..
What I'm trying to say is that there is no "implicit message"... the agreement factory is the agreement responder in this picture (for AI=MI in your terminology). It is one entity and we really should not say anything about the internal implementation structure.
I should have labeled the "agreement factory" in steps (3) and (4) as "renegotiated agreement factory" since we really haven't stated whether these would be separate port types. But it was my intention that these factories be interfaces to the same responder entity for the AI=MI case.
For the case where AI=MR, it gets more complicated just as the basic existing WS-Agreement is more complicated when you put agreement resources on both sides:
1. Agreement initiator sends offer to agreement responder's factory.
(with embedded PendingAgreement EPR in offer, representing initiator's view of the offered agreement, also combining the AgreementAcceptance port type)
2. Agreement responder sends accept (sync factory response or async Accept response)
3. Eventually initiator's agreement state progresses to Observed when he learns of acceptance (this is the decoupled distributed state transition we've discussed before)
everything above is possible in the existing WS-Agreement protocol.
...discovery magic happens...
4. Agreement responder, acting as renegotiation initiator, sends renegotiate offer to agreement initiator's renegotiation factory.
(with embedded PendingRenegotiatedAgreement EPR in offer, representing renegotiation inititator's view of the offered renegotiated agreement)
5. Agreement initiator, acting as renegotiation responder, sends accept (sync factory response or as async Accept response)
6. Eventually agreement responder's renegotiatedion agreement state progresses to Observed when he learns of acceptance (this again is the decoupled distributed state transition)
Several notes:
A. The magic discovery is there because the renegotiation initiator has to determine the appropriate renegotiated agreement factory EPR from the existing agreement information. I didn't want to attempt to address that technical issue here, but just assume it is dealt with somehow.
B. This symmetric arrangement established in (1)-(3) would support either AI=MI or AI=MR scenarios, since both parties would have discovered renegotiation endpoints for the other party. The simpler, asymmetric client-server arrangement of the previos email only supports AI=MI since there are no factory service endpoints on the agreement initiator side in that case.
C. With the right message schemas, one polymlorphic factory type could serve both initial and renegotiated agreement requests, so there would only need to be two factories (one per party) instead of the four logically separated roles above.
D. A somewhat hairy naming issue exists. Do we really want to create new Agreement resources and EPRs for each renegotiation, or is it better to treat the resource like an "envelope" and use some internal GUID-like name to name specific versions of agreement? (In this case, the agreement resource would hold info for the first, superceded, agreement and then the revised agreement, with stable addressing. I'm not sure which approach is better, but I seem to recall there being a versioning/naming mechanism inside the WS-Agreement schema already. I have a bad network connection today and cannot easily retrieve the current specification to verify this... apologies if I'm remembering something that got dropped during the standardization process.)
karl
-- Karl Czajkowski Software Architect
Univa UD 1001 Warrenville Road, Suite 550 Lisle, IL 60532
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