On Aug 29, parkinm@cs.man.ac.uk modulated:
WS-Agreement is going to be used where these institutions don't exist? Any resource provider (read business) potentially charging for work can't do this in splendid isolation of the existing local regulations and law...
My point was rather that we expect these audit and legal issues to be "mixed in" by a community that deploys WS-Agreement for a particular purpose. I think we've talked around in circles but more or less observe that the underlying semantics of WS-Agreement are consistent with typical legal contracting environments. It may not be complete, but that is because we did not have the charter to try to standardize all aspects of discovery, security, audit, nor domain-specific SLA terminology.
I presume that what you think may be contestable is whether the contract was actually formed or not if the agreement was never recieved. I think we've covered this.
Yes, and yes. We're close to counting angels on pins, I'm afraid...
If the message semantics/schema are defined and agreed to then you should be able to tell the difference and there is no practical ambiguity. If you haven't defined the semantics/schema (or have only partially defined them) then how can you interoperate at all?
I think the WS-Agreement decision semantics are clear, but what the terms of the SLA actually mean and how these terms bind the two parties is necessarily domain dependent. Maybe my philosophy is too strange for you, but I have trouble defining obligations and trust in the absence of these domain-dependent concepts. Keeping my spec-authoring hat on, I have to remind myself that I do not know how strongly or weakly the domain-specific terms will capture obligations between parties when someone applies WS-Agreement in practice.
WS-Agreement defines the initiator/responder roles (offeror and offeree as you say) and is silent on resource provider/consumer roles because these concepts are inherently domain-specific.
I don't agree - generally, this is domain-independent precisely because the supplier or provider won't want to commit their goods before they know they are being sold. It also gives them the opportunity to say 'no' in case they have made a mistake or want to offer them to someone else. I say generally, because this may happen but it's a marginal case. Can you give me some examples where the offeror is the supplier/provider?
The very concept of "supplier" and "goods" is necessarily domain dependent. Therefore, WS-Agreement cannot make normative statements about this since it does not actually define any normative terms for any actual application domain. That was the general thinking in the working group after this topic was debated before...
Also, if "the computing service mak[ing] the offer" is an "unusual scenario", why does the protocol Dominic wrote up from your emails [2] describe this very situation? (Step 5).
Because it was an "unusual" interpretation of what I wrote, i.e. I would say that this step is completely backwards from what I described in my email. Did my reply to Dominic and the graap-wg list not go through? I thought I already pointed out that it was backwards, and repeated the idiomatic advance-reservation solution for 2PC which has the coordinator acting as initiator to both agreements with the resource provider.
This is something we could have handled in SNAP via our invitation message, but the GRAAP-WG intentionally removed this capability. As I described in an earlier email, one could approximate this through a sophisticated use of advertisements (templates) and some template exchange system, but I think it is safe to say we marginalized this use case.
I'm interested to know why this is a marginal use case for GRAAP-WG. I feel it is central in any agreement process in order for both parties to let the other know what they want/are providing without issuing any binding offers.
To illustrate the underlying WS-Agreement model and roles, it is for a responder to be equipped to receive and consider binding offers, and to shout from the rooftops: here are my templates, please give me offers! And it is for the initiator to somehow (not specified in WS-Agreement) hear these shouted templates, choose among them, formulate an offer, and contact the responder to initiate the protocol. What was marginalized in WS-Agreement was the idea of a customized or multi-round advertisement. It was considered sufficient (for now) to publish advertisements unilaterally, and formulate offers in response to these advertisements. If you want to allow either party to initiate, then the WS-Agreement solution would be for all parties to publish their templates as responders, and for all parties to choose wisely when they would like to become an initiator and make an offer. If you want custom tailored advertisements that take into account your own interests, then you need something more sophisticated. Either an elaborate brokerage/search facility to locate templates or an explicit multi-round discovery protocol. Both of these were set explicitly out of scope for the first version of WS-Agreement.
Sorry, but what does "worst opportunity cost" mean? Please, in a couple of sentences :-)
Michael.
Well, would we agree with this layman's definition of opportunity cost: the lost benefit associated with "locking" a resource and taking it out of play? If so, then the "worst" one is the one that has a higher cost in some global value system! Your judgement about wanting resource providers to be the offeree to avoid live-lock comes from a global view of the system, where you've placed value on the opportunity cost for both parties. E.g., if we stick to the computing environment scenario: the consumer who ties up his "computational units" and the provider who ties up his "computation resources". Then, you've made a judgement that the tying up of resources is a worse outcome than the tying up of the units, presumably because you expect the resources to be scarce or utilization to be the most important metric. This relative evaluation is deeply mired in your assumptions about what the resources are and what it costs the system (society, whatever) to have them tied up. Might there not be a community where the resource providers are hungry for customers and would gladly act as offerors to bid for the right to execute their applications? That possibility is at the heart of our decision to remain silent and allow domain-specific profiles of WS-Agreement to choose how best to apply the protocol. I personally think that this decision should be allowed at runtime, because even within a particular application domain, different participants may have different risk and benefit assessments. In fact, these assessments may vary depending on who they are dealing with. A fully symmetric deployment of WS-Agreement would allow this. karl -- Karl Czajkowski Software Architect Univa Corporation 1001 Warrenville Road, Suite 550 Lisle, IL 60532 karlcz@univa.com www.univa.com ________________________________________________________________ www.univa.com. The Leaders of Open Source Cluster and Grid Software The information contained in this e-mail message is from Univa Corp. and may be privileged, confidential, and protected from disclosure. If you are not the intended recipient, any further disclosure or use, dissemination, distribution, or copying of this message or any attachment is strictly prohibited. If you think that you have received this e-mail message in error, please delete the e-mail, and either e-mail the sender at the above address or notify us at our address.