Hi Karl, On 29 Aug 2007, at 11:44, Karl Czajkowski wrote:
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
My point is that how do you know they can be "mixed in" successfully if they haven't been considered beforehand?
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.
With respect, we were talking generally, not specifically about WS- Agreement. I have no doubt the "decision semantics" in WS-Agreement are clear. I was making a general point because you said there were "practical ambiguities" in determining the differences between messages, which we both agree do not exist if the message schema and semantics are agreed to beforehand... About obligations and trust, I agree this is something we cannot solve completely here. But cross-administrative domain contracts in the presence of the threat of enforcement (legally) can help build trust between distrustful parties - therefore it is imperative any agreement/negotiation protocol is consistent with these requirements.
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.
Sorry, I still don't agree. The fact you can use the words "supplier" and "goods" without talking about what you're supplying or which goods you're referring to illustrates they are abstract, domain- independent concepts... I'll also ask my question again: can you give me some real-world examples where the offeror is the supplier/provider of goods? :-)
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?
Sorry, but there was no mention in your correspondence to Dominic that the protocol was an "unusual interpretation" of those emails. It doesn't say anything about you feeling step 5 was "completely backwards", though I agree your revised protocol does reverse the offer step. Thanks for clearing this up.
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.
Great! If step 5 is "backwards" we're agreed that the resource provider/supplier shouldn't make offers then?
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.
Yes, precisely my point from my last email - the offeror needs to take care. A wise provider/supplier should, therefore, always choose to be the offeree - the point we made in our paper.
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.
I agree that the provision of "tailored advertisements", or quotes, are something else to the general adverts you mention above (although there is no difference in law - they are both 'invites to treat'). But, I don't think this provision has to be "elaborate" or "sophisticated". As I said in a previous email, eCommerce websites, such as flight brokering firms, seem to have no problem providing this.
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.
As we said in the eChallenges paper, taking into account the wider picture, ensuring that (in this case) computational resources are not "tied up" is fairer for all customers too; no single customers can block other customers from making a definite offer on a particular resource unless they are committed to using the service by offering to enter into a binding contract for those resources.
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.
If you are referring to the eChallenges paper, then we used computational resource provision as an example because of the audience and conference it was intended for. Because we used this example it does not mean our/my general assumptions are "deeply mired" as to what the resources or goods are, as I hinted at in the 'domain-independent' comment above. From the example resources I gave in my last email (time, money, a book, a house... anything that can be traded) and my comments in previous emails I hoped this was clear, but obviously it wasn't...
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?
If these resource providers are "hungry for customers" it may mean they are unattractive or unknown to their potential customers. In the real-world a business would, for example, lower their prices, advertise to raise their profile, provide special discounts, etc. to attract customers. However, they still don't make binding offers - and by doing so they get the benefits of protecting themselves from making offers they cannot fulfil (i.e. mistakes), not having to commit goods until a customer has sent them a binding offer, and protection from denial of service possibilities that would leave them with even less income (as they can offer what they are selling for a higher price whilst another customer makes up their mind - again, allowing them to maximise revenue). As I mentioned above, their customers also get the benefits of knowing that other customers can't block them from making an offer on any goods or services too. Can you provide an example of where resource providers/suppiers would "gladly act as offerors"? :-) Thanks, Michael.