[GRAAP-WG] Modification to the wiki Page on Renegotiating anestablished Agreement

[Omer F. Rana]

Hi Karl,

Very interesthing thoughts. Just some quick comments below.

Karl Czajkowski wrote:
> Well, my practical view, keeping in mind bounded-rationality systems,
> is that if the template was insufficient to guide you to an acceptable
> agreement offer, then a "hint" would not fair any better.  Either the
> advertiser announces its policies/restrictions in detail sufficient to
> create an agreement, or it does not.  Why would it reveal more
> information on the next iteration?  If you're trying to address
> intelligent parties who do bluffing and bartering, then your problem
> is out of scope for WS-Agreement...
>   
It is certainly possible that the detail contained in a template may 
increase in complexity as
interaction between parties proceeds. For instance, one could consider a 
coarse-grained advertisement
that identifies the types of capability that a provider offers, and not 
necessarily the ranges associated
with those capabilities. The hint would then be a subsequent refinement 
of these capabilities in
future interations. Yes, therefore there could be revelation of 
additional information in subsequent
interactions.


> Another intractable problem is that the resource manager making the
> decision may not even be able to formulate a specific reason for "why
> it didn't match", e.g. in a scheduler that is matching many properties
> at once against a dynamic load of competing requests, it is not
> necessarily easy to determine what would need to change to make a
> request get handled above other requests. Furthermore, it would have
> race conditions since the dynamic load may be different by the time
> the next offer arrives.
>   
Yes, agree about the matching problem. However, it is possible to rank 
matches (or mis-matches)
using some "match distance" metric. This can range from a associating as 
weight with attributes that
are of most significance to a particular party -- say, I am more 
interested in having a certain disk space
rather than a specific processor speed.

The way to deal with dynamic load -- as often undertaken in other 
performance prediction efforts --
is to deal with summary and aggregate data -- rather than raw data. 
Hence, one would base a prediction
on average (or some other time-based aggregate statistic) rather than 
the value at a particular point in time.

> So I think in practice, an automated WS-Agreement initiator is going
> to operate with some narrowly-defined commodity offers and try
> fallback, retry, and fail-over among responders.  If this fails,
> offline analysis and problem determination will be required to
> understand what went wrong, and how to improve templates and offering
> systems to avoid these doomed offers.
>   
Yes, agree with this. In the abscence of well defined constraints, I can 
see a lot of problems with
the approach. There are some automated approaches that can help with 
doing some of the post-failure
analysis.

regards
Omer

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