[graap-wg] minutes from 2/28 telecon

[Karl Czajkowski]

I am not sure that I am following this concern, but to my knowledge
WS-ResourceProperties does not define any coherency or consistency
among resource properties.  It only states that query results will be
valid according to the schema.  This is not about "writers" but about
dynamic RP documents and the possible lack of synchronization in
constructing the RP elements in query results.  (WS-RF tries to be
lenient about what infrastructure is required to implement the basic
facilities.)

I think the best approach would be to define RPs that are meaningful
in isolation from one another and only loosely associated with each
other via their association to the resource identity; dynamic values
that have temporal associations should probably be part of one RP
element rather than spread across several.  I do not think there is
anything risky about stating that a particular RP will be updated
coherently (coherence amongs its attributes and subelements).

A particular specification could add requirements, but of course this
might restrict the WSRF tooling environments that are capable of
hosting the standard.  Also, I would be concerned if we required
strong consistency and didn't make it so that a WS-Agreement
environment would degrade gracefully if the consistency were violated;
for example, references across terms could use temporally unique IDs
for dynamic elements so that a consumer could detect a dangling
reference rather than making an incorrect dereference.  I suppose you
could call this an implementation detail, but I would like to think we
could encourage or even mandate some hygiene...

Can someone explain concisely what the consistency hazard is that has
been raised?


karl


On Feb 28, Jon MacLaren loaded a tape reading:
> >Issue 13: The only thing that can change is the term states because
> >there is no updates.  So, there is no concern for consistency, and no
> >need for consistent updates.  **Action: Respond that we don't think
> >this is a concern in the follow up.  **Jim will add the comment to the
> >tracker.
> 
> Just to clarify...  I realise that no external parties able to update 
> the monitoring information.  However, the service/resource is changing 
> state - is this state change any different from an external writer?  I 
> wasn't sure that WS-RF would guarantee the user sees a consistent state 
> at these times - I thought you only needed one writer and one reader 
> for consistency problems here.
> 
> Maybe someone who knows WS-RF better than me can clarify this.
> 
> Jon.

-- 
Karl Czajkowski
karlcz at univa.com