[ogsa-wg] BES query

[Steve Loughran]

Tom Maguire wrote:
> owner-ogsa-wg at ggf.org wrote on 08/31/2005 01:32:59 AM:
> 
>>The other major camp places a high priority on implementer and
>>application freedom to use different reference formats. It considers
>>that references always exist in some implicit relational model
>>(maintained by applications, communities, etc.) where interesting or
>>important identity attributes are maintained. As such, the references
>>themselves do not need to express identity for interop.
> 
> 
> Yes, Distributed Computing 101.  If you authoritatively want
> to test if two things are the same you MUST ask the things.
> Placing the identity in the reference is an "interesting" optimization
> technique. The real difficulty for me (and implementers) is the
> "universal" context in which these identities live.  One of the
> reasons that hierarchical namespace lookups exist is because they
> are capable of massively scaling. Logically flat identity spaces
> do not scale.  There may be ways of making AbstractNames scale but
> I am not suitably well versed to understand how.
> 

1. WSDM has a ResourceId (case?) property that is required to be unique. 
If you do a WSDM-compliant endpoint then anything can ask for the 
resource and all is well.

2. Having just submitted something to the editor, I am reluctant to keep 
chasing the moving targets that are the OGSA set of requirements. You 
cannot keep adding more and more unstable specifications to the 
requirement list if you ever want to see a working implementation ship.

I  actually had a lot of fun in the CDDLM trying to deal with the 
problem of fault tolerance (=different EPRs for things), and resource 
lifetime (=operations to delete resources at the end of the wire), and 
to address things consistently. The original WS-* specification (and 
functional implementation) used simple unique IDs to identify things. 
You pass the UID down to the endpoints with your requests, you got 
answers back. There was no need to have uniqe EPRs; any endpoint that 
acted as a portal to the set of nodes you were deploying onto should be 
able to handle requests related to the UID.

Its only once you add the notion of 
state-as-described-by-a-remote-reference into the equation that suddenly 
we are left with the problem that that you cant do fault tolerance in a 
resolvable address without extra magic in the system. Maybe this is a 
good argument for not using URLs/WS-A addresses in this way.

-Steve