RE: Policy Retrieval Algorithms

Hi Paul,

> there is no requirement that the IRI be resolvable

I would also note that the IRI CAN be resolvable.  Using resolvable IRIs seems like a natural and interoperable way of dealing with external references.

> defining a way to identify a retrieval mechanism could/should be in scope.

This seems unnecessary since IRI's already define a way to specify how to resolve them.  Supporting more creative resolution mechanisms seems like a Policy vNext feature.

Daniel Roth

________________________________
From: public-ws-policy-request@w3.org [mailto:public-ws-policy-request@w3.org] On Behalf Of Paul Denning
Sent: Friday, October 06, 2006 12:47 PM
To: public-ws-policy@w3.org
Subject: Policy Retrieval Algorithms

[1] http://tinyurl.com/ot5x5#Policy_References

Section 4.3.4 states

"...there is no requirement that the IRI be resolvable; retrieval mechanisms are beyond the scope of this specification."

I would agree that defining various retrieval mechanisms would be out of scope, but defining a way to identify a retrieval mechanism could/should be in scope.

Perhaps adding

<proposal>

wsp:PolicyReference/@RetrievalAlgorithm

  This optional URI attribute specifies the Retrieval Algorithm being used to resolve an external policy expression identified by ./@URI.

</proposal>


Note that this is modeled after the DigestAlgorithm.  You would not provide @Digest without specifying the @DigestAlgorithm used to calculate it.

@Digest is opaque and you cannot determine the digest algorithm by looking at its value.

Likewise, we should treat @URI as opaque and provide an identifier for the algorithm that can be used to resolve the external policy expression.

Paul