RE: [higgins-dev] Questions about IdAS registry

["Paul Trevithick" <paul@xxxxxxxxxxxxxxxxx>]

The idea behind adding the optional <Schema> element to the Context metadata
in the Service Endpoint (SEP) in the XRDS was to help find an appropriate
Context Provider that can realize/open this Context. 

The proposal currently allows only the <Type> element's value to drive
Context Provider selection. This will work fine for Context Providers that
can adapt themselves to whatever schema the Context in, say, a backing store
uses. But my concern was how to select a Context Provider from among a set
of candidate providers where some of them are highly optimized and/or
simplistic and only know how to open Contexts that have a specific schema.
In this case we'd need to at the target Context's schema as a consideration
for CP selection.

-Paul

Tom wrote:
> 
> I agree with Markus, I'm confused by that schema bit Paul just attempted
> to
> clarify.  In the JNDI Context Provider, I dynamically generate the
> ontology
> using what I find in the schema of the backing store and express it in
> terms
> of the base Higgins ontology.  It's not in a static file that can be
> pointed to
> nor something I expect to be specifiable (I've attached a sample generated
> output just FYI).  Anyway, I hadn't previously considered that the schema
> (ontology) was part of the resolution parameters for discovering the
> context
> needed.
> 
> Tom
> 
> >>> "Markus Sabadello" <markus.sabadello@xxxxxxxxx> 4/29/2007 9:29 AM >>>
> Thanks for the answers.
> 
> I still don't quite understand the role of the Schema. To define the
> "abstract Higgins Data Model" with an ontology makes perfect sense, but
> why
> would Contexts need ontologies of their own? And even if they do,
> shouldn't
> this be something that their respective Context Provider knows
> automatically, instead of having to look it up in the SEP?
> 
> I think I understand everything else.
> 
> Markus
> 
> On 4/29/07, Paul Trevithick <paul@xxxxxxxxxxxxxxxxx> wrote:
> >
> >  Hi Markus, see inline (Drummond plz scan for your name)
> >
> >
> >   ------------------------------
> >
> > *From:* higgins-dev-bounces@xxxxxxxxxxx [mailto:
> > higgins-dev-bounces@xxxxxxxxxxx] *On Behalf Of *Markus Sabadello
> > *Sent:* Saturday, April 28, 2007 8:25 PM
> > *To:* higgins-dev@xxxxxxxxxxx
> > *Subject:* [higgins-dev] Questions about IdAS registry
> >
> >
> >
> > Hi all,
> >
> > I have some background in XRI technology and I'm interested in helping
> > with the IdAS registry. I have a few questions about this page
> > <http://wiki.eclipse.org/index.php/IdAS_Registries_Proposal_2B>:
> >
> > - What is the difference between ContextId and ContextRef? They are the
> > same I think?
> >
> > Yes. ContextRef is the old/obsolete term for ContextId (see
> > http://wiki.eclipse.org/index.php/Concepts ) .
> >
> >
> > - The wiki page on "ContextId" says that a ContextId could be the URL of
> a
> > tab-delimited text file, but the page on "IdAS" makes me think that a
> > ContextId always involves XRI resolution? I understand that the IdAS
> looks
> > up a Context Provider based on the <Type> of a ContextId, but what does
> it
> > do if the ContextId is not an XRI?
> >
> >
> >
> > You have found another inconsistency in the wiki. What you call "IdAS"
> > page does not reflect the ideas
> here<http://wiki.eclipse.org/index.php/IdAS_Registries_Proposal_2B>because
> the latter is still just in the proposal stage. The proposal
> > (different from the ContextId wiki page says) implies is that a
> ContextId
> > always involves XRI resolution, although a ContextId is not necessarily
> an
> > XRI. What it boils down to is that a ContextId MUST reference (either
> > directly or through XRI resolution) an XRDS document. If a
> > file:///blahblah <http://blahblah/> does that, then fine.
> >
> >
> > - In Use case #1 on the "IdAS" page, the i-card manager first creates
> some
> > i-cards based on the <Type>s of <Service>s in an XRDS, and then the user
> can
> > click on one of them to perform XRI resolution and open a context based
> on
> > the found <Service>. I think there may be situations, in which the
> ContextId
> > could resolve to a different <Service> than the one it was originally
> > created from. In addition, I think there needs to be some way to check
> if
> > the XRDS changed between creation of the i-cards and opening of the
> Context.
> > Timestamping or hash values or something like that.
> >
> >
> >
> > Drummond, would you care to comment on this?
> >
> >
> > - Some wiki pages mention the "abstract IdAS data model of Digital
> > Subjects and Attributes" - does this exist already?
> >
> >
> >
> > That should say the "abstract Higgins data model." as described
> here<http://wiki.eclipse.org/index.php/Higgins_Data_Model>
> > .
> >
> >
> > - I assume XRI resolution will be based on a WD11-compliant resolver,
> even
> > if it does not exist yet? The new "strict" input parameter may be
> useful.
> >
> >
> >
> > Drummond?
> >
> >
> > - What exactly i
> s an i-card? Is it correct to say that an i-card has
> > exactly one ContextId, and that a ContextId leads to exactly one
> Context?
> >
> >
> >
> > See wikipedia (http://en.wikipedia.org/wiki/I-card) for an overview.
> >
> > See http://wiki.eclipse.org/index.php/I-Card for a Higgins perspective.
> >
> > Please email any inconsistencies you see in the above, or questions,
> etc.
> >
> >
> > - The description of the Context Registry mentions a <schema> element
> > within a <service> block. What is this schema? Something LDAP-specific?
> >
> >
> >
> > I just added something about Schema here
> >
> http://wiki.eclipse.org/index.php/IdAS_Registries_Proposal_2B#Context_Regi
> stry
> >
> >
> >
> > Drummond, I added this comment/question at the bottom of this entire
> page: [PaulT:
> > I wonder if in the Context Provider Registry described below we could
> and
> > should use both Type and Schema to find an appropriate Context Provider?
> > (Instead of just using Type)]
> >
> >
> > - Which software components relevant to this IdAS exist already?
> >
> > IdAS itself exists. (Click on the second row in this
> table<http://wiki.eclipse.org/index.php/Components#Identity_Attribute_Serv
> ice_and_Context_Providers>)
> > We are talking about building a new package within IdAS. Probably called
> > something like IdAS.contextResolver. We have not started on this. Jim
> > Sermersheim of Novell is the IdAS Component owner.
> >
> > greetings,
> > Markus
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
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> >
> >