From: Anthony Nadalin
[mailto:drsecure@xxxxxxxxxx]
Sent: Wednesday, April 23, 2008
12:29 AM
To: Paul
Trevithick
Cc: 'Higgins
(Trust Framework) Project developer discussions'
Subject: RE: [higgins-dev] I've
updated the HGG wiki and PPT
My point is that there is no global graph as you may
only have relative identifiers (and that is perfectly OK),
I’m trying
to understand what you’re saying. Today in the Higgins
model all Entities live within Contexts and all of these Contexts are
identified by ContextIds. Today we do allow ContextIds to be “local”
–that is, NOT discoverable globally. Here’s how. The creator of a
Context can choose to describe it in an XRDS file that is behind a firewall or
even in a file on the local machine. Entities living within such a “local”
Context are thus NOT part of the global graph. I do admit that the Higgins wiki doc has a “global” bias,
whereas I realize in writing this email that many Context developer/deployers
may choose to keep their Contexts and the Entities they contain off the global
grid, so to speak.
also there are many other types of universal
identifiers besides URIs. Lets take the case of the phone number the context ma
be country code (+1) and the entity may be the area code and local number
(512-222-2222) thus I have a universal identifier that is not a URI,
If
and only if an Entity needs
to be addressable from OUTSIDE its local Context (e.g. if the Entity needs to
be a part of the global graph, or even if it needs to be addressable in a graph
that spans Contexts but is entirely behind a firewall) then it needs an
EntityId. So if the Entity doesn’t need to be addressable then it doesn’t
need an EntityId at all. At the Provo F2F (for Higgins
1.1) we, instigated by you, introduced the new idea that some Entities do not
have EntityIds. We call these BlankEntities. So we have a way of dealing with
Entities that are just like elements in a relational database —not directly
addressable at all.
OTOH, if an
Entity needs to be addressable from OUTSIDE of its local Context, then it does
need an EntityId. Its containing Context’s ContextId is the prefix of the
EntityId and a string (e.g. a telephone number) forms the rest of the EntityId.
If an Entity wishes to use a “global” (e.g. a +1…) telephone
number as the relative part of the identifier, then that’s okay too. But
the ContextId prefix is still required. And since containing ContextId must be
a UDI URI (e.g. http://foo.com ) then the
contained EntityIds would look like this: http://foo.com#+1-512-222-2222 ,
etc. (modulo necessary character encoding/escaping)
also not sure one needs a universal identifier as I
may only want to reference within a context so I only need the 512-222-2222).
The “local” Entity (that you
call 512-222-2222) would have an EntityId of http://foo.com#512-222-2222 where http://foo.com (as above) is the ContextId of the
containing Context.
BTW, in the Higgins
1.1 IdAS implementation of the HGG model, IEntity interface perhaps should have
a “getLocalId()” method that just returns the relative/local
EntityId (512-222-2222 or +1-512-222-2222 or whatever) in addition to the “getEntityId()”
method that returns the absolute EntityId.
So not in favor of this UDI as you describe, and we should discuss, these
changes just seem to pop into place w/o any discussions.
UDI is just a
new name for a concept that has
been in Higgins from 2003. That’s
why I’m saying we have a terminological issue here. The UDI resolution is
already implemented in Higgins 1.0 in
the IdAS Context Registry (see [1]). UDI is analogous to the role that URLs
play to knit together the web. Try to imagine the web (HTTP and HTML) without
URIs.
[1] http://wiki.eclipse.org/IdAS_Registry
Anthony Nadalin | Work 512.838.0085 | Cell 512.289.4122
"Paul
Trevithick" ---04/22/2008 05:38:56 PM---I think we just
have a terminological issue here. I agree that a telephone number string can
certainly be used as the relative
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From:
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"Paul Trevithick"
<paul@xxxxxxxxxxxxxxxxx>
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To:
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Anthony
Nadalin/Austin/IBM@IBMUS
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Cc:
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"'Higgins \(Trust Framework\) Project developer
discussions'" <higgins-dev@xxxxxxxxxxx>
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Date:
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04/22/2008 05:38 PM
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Subject:
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RE: [higgins-dev]
I've updated the HGG wiki and PPT
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I think we just have a terminological issue here. I
agree that a telephone number string can certainly be used as the relative portion of a UDI (e.g. the phone
number in this UDI: https://example.com/contexts/context100.xrds#617-555-1212 that uses an HTTP URI to get to its XRDS document) to identify an
Entity. And when it is prepended with its containing Context’s id (aka
ContextId) we now have that Entity’s absolute
UDI. [It is also true that Entities can have any number of additional attributes any of which can be
used for queries and thus act as identifiers to distinguish one Entity from
others.]
Without universal data identifiers (UDIs) (formerly called Higgins identifiers) there is no “global
graph” (or “data web” as some call this kind of thing, or the
“linked data” web that the semweb folks call it) at all. By
requiring that every Entity have a UDI that persistently identifies it, you can
create Entity-to-Entity relationships, correlations, federation, etc.
See also http://en.wikipedia.org/wiki/Linked_Data for closely related ideas.
From: higgins-dev-bounces@xxxxxxxxxxx
[mailto:higgins-dev-bounces@xxxxxxxxxxx]
On Behalf Of Anthony Nadalin
Sent: Tuesday, April 22, 2008 4:07 PM
To: Higgins (Trust
Framework) Project developer discussions
Cc: higgins-dev-bounces@xxxxxxxxxxx;
'Higgins (Trust Framework) Project
developer discussions'
Subject: Re: [higgins-dev] I've updated the HGG wiki and PPT
There
should be no identifier defined, this is just an attribute and the attribute
does not have to be a URI or a XRI, this is far too constraining as it can be a
telephone number, etc. Note that an identifier is not the same as the ContextID
or EntityID.
Anthony Nadalin | Work 512.838.0085 | Cell 512.289.4122
"Paul Trevithick" ---04/22/2008 02:13:43
PM---Jim,
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From:
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"Paul Trevithick"
<paul@xxxxxxxxxxxxxxxxx>
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To:
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"'Jim Sermersheim'" <jimse@xxxxxxxxxx>
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Cc:
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"'Higgins \(Trust Framework\)
Project developer discussions'" <higgins-dev@xxxxxxxxxxx>
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Date:
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04/22/2008 02:13 PM
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Subject:
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[higgins-dev] I've updated the HGG wiki and PPT
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Jim,
The wiki pages rooted at [1] have now been updated per Higgins
1.1 in three ways. First, the sub-pages all have (or should have) a
“Version” section at the top. Second I have eliminated the 1.0
concept of Entity and changed zillions of places where Node was to now read
Entity. Finally, I’ve update a few of them per our decision to simply use
Entities as complex values. I have also edited the PPT here [2] per the latest
HGG 1.1 model.
I also renamed “Higgins
Identifier” to “UDI” and expanded its coverage from HTTP URIs
and XRIs to also include support for the semweb community’s “Linked
Data” HTTP URIs. We haven’t yet implemented support for Linked Data
URIs but I think that doing so would allow Higgins
IdAS to be used as a gateway to at least some of the emerging Linked Data data
sources. Parity will be contributing resources to implement this stuff. It will
help the IdAS/Higgins cause WRT both
the partially overlapping semweb and the dataportability crowds.
-Paul
[1] http://wiki.eclipse.org/Higgins_Global_Graph_1.1
[2] http://dev.eclipse.org/viewsvn/index.cgi/org.eclipse.higgins/trunk/doc/org.eclipse.higgins.doc/Higgins-Data-Model-Intro.ppt?root=Technology_SVN&view=co
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