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Re: [higgins-dev] Improving Higgins XDI syntax
Drummond, you're right about the urn's not being shorten-able. But they shouldn't have been urns in the first place. That was another error in the XDI example that I should have called out separately (I'll updated the wiki page now (http://wiki.eclipse.org/Higgins_PDS_Access#UDIs_not_URNs)).

1) UDIs not URNs

EntityIDs are supposed to be resource UDIs not URNs. So after we correct that error in our XDI then the entityIDs will look like this: 

=mydex.org@alice/$context$xdi+home+and+family//=alice

Where 
  • =mydex is the name of the PDS operator
  • @alice is the community name assigned to alice by Mydex
  • $context indicates that we're looking for a "context" service endpoint in the LDDR/XRD
  • $xdi indicates that this entityID can be accessed over XDI
  • +home+and+family is the id of the context 
  • =alice is the entityID within +home+and+family

Which as an XRI 3.0 in URI form would be:

http://xri.net/=mydex.org@alice/$context$xdi+home+and+family//=alice

or for external non-correlation purposes...

http://xri.net/=mydex@!F83.62B1.44F.2813/$context$xdi+home+and+family//=!2C75.AC49.21D3.1207

Where 
  • !F83.62B1.44F.2813 is an i-number (randomly generated per-RP pseudonym) that is associated with =mydex@alice

BTW, Mike and I a few weeks ago discussed the performance load on our active client to maintain a local cache of the resolutions of these UDIs. The active client will attempt resolution on every UDI and then cache the results of the resolution (by associating the resolved URI (or nil) with the UDI). It must maintain this cache else it will be attempting resolution every time it touches one of these UDIs.

2) Namespace contractions of UDI in XDI

With the correct form of the UDIs in the XDI per #1 above we see lots of UDIs with the same prefix:


and in fact multiple entityIDs (UDIs) in the home&family context that share this longer prefix:


Thus, if XDI added the ability to say:


Then we would have:

a:=alice

...or something similarly short and sweet.

On Aug 6, 2010, at 1:16 AM, Drummond Reed wrote:



*It would be nice if XDI had a convention for URI shortening based on a default namespace. That if relative entityIDs were used (e.g. "#245") we wouldn't have to have these long entityIDs like this one used below: "urn:efa25e71-5b6f-4844-b139-4ed26dd1c3e5". 

Interestingly, the example you use - of a URN - is not an address that can benefit from namespacing. All URNs are globally unique.

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