Re: [xdi] Quick note about "crawling" public link contracts

[Markus Sabadello <markus.sabadello@xdi.org>]

But still, in order to do a $get on

  $public/$is()/{}

For this message to succeed you would also need to reference the public link contract, right?

Markus

On Thu, Dec 19, 2013 at 10:11 AM, Drummond Reed <drummond.reed@xdi.org> wrote:

In the last TC call Animesh pointed out that, now that public link contracts are going to be authority-relative, it is more difficult for an "XDI graph crawler" to index public XDI data.

While doing the minutes of the meeting, a simple solution occurred to me for how authority-relative public link contracts could become easily discoverable by "XDI crawlers".

All it requires is for an XDI authority who wants his/her/its public XDI data at an XDI endpoint to be "crawled" to add a statement to the graph in the form of:

  $public/$is()/<--authority-id-->

where <--authority-id--> is the cloud number of the XDI authority. 

All the crawler code would need to do is send an XDI $get message to the XDI endpoint for

  $public/$is()/{}

Based on the response, the crawler could then request the public link contract for every XDI authority discovered in the first query.

Note that the $public/$is()/<--authority-id--> statement is graph-relative, not authority-relative, however this is fine because it meets the test of all graph-relative entity statements, i.e., it will be the same in all graphs, and you can merge any two XDI graphs without a conflict between graph-relative entity statements. For example, the statement

   $public/$is()/[=]!:uuid:f81d4fae-7dec-11d0-a765-00a0c91e0001

which states that [=]!:uuid:f81d4fae-7dec-11d0-a765-00a0c91e0001 has a subcontext $public, is the same statement in all XDI graphs no matter what XDI endpoint it appears in.

=Drummond