Merging RDF graphs

Hi,

As you may recall, I've asked this list about messaging/negotiating 
using linked data[1], and it led me and my colleagues to a concept of 
RDF-based agreements[2]. (Thanks again for your input!)

Now it's time for us to define how the negotiating parties come up with 
the data (set of rdf triples) that they agree on.

One Idea we have is that both particpants (P1,P2) specify 'goals', each 
consisting of a SHACL shapes graph and a data graph. Two goals can be 
tested for compatibility by merging the two data graphs and then testing 
if the resulting graph is valid given the shapes defined by both goals. 
The problem we face with this approach is merging the two data graphs. 
Consider the example in this gist:

https://gist.github.com/fkleedorfer/81b32e3235105a4a4743e9fa76ba9332

In that example, we would want to merge these two graphs:

ex1:p1g-data {
     ex1:ride1 a taxi:Ride .
     ex1:ride1 taxi:hasDriver ex1:p1 .
     ex1:ride1 taxi:hasPickupLocation ex1:pickup1;
}

and

ex2:p2g-data {
     ex2:myRide a taxi:Ride.
     ex2:myRide taxi:hasClient ex2:p2 .
     ex2:myRide taxi:hasPickupLocation ex2:myPickupLocation .
     ex2:myPickupLocation a s:GeoCoordinates ;
         s:latitude   "48.213814" ;
         s:longitude  "16.340870" .
}

We want that merge to happen in such a way that the shapes in 
ex1:p1g-shapes and ex2:p2g-shapes can be evaluated, which will require 
to merge some of the nodes. (In the example, we'll find out that a 
taxi:hasPickupTime property is missing. One of the participants is then 
to add that property, and the whole structure becomes valid according to 
both goals' shapes.)

The question is how exactly to achieve that merge. Intuitively, the 
result in this case should be

    :mergedNode1 a taxi:Ride .
    :mergedNode1 taxi:hasDriver ex1:p1 . # note: p1 links her own 
identifier to the structure
    :mergedNode1 taxi:hasPickupLocation :mergedNode2;
    :mergedNode1 a taxi:Ride.
    :mergedNode1 taxi:hasClient ex2:p2 .
    :mergedNode1 taxi:hasPickupLocation :mergedNode2 .
    :mergedNode2 a s:GeoCoordinates ;
         s:latitude   "48.213814" ;
         s:longitude  "16.340870" .

and after removal of duplicate triples

    :mergedNode1 a taxi:Ride .
    :mergedNode1 taxi:hasDriver ex1:p1 .
    :mergedNode1 taxi:hasClient ex2:p2 .
    :mergedNode1 taxi:hasPickupLocation :mergedNode2 .
    :mergedNode2 a s:GeoCoordinates ;
         s:latitude   "48.213814" ;
         s:longitude  "16.340870" .

(I currently don't care about the URIs of the mergedNodes - just 
something one can mint when doing the merge)


Do you have any hints on how to perform such a merge reliably, also with 
more complex structures?

Thank you very much in advance!

Best regards,
Florian


Links:
1. Negotiations discussion thread: 
https://lists.w3.org/Archives/Public/semantic-web/2017Jul/0004.html
2. Agreements paper: http://ceur-ws.org/Vol-1934/contribution-07.pdf

Received on Thursday, 16 November 2017 18:38:11 UTC