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Input needed from RDF group on JSON-LD skolemization

From: David Booth <david@dbooth.org>
Date: Thu, 13 Jun 2013 13:09:58 -0400
Message-ID: <51B9FCE6.2050005@dbooth.org>
To: public-rdf-comments <public-rdf-comments@w3.org>
The JSON-LD group would like input from the rest of the RDF Working 
Group about skolemization.

During the last JSON-LD call
http://json-ld.org/minutes/2013-06-11/
there was discussion of a proposal to require skolemization of JSON-LD 
blank nodes, when interpreting JSON-LD as RDF, in cases where they 
otherwise would be converted to RDF blank nodes but are used where a 
blank node is not allowed in RDF.  (At present they are prohibited as 
predicates and as graph names.)

The proposal was #1 at:
http://lists.w3.org/Archives/Public/public-rdf-comments/2013Jun/0072.html
[[
1. In RDF conversion algorithms in JSON-LD 1.0 Processing Algorithms and
API,
http://json-ld.org/spec/latest/json-ld-api/#rdf-conversion-algorithms
specify that **when JSON-LD is interpreted as RDF,** (i.e., when the
JSON-LD model is converted to the RDF model) skolem IRIs MUST be
generated using the well-known URI suffix "json-ld-genid" for any
JSON-LD blank node that would otherwise be mapped to an RDF blank node
in a position where an RDF blank node is not permitted.  Conversely,
when RDF is serialized as JSON-LD (or when an RDF model is converted to
a JSON-LD model), skolem IRIs having the well-known URI suffix
"json-ld-genid" SHOULD be serialized as JSON-LD blank nodes.  Finally,
register the well-known URI suffix "json-ld-genid", in accordance with
RFC5785:
http://tools.ietf.org/html/rfc5785
BACKGROUND NOTE: The existing well-known URI suffix "genid" is for
converting to/from RDF blank nodes (in positions where blank nodes are
*permitted* in RDF), whereas "json-ld-genid" will be used for *avoiding*
blank nodes (in positions where they are not allowed in RDF).
]]

There was also some follow up email discussion about what  well-known 
URI suffix to use, but that is probably a minor issue.

Before making a decision about this proposal, the JSON-LD group would 
like to know whether others think this proposal is reasonable and 
viable.  The goal is to make JSON-LD function more predictably as a 
concrete RDF syntax.  At present, such skolemization is optional, which 
means that a user cannot be assured of obtaining legal RDF or knowing 
whether the otherwise-illegal triples will simply be dropped.

Please let us know your thoughts.

Thanks,
David
Received on Thursday, 13 June 2013 17:10:30 UTC

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