Support for SPARQL CDTs (lists and maps as literals)

[hartig]

Version

5.1.0

Feature

The lack of built-in support for generic types of composite values such as lists and maps has been a long-standing issue for RDF and SPARQL. Together with a few other colleagues at the Amazon Neptune team we have developed an approach to represent lists and maps as literals in RDF data, and to extend SPARQL with features related to such literals. These extensions of SPARQL include:

• an aggregation function to produce these composite values (FOLD),
• functions to operate on these composite values in expressions, and
• a new operator (UNFOLD) to unfold such composite values into their individual components.

We have created a complete formal specification of the approach and a comprehensive test suite for implementers, which can be found in our Github repo: https://github.com/awslabs/SPARQL-CDTs

Perhaps before you dive into the aforementioned specification, you may take a look at our short paper, in which we provide a slightly more extensive motivation for this work and a (very!) brief summary of the approach. After that, Section 2 of the specification provides a more detailed informal description of the different parts of the approach.

I am happy to answer any questions that you may have, both about the approach in general and about the idea to integrate the approach into Jena. Also, if you have issues with some parts of the specification, feel free to create an issue in the aforementioned Github repo. (And in case you are wondering, yes we are planning to file the approach as a SPARQL Enhancement Proposal (SEP) for the SPARQL-dev Community Group).

Are you interested in contributing a solution yourself?

Yes