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Requirements: Scope and Prioritization

This page is to discuss the requirements of the RDB2RDF Mapping Language (R2RML) based on the scope of the RDB2RDF WG. The goal is to classify the requirements and prioritize them in order to define a set of features for R2RML (must-have/time-permitting).


The following requirements are directly copied from our charter, grouped by MUST/SHOULD:

MUST requirements

  • The mapping language MUST define the mapping of relational data and relational schemas to RDF and OWL.
  • The mapping language MUST define the set of relational algebra to be supported in the first release. This set to be supported SHOULD be as complete as possible and be defined as soon as possible after the WG official launch.
  • The mapping language MUST allow for a mechanism to create identifiers for database entities. The generation of identifiers should be designed to support the implementation of the linked data principles. Where possible, the language will encourage the reuse of public identifiers for long-lived entities such as persons, corporations and geo-locations.

SHOULD requirements

  • The mapping language SHOULD have a human-readable syntax as well as XML and RDF representations of the syntax for purposes of discovery and machine generation.
  • The mapping language SHOULD use W3C RIF whenever a rule engine is needed in the mapping language.
  • It SHOULD be possible to subset the mapping language for lightweight applications such as Web 2.0 applications. This feature of the language will be validated by creating a library of mappings for widely used applications such as Drupal, Wordpress, or phpBB.
  • The mapping language SHOULD be able to support vendor specific SQL data types.
  • The mapping language specification SHOULD include guidance with regard to mapping relational data to a subset of OWL such as OWL QL or OWL RL.