Conference Paper

Extending R2RML with Support for RDF Collections and Containers to Generate MADS-RDF Datasets

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Abstract

It is a best practice to avoid the use of RDF collections and containers when publishing Linked Data, but sometimes vocabularies such as MADS-RDF prescribe these constructs. The Library of Trinity College Dublin is building a new asset management system backed by a relational database and wants to publish their metadata according to these vocabularies. We chose to use the W3C Recommendation R2RML to relate the database to RDF datasets, but R2RML unfortunately does not provide support for collections and containers. In this paper, we propose an extension to R2RML to address this problem. We support gathering collections and containers from different fields in a row of a (logical) table as well as across rows. We furthermore prescribe how the extended R2RML engine deals with named graphs in the RDF dataset as well as empty sets. Examples and our demonstration on a part of the Library’s database prove the feasibility of our approach.

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... Its vocabulary also allowed to change the iterator within a term map and yield nested collections and containers. By contrast, [45] provided terms for creating (nested) collections and containers from within an iteration (same row) and across iterations (across rows) and provided a property for retaining empty collections and containers. The ontology presented in [45] also provided directive for generating collections or containers whose members may have different term types, whereas [76]'s vocabulary provided support for one term type. ...
... By contrast, [45] provided terms for creating (nested) collections and containers from within an iteration (same row) and across iterations (across rows) and provided a property for retaining empty collections and containers. The ontology presented in [45] also provided directive for generating collections or containers whose members may have different term types, whereas [76]'s vocabulary provided support for one term type. The vocabulary of both approaches did not provide support for named collections and containers, nor the generation of these as subjects. ...
Chapter
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The Relational to RDF Mapping Language (R2RML) became a W3C Recommendation a decade ago. Despite its wide adoption, its potential applicability beyond relational databases was swiftly explored. As a result, several extensions and new mapping languages were proposed to tackle the limitations that surfaced as R2RML was applied in real-world use cases. Over the years, one of these languages, the RDF Mapping Language (RML), has gathered a large community of contributors, users, and compliant tools. So far, there has been no well-defined set of features for the mapping language, nor was there a consensus-marking ontology. Consequently, it has become challenging for non-experts to fully comprehend and utilize the full range of the language’s capabilities. After three years of work, the W3C Community Group on Knowledge Graph Construction proposes a new specification for RML. This paper presents the new modular RML ontology and the accompanying SHACL shapes that complement the specification. We discuss the motivations and challenges that emerged when extending R2RML, the methodology we followed to design the new ontology while ensuring its backward compatibility with R2RML, and the novel features which increase its expressiveness. The new ontology consolidates the potential of RML, empowers practitioners to define mapping rules for constructing RDF graphs that were previously unattainable, and allows developers to implement systems in adherence with [R2]RML. Resource type : Ontology/ License : CC BY 4.0 International DOI : 10.5281/zenodo.7918478 / URL : http://w3id.org/rml/portal/
... This issue inspired a separate project in which an R2RML expansion supporting the mapping of RDF Collections (and Containers) was developed [11]. This expansion facilitated the uplift of all metadata in the database to RDF, allowing for the publication of complete MODS records. ...
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R2RML: RDB to RDF mapping language
  • S Das
  • S Sundara
  • R Cyganiak
Das, S., Sundara, S, Cyganiak, R.: R2RML: RDB to RDF mapping language. In: W3C Recommendation (2012)