RDF and Linked Data have broad applicability across many fields, from aircraft manufacturing to zoology. Requirements for detecting bad data differ across communities, fields, and tasks, but nearly all involve some form of data validation. This book introduces data validation and describes its practical use in day-to-day data exchange.

The Semantic Web offers a bold, new take on how to organize, distribute, index, and share data. Using Web addresses (URIs) as identifiers for data elements enables the construction of distributed databases on a global scale. Like the Web, the Semantic Web is heralded as an information revolution, and also like the Web, it is encumbered by data quality issues. The quality of Semantic Web data is compromised by the lack of resources for data curation, for maintenance, and for developing globally applicable data models.

At the enterprise scale, these problems have conventional solutions. Master data management provides an enterprise-wide vocabulary, while constraint languages capture and enforce data structures. Filling a need long recognized by Semantic Web users, shapes languages provide models and vocabularies for expressing such structural constraints.

This book describes two technologies for RDF validation: Shape Expressions (ShEx) and Shapes Constraint Language (SHACL), the rationales for their designs, a comparison of the two, and some example applications.

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Founder and main researcher of WESO (Web Semantics Oviedo) research group, which collaborates with different companies around the world applying semantic web technologies to solve practical problems. The development of data portals for several companies and public administrations led to his interest on RDF validation. Member of the W3C Data Shapes working group and of three W3C community groups: Shape Expressions, SHACL and RAX (RDF and XML interoperability). Chairman of the Best practices of Multilingual Linked Open Data community group. He implemented the SHACL and ShEx library Shaclex and maintains an online RDF validator service. He has also written an introductory book about Semantic Web in Spanish. Eric is the W3C staff contact for the Health Care and Life Sciences Interest Group, RDF Data Shapes (RDF Validation), LDP, RDF 1.1, SPARQL 1.1, RDB2RDF, SPARQL 1.0, SAWSDL and XML Protocol Working Groups. He has developed and designed multiple languages, including a significant contribution to SPARQL and ShEx. He developed the Javascript ShEx library to promote understanding about and exploitation of Shape Expressions. Iovka is an Associate Professor at University of Lille, France, and member of the Links research project affiliated to Inria - Lille Nord Europe and CRIStAL (Centre de Recherche en Informatique, Signal et Automatique). She has been working on expressive languages for describing and querying tree-structured data, and more recently on data exchange for relational and graph data. She was a member of the W3C RDF Data Shapes Working Group and is a member of the W3C Shape Expressions community group. She has developed the theoretical foundations of the Shape Expressions Language. Dimitris is a Knowledge Engineer and Semantic Web researcher at the University of Leipzig and the DBpedia Association. He has been working on knowledge representation and knowledge management of large-scale knowledge graphs and data quality. Dimitris is a member of the RDF Data Shapes working group, a member and the chairman of the Shape Expressions Community Group and co-editor of SHACL. He is the creator of RDFUnit, a tool and unit-testing framework for RDF validation that supports SHACL, OSLC Resource Shapes and DC Description Set Profiles.