Technical Guide: Implementing SHACL

The adoption of the new DCAT-AP-ES profile aligns Spain with the application profile in Europe (DCAT-AP), facilitating automatic federation between data catalogs defined in RDF (Resource Description Framework).

In this RDF graph environment where flexibility is the norm, the absence of traditional rigid schemas can lead to a silent degradation of data quality, if the standard is not rigorously followed. To mitigate this risk, there is SHACL (Shapes Constraint Language), a recommendation of the W3C. These guidelines make it possible to define "shapes" that function as true guardians of quality and compliance with interoperability. 

The stages of the SHACL validation process are as follows: 

1. An RDF data graph is available
2. A subset from the previous graph is selected
3. The SHACL constraints that apply to the previous subgraph are checked
4. A validation report is obtained with the compliant elements, with errors or with recommendations.

The following figure shows these stages:

Figure 1: Main stages of the SHACL validation process 

Objectives and target audience

This technical guide aims to help publishers and reusers incorporate SHACL validation as a continuous quality improvement practice, through a didactic and accessible approach, inspired by clear resources and open validation tools from the data ecosystem.

In addition, its relationship with DCAT-AP-ES is deepened in a special way, detailing a practical and exhaustive case of the complete workflow of validation and governance of a catalog according to this profile.

Structure and contents

The document follows a progressive approach, starting from theoretical foundations to technical implementation and automatic integration, structured in the following key blocks:

• Fundamentals of semantic validation: RDF and the challenge of the “open world, as well as SHACL as a mechanism to perform validations, defining key concepts such as Shape or Validation Report.
• DCAT-AP-ES and the adoption of SHACL for validation:  the SHACL forms defined in DCAT-AP-ES and the case of their application in the federation process of the National Catalogue are explained.
• Case Study: RDF Graph Validation: A step-by-step tutorial on how to validate a catalog with DCAT-AP-ES SHACL forms, troubleshooting common issues, and available tools.
• Conclusions: Reflections on the advantages of integrating SHACL validation to improve data catalog governance.

SHACL validation represents a paradigm shift in metadata quality management in data catalogs. This guide walks through the entire process from theoretical foundations to practical application, demonstrating that the adoption of SHACL is not simply a technical requirement, but an opportunity to strengthen and improve data governance.