Catalog Service Overview

The Catalog Service provides discovery and organization of data resources in the SDL ecosystem. It builds upon W3C DCAT v3 to support semantic indexing of datasets, distributions, and associated metadata.

It supports:

Hierarchical catalogs organized by workspace, platform, or user-defined scopes
Registration of datasets, their formats, and access services
Federated discovery across SDL deployments and external linked data sources
Integration with repository and storage services to surface available data

Core Concepts

Catalog

A dcat:Catalog acts as a collection of datasets and services. Multiple catalogs may exist across workspaces or deployments.

Dataset

A dcat:Dataset represents a logical data collection with associated metadata, provenance, and distributions.

Distribution

A dcat:Distribution describes an accessible form of a dataset, including file formats, download URLs, and media types.

DataService

A dcat:DataService describes an API or endpoint used to access distributions (e.g., S3, SPARQL, HTTPS, MQTT).

Example Dataset Entry

acl:xrdDataset a dcat:Dataset ;
  dct:title "XRD Diffraction Patterns - July 2025" ;
  dct:creator acl:ACLPlatform01 ;
  dct:issued "2025-07-15"^^xsd:date ;
  dcat:distribution acl:xrdDist123 ;
  dcat:theme <http://vocab.example.org/materials/crystallography> .

Example Distribution

acl:xrdDist123 a dcat:Distribution ;
  dcat:downloadURL <https://data.example.org/minio/acl-xrd-xye/scan789.xye> ;
  dct:format "text/plain" ;
  dcat:mediaType "application/x-xye" ;
  dcat:accessService acl:xrdRawService .

Example Catalog Structure

acl:aclCatalog a dcat:Catalog ;
  dct:title "ACL Platform Catalog" ;
  dcat:dataset acl:xrdDataset, acl:tgaDataset, acl:hplcDataset ;
  dcat:service acl:xrdRawService, acl:tgaStore, acl:hplcBroker .

Federation and Discovery

Catalogs can be queried via SPARQL or JSON-LD interfaces
External catalogs can be linked via dcat:catalog or dcat:dataset
Supports import of metadata from repositories or storage providers

Let me know when you’re ready to define custom themes, query templates, or catalog synchronization patterns.