Introduction

Gno is a library for managing RDF datasets in SPARQL triple stores. It provides a unified API that abstracts the differences between storage backends, so you can work with your data the same way regardless of the underlying SPARQL triple store.

Gno uses DCAT-R (opens new window) (Data Catalog Vocabulary for RDF Repositories) for its structural model. DCAT-R extends the W3C's DCAT (opens new window) vocabulary to describe how RDF repositories are organized internally. In practice, this means your repository structure and configuration are described in RDF itself.

Core Concepts

Service, Repository, Dataset

Gno organizes data in a three-level hierarchy:

• A Service is the entry point. It combines a repository with a store backend and commit operation configuration.
• A Repository is a DCAT-R catalog that contains the dataset and repository metadata.
• A Dataset contains the actual RDF data as named graphs.

Services are typically loaded from RDF configuration files (manifests) written in Turtle.

Changeset System

Gno provides a structured way to express changes to RDF data. A Gno.Changeset declares intended changes through four actions: add, update, replace, and remove. Before applying changes, a changeset can be converted to an effective changeset that computes only the minimal changes needed based on the current state of the data.

Commit System

The commit system applies changesets transactionally with automatic rollback on failure. It supports a middleware pipeline for extensible processing such as validation, logging, and metadata enrichment.

Store Adapters

Gno supports multiple SPARQL backends through a store adapter system. Built-in adapters are available for:

• Apache Jena Fuseki
• Oxigraph
• QLever
• Ontotext GraphDB

You can also configure a generic store with explicit endpoint URLs for any SPARQL 1.1-compatible backend.

Guide Structure

This guide is structured into the following sections:

1. Installation instructions
2. Configuration explains the manifest system and store adapter setup
3. Querying data covers SPARQL queries and graph retrieval
4. Managing data covers data updates, changesets, and commits

A basic understanding of RDF.ex is assumed. If this is not given, please consult the corresponding user guide first. Familiarity with SPARQL.ex and SPARQL.Client is also helpful but not required.