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Introduction

OBIS Schema Extractor (v2) is a Java-based web application for data schema extraction from SPARQL endpoints.

OBIS Schema Extractor artifact is a packaged executable JAR file and needs Java 17 to run.

For running OBIS Schema Extractor locally:

1. install Java
2. copy build/schema-extractor-exec.jar, together with the entire build folder contents, to any folder
3. run executable JAR file java -jar schema-extractor-exec.jar
4. navigate to http://server:port/swagger-ui.html (default URL - http://localhost:8080/swagger-ui.html)
5. configure the parameters, as described on the browser page, or use create the configuration file (a sample configuration file is available in the build folder)

Extractor Parameters

The parameters available in Swagger-based extractor execution are most conveniently accessible from the browser page for running the extractor.

The specifications of all parameters, including the ones currently hidden (@ApiParam(hidden = true)) from the browser UI (but available for use from the configuration file), are available in the parameter description code.

An example configuration file is provided along with the extractor, as well (when extracting all classes and/or properties from an endpoint, set the includedClasses and/or includedProperties parameters to []).

The Extractor extracts the schema from a SPARQL Endpoint by means of (possibly long) series of SPARQL SELECT queries issued against it. The query templates are provided in a separate Source File.

Example Execution

We provide a resulting Schema file, a Configuration file and the Execution log for extracting the schema from Nobel Prizes SPARQL API endpoint (overall schema extraction time is below 3 minutes).

Further possible use of the schema is to upload it into Data Shape Server that can be set up either independently, or as a part of ViziQuer Tools container system. The schema upload is done by DSS Schema import utility.