migrants/README.md

Theatre Migrants

To generate a knowledge graph about migrants in the theatre in Europe.

Generating the ontology

Next there are set of steps describing how to generate the migrants RDF graph.

Step 1 - Loading the input data into a relational database

Task

The file teatre-migrants.sql contains the dump of a MariaDB database. The tables involved in this schema are described in the file db_schema.md. We will load this data in MariaDB to access the data with SQL. To this end:

1. Create a Dockerfile to create a docker container for MariaDB.

2. Upload the dump into a database in the container.

3. Create a Ruby script map/step-01.rb that uses the gem sequel to connect to the database. This Ruby script should return a file called graph-01.ttl containing all the data from the tables loaded in the database using the direct mapping from relational databases to RDF.

Summary

The Dockerfile creates a MariaDB 10.11 container that automatically loads teatre-migrants.sql on first start. The docker-compose.yml exposes the database on port 3306 with a healthcheck.

The script map/step-01.rb connects to the database via sequel and implements the W3C Direct Mapping for all 9 tables (location, migration_table, organisation, person, person_profession, personnames, relationship, religions, work). Each table row becomes an RDF resource identified by its primary key, each column becomes a datatype property, and each foreign key becomes an object property linking to the referenced row. The output file graph-01.ttl contains 162,029 triples.

To run:

docker compose up -d
bundle exec ruby map/step-01.rb

Step 2 -