The map service starts a container that runs a Jena sparql commandline tool executed on a specified dataset using the specified query. By using a SPARQL CONSTRUCT query the resulting output is a valid Linked Data resultset. It defaults to the Turtle serialization format but this can be overridden using the --format option.
The default mapping file schema2edm.rq is written for a Schema.org to EDM transformaton and is based on the requirements described in "Guidelines for providing and handling Schema.org metadata in compliance with Europeana".
Europeana requires a reference to the provider responsible for performing the lod-aggregation. Before excuting the query the starter.sh script replaces the placeholder VAR_PROVIDER in the sparql query with the specific identifier for this configuration. The VAR_PROVIDER variable can be specified during run time using the --provider {provider naam} option or by setting the VAR_PROVIDER environment variable using the .env file.