Usage

The client has many parameters, which describe what data needs to be downloaded, and how it needs to be converted. There are many ways to use the client, which are described in the following chapters.

Databus Client Parameters

Option	Description	Default
-s, --source	Set the source you want to convert. A source can either be a [file/directory] to convert already existing files, or a [query file/query string/collection URI] to convert queried files. Notice that query files must have .sparql/.query as extension to be recognized.
-e, --endpoint	Set the sparql endpoint, where the query should be fired to. If you use a collection you don't need this parameter, because its detected automatically. Otherwise its mandatory.
-t, --target	Set the target directory for converted files	./files/
-c, --compression	Set the compression format of the output file	same
-f, --format	Set the file format of the output file	same
-m, --mapping	Set the mapping file for format-conversion to different format equivalence class
-d, --delimiter	Set the delimiter (only necessary for some formats)	,
-q, --quotation	Set the quotation (only necessary for some formats)	"
--createMapping	Do you want to create mapping files for mapped sources?	false
-g, --graphURI	Set the graph uri for mapping from rdf triples to rdf quads
-b, --baseURI	set the base URI to resolve relative URIs
-o, --overwrite	true -> overwrite files in cache, false -> use cache	true
--clear	true -> clear Cache	false
--help	Show this message

Queries

Various datasets are registered on the DBpedia Databus in the form of files. A query specifies an exact selection of these records of the DBpedia Databus to be processed by the Databus Client. Therefore, the query is one of, if not the most important parameter of the client.

Possible queries

You can pass any query that selects the object of the predicate databus:file, the name of the variable does not matter. The query should look like. SELECT ?o WHERE { ?s databus:file ?o}

How to pass queries

There are three different ways to pass a query to the Databus Client:

1. Pass the query string directly as a parameter.

   • Note: this option does not work for CLI

2. Save the query in a file and pass the file path as a parameter.

   • The file extension of the query file must be .sparql or .query.

3. Collection URIs are also supported. The client receives the associated query itself.

   • e.g. https://dev.databus.dbpedia.org/testuser/collections/testcollection/