gsoc26: Format Conversion Layer (Layer 2)

[DhanashreePetare]

Feature Request

Describe the feature you'd like
Add Layer 2 (within-class format conversion) to the Databus Python Client download pipeline. Users should be able to convert downloaded RDF and tabular files to a different serialization format in a single command using a new --convert-format flag.

Why is this feature important?
Currently the client downloads files exactly as published. If a dataset is published in Turtle but the consuming application needs N-Triples or CSV, the user must manually convert after downloading. This feature eliminates that step and brings the Python client to feature parity with the Java Databus Client's Layer 2 implementation.

Describe alternatives you've considered
The Java client uses Apache Jena and Spark for this layer. For the Python
client, rdflib is already a project dependency and natively supports all
required formats, making it the natural choice without adding new dependencies.

Additional context
Equivalence classes and supported conversions:

From Class	To Class	Formats
RDF Triples	RDF Triples	ntriples, turtle, rdf-xml
RDF Quads	RDF Quads	nquads, trig, json-ld
Tabular	Tabular	csv, tsv