Overview and supported features

What is Jelly and pyjelly?

Jelly is a high-performance serialization format and streaming protocol for RDF knowledge graphs. It enables fast, compact, and flexible transmission of RDF data with Protobuf, supporting both flat and structured streams of triples, quads, graphs, and datasets. Jelly is designed to work well in both batch and real-time settings, including use over files, sockets, or stream processing systems like Kafka or gRPC.

pyjelly is a Python implementation of the Jelly protocol. It provides:

Full support for reading and writing Jelly-encoded RDF data
Seamless integration with RDFLib ("works just like Turtle")
Support for all Jelly stream types
Tools for working with delimited and non-delimited Jelly streams
Fine-grained control over serialization options, compression, and framing

Overview

Use cases

pyjelly is suitable for:

Compact serialization of large RDF graphs and datasets.
Incremental or streaming processing of RDF data.
Writing or reading .jelly files in data pipelines.
Efficient on-disk storage of RDF collections.
Interchange of RDF data between systems.

Supported stream types

pyjelly supports all physical stream types including TRIPLES, QUADS and GRAPHS.

See the full stream type matrix for an overview of valid combinations.

Conformance to the Jelly protocol

pyjelly is designed to conform to version dev of the Jelly specification. It adheres to:

Stream header structure and metadata.
Frame structure and ordering guarantees.
Compression rules and lookup tables.
Namespace declarations and stream options.

Parsing includes automatic validation of conformance raised when violations occur.

Limitations

Grouped logical stream types are not yet supported.
Quoted graphs (RDF-star nested triples) are not supported.
Multi-dataset streams cannot currently be parsed into a single Dataset.
Logical stream type detection is not automatic; it must be set explicitly via options.