BURP-Error: A Basic and Unassuming RML Processor with RML Execution Report

BURP (Basic and Unassuming RML Processor) is a reference implementation for the new RML specification which has been written from scratch to have no influence from prior implementations of RML. BURP was created to serve as a reference RML implementation for the Knowledge Graph Construction community and to verify the RML specifications, their feasibility, and coverage of their test cases.

BURP-Error is a fork of BURP that adds error handling to the RML processor, according to the RML Execution Report. The project is a proof of concept, no maintenance guaranteed, but if you have any questions or issues, feel free to open an issue on GitHub.

Warning: Joins are quadratic, in terms of iterations and number of multivalued join conditions values.

Coverage matrix

RML module	Test Cases: Pass / Fail / Total
RML-Core	✅ 76 / 0 / 76
RML-IO	✔️ 56 / 0 / 56*
RML-IO-Registry	🚧️ 52 / 50 / 102 Details below
RML-CC	✅ 35 / 0 / 35
RML-FNML	✅️ 20 / 0 / 20
RML-Star	❌ Not implemented
RML-LV	✅️ 41 / 0 / 41
RER	🪅 Demo implementation

* We consider 17 test cases in RML-IO to have issues.

RML-IO-Registry coverage details

BURP supports natively the following input sources:

• rml:FilePath or rml:RelativePathSource — local files (supports rml:root and rml:path)

• rml:CSV — CSV files (including CSVW tables and their dialects: encoding, delimiter, header, nulls)

• rml:JSONPath — JSON sources (RFC 9535 JSONPath iterator)

• rml:XPath — XML sources (XPath 1.0 iterator; supports namespace/prefix mappings for XPath reference formulations)

• rml:SPARQL Results (CSV/TSV/XML/JSON) — SPARQL result files, SPARQL endpoints/services, and data dumps (VOID/SD)

• rml:SQL2008Query and rml:SQL2008Table — relational database sources (via D2RQ properties such as d2rq:jdbcDSN, d2rq:jdbcDriver, username, password)

• DCAT Distribution / CSVW Table — remote files via DCAT downloadURL or CSVW url

• Extensions possible see extending BURP

About the RML Execution Report

The RML Execution Report (RER) is a taxonomy for describing the execution of an RML mapping, defined at https://w3id.org/dre/rer.

BURP-Error can output the execution report using the rer vocabulary. In addition, if your mapping is in Turtle format, BURP-Error will also output the execution report in a textual format with code snippets or your mappings instead of the rdf 1.2 statements pointers (ptr).

Notice; to locate prescicely the turtle token location, we use a custom turtle parser (in turtleprov) that admitedly is only 39/103 (37%) of RDF1.2 test cases and 217/313 (69%) of RDF1.1 test cases.

Building BURP

To build the project and copy its dependencies, execute

$ mvn package 
$ mvn dependency:copy-dependencies

You can add -DskipTests after mvn package to skip the unit tests. The tests do rely on Docker for testing mappings on top of MySQL and PostgreSQL.

Some libraries are available on GitHub's maven repository. Add a GitHub authentication token to your Apache Maven settings.xml file. More information can be found here.

Using BURP

You can run BURP using JBang:

$ jbang burp@jduchateau [-h] [-b=<baseIRI>] -m=<mappingFile> [-o=<outputFile>]

Note: JBang will automatically download the required JDK and resolve all project dependencies on the first run.

If you don't have JBang installed yet, see the JBang Installation Guide to install it.

Alternatively, if you prefer to run it using a local pre-built fat JAR and standard Java, execute the following command:

$ java -jar burp.jar [-h] [-b=<baseIRI>] -m=<mappingFile> [-o=<outputFile>]

A fat jar is also provided with the Apache Maven Shade Plugin. It does not depend on the dependency folder.

Usage: burp [-h] [-b=<baseIRI>] -m=<mappingFile> [-o=<outputFile>]
  -b, --baseIRI=<baseIRI>   Used in resolving relative IRIs produced by the RML mapping
  -h, --help                Display a help message
  -m, --mappingFile=<mappingFile>
                            The RML mapping file
  -o, --outputFile=<outputFile>
                            The output file

If no outputFile is provided and the RML mapping does not rely on RML-IO for targets, then the output is written to the standard output.

Citation

If you use BURP-Error, please cite our paper:

@inproceedings{duchateau2026rml-execution-report,
  author       = {Jakub Duchateau and Dylan {Van Assche} and Christophe Debruyne},
  editor       = {},
  title        = {Beyond Exit Code 1: A Vocabulary for Execution Report of RML Processors (RER)},
  booktitle    = {Proceedings of the 7th International Workshop on Knowledge Graph Construction
                  co-located with 23rd Extended Semantic Web Conference ({ESWC} 2026),
                  Dubrovnik, Croatia, May 10, 2026},
  series       = {{CEUR} Workshop Proceedings},
  volume       = {X},
  publisher    = {CEUR-WS.org},
  year         = {2026},
  url          = {https://ceur-ws.org/Vol-X/paperX.pdf}
}

If you use BURP, please cite our paper:

@inproceedings{DBLP:conf/kgcw/AsscheD24,
  author       = {Dylan {Van Assche} and Christophe Debruyne},
  editor       = {David Chaves{-}Fraga and Anastasia Dimou and
                  Ana Iglesias{-}Molina and Umutcan Serles and
                  Dylan {Van Assche}},
  title        = {BURPing Through {RML} Test Cases},
  booktitle    = {Proceedings of the 5th International Workshop on Knowledge Graph Construction
                  co-located with 21th Extended Semantic Web Conference ({ESWC} 2024),
                  Hersonissos, Greece, May 27, 2024},
  series       = {{CEUR} Workshop Proceedings},
  volume       = {3718},
  publisher    = {CEUR-WS.org},
  year         = {2024},
  url          = {https://ceur-ws.org/Vol-3718/paper4.pdf}
}

License

BURP is released under the MIT license.