FlexRML-node

FlexRML-node is a Node.js compatible version of FlexRML compiled to WebAssembly. This implementation is based on the ESP32 version of FlexRML, meaning all data is mapped in memory and performed in a single thread. The package is tested on Ubuntu 24.04 using node v22.3.0 and Windows 10 using node v16.13.2.

How to Use

Loading the Module

const flexrml = require("flexrml-node");

Map RDF data with FlexRML

To map data using flexrml-node, call the mapData function:

const result = await flexrml.mapData(input, rmlRule);

• rmlRule: The definition of the RML rule as string.
• input: An object where the dataset name is the key, and the input data to map is the value in string format. Following the convention introduced by Dasoulas et al. for mapping in memeory datasources. Currently, only CSV data is supported as input for flexrml-node.

Example

For an example, check out the example.js.

Building form source

flexrml-node can be built from source using emscripten. This version is compiled with emcc version 3.1.61.

To compile make sure your are in the flex-rml-node directory and execute this command:

emcc src/FlexRML.cpp src/base64.cpp src/byte_source.cpp src/conversion.cpp src/csv_reader.cpp src/custom_io.cpp src/env.cpp src/flexinput.cpp src/n3.cpp src/node.cpp src/rdf_parser.cpp src/rdf_vector_helper.cpp src/reader.cpp src/rml_extractor.cpp src/string.cpp src/string_helper.cpp src/system.cpp src/termtype_helper.cpp src/uri.cpp src/writer.cpp -o flex.js -s WASM=1 -s MODULARIZE=1 -s EXPORT_NAME="createModule" -s ALLOW_MEMORY_GROWTH=1 -s ENVIRONMENT=node -O3 --bind

The file index.js contains a wrapper for the WebAssembly code and handles data transformations.