Sage: a SPARQL query engine for public Linked Data providers

Python implementation of SaGe, a stable, responsive and unrestricted SPARQL query server.

Table of contents

• Installation
• Getting started
  • Installation
  • Starting the server
• Sage Docker image
• Documentation

Installation

Installation in a virtualenv is strongly advised!

Requirements:

• git
• pip
• npm (shipped with Node.js on most systems)
• gcc/clang with c++11 support
• Python Development headers

You should have the Python.h header available on your system.
For example, for Python 3.6, install the python3.6-dev package on Debian/Ubuntu systems.

git clone https://github.com/sage-org/sage-bgp
cd sage-engine/
pip install pybind11
pip install -r requirements.txt
python setup.py install

Getting started

Server configuration

A Sage server is configured using a configuration file in YAML syntax. You will find below a minimal working example of such configuration file. A full example is available in the config_examples/ directory

name: SaGe Test server
maintainer: Chuck Norris
quota: 75
max_results: 2000
datasets:
-
  name: dbpedia
  description: DBPedia
  backend: hdt-file
  file: datasets/dbpedia.2016.hdt

The quota and max_results fields are used to set the maximum time quantum and the maximum number of results allowed per request, respectively.

Each entry in the datasets field declare a RDF dataset with a name, description, backend and options specific to this backend. Currently, only the hdt-file backend is supported, which allow a Sage server to load RDF datasets from HDT files. Sage uses pyHDT to load and query HDT files.

Starting the server

The sage executable, installed alongside the Sage server, allows to easily start a Sage server from a configuration file using Gunicorn, a Python WSGI HTTP Server.

# launch Sage server with 4 workers on port 8000
sage my_config.yaml -w 4 -p 8000

The full usage of the sage executable is detailed below:

usage: sage [-h] [-p P] [-w W] [--log-level LEVEL] config

Launch the Sage server using a configuration file

positional arguments:
  config             Path to the configuration file

optional arguments:
  -h, --help         show this help message and exit
  -p P, --port P     The port to bind (default: 8000)
  -w W, --workers W  The number of server workers (default: 4)
  --log-level LEVEL  The granularity of log outputs (default: info)

Sage Docker image

The Sage server is also available through a Docker image. In order to use it, do not forget to mount in the container the directory that contains you configuration file and your datasets.

docker pull callidon/sage
docker run -v path/to/config-file:/opt/data/ -p 8000:8000 callidon/sage sage /opt/data/config.yaml -w 4 -p 8000

Notice: you can also use docker-compose.yml instead of the long docker run command.

Documentation

To generate the documentation, you must install the following dependencies

pip install sphinx sphinx_rtd_theme sphinxcontrib-httpdomain

Then, navigate in the docs directory and generate the documentation

cd docs/
make html
open build/html/index.html

Copyright 2017-2018 - GDD Team, LS2N, University of Nantes