The (semantic) web is one of the most promising application areas for SWI-Prolog. Prolog handles the semantic web Resource Description Framework (RDF) model naturally, where RDF provides a stable model for knowledge representation with shared semantics. Prolog is also quite capable of providing web services (HTTP), especially where it comes to generating HTML pages dynamically and providing data for Javascript web applications using the JSON serialisation.

Standard packages

Below are the most vital packages for programming web services and RDF processing.

Web server and client library

Core web package. Provides an HTTP server and client, session handling, authorization, logging, etc. Libraries are also included for generating HTML pages and JSON (JavaScript Object Notation).

RDF storage and query library

Load/save RDF and query it. The library loads and saves XML/RDF and Turtle. Its database scales to approx. 20M triples on 32-bit hardware and 300M triples on a 64-bit machine with 64 Gb memory. Also provides simple RDFS and OWL support.

The GIT version in the development tree has been updated to semweb3.txt.

Spatial indexing library

SWI-Prolog interface to Spatial Index and GEOS libraries, providing spatial indexing of URIs. Supports import and export to GML, KML, and RDF with GeoRSS Simple, GeoRSS GML, and W3C WGS84 vocabulary properties.

This package is provided in the source, but not (yet) in the binary distributions. The source contains instructions for building the dependencies and the indexer itself.

Separately distributed packages

Some packages are distributed separately.

The ClioPatria semantic search web server

This library provides a ready-to-run web server that includes a SPARQL endpoint, user rights management and RDF development tools. ClioPatria is an RDF-application development framework.

Thea, an OWL library for SWI-Prolog

Provides access to OWL ontologies at the level of the abstract syntax. Can interact with external DL reasoner using DIG. The project is hosted on GitHUB. See also Blip Blog, Logic Programming in Biology

Triple20.txt

Graphical tool for browsing and editing ontologies. Not very well maintained, but useful for browsing loaded RDF and it has two nice features: it scales well and it can handle multiple ontologies and allows for editing them in a unified view.

See also

- Publications

- documentation overview

- Topos: A Semantic Web, Linked Data application

- DBTune blogs tagged SWI-Prolog