Simple LD Server

Expose Resources from a SPARQL Server as Linked Data.

This project shall provide a minimal usable extendable implementation and serve as an example.

Building and running

You can build slds directly with maven or use Docker.

Maven

Run the following command:

mvn install -P executable

this will create an executable jar e.g. slds-1.0.0-SNAPSHOT.jar in the target directory.

Run the executable jar with one argument pointing to the configuration in a turtle file, for example

java -jar slds-1.0.0-SNAPSHOT-executable.jar ../example-config.ttl

Using Docker

You can build a docker image named slds with

docker build -t slds .

The image will launch slds with /config.ttl as configuration by default. The easiest way to start it with you own config is to mount a file from your local filesystem at that location. You can then run the image with something like:

docker run -ti -p 5000:5000 -v C:\Users\me\path\to\config.ttl:/config.ttl slds 

Configuration

The configuration file is a Turtle file with one resource matching the IRI of the location of the file, i.e. the resource which can be referred in Turtle as <>.

@prefix slds: <http://vocab.linked.solutions/slds#> .

Defining the slds prefix makes the rest of the file more compact and easier to read.

<> 
    slds:port 5000 ;
    slds:resourceDescriptionProvider [
        slds:javaClass "solutions.linked.slds.providers.GraphAndContext";
        slds:sparqlEndpoint <https://lindasprd.netrics.ch:8443/lindas/query> 
    ].

The above defines the port on which SLDS shall listen and the SPARQL Endpoint SLDS shall query.

<> 
    slds:port 5000 ;
    slds:resourceDescriptionProvider [
        slds:javaClass "solutions.linked.slds.providers.GraphAndContext";
        slds:sparqlEndpoint <https://lindasprd.netrics.ch:8443/lindas/query> 
        slds:iriTranslators (
            [
                slds:backendPrefix "http://treatment.plazi.org/"; 
                slds:frontendPrefix "http://localhost:5000/"
            ]
            [
                slds:backendPrefix "http://publication.plazi.org/"; 
                slds:frontendPrefix "http://127.0.0.1:5000/"
            ]) 
    ].

Unless the resources in the triple store already have the URIs under which they are to be published IRI-Translation rules are required. The above two additional properties define how the prefixes in the IRIs served by SLDS (frontend-prefix) map to prefixes in the IRIs in the triple store (backend-prefix).

<https://lindasprd.netrics.ch:8443/lindas/query> 
    slds:userName "public" ;
    slds:password "public".

If the SPARQL endpoint needs authentication the username and password can be specified as properties of the SPARQL Endpoint resource itself.

SSL Certificates

SLDS conatains code to accept any SSL certificate the SPARQL Server (or the man in the middle) uses. Override ConfigUtils.createHttpClient() for some serious security.