Lyo Store

Lyo Store is a library that provides a simple interface for working with a triplestore via Java objects representing OSLC Resources. Lyo Store and Jena Models in the triple stores.

Lyo Store Javadoc

Prerequisites

• For an in-memory option: JVM heap should be set to 1G or above (see Jena documentation for more information on this).
• For an on-disk option: an empty writable folder on disk, around 200MB of space is pre-allocated.
• For a SPARQL option: a pair of SPARQL Query and SPARQL Update URLs, optionally with basic authentication.

Maven dependency

<dependency>
  <groupId>org.eclipse.lyo.tools</groupId>
  <artifactId>lyo-store</artifactId>
  <version>0.24.0-SNAPSHOT</version>
</dependency>

More build systems are covered here: http://assume.gitlab.io/jena-cache/dependency-info.html

Initialisation

SPARQL

String sparqlQueryEndpoint = properties.getProperty("sparqlQueryEndpoint");
String sparqlUpdateEndpoint = properties.getProperty("sparqlUpdateEndpoint");
Store store = StoreFactory.sparql(sparqlQueryEndpoint, sparqlUpdateEndpoint);

On-disk

String storeDirProp = properties.getProperty("storeDir");
Path storeDir = Paths.get(storeDirProp);
Store store = StoreFactory.onDisk(storeDir);

In-memory

Store store = StoreFactory.inMemory();

Basic usage

Add the new resources and overwrite the existing ones

try {
    store.updateResources(GRAPH_NAME, // URI of the named graph
            resourceArray);           // an array of OSLC Resources
} catch (StoreAccessException e) {
    logger.error("Error executing a query on a triplestore");
}

Retrieving the resources from the triplestore

if (store.namedGraphExists(GRAPH_NAME)) {
    try {
        final int limit = 10; // fetch 10 resources
        final int offset = 0; // start with the first page
        // 'limit+1' is a technique that allows you to determine if there are
        // more results on the next page
        List<Requirement> requirements = store.getResources(GRAPH_NAME,
                Requirement.class, // resources of this class will be fetched and unmarshalled
                limit + 1,         // resource limit
                offset));          // how many resources to skip, use for paging
    } catch (StoreAccessException e) {
        logger.error("Error executing a query on a triplestore");
    } catch ( ModelUnmarshallingException e) {
        logger.error("Error unmarshalling the RDF from triplestore into Requirement class instances");
    }
}