是否可以使用 sparql 端点创建 Sail 存储库？

Question

我有本地 GraphDB SailRepository 的 config.ttl 文件，但我还想不仅通过直接 java 调用而且还通过 SPARQL 端点来访问它。我的 config.ttl 文件如下所示：

# RDF4J configuration template for a GraphDB Free repository

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix rep: <http://www.openrdf.org/config/repository#>.
@prefix sr: <http://www.openrdf.org/config/repository/sail#>.
@prefix sail: <http://www.openrdf.org/config/sail#>.
@prefix owlim: <http://www.ontotext.com/trree/owlim#>.
@prefix sparql: <http://www.openrdf.org/config/repository/sparql#>.

[] a rep:Repository ;
    rep:repositoryID "test" ;
    rep:repositoryImpl [
        rep:repositoryType "graphdb:FreeSailRepository" ;
        sparql:query-endpoint <http://localhost:7200/repositories/test> ;
        sparql:update-endpoint <http://localhost:7200/repositories/test/statements> ;
        sr:sailImpl [
            sail:sailType "graphdb:FreeSail" ;
            ...
        ]
    ].

此配置是 SPARQL 和 Sail 存储库的组合 (https ://rdf4j.org/documentation/reference/configuration/ 1.1 和 1.3）。虽然可以通过 org.eclipse.rdf4j.repository.sail.SailRepository 进行访问，但我无法通过 org.eclipse.rdf4j.repository.sparql.SPARQLRepository 访问我的本地存储库

这是完整的代码：

private static LocalRepositoryManager repositoryManager;
private static RepositoryConnection embeddedRepoCon;
private static SPARQLProtocolSession session;

@BeforeClass
public static void init() {
    try {
        //Create local repo
        File baseDir = new File("target","GraphDB");
        if (!baseDir.exists())
            baseDir.mkdirs();
        repositoryManager = new LocalRepositoryManager(baseDir);
        repositoryManager.init();
        if(new File("target/GraphDB/repositories/test").exists()) {
            repositoryManager.removeRepository("test");
            System.out.println("Repository removed.");
        }

        //Add repository config to repository manager
        InputStream config = TestRDFStarTimestampingPlugin.class.getResourceAsStream("/repo-defaults.ttl");
        Model repo_config_graph = Rio.parse(config, "", RDFFormat.TURTLE);
        Resource repositoryNode = Models.subject(repo_config_graph.filter(null, RDF.TYPE, RepositoryConfigSchema.REPOSITORY)).orElse(null);
        RepositoryConfig repositoryConfig = RepositoryConfig.create(repo_config_graph, repositoryNode);
        repositoryManager.addRepositoryConfig(repositoryConfig);

        //Initialize repo
        //Repository repo = repositoryManager.getRepository("test");
        SailRepository repo = (SailRepository) repositoryManager.getRepository("test");
        repo.init();

        //Establish connection to repo
        embeddedRepoCon = repo.getConnection();

    } catch (RDFHandlerException | RDFParseException | IOException | RepositoryConfigException | RepositoryException  e) {
        System.err.println("The GraphDB repository will not be created.");
        System.err.println(e.getMessage());
    }

}

以下测试通过

   @Test
    public void repoSailConnectionTest() {
        //Test queries
        BooleanQuery query = embeddedRepoCon.prepareBooleanQuery("ask from <http://example.com/testGraph> { ?s ?p ?o }");
        boolean hasResults = query.evaluate();
        assertFalse("No triples should be in the graph yet.", hasResults);
        System.out.println("Result from ask query: " + hasResults);
        System.out.println("Read queries are executable against the embedded repository");

        // Test update statements
        String updateString;
        updateString = "clear graph <http://example.com/testGraph>";
        embeddedRepoCon.prepareUpdate(updateString).execute();
        embeddedRepoCon.commit();

        updateString = "delete data {graph <http://example.com/testGraph> " +
                "{<http://example.com/s/v1> <http://example.com/p/v2> <http://example.com/o/v3>}}";
        embeddedRepoCon.prepareUpdate(updateString).execute();
        embeddedRepoCon.commit();
        System.out.println("Write statements are executable against the embedded repository");

但通过 SPARQLRepository 测试进行访问未通过，因为连接被拒绝：

@Test
public void repoSPARQLConnectionTest() {
    //Test queries
    SPARQLRepository repo = new SPARQLRepository("http://localhost:7200/repositories/test");
    repo.init();
    try (RepositoryConnection connection = repo.getConnection()) {
        BooleanQuery query = connection.prepareBooleanQuery("ask from <http://example.com/testGraph> { ?s ?p ?o }");
        boolean hasResults = query.evaluate();
        assertFalse("No triples should be in the graph yet.", hasResults);
        System.out.println("Result from ask query: " + hasResults);
        System.out.println("Read queries are executable against the embedded repository");
    }
    repo.shutDown();

    // Test update statements
    repo = new SPARQLRepository("http://localhost:7200/repositories/test/statements");
    repo.init();
    try (RepositoryConnection connection = repo.getConnection()) {
        String updateString;
        updateString = "clear graph <http://example.com/testGraph>";
        connection.begin();
        connection.prepareUpdate(updateString).execute();
        connection.commit();

        updateString = "delete data {graph <http://example.com/testGraph> " +
                "{<http://example.com/s/v1> <http://example.com/p/v2> <http://example.com/o/v3>}}";
        connection.prepareUpdate(updateString).execute();
        connection.commit();
        System.out.println("Write statements are executable against the embedded repository");
    }
}

异常：

org.eclipse.rdf4j.query.QueryEvaluationException: Connect to localhost:7200 [localhost/127.0.0.1] failed: Connection refused (Connection refused)

Answer 1

GraphDB 服务器需要首先在 localhost:7200 上运行，并且 SailRepository 应构建到 GraphDB 的本地数据目录中，通常位于 ~/.graphdb/data 上。 SailRepository 只是“存储库部分”，它不提供任何服务器。这就是 SailRepositorie 的优点，它们可以安装在任何实现其规范的服务器上。