java - 由于键入文字而无法获取结果 (xsd :string) querying SPARQL from Jena;

Question

我的 Virtuoso 服务器在加载的本体上运行，以下查询通过将其粘贴到网络上 sparql 端点的文本字段来工作(ronto，由于安全原因我跳过了本体的前缀(抱歉)，但我确信它的定义正确，因为查询可以工作但返回空列表，这是一个问题):

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
select distinct (str(?p) as ?theme) where {?s ronto:isin "id-XXXX"^^xsd:string; ronto:mainThemes ?p}

以下不起作用(返回空列表)；注意跳过的内容

xsd:string

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
select distinct (str(?p) as ?theme) where {?s ronto:isin "id-XXXX"; ronto:mainThemes ?p}

所以，问题:我无法从 Java 中获得相同的结果，Jena 部门是:

        <dependency>
            <groupId>org.apache.jena</groupId>
            <artifactId>jena-arq</artifactId>
            <version>3.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.jena</groupId>
            <artifactId>jena-core</artifactId>
            <version>3.0.1</version>
        </dependency>

所以，玩具代码:

   public static void main(String[] args) {
        String isin = "id-XXXX";
        final ParameterizedSparqlString qs = new ParameterizedSparqlString(
                "select ?p where {?s ronto:isin ?isin^^xsd:string; ronto:mainThemes ?p.}");
        qs.setBaseUri(base);
        qs.setNsPrefix("owl", "http://www.w3.org/2002/07/owl#");
        qs.setNsPrefix("xsd", "http://www.w3.org/2001/XMLSchema#");
        qs.setNsPrefix("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
        qs.setNsPrefix("rdfs", "http://www.w3.org/2000/01/rdf-schema#");

        qs.setLiteral("isin", isin);

        System.out.println("Running as a query " +qs.asQuery());
        try (QueryExecution exec = QueryExecutionFactory.sparqlService(publicSparqlEndpoint, qs.asQuery())) {
            final ResultSet resultSet = exec.execSelect();
            System.out.println(exec.getQuery());
            ResultSetFormatter.out(resultSet);
        }
        System.out.println("Running as a string " + qs.toString());
        try (QueryExecution exec = QueryExecutionFactory.sparqlService(publicSparqlEndpoint, qs.toString())) {
            final ResultSet resultSet = exec.execSelect();
            System.out.println(exec.getQuery());
            ResultSetFormatter.out(resultSet);
        }

输出是

PREFIX  xsd:  <http://www.w3.org/2001/XMLSchema#>
PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX  owl:  <http://www.w3.org/2002/07/owl#>
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>


SELECT  ?p
WHERE
  { ?s  ronto:isin        "id-XXXX" ;
        ronto:mainThemes  ?p
  }
PREFIX  xsd:  <http://www.w3.org/2001/XMLSchema#>
PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX  owl:  <http://www.w3.org/2002/07/owl#>
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT  ?p
WHERE
  { ?s  ronto:isin        "id-XXXX" ;
        ronto:mainThemes  ?p
  }

-----
| p |
=====
-----
Running as a string
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

select ?p where {?s ronto:isin "id-XXXX"^^xsd:string; ronto:mainThemes ?p.}

PREFIX  xsd:  <http://www.w3.org/2001/XMLSchema#>
PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX  owl:  <http://www.w3.org/2002/07/owl#>
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT  ?p
WHERE
  { ?s  ronto:isin        "id-XXXX" ;
        ronto:mainThemes  ?p
  }

-----
| p |
=====
-----

其中 p 框是来自端点的空列表结果；

我测试了不基于类型文字的更简单的查询(此处为 xsd:string)，它们给了我非空结果；

因此，很容易发现 exec 对象具有跳过的 xsd:string 查询，我猜这是导致结果为空列表的问题，但为什么它会以这种方式工作？解决方法的干净方法是什么？

解决方案我感谢@AndyS(注意两个更改:查询中的过滤器和QueryEngineHTTP):

public static void main(String[] args) {
    String isin = "id-XXXX";
    final ParameterizedSparqlString qs = new ParameterizedSparqlString(
            "select ?p where {?s ronto:isin ?X; ronto:mainThemes ?p. FILTER (?X= ?isin^^xsd:string)}");
    qs.setBaseUri(base);
    qs.setNsPrefix("owl", "http://www.w3.org/2002/07/owl#");
    qs.setNsPrefix("xsd", "http://www.w3.org/2001/XMLSchema#");
    qs.setNsPrefix("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
    qs.setNsPrefix("rdfs", "http://www.w3.org/2000/01/rdf-schema#");
    qs.setNsPrefix("ronto", "....");

    qs.setLiteral("isin", isin);

    System.out.println("Running as a string " + qs.toString());
    try (QueryEngineHTTP exec = new QueryEngineHTTP(publicSparqlEndpoint, qs.toString())) {
        final ResultSet resultSet = exec.execSelect();
        System.out.println(exec.getQuery());
        ResultSetFormatter.out(resultSet);
    }
}

Answer 1

在 RDF 1.1 中，不带 xsd:string 的字符串和带 xsd:string 的字符串是相同的 RDF 术语。是否写入 ^^xsd:string 并不重要。

ARQ 打印不带 ^^xsd:string 的查询，这用于远程 SPARQL 调用。

Virtuoso 实例似乎与 RDF 1.1 不兼容。

您可以在查询中尝试使用值表达式:

{ ?s ronto:isin ?X;
     ronto:mainThemes ?p.
  FILTER ( ?X = "id-XXXX"^^xsd:string)
}

适用于 RDF 1.0 和 RDF 1.1 以及混合系统。

或者，直接使用 QueryEngineHTTP，而不是 QueryExecutionFactory。这允许应用程序传入一个字符串作为发送到远程端点的查询，而无需解析或检查。