Question

这是我的查询

    PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix no: <http://www.newontology.org/no#>
prefix rs: <http://semanticrecommender.com/rs#>
prefix mo: <http://music.org/musicontology/mo#>
prefix : <http://www.MusicSemanticOntology.com/mso#>

select ?item (SUM(?similarity * ?importance * ?levelImportance * ?ratingValue) as ?summedSimilarity) 
(group_concat(distinct ?x) as ?commingFromLikingThisInstance)
(group_concat(?becauseOf ; separator = " ,and ") as ?reason)
where
{
  values ?user { :ania }
  #the variable ?x is bound to the items the user :ania has liked.
  ?user rs:hasRated ?ratings.
  ?ratings a rs:Likes.
  ?ratings rs:about ?x.
  ?ratings rs:ratesBy ?ratingValue.
 ?ratings rs:createdOn ?ratingDate.

  #level 0 class similarities
  {
    #extract all the items that are from the same class (type) as the liked items.
    #I assumed the being from the same class accounts for 50% of the similarities.
    #This value can be changed according to the test or the application domain.
    values ?classImportance {0.5} #class level
    ?x  a ?class .
    ?item a ?class .
    ?class rs:hasSimilarityValue ?similarity .
    bind (?classImportance as ?importance)
    bind( 4/7 as ?levelImportance)
    bind (concat("it shares the same class, which is ", str(?class), " with ", str(?x)) as ?becauseOf)
  }


}
group by ?item
order by desc(?summedSimilarity)

如果我将它放在fuseki sparql接口中，它会工作，但是如果我把它放在一个文件中并从jena调用该文件，我会得到以下例外：

EVERE: Servlet.service() for servlet [com.semanticrecommender.web.Main] in context with path [/SemanticRecommender] threw exception
HttpException: 400
    at org.apache.jena.sparql.engine.http.HttpQuery.rewrap(HttpQuery.java:411)
    at org.apache.jena.sparql.engine.http.HttpQuery.execPost(HttpQuery.java:399)
    at org.apache.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:291)
    at org.apache.jena.sparql.engine.http.QueryEngineHTTP.execResultSetInner(QueryEngineHTTP.java:359)
    at org.apache.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:351)

虽然我打印了jena从文件加载并将其复制到fuseki的查询，但它在fuseki上完美运行

这是我加载查询的方式（但我确定这与实际问题无关）

InputStream testIn = getClass().getResourceAsStream("/recommend.rq");
        String queryTemplate = IOUtils.toString(testIn);
System.out.println(queryTemplate);
        QueryExecution x = QueryExecutionFactory.sparqlService(
                "http://localhost:3030/rs/query", queryTemplate);
        ResultSet results = x.execSelect();
        ResultSetFormatter.out(System.out, results);

更新

此代码工作

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix no: <http://www.newontology.org/no#>
prefix rs: <http://semanticrecommender.com/rs#>
prefix mo: <http://music.org/musicontology/mo#>
prefix : <http://www.MusicSemanticOntology.com/mso#>

select *
where
{
  values ?user { :ania }
  #the variable ?x is bound to the items the user :ania has liked.
  ?user rs:hasRated ?ratings.
  ?ratings a rs:Likes.
  ?ratings rs:about ?x.
  ?ratings rs:ratesBy ?ratingValue.
 ?ratings rs:createdOn ?ratingDate.

  #level 0 class similarities
  {
    #extract all the items that are from the same class (type) as the liked items.
    #I assumed the being from the same class accounts for 50% of the similarities.
    #This value can be changed according to the test or the application domain.
    values ?classImportance {0.5} #class level
    ?x  a ?class .
    ?item a ?class .
    ?class rs:hasSimilarityValue ?similarity .
    bind (?classImportance as ?importance)
    bind( 4/7 as ?levelImportance)
    bind (concat("it shares the same class, which is ", str(?class), " with ", str(?x)) as ?becauseOf)
  }


}

除了group by之外，这两个查询是相同的，一个with group by只能在Fuseki界面上工作，而不是eclipse java，但另一个同时适用于

Update3

问题发生在这两行

(group_concat(distinct ?x) as ?commingFromLikingThisInstance)
(group_concat(?becauseOf ; separator = " ,and ") as ?reason)

当我删除它们时，一切正常，但是当我把它们放入时我得到了那个错误

更新4

日志是：

2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "Error 400: Parse error: [\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "PREFIX  :     <http://www.MusicSemanticOntology.com/mso#>[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "PREFIX  rs:   <http://semanticrecommender.com/rs#>[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "SELECT  ?item (SUM(( ( ( ?similarity * ?importance ) * ?levelImportance ) * ?ratingValue )) AS ?summedSimilarity) (GROUP_CONCAT DISTINCT (?x) AS ?commingFromLikingThisInstance) (GROUP_CONCAT (?becauseOf ; separator=' ,and ') AS ?reason)[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "WHERE[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "  { VALUES ?user { :ania }[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "    ?user     rs:hasRated  ?ratings .[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "    ?ratings  rdf:type     rs:Likes ;[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "              rs:about     ?x ;[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "              rs:ratesBy   ?ratingValue[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "    { VALUES ?classImportance { 0.5 }[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "      BIND(?classImportance AS ?importance)[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "      BIND(( 4 / 7 ) AS ?levelImportance)[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "      ?x      rdf:type              ?class .[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "      ?item   rdf:type              ?class .[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "      ?class  rs:hasSimilarityValue  ?similarity[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "      BIND(concat("it shares the same class, which is ", str(?class), " with ", str(?x)) AS ?becauseOf)[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "    }[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "  }[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "GROUP BY ?item[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "ORDER BY DESC(?summedSimilarity)[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "[\r]Encountered " "distinct" "DISTINCT "" at line 6, column 129.[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "Was expecting:[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "    "(" ...[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "    [\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.wire:63 - << "Fuseki - version 2.3.1 (Build date: 2015-12-08T09:24:07+0000)[\n]"
2016-03-28 11:17:50 DEBUG org.apache.http.impl.conn.PoolingClientConnectionManager:274 - Connection [id: 0][route: {}->http://localhost:3030] can be kept alive indefinitely
2016-03-28 11:17:50 DEBUG org.apache.http.impl.conn.PoolingClientConnectionManager:281 - Connection released: [id: 0][route: {}->http://localhost:3030][total kept alive: 1; route allocated: 1 of 5; total allocated: 1 of 10]

更新5

现在我发现了真正的问题，它是单词DISTINCT，当我删除它时，一切正常，当我把它放回去时，它只是从fuseki接口工作而不是来自jena java :( help伙计们

Answer 1

我认为如果可以的话，你可能希望Jena避免本地解析，并在这种情况下直接将查询发送到远程端点。 answer.semanticweb.com上的jena throws QueryParsingException on correct but non-standard SPARQL问题描述了这种方法。我们的想法是使用查询字符串创建 QueryEngineHTTP 。

至于为什么您收到此错误，我认为这可能是Jena结束时的错误。我有一些证据和一些假设。调查一下，并与sparql.org's query validator（由耶拿支持）玩，有一些奇怪的事情发生。如果输入查询

select (group_concat(distinct ?x) as ?y) (sum(distinct ?x) as ?z) {}

进入解析器后，格式化的解析查询显示为：

SELECT  (GROUP_CONCAT DISTINCT (?x) AS ?y) (SUM(DISTINCT ?x) AS ?z) WHERE {}

不合法。（注意关闭的不同位置 GROUP_CONCAT。另请注意，它出现在 group_concat 中，但与 sum 无关。）

当使用Jena将查询发送到远程端点时，如果Jena是第一个解析输入查询，然后将重新格式化的查询发送到远程端点，它可以解释调试日志消息和解析错误，但是我不确定这是否是如何实施的。

SPARQL查询适用于Fuseki界面但在Jena中

更新

Update3

更新4

更新5

1 个答案: