Module org.apache.jena.arq
Package org.apache.jena.sparql.exec.http

Class QueryExecHTTP

java.lang.Object
org.apache.jena.sparql.exec.http.QueryExecHTTP
All Implemented Interfaces:
AutoCloseable, QueryExec
public class QueryExecHTTP extends Object implements QueryExec
A QueryExec implementation where queries are executed against a remote service over HTTP.

  • Field Details

  • Constructor Details

  • Method Details

    • newBuilder

      public static QueryExecHTTPBuilder newBuilder()
      Description copied from interface: QueryExec
      Create an uninitialized QueryExecDatasetBuilder.

    • service

      public static QueryExecHTTPBuilder service(String serviceURL)
      Description copied from interface: QueryExec
      Create a QueryExecBuilder for a remote endpoint.

    • getAppProvidedAcceptHeader

      public String getAppProvidedAcceptHeader()
      Getter for the appProvidedAcceptHeader. Only used for testing.

    • getHttpResponseContentType

      public String getHttpResponseContentType()
      The Content-Type response header received (null before the remote operation is attempted).

    • select

      public RowSet select()
      Description copied from interface: QueryExec
      Execute a SELECT query

      Important: The name of this method is somewhat of a misnomer in that depending on the underlying implementation this typically does not execute the SELECT query but rather answers a wrapper over an internal data structure that can be used to answer the query. In essence calling this method only returns a plan for executing this query which only gets evaluated when you actually start iterating over the results.

      Specified by:
      select in interface QueryExec

    • ask

      public boolean ask()
      Description copied from interface: QueryExec
      Execute an ASK query
      Specified by:
      ask in interface QueryExec

    • construct

      public org.apache.jena.graph.Graph construct(org.apache.jena.graph.Graph graph)
      Description copied from interface: QueryExec
      Execute a CONSTRUCT query, putting the statements into a graph.
      Specified by:
      construct in interface QueryExec
      Returns:
      Graph The graph argument for cascaded code.

    • constructTriples

      public Iterator<org.apache.jena.graph.Triple> constructTriples()
      Description copied from interface: QueryExec
      Execute a CONSTRUCT query, returning the results as an iterator of Triple.

      Caution: This method may return duplicate Triples. This method may be useful if you only need the results for stream processing, as it can avoid having to place the results in a Model.

      Important: The name of this method is somewhat of a misnomer in that depending on the underlying implementation this typically does not execute the CONSTRUCT query but rather answers a wrapper over an internal data structure that can be used to answer the query. In essence calling this method only returns a plan for executing this query which only gets evaluated when you actually start iterating over the results.

      Specified by:
      constructTriples in interface QueryExec
      Returns:
      An iterator of Triple objects (possibly containing duplicates) generated by applying the CONSTRUCT template of the query to the bindings in the WHERE clause.

    • constructQuads

      public Iterator<Quad> constructQuads()
      Description copied from interface: QueryExec
      Execute a CONSTRUCT query, returning the results as an iterator of Quad.

      Caution: This method may return duplicate Quads. This method may be useful if you only need the results for stream processing, as it can avoid having to place the results in a Model.

      See QueryExec.constructTriples() for usage and features.

      Specified by:
      constructQuads in interface QueryExec
      Returns:
      An iterator of Quad objects (possibly containing duplicates) generated by applying the CONSTRUCT template of the query to the bindings in the WHERE clause.

    • constructDataset

      public DatasetGraph constructDataset()
      Description copied from interface: QueryExec
      Execute a CONSTRUCT query, putting the statements into 'dataset'. This maybe an extended syntax query (if supported).
      Specified by:
      constructDataset in interface QueryExec

    • constructDataset

      public DatasetGraph constructDataset(DatasetGraph dataset)
      Description copied from interface: QueryExec
      Execute a CONSTRUCT query, putting the statements into 'dataset'. This may be an extended syntax query (if supported).
      Specified by:
      constructDataset in interface QueryExec

    • describe

      public org.apache.jena.graph.Graph describe(org.apache.jena.graph.Graph graph)
      Description copied from interface: QueryExec
      Execute a DESCRIBE query, putting the statements into a graph.
      Specified by:
      describe in interface QueryExec
      Returns:
      Graph The model argument for cascaded code.

    • describeTriples

      public Iterator<org.apache.jena.graph.Triple> describeTriples()
      Description copied from interface: QueryExec
      Execute a DESCRIBE query, returning the results as an iterator of Triple.

      Caution: This method may return duplicate Triples. This method may be useful if you only need the results for stream processing, as it can avoid having to place the results in a Model.

      Important: The name of this method is somewhat of a misnomer in that depending on the underlying implementation this typically does not execute the DESCRIBE query but rather answers a wrapper over an internal data structure that can be used to answer the query. In essence calling this method only returns a plan for executing this query which only gets evaluated when you actually start iterating over the results.

      Specified by:
      describeTriples in interface QueryExec
      Returns:
      An iterator of Triple objects (possibly containing duplicates) generated as the output of the DESCRIBE query.

    • execJson

      public JsonArray execJson()
      Description copied from interface: QueryExec
      Execute a JSON query and return a json array
      Specified by:
      execJson in interface QueryExec

    • execJsonItems

      public Iterator<JsonObject> execJsonItems()
      Description copied from interface: QueryExec
      Execute a JSON query and return an iterator
      Specified by:
      execJsonItems in interface QueryExec

    • getContext

      public Context getContext()
      Description copied from interface: QueryExec
      The properties associated with a query execution - implementation specific parameters This includes Java objects (so it is not an RDF graph). Keys should be URIs as strings. May be null (this implementation does not provide any configuration).
      Specified by:
      getContext in interface QueryExec

    • getDataset

      public DatasetGraph getDataset()
      Description copied from interface: QueryExec
      The dataset against which the query will execute. May be null - the dataset may be remote or the query itself has a dataset description.
      Specified by:
      getDataset in interface QueryExec

    • getQuery

      public Query getQuery()
      Description copied from interface: QueryExec
      The query associated with a query execution. May be null (QueryExec may have been created by other means)
      Specified by:
      getQuery in interface QueryExec

    • getQueryString

      public String getQueryString()
      Return the query string. If this was supplied as a string, there is no guarantee this is legal SPARQL syntax.
      Specified by:
      getQueryString in interface QueryExec

    • cancel

      public void cancel()
      Cancel query evaluation

    • abort

      public void abort()
      Description copied from interface: QueryExec
      Stop in mid execution. This method can be called in parallel with other methods on the QueryExecution object. There is no guarantee that the concrete implementation actual will stop or that it will do so immediately. No operations on the query execution or any associated result set are permitted after this call and may cause exceptions to be thrown.
      Specified by:
      abort in interface QueryExec

    • close

      public void close()
      Description copied from interface: QueryExec
      Close the query execution and stop query evaluation as soon as convenient. QExec objects, and a RowSet from QueryExec.select(), can not be used once the QExec is closed. Model results from QueryExec.construct() and QueryExec.describe() are still valid.

      It is important to close query execution objects in order to release resources such as working memory and to stop the query execution. Some storage subsystems require explicit ends of operations and this operation will cause those to be called where necessary. No operations on the query execution or any associated result set are permitted after this call.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface QueryExec

    • isClosed

      public boolean isClosed()
      Description copied from interface: QueryExec
      Answer whether this QueryExecution object has been closed or not.
      Specified by:
      isClosed in interface QueryExec
      Returns:
      boolean