com.bigdata.rdf.sparql.ast.service.storedquery

Class StoredQueryService

java.lang.Object

com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactoryBase

com.bigdata.rdf.sparql.ast.service.storedquery.StoredQueryService

All Implemented Interfaces:

ServiceFactory

Direct Known Subclasses:

SimpleStoredQueryService

public abstract class StoredQueryService
extends AbstractServiceFactoryBase

A SERVICE that exposes a stored query for execution. The stored query may be a SPARQL query or arbitrary procedural application logic, but it must evaluate to a solution multi-set. The service interface is written to the openrdf interfaces in order to remove the burden of dealing with bigdata IVs from the application.

In order to use a stored query, a concrete instance of this class must be registered against the ServiceRegistry. The choice of the SERVICE URI is up to the application. The effective value of the baseURI during query evaluation will be the SERVICE URI.

 final URI serviceURI = new URIImpl(
         "http://www.bigdata.com/rdf/stored-query#my-stored-query");
 
 ServiceRegistry.getInstance().add(serviceURI, new MyStoredQueryService());
 

Thereafter, the stored query may be referenced from SPARQL using its assigned service URI:

 SELECT * {
    SERVICE  { }
 }
 

The SERVICE invocation may include a group graph pattern that will be parsed and made accessible to the stored query service as a ServiceParams object. For example:

 SELECT * {
    SERVICE  {
       bd:serviceParam :color :"blue" .
       bd:serviceParam :color :"green" .
       bd:serviceParam :size  :"large" .
    }
 }
 

will provide the stored query with two bindings for the :color = {"blue", "green"} and one binding for :size = {"large"}. The value key names, the allowed value types for each key name, and the interpretation of those values are all specific to a given stored query service implementation class. They will be provided to that class as a ServiceParams object.

Author:

Bryan Thompson

See Also:

Stored Query Service FIXME Wiki page. FIXME Generalize to support groovy scripting. TODO We could use {@link ASTEvalHelper} to evaluate at the bigdata level without forcing the materialization of any variable bindings from the lexicon indices. This would be faster for some purposes, especially if the stored procedure is only used to JOIN into an outer query as in SELECT * { SERVICE bsq:my-service {} }

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	StoredQueryService.Options

Constructor Summary

Constructors

Constructor and Description
StoredQueryService()

Method Summary

Methods

Modifier and Type	Method and Description
ExternalServiceCall	create(ServiceCallCreateParams params) Create a service invocation object.
ExternalServiceCall	create(ServiceCallCreateParams createParams, ServiceParams serviceParams)
protected abstract org.openrdf.query.TupleQueryResult	doQuery(BigdataSailRepositoryConnection cxn, ServiceCallCreateParams createParams, ServiceParams serviceParams) Abstract method for core application logic.
IServiceOptions	getServiceOptions() Return options for the service end point.

Methods inherited from class com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactoryBase

getDesiredBound, getRequiredBound

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StoredQueryService

public StoredQueryService()

Method Detail

getServiceOptions

public IServiceOptions getServiceOptions()

Description copied from interface: ServiceFactory

Return options for the service end point. Depending on the implementation, these options MAY be configurable.

create

public final ExternalServiceCall create(ServiceCallCreateParams params)

Description copied from interface: ServiceFactory

Create a service invocation object.

Parameters:

params - The pararameters, which are encapsulated by this interface.

Returns:

The object which can be used to evaluate the SERVICE clause.

create

public ExternalServiceCall create(ServiceCallCreateParams createParams,
                         ServiceParams serviceParams)

doQuery

protected abstract org.openrdf.query.TupleQueryResult doQuery(BigdataSailRepositoryConnection cxn,
                                         ServiceCallCreateParams createParams,
                                         ServiceParams serviceParams)
                                                       throws Exception

Abstract method for core application logic. The implementation may execute a SPARQL query, or a series or SPARQL or other operations under application control.

Parameters:

cxn - The connection that should be used to read on the SPARQL database. The connection will be closed by the caller.

createParams - The SERVICE creation parameters.

serviceParams - The SERVICE invocation parameters.

Returns:

The solution multi-set.

Throws:

Exception