org.globus.ogsa
Interface QueryEngine

All Known Implementing Classes:

QueryEngineImpl

public interface QueryEngine

The QueryEngine interface is used to map queries on the service data of a service to the appropriate ExpressionEvaluators and then return the result. ExpressionEvaluators can be preconfigured or dynamically added at runtime.

See Also:

ExpressionEvaluator

Method Summary

Object	executeQuery(ExtensibilityType queryExpression, ServiceDataSet serviceDataSet) If no external query evaluators are registered for an incoming query expression, then executeQuery is called on the engine.
ExpressionEvaluator	getEvaluator(javax.xml.namespace.QName qname) Gets the evaluator currently registered to handle an expression of the specified qualified name (from the top level element of the XML Schema definition of the expression)
void	registerEvaluator(ExpressionEvaluator evaluator) registers a new evaluator that can be used to evaluate queries on a service.
void	setGlobalEngine(QueryEngine engine) Sets the global engine to delegate to if this engine cannot handle the request.

Method Detail

registerEvaluator

public void registerEvaluator(ExpressionEvaluator evaluator)

registers a new evaluator that can be used to evaluate queries on a service.

Parameters:

evaluator - implementation of evaluator to be used for evaluating queries specified in its XML Schema definition.

executeQuery

public Object executeQuery(ExtensibilityType queryExpression,
                           ServiceDataSet serviceDataSet)
                    throws FaultType

If no external query evaluators are registered for an incoming query expression, then executeQuery is called on the engine.

Parameters:

serviceDataSet - ServiceDataSet belonging to Grid service instance to execute the query against

Throws:

FaultType - if the query could not be evaluated

getEvaluator

public ExpressionEvaluator getEvaluator(javax.xml.namespace.QName qname)

Gets the evaluator currently registered to handle an expression of the specified qualified name (from the top level element of the XML Schema definition of the expression)

Returns:

the matching expression evaluator or null if none was found

setGlobalEngine

public void setGlobalEngine(QueryEngine engine)

Sets the global engine to delegate to if this engine cannot handle the request.

Parameters:

engine - a query engine common for all services in a Grid service container