org.globus.wsrf.query
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

java.lang.Object	executeQuery(QueryExpressionType queryExpression, ResourcePropertySet resourcePropertySet) Executes a query against a resource property set.
ExpressionEvaluator	getEvaluator(java.lang.String dialect) 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.

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 java.lang.Object executeQuery(QueryExpressionType queryExpression,
                                     ResourcePropertySet resourcePropertySet)
                              throws UnsupportedQueryDialectException,
                                     QueryEvaluationException,
                                     InvalidQueryExpressionException,
                                     QueryException

Executes a query against a resource property set. The appropraite ExpressionEvaluator is used for the query based on the dialect attribute.

Parameters:

queryExpression - query expression

resourcePropertySet - resource properties set to execute the query against

Returns:

the result of the evaluation which depends on the expression. The results must be an xml serializable object in order to be passed back correctly to a remote client. The easiest way of achieving this is to model it as a Bean, or simply return a SOAPElment or DOM Element. If the result object returned is null an empty query result is returned.

Throws:

UnsupportedQueryDialectException - if query dialect is unsupported.

QueryEvaluationException - if query evaluation fails.

InvalidQueryExpressionException - if query expression is invalid.

QueryException - if any other error

getEvaluator

public ExpressionEvaluator getEvaluator(java.lang.String dialect)

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