org.globus.wsrf.query
Interface ExpressionEvaluator

All Known Implementing Classes:

XPathExpressionEvaluator

public interface ExpressionEvaluator

An ExpressionEvaluator is used to implement a query expression evaluation of a ResourcePropertySet. An evaluator can be registered with a QueryEngine, which in turn calls the evaluator when a matching expression is found.

See Also:

ResourcePropertySet, QueryEngine

Method Summary

java.lang.Object	evaluate(QueryExpressionType expression, ResourcePropertySet resourcePropertySet) Evaluates the expression over a ResourcePropertySet and returns the result.
java.lang.String[]	getDialects() Gets the list of dialects that this evaluator can handle.

Method Detail

evaluate

public java.lang.Object evaluate(QueryExpressionType expression,
                                 ResourcePropertySet resourcePropertySet)
                          throws UnsupportedQueryDialectException,
                                 QueryEvaluationException,
                                 InvalidQueryExpressionException,
                                 QueryException

Evaluates the expression over a ResourcePropertySet and returns the result.

Parameters:

expression - object passed by client representing query expression.

resourcePropertySet - ResourcePropertySet associated with resource. The expression is evaluated against this set.

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

getDialects

public java.lang.String[] getDialects()

Gets the list of dialects that this evaluator can handle.

Returns:

list of dialects supported by this evaluator.