org.objectweb.medor.datasource.api
Interface Wrapper

All Known Implementing Classes:

JDBCWrapper, TCWrapper

public interface Wrapper

Represents a wrapper to access data from a QueryLeaf at query evaluation time.

A Wrapper is associated to a QueryLeaf at a given point of time. There can be several Wrappers of the same type. One Wrapper can be associated sequentially to several QueryLeaves.

Author:

Sebastien Chassande-Barrioz

Method Summary

TupleCollection

fetchData(QueryLeaf ql, ParameterOperand[] parameters, java.lang.Object connection, EvaluationMetaData evalmd) This method links the wrapper to a particular QueryLeaf, and executes the query on the underlying data store.

Method Detail

fetchData

public TupleCollection fetchData(QueryLeaf ql,
                                 ParameterOperand[] parameters,
                                 java.lang.Object connection,
                                 EvaluationMetaData evalmd)
                          throws EvaluationException

This method links the wrapper to a particular QueryLeaf, and executes the query on the underlying data store.

Parameters:

ql - the QueryLeaf

parameters - the parameters necessary for obtaining data from the QueryLeaf (in the case the QueryLeaf contains an expression)

connection - an Object which contains information for connecting to the DataStore behind the QueryLeaf (could be a JDBC connection, ...)s

Returns:

the TupleCollection containing the result of the execution.

Throws:

EvaluationException - in case of problems during the evaluation.