org.objectweb.medor.datasource.api

Interface Wrapper

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, Object connection, EvaluationMetaData evalmd)
This method links the wrapper to a particular QueryLeaf, and executes the query on the underlying data store.

Method Details

fetchData

public TupleCollection fetchData(QueryLeaf ql,
                                 ParameterOperand[] parameters,
                                 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.