/*******************************************************************************
* Copyright (c) 1998, 2009 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.internal.sessions.remote;
import java.rmi.server.ObjID;
import java.util.*;
import org.eclipse.persistence.sessions.remote.*;
import org.eclipse.persistence.queries.*;
import org.eclipse.persistence.exceptions.*;
import org.eclipse.persistence.internal.helper.*;
/**
* <p><b>Purpose</b>:
* The object is used as a wrapper to the CursoredStream object in the remote transaction (via RMI, CORBA, etc.)
* <p>
* <p><b>Responsibilities</b>:
* Wraps a database result set cursor to provide a stream to the remote client side on the resulting selected objects.
*
* @author King (Yaoping) Wang
* @since TOPLink/Java 3.0
*/
public class RemoteCursoredStream extends CursoredStream {
/** This is a unique id for remote cursored stream */
protected ObjID id;
/** Return if the stream is closed. */
protected boolean isClosed;
/** Return the cursored stream page size. */
protected int pageSize;
public RemoteCursoredStream(CursoredStream serverCursoredStream) {
this.id = new ObjID();
this.position = serverCursoredStream.getPosition();
this.pageSize = serverCursoredStream.getPageSize();
this.isClosed = (serverCursoredStream.getResultSet() == null);
}
/**
* Close the wrapped cursored stream
* This should be performed whenever the user has finished with the stream.
*/
public void close() throws DatabaseException {
if (isClosed()) {
return;
}
(((RemoteSession)getSession()).getRemoteConnection()).cursoredStreamClose(getID());
}
/**
* INTERNAL:
* Retreive the size of the wrapped cursored stream.
*/
protected int getCursorSize() {
return (((RemoteSession)getSession()).getRemoteConnection()).cursoredStreamSize(getID());
}
/**
* INTERNAL:
* Retreive the OID of the wrapped cursored stream.
*/
public ObjID getID() {
return this.id;
}
/**
* INTERNAL:
* Return if the stream is closed.
*/
public boolean isClosed() {
return isClosed;
}
/**
* Read the next page of objects from the server.
*/
protected Object retrieveNextPage() throws DatabaseException {
if (isClosed()) {
return null;
}
Vector nextPageObjects = (((RemoteSession)getSession()).getRemoteConnection()).cursoredStreamNextPage(this, getPolicy().getQuery(), (RemoteSession)getSession(), getPageSize());
if ((nextPageObjects == null) || nextPageObjects.isEmpty()) {
return null;
}
Helper.addAllToVector(getObjectCollection(), nextPageObjects);
return getObjectCollection().lastElement();
}
}