/******************************************************************************* | |
* Copyright (c) 1998, 2013 Oracle and/or its affiliates. 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.*; | |
/** | |
* <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; | |
} | |
(((DistributedSession)getSession()).getRemoteConnection()).cursoredStreamClose(getID()); | |
} | |
/** | |
* INTERNAL: | |
* Retreive the size of the wrapped cursored stream. | |
*/ | |
protected int getCursorSize() { | |
return (((DistributedSession)getSession()).getRemoteConnection()).cursoredStreamSize(getID()); | |
} | |
/** | |
* INTERNAL: | |
* Retrieve 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 = (((DistributedSession)getSession()).getRemoteConnection()).cursoredStreamNextPage(this, getPolicy().getQuery(), (DistributedSession)getSession(), getPageSize()); | |
if ((nextPageObjects == null) || nextPageObjects.isEmpty()) { | |
return null; | |
} | |
getObjectCollection().addAll(nextPageObjects); | |
return getObjectCollection().get(getObjectCollection().size() - 1); | |
} | |
} |