/**
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "Exolab" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Intalio, Inc. For written permission,
* please contact info@exolab.org.
*
* 4. Products derived from this Software may not be called "Exolab"
* nor may "Exolab" appear in their names without prior written
* permission of Intalio, Inc. Exolab is a registered
* trademark of Intalio, Inc.
*
* 5. Due credit should be given to the Exolab Project
* (http://www.exolab.org/).
*
* THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* INTALIO, INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 1999 (C) Intalio, Inc. All Rights Reserved.
*
* $Id$
*/
package org.exolab.castor.persist.spi;
import org.castor.persist.ProposedEntity;
import org.exolab.castor.jdo.PersistenceException;
import org.exolab.castor.mapping.AccessMode;
/**
* The persistence engine implements this interface in order to allow
* queries to be performed and multiple objects to be returned. This is
* an extension of {@link Persistence#load} for dealing with complex
* queries.
* <p>
* The caller takes full responsibility to assure integrity of
* transactions and object caching and only relies on the engine to
* assist in assuring that through the mechanisms available to it.
* <p>
* A query may be created once and used multiple times by calling the
* {@link #execute(Object, AccessMode, boolean)} method. Query parameters are set each time prior
* to executing the query.
* <p>
* See {@link Persistence} for information about locks, loading
* objects, identities and stamps.
*
* @author <a href="arkin@intalio.com">Assaf Arkin</a>
* @version $Revision$ $Date: 2006-04-11 15:26:07 -0600 (Tue, 11 Apr 2006) $
* @see Persistence
*/
public interface PersistenceQuery {
/**
* Sets the value of a paramter. Will complain if the parameter
* is not of the specified type.
*
* @param index The parameter index
* @param value The parameter value
*/
void setParameter(int index, Object value);
/**
* Returns the type of object returned by this query.
*
* @return The type of object returned by this query
*/
Class<?> getResultType();
/**
* Execute the query with the give connection and lock type.
* After a successful return the query results will be returned
* by calling {@link #nextIdentity} and {@link #fetch}. The
* query parameters will be reset. A new query may be issued by
* providing new query parameters and calling {@link #execute(Object, AccessMode, boolean)}.
*
* @param conn An open connection
* @param accessMode The access mode (null equals shared)
* @param scrollable The db cursor mode.
* @throws PersistenceException An invalid query or an error reported
* by the persistence engine.
*/
void execute(Object conn, AccessMode accessMode, boolean scrollable)
throws PersistenceException;
/**
* Returns the identity of the next object to be returned.
* Calling this method multiple time will skip objects.
* When the result set has been exhuasted, this method will
* return null.
*
* @param identity The identity of the previous object,
* null if this method is called for the first time
* @return The identity of the next object, null if the
* result set has been exhausted
* @throws PersistenceException An error reported by the
* persistence engine
*/
Identity nextIdentity(Identity identity) throws PersistenceException;
/**
* Loades the object. This method must be called immediately
* after {@link #nextIdentity} with the same identity.
* <p>
* If the object is locked by another transaction this method will
* block until the lock is released, or a timeout occured. If a
* timeout occurs or the object has been deleted by the other
* transaction, this method will report an {@link
* ObjectNotFoundException}. The query may proceed to the next
* identity.
* <p>
* This method is equivalent to {@link Persistence#load} with a
* known cache engine and access mode and acts on the query
* results rather than issuing a new query to load the object.
*
* @param proposedObject The fields to load into
* @throws PersistenceException The object was not found in
* persistent storage or any other persistence error occured.
* @see Persistence#load
*/
void fetch(ProposedEntity proposedObject) throws PersistenceException;
/**
* Close the query and release all resources held by the query.
*/
void close();
/**
* Moves the result of the query to the absolute position in the
* resultset.
*
* @param row The row to move to
* @throws PersistenceException A persistence error occured
*/
boolean absolute(int row) throws PersistenceException;
/**
* Finds the size of the resulting resultset from the query.
*/
int size() throws PersistenceException;
}