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Cayenne Object Persistence Framework
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 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
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package org.apache.cayenne;

import java.io.Serializable;
import java.util.Collection;
import java.util.List;

import org.apache.cayenne.graph.GraphManager;
import org.apache.cayenne.map.EntityResolver;
import org.apache.cayenne.query.Query;

/**
 * A Cayenne object facade to a persistent store. Instances of ObjectContext are used in
 * the application code to access Cayenne persistence features.
 * 
 * @since 1.2
 * @author Andrus Adamchik
 */
public interface ObjectContext extends Serializable {

    /**
     * Returns EntityResolver that stores all mapping information accessible by this
     * ObjectContext.
     */
    EntityResolver getEntityResolver();

    /**
     * Returns a collection of objects that are registered with this ObjectContext and
     * have a state PersistenceState.NEW
     */
    Collection newObjects();

    /**
     * Returns a collection of objects that are registered with this ObjectContext and
     * have a state PersistenceState.DELETED
     */
    Collection deletedObjects();

    /**
     * Returns a collection of objects that are registered with this ObjectContext and
     * have a state PersistenceState.MODIFIED
     */
    Collection modifiedObjects();

    /**
     * Returns a collection of MODIFIED, DELETED or NEW objects.
     */
    Collection uncommittedObjects();

    /**
     * Returns an object local to this ObjectContext and matching the ObjectId. If
     * prototype is not null, local object is refreshed with the prototype
     * values.
     * 
     * This method can do both "mapping" (i.e. finding an object with the same id in this
     * context) and "synchronization" (i.e. updating the state of the found object with
     * the state of the prototype object).
     * 
     */
    Persistent localObject(ObjectId id, Persistent prototype);

    /**
     * Creates a new persistent object scheduled to be inserted to the database on next
     * commit.
     */
    Persistent newObject(Class persistentClass);

    /**
     * Schedules a persistent object for deletion on next commit.
     * 
     * @throws DeleteDenyException if a
     *             {@link org.apache.cayenne.map.DeleteRule#DENY} delete rule is
     *             applicable for object deletion.
     */
    void deleteObject(Persistent object) throws DeleteDenyException;

    /**
     * A callback method that child Persistent objects are expected to call from inside
     * the getter before returning a value of a persistent property. Such callback allows
     * ObjectContext to "inflate" unresolved objects on demand.
     */
    void prepareForAccess(Persistent object, String property);

    /**
     * A callback method that child Persistent objects are expected to call from inside
     * the setter after modifying a value of a persistent property.
     */
    void propertyChanged(
            Persistent object,
            String property,
            Object oldValue,
            Object newValue);

    /**
     * Flushes all changes to objects in this context to the parent DataChannel, cascading
     * flush operation all the way through the stack, ultimately saving data in the
     * database.
     */
    void commitChanges();

    /**
     * Flushes all changes to objects in this context to the parent DataChannel. Same as
     * {@link #commitChanges()}, but no cascading flush occurs.
     */
    void commitChangesToParent();

    /**
     * Resets all uncommitted changes made to the objects in this ObjectContext, cascading
     * rollback operation all the way through the stack.
     */
    void rollbackChanges();

    /**
     * Resets all uncommitted changes made to the objects in this ObjectContext. Same as
     * {@link #rollbackChanges()()}, but rollback is local to this context and no
     * cascading changes undoing occurs.
     */
    void rollbackChangesLocally();

    /**
     * Executes a selecting query, returning a list of persistent objects or data rows.
     */
    List performQuery(Query query);

    /**
     * Executes any kind of query providing the result in a form of QueryResponse.
     */
    QueryResponse performGenericQuery(Query query);

    /**
     * Returns GraphManager that manages object graph associated with this context.
     */
    GraphManager getGraphManager();

    /**
     * Returns an DataChannel used by this context.
     */
    DataChannel getChannel();
}