/*
* 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.
*/
package org.apache.geode;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
/**
* This interface defines a contract between the application and GemFire that allows GemFire to
* determine whether an application object contains a delta, allows GemFire to extract the delta
* from an application object, and generate a new application object by applying a delta to an
* existing application object. The difference in object state is contained in the
* {@link DataOutput} and {@link DataInput} parameters.
*
* @since GemFire 6.1
*
*/
public interface Delta {
/**
* Returns true if this object has pending changes it can write out.
*/
boolean hasDelta();
/**
* This method is invoked on an application object at the delta sender, if GemFire determines the
* presence of a delta by calling {@link Delta#hasDelta()} on the object. The delta is written to
* the {@link DataOutput} object provided by GemFire.
*
* Any delta state should be reset in this method.
*
* @throws IOException
*/
void toDelta(DataOutput out) throws IOException;
/**
* This method is invoked on an existing application object when an update is received as a delta.
* This method throws an {@link InvalidDeltaException} when the delta in the {@link DataInput}
* cannot be applied to the object. GemFire automatically handles an {@link InvalidDeltaException}
* by reattempting the update by sending the full application object.
*
* @throws IOException
* @throws InvalidDeltaException
*/
void fromDelta(DataInput in) throws IOException, InvalidDeltaException;
}