/*
* Copyright 2011 Google Inc.
*
* Licensed 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.bitcoinj.core.listeners;
import org.bitcoinj.core.*;
/**
* <p>Implementors can listen to events like blocks being downloaded/transactions being broadcast/connect/disconnects,
* they can pre-filter messages before they are procesesed by a {@link Peer} or {@link PeerGroup}, and they can
* provide transactions to remote peers when they ask for them.</p>
*/
public interface PreMessageReceivedEventListener {
/**
* <p>Called when a message is received by a peer, before the message is processed. The returned message is
* processed instead. Returning null will cause the message to be ignored by the Peer returning the same message
* object allows you to see the messages received but not change them. The result from one event listeners
* callback is passed as "m" to the next, forming a chain.</p>
*
* <p>Note that this will never be called if registered with any executor other than
* {@link org.bitcoinj.utils.Threading#SAME_THREAD}</p>
*/
Message onPreMessageReceived(Peer peer, Message m);
}