modules/network-api/src/main/java/org/apache/ignite/network/NetworkMessage.java

/*
 * 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.ignite.network;

/**
 * Message for exchanging information in a cluster.
 */
public interface NetworkMessage {
    /** Size of the message type (in bytes), used during (de-)serialization. */
    static final int MSG_TYPE_SIZE_BYTES = 4;

    /**
     * Message type. Must be <b>distinct</b> among all messages in a <i>message group</i>. Only positive values are
     * allowed.
     * <p>
     * Message types are not required to be universally unique among multiple groups.
     *
     * @return message type.
     */
    short messageType();

    /**
     * Message group type. Must be the <b>same</b> for all messages in a <i>message group</i>. Only positive values are
     * allowed.
     * <p>
     * Message group types are required to be universally unique among all groups.
     *
     * @return group type.
     */
    short groupType();
}