java/org/apache/catalina/tribes/Member.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.catalina.tribes;

import java.io.Serializable;

/**
 * The Member interface, defines a member in the group. Each member can carry a set of properties, defined by the actual
 * implementation.
 * <p>
 * A member is identified by the host/ip/uniqueId.
 * <ul>
 * <li>The host is what interface the member is listening to, to receive data</li>
 * <li>The port is what port the member is listening to, to receive data</li>
 * <li>The uniqueId defines the session id for the member. This is an important feature since a member that has crashed
 * and the starts up again on the same port/host is not guaranteed to be the same member, so no state transfers will
 * ever be confused.</li>
 * </ul>
 */
public interface Member extends Serializable {

    /**
     * When a member leaves the cluster, the payload of the memberDisappeared member will be the following bytes. This
     * indicates a soft shutdown, and not a crash
     */
    byte[] SHUTDOWN_PAYLOAD = new byte[] { 66, 65, 66, 89, 45, 65, 76, 69, 88 };

    /**
     * @return the name of this node, should be unique within the group.
     */
    String getName();

    /**
     * Returns the listen host for the ChannelReceiver implementation
     *
     * @return IPv4 or IPv6 representation of the host address this member listens to incoming data
     *
     * @see ChannelReceiver
     */
    byte[] getHost();

    /**
     * Returns the listen port for the ChannelReceiver implementation
     *
     * @return the listen port for this member, -1 if it's not listening on an insecure port
     *
     * @see ChannelReceiver
     */
    int getPort();

    /**
     * Returns the secure listen port for the ChannelReceiver implementation. Returns -1 if it's not listening to a
     * secure port.
     *
     * @return the listen port for this member, -1 if it's not listening on a secure port
     *
     * @see ChannelReceiver
     */
    int getSecurePort();

    /**
     * Returns the UDP port that this member is listening to for UDP messages.
     *
     * @return the listen UDP port for this member, -1 if it's not listening on a UDP port
     */
    int getUdpPort();


    /**
     * Contains information on how long this member has been online. The result is the number of milliseconds this
     * member has been broadcasting its membership to the group.
     *
     * @return nr of milliseconds since this member started.
     */
    long getMemberAliveTime();

    /**
     * Set the alive time in ms.
     *
     * @param memberAliveTime the value to set
     */
    void setMemberAliveTime(long memberAliveTime);

    /**
     * The current state of the member.
     *
     * @return {@code true} if the member is functioning correctly
     */
    boolean isReady();

    /**
     * The current state of the member.
     *
     * @return {@code true} if the member is suspect, but the crash has not been confirmed
     */
    boolean isSuspect();

    /**
     * @return {@code true} if the member has been confirmed to malfunction
     */
    boolean isFailing();

    /**
     * returns a UUID unique for this member over all sessions. If the member crashes and restarts, the uniqueId will be
     * different.
     *
     * @return byte[]
     */
    byte[] getUniqueId();

    /**
     * @return the payload associated with this member
     */
    byte[] getPayload();

    /**
     * Set the payload associated with this member.
     *
     * @param payload the payload
     */
    void setPayload(byte[] payload);

    /**
     * @return the command associated with this member
     */
    byte[] getCommand();

    /**
     * Set the command associated with this member.
     *
     * @param command the command
     */
    void setCommand(byte[] command);

    /**
     * @return the domain for this cluster
     */
    byte[] getDomain();

    /**
     * Highly optimized version of serializing a member into a byte array Returns a cached byte[] reference, do not
     * modify this data
     *
     * @param getalive calculate memberAlive time
     *
     * @return the data as a byte array
     */
    byte[] getData(boolean getalive);

    /**
     * Highly optimized version of serializing a member into a byte array Returns a cached byte[] reference, do not
     * modify this data
     *
     * @param getalive calculate memberAlive time
     * @param reset    reset the cached data package, and create a new one
     *
     * @return the data as a byte array
     */
    byte[] getData(boolean getalive, boolean reset);

    /**
     * Length of a message obtained by {@link #getData(boolean)} or {@link #getData(boolean, boolean)}.
     *
     * @return the data length
     */
    int getDataLength();

    /**
     * @return {@code true} if the member is local member
     */
    boolean isLocal();

    /**
     * Set if the member is local.
     *
     * @param local set to {@code true} if this is the local member
     */
    void setLocal(boolean local);
}