hadoop-yarn-project/hadoop-yarn/hadoop-yarn-registry/src/main/java/org/apache/hadoop/registry/client/types/AddressTypes.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.hadoop.registry.client.types;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

/**
 * Enum of address types -as integers.
 * Why integers and not enums? Cross platform serialization as JSON
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface AddressTypes {

  /**
   * hostname/FQDN and port pair: {@value}.
   * The host/domain name and port are set as separate strings in the address
   * list, e.g.
   * <pre>
   *   ["namenode.example.org", "50070"]
   * </pre>
   */
  public static final String ADDRESS_HOSTNAME_AND_PORT = "host/port";
  public static final String ADDRESS_HOSTNAME_FIELD = "host";
  public static final String ADDRESS_PORT_FIELD = "port";


  /**
   * Path <code>/a/b/c</code> style: {@value}.
   * The entire path is encoded in a single entry
   *
   * <pre>
   *   ["/users/example/dataset"]
   * </pre>
   */
  public static final String ADDRESS_PATH = "path";



  /**
   * URI entries: {@value}.
   * <pre>
   *   ["http://example.org"]
   * </pre>
   */
  public static final String ADDRESS_URI = "uri";

  /**
   * Zookeeper addresses as a triple : {@value}.
   * <p>
   * These are provide as a 3 element tuple of: hostname, port
   * and optionally path (depending on the application)
   * <p>
   *   A single element would be
   * <pre>
   *   ["zk1","2181","/registry"]
   * </pre>
   *  An endpoint with multiple elements would list them as
   * <pre>
   *   [
   *    ["zk1","2181","/registry"]
   *    ["zk2","1600","/registry"]
   *   ]
   * </pre>
   *
   * the third element in each entry , the path, MUST be the same in each entry.
   * A client reading the addresses of an endpoint is free to pick any
   * of the set, so they must be the same.
   *
   */
  public static final String ADDRESS_ZOOKEEPER = "zktriple";

  /**
   * Any other address: {@value}.
   */
  public static final String ADDRESS_OTHER = "";
}