/** * 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.contrib.dlucene;import java.io.IOException;import org.apache.hadoop.ipc.VersionedProtocol;/** datanode to namenode protocol. */public interface DataNodeToNameNodeProtocol extends VersionedProtocol {  /** The version of the protocol. */  long VERSION_ID = 1L;  /**   * Send a heartbeat message to the namenode.   *    * @param status The status of the datanode.   * @param searchableIndexes The indexes on the datanode.   * @param leases The leases owned by the datanode.   * @return the indexes to replicate   * @throws IOExceptiuon   */  HeartbeatResponse heartbeat(DataNodeStatus status,      IndexLocation[] searchableIndexes, Lease[] leases)   throws IOException;  /**   * Get a lease to be the primary replica for a specific index.   *    * @param index The index requiring the lease.   * @return the lease.   * @throws LeaseException   */  Lease getLease(IndexLocation index) throws IOException ;  /**   * Relinquish a lease.   *    * @param lease the lease.   * @return was operation successful   */  public boolean relinquishLease(Lease lease) throws IOException ;}