hadoop/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/NamenodeProtocol.proto

/**
 * 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.
 */

// This file contains protocol buffers that are used throughout HDFS -- i.e.
// by the client, server, and data transfer protocols.

option java_package = "org.apache.hadoop.hdfs.protocol.proto";
option java_outer_classname = "NamenodeProtocolProtos";
option java_generic_services = true;
option java_generate_equals_and_hash = true;
package hadoop.hdfs;

import "hdfs.proto";

/**
 * Get list of blocks for a given datanode with the total length 
 * of adding up to given size
 * datanode - Datanode ID to get list of block from
 * size - size to which the block lengths must add up to
 */
message GetBlocksRequestProto {
  required DatanodeIDProto datanode = 1; // Datanode ID
  required uint64 size = 2;              // Size in bytes
}

 
/**
 * blocks - List of returned blocks
 */
message GetBlocksResponseProto {
  required BlocksWithLocationsProto blocks = 1; // List of blocks
}

/**
 * void request
 */
message GetBlockKeysRequestProto {
}

/**
 * keys - Information about block keys at the active namenode
 */
message GetBlockKeysResponseProto {
  optional ExportedBlockKeysProto keys = 1;
}

/**
 * void request
 */
message GetTransactionIdRequestProto {
}

/**
 * txId - Transaction ID of the most recently persisted edit log record
 */
message GetTransactionIdResponseProto {
  required uint64 txId = 1;   // Transaction ID
}

/**
 * void request
 */
message RollEditLogRequestProto {
}

/**
 * signature - A unique token to identify checkpoint transaction
 */
message RollEditLogResponseProto {
  required CheckpointSignatureProto signature = 1;
}

/**
 * void request
 */
message GetMostRecentCheckpointTxIdRequestProto {
}

message GetMostRecentCheckpointTxIdResponseProto{
  required uint64 txId = 1;
}

/**
 * registration - Namenode reporting the error
 * errorCode - error code indicating the error
 * msg - Free text description of the error
 */
message ErrorReportRequestProto {
  required NamenodeRegistrationProto registration = 1; // Registration info
  required uint32 errorCode = 2;  // Error code
  required string msg = 3;        // Error message
}

/**
 * void response
 */
message ErrorReportResponseProto {
}

/**
 * registration - Information of the namenode registering with primary namenode
 */
message RegisterRequestProto {
  required NamenodeRegistrationProto registration = 1; // Registration info
}

/**
 * registration - Updated registration information of the newly registered
 *                datanode.
 */
message RegisterResponseProto {
  required NamenodeRegistrationProto registration = 1; // Registration info
}

/**
 * Start checkpoint request
 * registration - Namenode that is starting the checkpoint
 */
message StartCheckpointRequestProto {
  required NamenodeRegistrationProto registration = 1; // Registration info
}

/**
 * command - Command returned by the active namenode to be
 *           be handled by the caller.
 */
message StartCheckpointResponseProto {
  required NamenodeCommandProto command = 1;
}

/**
 * End or finalize the previously started checkpoint
 * registration - Namenode that is ending the checkpoint
 * signature - unique token to identify checkpoint transaction,
 *             that was received when checkpoint was started.
 */
message EndCheckpointRequestProto {
  required NamenodeRegistrationProto registration = 1; // Registration info
  required CheckpointSignatureProto signature = 2;
}

/**
 * void response
 */
message EndCheckpointResponseProto {
}

/**
 * sinceTxId - return the editlog information for transactions >= sinceTxId
 */
message GetEditLogManifestRequestProto {
  required uint64 sinceTxId = 1;  // Transaction ID
}

/**
 * manifest - Enumeration of editlogs from namenode for 
 *            logs >= sinceTxId in the request
 */
message GetEditLogManifestResponseProto {
  required RemoteEditLogManifestProto manifest = 1; 
}

/**
 * Protocol used by the sub-ordinate namenode to send requests
 * the active/primary namenode.
 *
 * See the request and response for details of rpc call.
 */
service NamenodeProtocolService {
  /**
   * Get list of blocks for a given datanode with length
   * of blocks adding up to given size.
   */
  rpc getBlocks(GetBlocksRequestProto) returns(GetBlocksResponseProto);

  /**
   * Get the current block keys
   */
  rpc getBlockKeys(GetBlockKeysRequestProto) returns(GetBlockKeysResponseProto);

  /**
   * Get the transaction ID of the most recently persisted editlog record
   */
  rpc getTransactionId(GetTransactionIdRequestProto) 
      returns(GetTransactionIdResponseProto);

  /**
   * Get the transaction ID of the most recently persisted editlog record
   */
  rpc getMostRecentCheckpointTxId(GetMostRecentCheckpointTxIdRequestProto) 
      returns(GetMostRecentCheckpointTxIdResponseProto);

  /**
   * Close the current editlog and open a new one for checkpointing purposes
   */
  rpc rollEditLog(RollEditLogRequestProto) returns(RollEditLogResponseProto);

  /**
   * Request info about the version running on this NameNode
   */
  rpc versionRequest(VersionRequestProto) returns(VersionResponseProto);

  /**
   * Report from a sub-ordinate namenode of an error to the active namenode.
   * Active namenode may decide to unregister the reporting namenode 
   * depending on the error.
   */
  rpc errorReport(ErrorReportRequestProto) returns(ErrorReportResponseProto);

  /**
   * Request to register a sub-ordinate namenode
   */
  rpc register(RegisterRequestProto) returns(RegisterResponseProto);

  /**
   * Request to start a checkpoint. 
   */
  rpc startCheckpoint(StartCheckpointRequestProto) 
      returns(StartCheckpointResponseProto);

  /**
   * End of finalize the previously started checkpoint
   */
  rpc endCheckpoint(EndCheckpointRequestProto) 
      returns(EndCheckpointResponseProto);

  /**
   * Get editlog manifests from the active namenode for all the editlogs
   */
  rpc getEditLogManifest(GetEditLogManifestRequestProto) 
      returns(GetEditLogManifestResponseProto);
}