hadoop/hadoop-common-project/hadoop-common/src/main/proto/hadoop_rpc.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.
 */

/**
 * These are the messages used by Hadoop RPC to marshal the
 * request and response in the RPC layer.
 */
option java_package = "org.apache.hadoop.ipc.protobuf";
option java_outer_classname = "HadoopRpcProtos";
option java_generate_equals_and_hash = true;

/**
 * Message used to marshal the client request
 * from RPC client to the RPC server.
 */
message HadoopRpcRequestProto {
  /** Name of the RPC method */
  required string methodName = 1;

  /** Bytes corresponding to the client protobuf request */
  optional bytes request = 2;
  
  /** protocol name of class declaring the called method */ 
  required string declaringClassProtocolName = 3;
  
  /** protocol version of class declaring the called method */
  required uint64 clientProtocolVersion = 4;
}

/**
 * At the RPC layer, this message is used to indicate
 * the server side exception the the RPC client.
 *
 * Hadoop RPC client throws an exception indicated
 * by exceptionName with the stackTrace.
 */
message HadoopRpcExceptionProto {
  /** Class name of the exception thrown from the server */

  optional string exceptionName = 1;
  /** Exception stack trace from the server side */
  optional string stackTrace = 2;
}

/**
 * This message is used to marshal the response from
 * RPC server to the client.
 */
message HadoopRpcResponseProto {
  /** Status of IPC call */
  enum ResponseStatus {
    SUCCESS = 1;
    ERRROR = 2;
  }

  required ResponseStatus status = 1;

  // Protobuf response payload from the server, when status is SUCCESS.
  optional bytes response = 2;

  // Exception when status is ERROR or FATAL
  optional HadoopRpcExceptionProto exception = 3;
}