Merged r1179877 from trunk for HDFS-2181.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23-PB@1229479 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -13,6 +13,8 @@ Release 0.23-PB - Unreleased
 
     HDFS-2337. DFSClient shouldn't keep multiple RPC proxy references (atm)
  
+    HDFS-2181. Separate HDFS Client wire protocol data types (sanjay)
+
 Release 0.23.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java

@@ -19,6 +19,7 @@
 package org.apache.hadoop.hdfs;
 
 import java.io.BufferedOutputStream;
+import java.io.Closeable;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.FileNotFoundException;
@@ -290,7 +291,7 @@ public class DFSClient implements java.io.Closeable {
     this.clientName = leaserenewer.getClientName(dfsClientConf.taskId);
     this.socketCache = new SocketCache(dfsClientConf.socketCacheCapacity);
     if (nameNodeAddr != null && rpcNamenode == null) {
-      this.namenode = DFSUtil.createNamenode(nameNodeAddr, conf);
+      this.namenode = DFSUtil.createNamenode(nameNodeAddr, conf, ugi);
     } else if (nameNodeAddr == null && rpcNamenode != null) {
       //This case is used for testing.
       this.namenode = rpcNamenode;
@@ -379,11 +380,30 @@ public class DFSClient implements java.io.Closeable {
     }
   }
   
+  /**
+   * Close connections the Namenode.
+   * The namenode variable is either a rpcProxy passed by a test or 
+   * created using the protocolTranslator which is closeable.
+   * If closeable then call close, else close using RPC.stopProxy().
+   */
+  void closeConnectionToNamenode() {
+    if (namenode instanceof Closeable) {
+      try {
+        ((Closeable) namenode).close();
+        return;
+      } catch (IOException e) {
+        // fall through - lets try the stopProxy
+        LOG.warn("Exception closing namenode, stopping the proxy");
+      }     
+    }
+    RPC.stopProxy(namenode);
+  }
+  
   /** Abort and release resources held.  Ignore all errors. */
   void abort() {
     clientRunning = false;
     closeAllFilesBeingWritten(true);
-    RPC.stopProxy(namenode); // close connections to the namenode
+    closeConnectionToNamenode();
   }
 
   /** Close/abort all files being written. */
@@ -423,7 +443,7 @@ public class DFSClient implements java.io.Closeable {
       clientRunning = false;
       leaserenewer.closeClient(this);
       // close connections to the namenode
-      RPC.stopProxy(namenode);
+      closeConnectionToNamenode();
     }
   }
 
@@ -604,7 +624,7 @@ public class DFSClient implements java.io.Closeable {
       LOG.info("Renewing " + 
                DelegationTokenIdentifier.stringifyToken(delToken));
       ClientProtocol nn = 
-        DFSUtil.createRPCNamenode
+        DFSUtil.createNamenode
            (NameNode.getAddress(token.getService().toString()),
             conf, UserGroupInformation.getCurrentUser());
       try {
@@ -622,7 +642,7 @@ public class DFSClient implements java.io.Closeable {
           (Token<DelegationTokenIdentifier>) token;
       LOG.info("Cancelling " + 
                DelegationTokenIdentifier.stringifyToken(delToken));
-      ClientProtocol nn = DFSUtil.createRPCNamenode(
+      ClientProtocol nn = DFSUtil.createNamenode(
           NameNode.getAddress(token.getService().toString()), conf,
           UserGroupInformation.getCurrentUser());
       try {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSUtil.java

@@ -41,11 +41,12 @@ import java.util.Random;
 import java.util.StringTokenizer;
 import java.util.concurrent.TimeUnit;
 
+import javax.net.SocketFactory;
+
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.BlockLocation;
-import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
 import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
@@ -626,25 +627,29 @@ public class DFSUtil {
 
 
   /** Create a {@link NameNode} proxy */
-  public static ClientProtocol createNamenode(Configuration conf) throws IOException {
+  public static ClientProtocol createNamenode(Configuration conf)
+      throws IOException {
     return createNamenode(NameNode.getAddress(conf), conf);
   }
 
   /** Create a {@link NameNode} proxy */
   public static ClientProtocol createNamenode( InetSocketAddress nameNodeAddr,
       Configuration conf) throws IOException {   
-    return createNamenode(createRPCNamenode(nameNodeAddr, conf,
+    return createNamenode(nameNodeAddr, conf,
-        UserGroupInformation.getCurrentUser()));
+        UserGroupInformation.getCurrentUser());
-    
   }
     
   /** Create a {@link NameNode} proxy */
-  static ClientProtocol createRPCNamenode(InetSocketAddress nameNodeAddr,
+  public static ClientProtocol createNamenode( InetSocketAddress nameNodeAddr,
-      Configuration conf, UserGroupInformation ugi) 
+      Configuration conf, UserGroupInformation ugi) throws IOException {
-    throws IOException {
+    /** 
-    return (ClientProtocol)RPC.getProxy(ClientProtocol.class,
+     * Currently we have simply burnt-in support for a SINGLE
-        ClientProtocol.versionID, nameNodeAddr, ugi, conf,
+     * protocol - protocolR23Compatible. This will be replaced
-        NetUtils.getSocketFactory(conf, ClientProtocol.class));
+     * by a way to pick the right protocol based on the 
+     * version of the target server.  
+     */
+    return new org.apache.hadoop.hdfs.protocolR23Compatible.
+        ClientNamenodeProtocolTranslatorR23(nameNodeAddr, conf, ugi);
   }
 
   /** Create a {@link NameNode} proxy */
@@ -690,31 +695,18 @@ public class DFSUtil {
   /** Create a {@link ClientDatanodeProtocol} proxy */
   public static ClientDatanodeProtocol createClientDatanodeProtocolProxy(
       DatanodeID datanodeid, Configuration conf, int socketTimeout,
-      LocatedBlock locatedBlock)
+      LocatedBlock locatedBlock) throws IOException {
-      throws IOException {
+    return new org.apache.hadoop.hdfs.protocolR23Compatible.
-    InetSocketAddress addr = NetUtils.createSocketAddr(
+        ClientDatanodeProtocolTranslatorR23(datanodeid, conf, socketTimeout,
-      datanodeid.getHost() + ":" + datanodeid.getIpcPort());
+             locatedBlock);
-    if (ClientDatanodeProtocol.LOG.isDebugEnabled()) {
-      ClientDatanodeProtocol.LOG.debug("ClientDatanodeProtocol addr=" + addr);
   }
   
-    // Since we're creating a new UserGroupInformation here, we know that no
+  /** Create a {@link ClientDatanodeProtocol} proxy */
-    // future RPC proxies will be able to re-use the same connection. And
+  public static ClientDatanodeProtocol createClientDatanodeProtocolProxy(
-    // usages of this proxy tend to be one-off calls.
+      InetSocketAddress addr, UserGroupInformation ticket, Configuration conf,
-    //
+      SocketFactory factory) throws IOException {
-    // This is a temporary fix: callers should really achieve this by using
+    return new org.apache.hadoop.hdfs.protocolR23Compatible.
-    // RPC.stopProxy() on the resulting object, but this is currently not
+        ClientDatanodeProtocolTranslatorR23(addr, ticket, conf, factory);
-    // working in trunk. See the discussion on HDFS-1965.
-    Configuration confWithNoIpcIdle = new Configuration(conf);
-    confWithNoIpcIdle.setInt(CommonConfigurationKeysPublic
-        .IPC_CLIENT_CONNECTION_MAXIDLETIME_KEY, 0);
-
-    UserGroupInformation ticket = UserGroupInformation
-        .createRemoteUser(locatedBlock.getBlock().getLocalBlock().toString());
-    ticket.addToken(locatedBlock.getBlockToken());
-    return (ClientDatanodeProtocol)RPC.getProxy(ClientDatanodeProtocol.class,
-        ClientDatanodeProtocol.versionID, addr, ticket, confWithNoIpcIdle,
-        NetUtils.getDefaultSocketFactory(conf), socketTimeout);
   }
   
   /**

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ClientDatanodeProtocol.java

@@ -41,8 +41,30 @@ import org.apache.hadoop.security.token.TokenInfo;
 public interface ClientDatanodeProtocol extends VersionedProtocol {
   public static final Log LOG = LogFactory.getLog(ClientDatanodeProtocol.class);
 
+  
   /**
+   * Until version 9, this class ClientDatanodeProtocol served as both
+   * the client interface to the DN AND the RPC protocol used to 
+   * communicate with the NN.
+   * 
+   * Post version 10 (release 23 of Hadoop), the protocol is implemented in
+   * {@literal ../protocolR23Compatible/ClientDatanodeWireProtocol}
+   * 
+   * This class is used by both the DFSClient and the 
+   * DN server side to insulate from the protocol serialization.
+   * 
+   * If you are adding/changing DN's interface then you need to 
+   * change both this class and ALSO
+   * {@link org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol}.
+   * These changes need to be done in a compatible fashion as described in 
+   * {@link org.apache.hadoop.hdfs.protocolR23Compatible.ClientNamenodeWireProtocol}
+   * 
+   * The log of historical changes can be retrieved from the svn).
    * 9: Added deleteBlockPool method
+   * 
+   * 9 is the last version id when this class was used for protocols
+   *  serialization. DO not update this version any further. 
+   *  Changes are recorded in R23 classes.
    */
   public static final long versionID = 9L;
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java

@@ -64,10 +64,28 @@ import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSelector;
 public interface ClientProtocol extends VersionedProtocol {
 
   /**
-   * Compared to the previous version the following changes have been introduced:
+   * Until version 69, this class ClientProtocol served as both
-   * (Only the latest change is reflected.
+   * the client interface to the NN AND the RPC protocol used to 
+   * communicate with the NN.
+   * 
+   * Post version 70 (release 23 of Hadoop), the protocol is implemented in
+   * {@literal ../protocolR23Compatible/ClientNamenodeWireProtocol}
+   * 
+   * This class is used by both the DFSClient and the 
+   * NN server side to insulate from the protocol serialization.
+   * 
+   * If you are adding/changing NN's interface then you need to 
+   * change both this class and ALSO
+   * {@link org.apache.hadoop.hdfs.protocolR23Compatible.ClientNamenodeWireProtocol}.
+   * These changes need to be done in a compatible fashion as described in 
+   * {@link org.apache.hadoop.hdfs.protocolR23Compatible.ClientNamenodeWireProtocol}
+   * 
    * The log of historical changes can be retrieved from the svn).
    * 69: Eliminate overloaded method names.
+   * 
+   * 69L is the last version id when this class was used for protocols
+   *  serialization. DO not update this version any further. 
+   *  Changes are recorded in R23 classes.
    */
   public static final long versionID = 69L;
   
@@ -366,10 +384,7 @@ public interface ClientProtocol extends VersionedProtocol {
    * or if the new name already belongs to the namespace.
    * 
    * @throws IOException an I/O error occurred 
-   * 
-   * @deprecated Use {@link #rename(String, String, Options.Rename...)} instead.
    */
-  @Deprecated
   public boolean rename(String src, String dst) 
       throws UnresolvedLinkException, IOException;
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeInfo.java

@@ -75,6 +75,13 @@ public class DatanodeInfo extends DatanodeID implements Node {
     public String toString() {
       return value;
     }
+    
+    public static AdminStates fromValue(final String value) {
+      for (AdminStates as : AdminStates.values()) {
+        if (as.value.equals(value)) return as;
+      }
+      return NORMAL;
+    }
   }
 
   @Nullable
@@ -110,12 +117,21 @@ public class DatanodeInfo extends DatanodeID implements Node {
     this.adminState = null;    
   }
   
-  protected DatanodeInfo(DatanodeID nodeID, String location, String hostName) {
+  public DatanodeInfo(DatanodeID nodeID, String location, String hostName) {
     this(nodeID);
     this.location = location;
     this.hostName = hostName;
   }
   
+  public DatanodeInfo(DatanodeID nodeID, String location, String hostName,
+      final long capacity, final long dfsUsed, final long remaining,
+      final long blockPoolUsed, final long lastUpdate, final int xceiverCount,
+      final AdminStates adminState) {
+    this(nodeID.getName(), nodeID.getStorageID(), nodeID.getInfoPort(), nodeID
+        .getIpcPort(), capacity, dfsUsed, remaining, blockPoolUsed, lastUpdate,
+        xceiverCount, location, hostName, adminState);
+  }
+
   /** Constructor */
   public DatanodeInfo(final String name, final String storageID,
       final int infoPort, final int ipcPort,

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/HdfsConstants.java

@@ -31,6 +31,15 @@ public class HdfsConstants {
   protected HdfsConstants() {
   }
   
+  /**
+   * HDFS Protocol Names:  
+   */
+  public static final String CLIENT_NAMENODE_PROTOCOL_NAME = 
+      "org.apache.hadoop.hdfs.protocol.ClientProtocol";
+  public static final String CLIENT_DATANODE_PROTOCOL_NAME = 
+      "org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol";
+  
+  
   public static int MIN_BLOCKS_FOR_WRITE = 5;
 
   // Long that indicates "leave current quota unchanged"

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/HdfsFileStatus.java

@@ -242,6 +242,10 @@ public class HdfsFileStatus implements Writable {
     return DFSUtil.bytes2String(symlink);
   }
   
+  final public byte[] getSymlinkInBytes() {
+    return symlink;
+  }
+
   //////////////////////////////////////////////////
   // Writable
   //////////////////////////////////////////////////

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/LocatedBlock.java

@@ -55,6 +55,11 @@ public class LocatedBlock implements Writable {
     this(new ExtendedBlock(), new DatanodeInfo[0], 0L, false);
   }
   
+
+  public LocatedBlock(ExtendedBlock eb) {
+    this(eb, new DatanodeInfo[0], 0L, false);
+  }
+
   public LocatedBlock(String bpid, Block b, DatanodeInfo[] locs) {
     this(new ExtendedBlock(bpid, b), locs, -1, false); // startOffset is unknown
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolProtocolBuffers/overview.html

@@ -0,0 +1,29 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+<html>
+<!--
+   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.
+-->
+<head>
+   <title>Protocol Buffers based data types for NN protocols</title>
+</head>
+<body>
+<p>
+The Protocol Buffers data types for NN protocols that use 
+PB go in this package.
+</p>
+
+
+

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ClientDatanodeProtocolServerSideTranslatorR23.java

@@ -0,0 +1,129 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
+import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
+import org.apache.hadoop.ipc.ProtocolSignature;
+import org.apache.hadoop.ipc.RPC;
+import org.apache.hadoop.security.token.Token;
+
+/**
+ * This class is used on the server side.
+ * Calls come across the wire for the protocol family of Release 23 onwards.
+ * This class translates the R23 data types to the internal data types used
+ * inside the DN as specified in the generic ClientDatanodeProtocol.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class ClientDatanodeProtocolServerSideTranslatorR23 implements
+  ClientDatanodeWireProtocol {
+  
+  final private ClientDatanodeProtocol server;
+
+  /**
+   * 
+   * @param server - the NN server
+   * @throws IOException
+   */
+  public ClientDatanodeProtocolServerSideTranslatorR23(
+      ClientDatanodeProtocol server) throws IOException {
+    this.server = server;
+  }
+  
+  /**
+   * the client side will redirect getProtocolSignature to 
+   * getProtocolSignature2.
+   * 
+   * However the RPC layer below on the Server side will call
+   * getProtocolVersion and possibly in the future getProtocolSignature.
+   * Hence we still implement it even though the end client's call will
+   * never reach here.
+   */
+  @Override
+  public ProtocolSignature getProtocolSignature(String protocol,
+      long clientVersion, int clientMethodsHash) throws IOException {
+    /**
+     * Don't forward this to the server. The protocol version and
+     * signature is that of  {@link ClientDatanodeProtocol}
+     */
+    if (!protocol.equals(RPC.getProtocolName(
+        ClientDatanodeWireProtocol.class))) {
+      throw new IOException("Datanode Serverside implements " + 
+          ClientDatanodeWireProtocol.class + 
+          ". The following requested protocol is unknown: " + protocol);
+    }
+    
+    return ProtocolSignature.getProtocolSignature(clientMethodsHash, 
+        ClientDatanodeWireProtocol.versionID, 
+        ClientDatanodeWireProtocol.class);
+  }
+
+  @Override
+  public ProtocolSignatureWritable 
+    getProtocolSignature2(
+        String protocol, long clientVersion, int clientMethodsHash)
+      throws IOException {
+    /**
+     * Don't forward this to the server. The protocol version and
+     * signature is that of  {@link ClientNamenodeProtocol}
+     */
+   return ProtocolSignatureWritable.convert(
+        this.getProtocolSignature(protocol, clientVersion, clientMethodsHash));
+
+  }
+
+  @Override
+  public long getProtocolVersion(String protocol, long clientVersion) throws IOException {
+    if (protocol.equals(RPC.getProtocolName(
+        ClientDatanodeWireProtocol.class))) {
+      return ClientDatanodeWireProtocol.versionID; 
+    }
+    throw new IOException("Datanode Serverside implements " + 
+        ClientDatanodeWireProtocol.class + 
+        ". The following requested protocol is unknown: " + protocol);
+  }
+
+  @Override
+  public long getReplicaVisibleLength(ExtendedBlockWritable b) throws IOException {
+    return 
+        server.getReplicaVisibleLength(ExtendedBlockWritable.convertExtendedBlock(b));
+  }
+
+  @Override
+  public void refreshNamenodes() throws IOException {
+    server.refreshNamenodes();
+  }
+
+  @Override
+  public void deleteBlockPool(String bpid, boolean force) throws IOException {
+    server.deleteBlockPool(bpid, force);
+  }
+
+  @Override
+  public BlockLocalPathInfo getBlockLocalPathInfo(ExtendedBlock block,
+      Token<BlockTokenIdentifier> token) throws IOException {
+    return server.getBlockLocalPathInfo(block, token);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ClientDatanodeProtocolTranslatorR23.java

@@ -0,0 +1,145 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+
+import javax.net.SocketFactory;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
+import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
+import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
+import org.apache.hadoop.hdfs.protocol.DatanodeID;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
+import org.apache.hadoop.ipc.ProtocolSignature;
+import org.apache.hadoop.ipc.RPC;
+import org.apache.hadoop.net.NetUtils;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.token.Token;
+
+
+/**
+ * This class forwards ClientDatanodeProtocol calls as RPC to the DN server
+ * while translating from the parameter types used in ClientDatanodeProtocol to
+ * those used in protocolR23Compatile.*.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class ClientDatanodeProtocolTranslatorR23 implements 
+  ClientDatanodeProtocol {
+  
+  final private ClientDatanodeWireProtocol rpcProxy;
+  
+  public ClientDatanodeProtocolTranslatorR23(DatanodeID datanodeid,
+      Configuration conf, int socketTimeout, LocatedBlock locatedBlock)
+      throws IOException {
+    rpcProxy = createClientDatanodeProtocolProxy( datanodeid, conf, 
+                  socketTimeout, locatedBlock);
+  }
+  
+  /** used for testing */
+  public ClientDatanodeProtocolTranslatorR23(InetSocketAddress addr,
+      UserGroupInformation ticket,
+      Configuration conf,
+      SocketFactory factory) throws IOException {
+    rpcProxy = createClientDatanodeProtocolProxy(addr, ticket, conf, factory);
+  }
+  
+  static ClientDatanodeWireProtocol createClientDatanodeProtocolProxy(
+      DatanodeID datanodeid, Configuration conf, int socketTimeout,
+      LocatedBlock locatedBlock)
+      throws IOException {
+    InetSocketAddress addr = NetUtils.createSocketAddr(
+      datanodeid.getHost() + ":" + datanodeid.getIpcPort());
+    if (ClientDatanodeWireProtocol.LOG.isDebugEnabled()) {
+      ClientDatanodeWireProtocol.LOG.debug(
+          "ClientDatanodeProtocol addr=" + addr);
+    }
+    
+    // Since we're creating a new UserGroupInformation here, we know that no
+    // future RPC proxies will be able to re-use the same connection. And
+    // usages of this proxy tend to be one-off calls.
+    //
+    // This is a temporary fix: callers should really achieve this by using
+    // RPC.stopProxy() on the resulting object, but this is currently not
+    // working in trunk. See the discussion on HDFS-1965.
+    Configuration confWithNoIpcIdle = new Configuration(conf);
+    confWithNoIpcIdle.setInt(CommonConfigurationKeysPublic
+        .IPC_CLIENT_CONNECTION_MAXIDLETIME_KEY, 0);
+
+    UserGroupInformation ticket = UserGroupInformation
+        .createRemoteUser(locatedBlock.getBlock().getLocalBlock().toString());
+    ticket.addToken(locatedBlock.getBlockToken());
+    return RPC.getProxy(ClientDatanodeWireProtocol.class,
+      ClientDatanodeWireProtocol.versionID, addr, ticket, confWithNoIpcIdle,
+        NetUtils.getDefaultSocketFactory(conf), socketTimeout);
+  }
+  
+  static ClientDatanodeWireProtocol createClientDatanodeProtocolProxy(
+      InetSocketAddress addr, UserGroupInformation ticket, Configuration conf,
+      SocketFactory factory) throws IOException {
+    return RPC.getProxy(ClientDatanodeWireProtocol.class,
+        ClientDatanodeWireProtocol.versionID, addr, ticket, conf,
+        factory);
+  }
+
+  @Override
+  public ProtocolSignature getProtocolSignature(
+      String protocolName, long clientVersion, int clientMethodHash)
+      throws IOException {
+    return ProtocolSignatureWritable.convert(
+        rpcProxy.getProtocolSignature2(
+            protocolName, clientVersion, clientMethodHash));
+  }
+
+  @Override
+  public long getProtocolVersion(String protocolName, long clientVersion)
+      throws IOException {
+    return rpcProxy.getProtocolVersion(protocolName, clientVersion);
+  }
+
+  @Override
+  public long getReplicaVisibleLength(ExtendedBlock b) throws IOException {
+    return rpcProxy.getReplicaVisibleLength(
+        ExtendedBlockWritable.convertExtendedBlock(b));
+  }
+
+  @Override
+  public void refreshNamenodes() throws IOException {
+    rpcProxy.refreshNamenodes();
+
+  }
+
+  @Override
+  public void deleteBlockPool(String bpid, boolean force) throws IOException {
+    rpcProxy.deleteBlockPool(bpid, force);
+
+  }
+
+  @Override
+  public BlockLocalPathInfo getBlockLocalPathInfo(ExtendedBlock block,
+      Token<BlockTokenIdentifier> token) throws IOException {
+    return rpcProxy.getBlockLocalPathInfo(block, token);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ClientDatanodeWireProtocol.java

@@ -0,0 +1,101 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.IOException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
+import org.apache.hadoop.hdfs.security.token.block.BlockTokenSelector;
+import org.apache.hadoop.ipc.ProtocolInfo;
+import org.apache.hadoop.ipc.VersionedProtocol;
+import org.apache.hadoop.security.KerberosInfo;
+import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.security.token.TokenInfo;
+
+/** 
+ * This class defines the actual protocol used to communicate with the
+ * DN via RPC using writable types.
+ * The parameters in the methods which are specified in the
+ * package are separate from those used internally in the DN and DFSClient
+ * and hence need to be converted using {@link ClientDatanodeProtocolTranslatorR23}
+ * and {@link ClientDatanodeProtocolServerSideTranslatorR23}.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+@KerberosInfo(
+    serverPrincipal = DFSConfigKeys.DFS_DATANODE_USER_NAME_KEY)
+@TokenInfo(BlockTokenSelector.class)
+@ProtocolInfo(protocolName = HdfsConstants.CLIENT_DATANODE_PROTOCOL_NAME)
+public interface ClientDatanodeWireProtocol extends VersionedProtocol {
+  public static final Log LOG = 
+      LogFactory.getLog(ClientDatanodeWireProtocol.class);
+
+  /**
+   * The  rules for changing this protocol are the same as that for
+   * {@link ClientNamenodeWireProtocol} - see that java file for details.
+   * 9: Added deleteBlockPool method
+   * 10 Moved the R23 protocol
+   */
+  public static final long versionID = 10L;
+
+  /**
+   * The specification of this method matches that of
+   * 
+   * {@link org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol
+   * #getReplicaVisibleLength(org.apache.hadoop.hdfs.protocol.ExtendedBlock)}
+   */
+  long getReplicaVisibleLength(ExtendedBlockWritable b) throws IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol#refreshNamenodes()}
+   */
+  void refreshNamenodes() throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol#deleteBlockPool(String, boolean)}
+   */
+  void deleteBlockPool(String bpid, boolean force) throws IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol
+   * #getBlockLocalPathInfo(ExtendedBlock, Token)}
+   */
+  BlockLocalPathInfo getBlockLocalPathInfo(ExtendedBlock block,
+      Token<BlockTokenIdentifier> token) throws IOException;
+  
+  /**
+   * This method is defined to get the protocol signature using 
+   * the R23 protocol - hence we have added the suffix of 2 to the method name
+   * to avoid conflict.
+   */
+  public org.apache.hadoop.hdfs.protocolR23Compatible.ProtocolSignatureWritable
+           getProtocolSignature2(String protocol, 
+      long clientVersion,
+      int clientMethodsHash) throws IOException;
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ClientNamenodeProtocolServerSideTranslatorR23.java

@@ -0,0 +1,462 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.CreateFlag;
+import org.apache.hadoop.fs.FileAlreadyExistsException;
+import org.apache.hadoop.fs.Options.Rename;
+import org.apache.hadoop.fs.ParentNotDirectoryException;
+import org.apache.hadoop.fs.UnresolvedLinkException;
+import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
+import org.apache.hadoop.hdfs.protocol.ClientProtocol;
+import org.apache.hadoop.hdfs.protocol.DSQuotaExceededException;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.UpgradeAction;
+import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
+import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
+import org.apache.hadoop.hdfs.server.namenode.NotReplicatedYetException;
+import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
+import org.apache.hadoop.io.EnumSetWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.ipc.ProtocolSignature;
+import org.apache.hadoop.ipc.RPC;
+import org.apache.hadoop.security.AccessControlException;
+import org.apache.hadoop.security.token.Token;
+
+/**
+ * This class is used on the server side. Calls come across the wire for the
+ * protocol family of Release 23 onwards. This class translates the R23 data
+ * types to the native data types used inside the NN as specified in the generic
+ * ClientProtocol.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class ClientNamenodeProtocolServerSideTranslatorR23 implements
+    ClientNamenodeWireProtocol {
+  final private ClientProtocol server;
+
+  /**
+   * Constructor
+   * 
+   * @param server - the NN server
+   * @throws IOException
+   */
+  public ClientNamenodeProtocolServerSideTranslatorR23(ClientProtocol server)
+      throws IOException {
+    this.server = server;
+  }
+
+  /**
+   * The client side will redirect getProtocolSignature to
+   * getProtocolSignature2.
+   * 
+   * However the RPC layer below on the Server side will call getProtocolVersion
+   * and possibly in the future getProtocolSignature. Hence we still implement
+   * it even though the end client's call will never reach here.
+   */
+  @Override
+  public ProtocolSignature getProtocolSignature(String protocol,
+      long clientVersion, int clientMethodsHash) throws IOException {
+    /**
+     * Don't forward this to the server. The protocol version and signature is
+     * that of {@link ClientNamenodeProtocol}
+     * 
+     */
+    if (!protocol.equals(RPC.getProtocolName(
+        ClientNamenodeWireProtocol.class))) {
+      throw new IOException("Namenode Serverside implements " +
+          RPC.getProtocolName(ClientNamenodeWireProtocol.class) +
+          ". The following requested protocol is unknown: " + protocol);
+    }
+
+    return ProtocolSignature.getProtocolSignature(clientMethodsHash,
+        ClientNamenodeWireProtocol.versionID,
+        ClientNamenodeWireProtocol.class);
+  }
+
+  @Override
+  public ProtocolSignatureWritable 
+          getProtocolSignature2(
+      String protocol, long clientVersion, int clientMethodsHash)
+      throws IOException {
+    /**
+     * Don't forward this to the server. The protocol version and signature is
+     * that of {@link ClientNamenodeProtocol}
+     * 
+     */
+
+    return ProtocolSignatureWritable.convert(
+        this.getProtocolSignature(protocol, clientVersion, clientMethodsHash));
+  }
+
+  @Override
+  public long getProtocolVersion(String protocol, long clientVersion)
+      throws IOException {
+    if (protocol.equals(RPC.getProtocolName(
+        ClientNamenodeWireProtocol.class))) {
+      return ClientNamenodeWireProtocol.versionID;
+    }
+    throw new IOException("Namenode Serverside implements " +
+        RPC.getProtocolName(ClientNamenodeWireProtocol.class) +
+        ". The following requested protocol is unknown: " + protocol);
+  }
+
+  @Override
+  public LocatedBlocksWritable getBlockLocations(
+      String src, long offset, long length)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    return LocatedBlocksWritable.convertLocatedBlocks(
+        server.getBlockLocations(src, offset, length));
+  }
+
+  @Override
+  public FsServerDefaultsWritable getServerDefaults() throws IOException {
+    return FsServerDefaultsWritable.convert(server.getServerDefaults());
+  }
+
+  @Override
+  public void create(String src, FsPermissionWritable masked, String clientName,
+      EnumSetWritable<CreateFlag> flag, boolean createParent,
+      short replication, long blockSize) throws AccessControlException,
+      AlreadyBeingCreatedException, DSQuotaExceededException,
+      FileAlreadyExistsException, FileNotFoundException,
+      NSQuotaExceededException, ParentNotDirectoryException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    server.create(src, FsPermissionWritable.convertPermission(masked),
+        clientName, flag, createParent, replication, blockSize);
+
+  }
+
+  @Override
+  public LocatedBlockWritable append(String src, String clientName)
+      throws AccessControlException, DSQuotaExceededException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return LocatedBlockWritable.convertLocatedBlock(
+        server.append(src, clientName));
+  }
+
+  @Override
+  public boolean setReplication(String src, short replication)
+      throws AccessControlException, DSQuotaExceededException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return server.setReplication(src, replication);
+  }
+
+  @Override
+  public void setPermission(String src, FsPermissionWritable permission)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    server.setPermission(src, 
+        FsPermissionWritable.convertPermission(permission));
+
+  }
+
+  @Override
+  public void setOwner(String src, String username, String groupname)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    server.setOwner(src, username, groupname);
+
+  }
+
+  @Override
+  public void abandonBlock(ExtendedBlockWritable b, String src, String holder)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    server.abandonBlock(
+        ExtendedBlockWritable.convertExtendedBlock(b), src, holder);
+
+  }
+
+  @Override
+  public LocatedBlockWritable addBlock(String src, String clientName,
+      ExtendedBlockWritable previous, DatanodeInfoWritable[] excludeNodes)
+      throws AccessControlException, FileNotFoundException,
+      NotReplicatedYetException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return LocatedBlockWritable.convertLocatedBlock(
+        server.addBlock(src, clientName,
+        ExtendedBlockWritable.convertExtendedBlock(previous),
+        DatanodeInfoWritable.convertDatanodeInfo(excludeNodes)));
+  }
+
+  @Override
+  public LocatedBlockWritable getAdditionalDatanode(String src, ExtendedBlockWritable blk,
+      DatanodeInfoWritable[] existings, DatanodeInfoWritable[] excludes,
+      int numAdditionalNodes, String clientName) throws AccessControlException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return LocatedBlockWritable.convertLocatedBlock(
+        server.getAdditionalDatanode(src,
+              ExtendedBlockWritable.convertExtendedBlock(blk),
+              DatanodeInfoWritable.convertDatanodeInfo(existings),
+              DatanodeInfoWritable.convertDatanodeInfo(excludes),
+              numAdditionalNodes, clientName));
+  }
+
+  @Override
+  public boolean complete(String src, String clientName, ExtendedBlockWritable last)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    return server.complete(src, clientName,
+        ExtendedBlockWritable.convertExtendedBlock(last));
+  }
+
+  @Override
+  public void reportBadBlocks(LocatedBlockWritable[] blocks) throws IOException {
+    server.reportBadBlocks(LocatedBlockWritable.convertLocatedBlock(blocks));
+
+  }
+
+  @Override
+  public boolean rename(String src, String dst) throws UnresolvedLinkException,
+      IOException {
+    return server.rename(src, dst);
+  }
+
+  @Override
+  public void concat(String trg, String[] srcs) throws IOException,
+      UnresolvedLinkException {
+    server.concat(trg, srcs);
+
+  }
+
+  @Override
+  public void rename2(String src, String dst, Rename... options)
+      throws AccessControlException, DSQuotaExceededException,
+      FileAlreadyExistsException, FileNotFoundException,
+      NSQuotaExceededException, ParentNotDirectoryException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    server.rename2(src, dst, options);
+  }
+
+  @Override
+  public boolean delete(String src, boolean recursive)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    return server.delete(src, recursive);
+  }
+
+  @Override
+  public boolean mkdirs(String src, FsPermissionWritable masked, boolean createParent)
+      throws AccessControlException, FileAlreadyExistsException,
+      FileNotFoundException, NSQuotaExceededException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      IOException {
+
+    return server.mkdirs(src, FsPermissionWritable.convertPermission(masked),
+        createParent);
+  }
+
+  @Override
+  public DirectoryListingWritable getListing(String src, byte[] startAfter,
+      boolean needLocation) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException {
+    return DirectoryListingWritable.convertDirectoryListing(
+        server.getListing(src, startAfter, needLocation));
+  }
+
+  @Override
+  public void renewLease(String clientName) throws AccessControlException,
+      IOException {
+    server.renewLease(clientName);
+
+  }
+
+  @Override
+  public boolean recoverLease(String src, String clientName) throws IOException {
+    return server.recoverLease(src, clientName);
+  }
+
+  @Override
+  public long[] getStats() throws IOException {
+    return server.getStats();
+  }
+
+  @Override
+  public DatanodeInfoWritable[] getDatanodeReport(DatanodeReportType type)
+      throws IOException {
+    return DatanodeInfoWritable
+        .convertDatanodeInfo(server.getDatanodeReport(type));
+  }
+
+  @Override
+  public long getPreferredBlockSize(String filename) throws IOException,
+      UnresolvedLinkException {
+    return server.getPreferredBlockSize(filename);
+  }
+
+  @Override
+  public boolean setSafeMode(SafeModeAction action) throws IOException {
+    return server.setSafeMode(action);
+  }
+
+  @Override
+  public void saveNamespace() throws AccessControlException, IOException {
+    server.saveNamespace();
+
+  }
+
+  @Override
+  public boolean restoreFailedStorage(String arg) throws AccessControlException {
+    return server.restoreFailedStorage(arg);
+  }
+
+  @Override
+  public void refreshNodes() throws IOException {
+    server.refreshNodes();
+
+  }
+
+  @Override
+  public void finalizeUpgrade() throws IOException {
+    server.finalizeUpgrade();
+
+  }
+
+  @Override
+  public UpgradeStatusReportWritable distributedUpgradeProgress(UpgradeAction action)
+      throws IOException {
+    return UpgradeStatusReportWritable.convert(
+        server.distributedUpgradeProgress(action));
+  }
+
+  @Override
+  public CorruptFileBlocksWritable listCorruptFileBlocks(String path, String cookie)
+      throws IOException {
+    return CorruptFileBlocksWritable.convertCorruptFilesBlocks(
+        server.listCorruptFileBlocks(path, cookie));
+  }
+
+  @Override
+  public void metaSave(String filename) throws IOException {
+    server.metaSave(filename);
+
+  }
+
+  @Override
+  public HdfsFileStatusWritable getFileInfo(String src) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException {
+    return HdfsFileStatusWritable.convertHdfsFileStatus(
+        server.getFileInfo(src));
+  }
+
+  @Override
+  public HdfsFileStatusWritable getFileLinkInfo(String src)
+      throws AccessControlException, UnresolvedLinkException, IOException {
+    return HdfsFileStatusWritable.convertHdfsFileStatus(
+        server.getFileLinkInfo(src));
+  }
+
+  @Override
+  public ContentSummaryWritable getContentSummary(String path)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    return ContentSummaryWritable.convert(server.getContentSummary(path));
+  }
+
+  @Override
+  public void setQuota(String path, long namespaceQuota, long diskspaceQuota)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    server.setQuota(path, namespaceQuota, diskspaceQuota);
+
+  }
+
+  @Override
+  public void fsync(String src, String client) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException {
+    server.fsync(src, client);
+
+  }
+
+  @Override
+  public void setTimes(String src, long mtime, long atime)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    server.setTimes(src, mtime, atime);
+
+  }
+
+  @Override
+  public void createSymlink(String target, String link, FsPermissionWritable dirPerm,
+      boolean createParent) throws AccessControlException,
+      FileAlreadyExistsException, FileNotFoundException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    server.createSymlink(target, link, FsPermissionWritable.convertPermission(dirPerm),
+        createParent);
+
+  }
+
+  @Override
+  public String getLinkTarget(String path) throws AccessControlException,
+      FileNotFoundException, IOException {
+    return server.getLinkTarget(path);
+  }
+
+  @Override
+  public LocatedBlockWritable updateBlockForPipeline(ExtendedBlockWritable block,
+      String clientName) throws IOException {
+    return LocatedBlockWritable.convertLocatedBlock(
+        server.updateBlockForPipeline(
+        ExtendedBlockWritable.convertExtendedBlock(block), clientName));
+  }
+
+  @Override
+  public void updatePipeline(String clientName, ExtendedBlockWritable oldBlock,
+      ExtendedBlockWritable newBlock, DatanodeIDWritable[] newNodes)
+    throws IOException {
+    server.updatePipeline(clientName, 
+              ExtendedBlockWritable.convertExtendedBlock(oldBlock), 
+              ExtendedBlockWritable.convertExtendedBlock(newBlock),
+              DatanodeIDWritable.convertDatanodeID(newNodes));
+  }
+
+  @Override
+  public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer)
+      throws IOException {
+    return server.getDelegationToken(renewer);
+  }
+
+  @Override
+  public long renewDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException {
+    return server.renewDelegationToken(token);
+  }
+
+  @Override
+  public void cancelDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException {
+    server.cancelDelegationToken(token);
+  }
+
+  @Override
+  public void setBalancerBandwidth(long bandwidth) throws IOException {
+    server.setBalancerBandwidth(bandwidth);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ClientNamenodeProtocolTranslatorR23.java

@@ -0,0 +1,485 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.Closeable;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.ContentSummary;
+import org.apache.hadoop.fs.CreateFlag;
+import org.apache.hadoop.fs.FileAlreadyExistsException;
+import org.apache.hadoop.fs.FsServerDefaults;
+import org.apache.hadoop.fs.ParentNotDirectoryException;
+import org.apache.hadoop.fs.UnresolvedLinkException;
+import org.apache.hadoop.fs.Options.Rename;
+import org.apache.hadoop.fs.permission.FsPermission;
+import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
+import org.apache.hadoop.hdfs.protocol.ClientProtocol;
+import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
+import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
+import org.apache.hadoop.hdfs.protocol.DSQuotaExceededException;
+import org.apache.hadoop.hdfs.protocol.DatanodeID;
+import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
+import org.apache.hadoop.hdfs.protocol.DirectoryListing;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
+import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.UpgradeAction;
+import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
+import org.apache.hadoop.hdfs.server.common.UpgradeStatusReport;
+import org.apache.hadoop.hdfs.server.namenode.NameNode;
+import org.apache.hadoop.hdfs.server.namenode.NotReplicatedYetException;
+import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
+import org.apache.hadoop.io.EnumSetWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.retry.RetryPolicies;
+import org.apache.hadoop.io.retry.RetryPolicy;
+import org.apache.hadoop.io.retry.RetryProxy;
+import org.apache.hadoop.ipc.ProtocolSignature;
+import org.apache.hadoop.ipc.RPC;
+import org.apache.hadoop.ipc.RemoteException;
+import org.apache.hadoop.net.NetUtils;
+import org.apache.hadoop.security.AccessControlException;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+
+/**
+ * This class forwards NN's ClientProtocol calls as RPC calls to the NN server
+ * while translating from the parameter types used in ClientProtocol to those
+ * used in protocolR23Compatile.*.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class ClientNamenodeProtocolTranslatorR23 implements
+    ClientProtocol, Closeable {
+  final private ClientNamenodeWireProtocol rpcProxyWithoutRetry;
+  final private ClientNamenodeWireProtocol rpcProxy;
+
+  private static ClientNamenodeWireProtocol createNamenode(
+      InetSocketAddress nameNodeAddr, Configuration conf,
+      UserGroupInformation ugi) throws IOException {
+    return RPC.getProxy(ClientNamenodeWireProtocol.class,
+        ClientNamenodeWireProtocol.versionID, nameNodeAddr, ugi, conf,
+        NetUtils.getSocketFactory(conf, ClientNamenodeWireProtocol.class));
+  }
+
+  /** Create a {@link NameNode} proxy */
+  static ClientNamenodeWireProtocol createNamenodeWithRetry(
+      ClientNamenodeWireProtocol rpcNamenode) {
+    RetryPolicy createPolicy = RetryPolicies
+        .retryUpToMaximumCountWithFixedSleep(5,
+            HdfsConstants.LEASE_SOFTLIMIT_PERIOD, TimeUnit.MILLISECONDS);
+
+    Map<Class<? extends Exception>, RetryPolicy> remoteExceptionToPolicyMap = new HashMap<Class<? extends Exception>, RetryPolicy>();
+    remoteExceptionToPolicyMap.put(AlreadyBeingCreatedException.class,
+        createPolicy);
+
+    Map<Class<? extends Exception>, RetryPolicy> exceptionToPolicyMap = 
+        new HashMap<Class<? extends Exception>, RetryPolicy>();
+    exceptionToPolicyMap.put(RemoteException.class, RetryPolicies
+        .retryByRemoteException(RetryPolicies.TRY_ONCE_THEN_FAIL,
+            remoteExceptionToPolicyMap));
+    RetryPolicy methodPolicy = RetryPolicies.retryByException(
+        RetryPolicies.TRY_ONCE_THEN_FAIL, exceptionToPolicyMap);
+    Map<String, RetryPolicy> methodNameToPolicyMap = new HashMap<String, RetryPolicy>();
+
+    methodNameToPolicyMap.put("create", methodPolicy);
+
+    return (ClientNamenodeWireProtocol) RetryProxy.create(
+        ClientNamenodeWireProtocol.class, rpcNamenode, methodNameToPolicyMap);
+  }
+
+  public ClientNamenodeProtocolTranslatorR23(InetSocketAddress nameNodeAddr,
+      Configuration conf, UserGroupInformation ugi) throws IOException {
+    rpcProxyWithoutRetry = createNamenode(nameNodeAddr, conf, ugi);
+    rpcProxy = createNamenodeWithRetry(rpcProxyWithoutRetry);
+  }
+
+  public Object getProxyWithoutRetry() {
+    return rpcProxyWithoutRetry;
+  }
+
+  public void close() {
+    RPC.stopProxy(rpcProxyWithoutRetry);
+  }
+
+  @Override
+  public ProtocolSignature getProtocolSignature(String protocolName,
+      long clientVersion, int clientMethodHash)
+      throws IOException {
+    return ProtocolSignatureWritable.convert(rpcProxy.getProtocolSignature2(
+        protocolName, clientVersion, clientMethodHash));
+  }
+
+  @Override
+  public long getProtocolVersion(String protocolName, long clientVersion) throws IOException {
+    return rpcProxy.getProtocolVersion(protocolName, clientVersion);
+  }
+
+  @Override
+  public LocatedBlocks getBlockLocations(String src, long offset, long length)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    return LocatedBlocksWritable
+        .convertLocatedBlocks(rpcProxy.getBlockLocations(src, offset, length));
+  }
+
+  @Override
+  public FsServerDefaults getServerDefaults() throws IOException {
+    return FsServerDefaultsWritable
+        .convert(rpcProxy.getServerDefaults());
+  }
+
+  @Override
+  public void create(String src, FsPermission masked, String clientName,
+      EnumSetWritable<CreateFlag> flag, boolean createParent,
+      short replication, long blockSize) throws AccessControlException,
+      AlreadyBeingCreatedException, DSQuotaExceededException,
+      FileAlreadyExistsException, FileNotFoundException,
+      NSQuotaExceededException, ParentNotDirectoryException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    rpcProxy.create(src, FsPermissionWritable.convertPermission(masked),
+        clientName, flag, createParent, replication, blockSize);
+
+  }
+
+  @Override
+  public LocatedBlock append(String src, String clientName)
+      throws AccessControlException, DSQuotaExceededException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return LocatedBlockWritable
+        .convertLocatedBlock(rpcProxy.append(src, clientName));
+  }
+
+  @Override
+  public boolean setReplication(String src, short replication)
+      throws AccessControlException, DSQuotaExceededException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return rpcProxy.setReplication(src, replication);
+  }
+
+  @Override
+  public void setPermission(String src, FsPermission permission)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    rpcProxy.setPermission(src,
+        FsPermissionWritable.convertPermission(permission));
+
+  }
+
+  @Override
+  public void setOwner(String src, String username, String groupname)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    rpcProxy.setOwner(src, username, groupname);
+
+  }
+
+  @Override
+  public void abandonBlock(ExtendedBlock b, String src, String holder)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    rpcProxy.abandonBlock(
+        ExtendedBlockWritable.convertExtendedBlock(b), src, holder);
+
+  }
+
+  @Override
+  public LocatedBlock addBlock(String src, String clientName,
+      ExtendedBlock previous, DatanodeInfo[] excludeNodes)
+      throws AccessControlException, FileNotFoundException,
+      NotReplicatedYetException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return LocatedBlockWritable
+        .convertLocatedBlock(rpcProxy.addBlock(src, clientName,
+            ExtendedBlockWritable.convertExtendedBlock(previous),
+            DatanodeInfoWritable.convertDatanodeInfo(excludeNodes)));
+  }
+
+  @Override
+  public LocatedBlock getAdditionalDatanode(String src, ExtendedBlock blk,
+      DatanodeInfo[] existings, DatanodeInfo[] excludes,
+      int numAdditionalNodes, String clientName) throws AccessControlException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    return LocatedBlockWritable
+        .convertLocatedBlock(rpcProxy.getAdditionalDatanode(src,
+            ExtendedBlockWritable.convertExtendedBlock(blk),
+            DatanodeInfoWritable.convertDatanodeInfo(existings),
+            DatanodeInfoWritable.convertDatanodeInfo(excludes),
+            numAdditionalNodes, clientName));
+  }
+
+  @Override
+  public boolean complete(String src, String clientName, ExtendedBlock last)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    return rpcProxy.complete(src, clientName,
+        ExtendedBlockWritable.convertExtendedBlock(last));
+  }
+
+  @Override
+  public void reportBadBlocks(LocatedBlock[] blocks) throws IOException {
+    rpcProxy.reportBadBlocks(LocatedBlockWritable.convertLocatedBlock(blocks));
+
+  }
+
+  @Override
+  public boolean rename(String src, String dst) throws UnresolvedLinkException,
+      IOException {
+    return rpcProxy.rename(src, dst);
+  }
+
+  @Override
+  public void concat(String trg, String[] srcs) throws IOException,
+      UnresolvedLinkException {
+    rpcProxy.concat(trg, srcs);
+
+  }
+
+  @Override
+  public void rename2(String src, String dst, Rename... options)
+      throws AccessControlException, DSQuotaExceededException,
+      FileAlreadyExistsException, FileNotFoundException,
+      NSQuotaExceededException, ParentNotDirectoryException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    rpcProxy.rename2(src, dst, options);
+
+  }
+
+  @Override
+  public boolean delete(String src, boolean recursive)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException {
+    return rpcProxy.delete(src, recursive);
+  }
+
+  @Override
+  public boolean mkdirs(String src, FsPermission masked, boolean createParent)
+      throws AccessControlException, FileAlreadyExistsException,
+      FileNotFoundException, NSQuotaExceededException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      IOException {
+
+    return rpcProxy.mkdirs(src,
+        FsPermissionWritable.convertPermission(masked), createParent);
+  }
+
+  @Override
+  public DirectoryListing getListing(String src, byte[] startAfter,
+      boolean needLocation) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException {
+    return DirectoryListingWritable.convertDirectoryListing(
+        rpcProxy.getListing(src, startAfter, needLocation));
+  }
+
+  @Override
+  public void renewLease(String clientName) throws AccessControlException,
+      IOException {
+    rpcProxy.renewLease(clientName);
+
+  }
+
+  @Override
+  public boolean recoverLease(String src, String clientName) throws IOException {
+    return rpcProxy.recoverLease(src, clientName);
+  }
+
+  @Override
+  public long[] getStats() throws IOException {
+    return rpcProxy.getStats();
+  }
+
+  @Override
+  public DatanodeInfo[] getDatanodeReport(DatanodeReportType type)
+      throws IOException {
+    return DatanodeInfoWritable.convertDatanodeInfo(
+        rpcProxy.getDatanodeReport(type));
+  }
+
+  @Override
+  public long getPreferredBlockSize(String filename) throws IOException,
+      UnresolvedLinkException {
+    return rpcProxy.getPreferredBlockSize(filename);
+  }
+
+  @Override
+  public boolean setSafeMode(SafeModeAction action) throws IOException {
+    return rpcProxy.setSafeMode(action);
+  }
+
+  @Override
+  public void saveNamespace() throws AccessControlException, IOException {
+    rpcProxy.saveNamespace();
+
+  }
+
+  @Override
+  public boolean restoreFailedStorage(String arg) throws AccessControlException {
+    return rpcProxy.restoreFailedStorage(arg);
+  }
+
+  @Override
+  public void refreshNodes() throws IOException {
+    rpcProxy.refreshNodes();
+
+  }
+
+  @Override
+  public void finalizeUpgrade() throws IOException {
+    rpcProxy.finalizeUpgrade();
+
+  }
+
+  @Override
+  public UpgradeStatusReport distributedUpgradeProgress(UpgradeAction action)
+      throws IOException {
+    return UpgradeStatusReportWritable.convert(
+        rpcProxy.distributedUpgradeProgress(action));
+  }
+
+  @Override
+  public CorruptFileBlocks listCorruptFileBlocks(String path, String cookie)
+      throws IOException {
+    return CorruptFileBlocksWritable.convertCorruptFileBlocks(
+        rpcProxy.listCorruptFileBlocks(path, cookie));
+  }
+
+  @Override
+  public void metaSave(String filename) throws IOException {
+    rpcProxy.metaSave(filename);
+
+  }
+
+  @Override
+  public HdfsFileStatus getFileInfo(String src) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException {
+    return HdfsFileStatusWritable.convertHdfsFileStatus(
+        rpcProxy.getFileInfo(src));
+  }
+
+  @Override
+  public HdfsFileStatus getFileLinkInfo(String src)
+      throws AccessControlException, UnresolvedLinkException, IOException {
+    return HdfsFileStatusWritable
+        .convertHdfsFileStatus(rpcProxy.getFileLinkInfo(src));
+  }
+
+  @Override
+  public ContentSummary getContentSummary(String path)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    return ContentSummaryWritable
+        .convert(rpcProxy.getContentSummary(path));
+  }
+
+  @Override
+  public void setQuota(String path, long namespaceQuota, long diskspaceQuota)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    rpcProxy.setQuota(path, namespaceQuota, diskspaceQuota);
+
+  }
+
+  @Override
+  public void fsync(String src, String client) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException {
+    rpcProxy.fsync(src, client);
+
+  }
+
+  @Override
+  public void setTimes(String src, long mtime, long atime)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException {
+    rpcProxy.setTimes(src, mtime, atime);
+
+  }
+
+  @Override
+  public void createSymlink(String target, String link, FsPermission dirPerm,
+      boolean createParent) throws AccessControlException,
+      FileAlreadyExistsException, FileNotFoundException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      IOException {
+    rpcProxy.createSymlink(target, link,
+        FsPermissionWritable.convertPermission(dirPerm), createParent);
+
+  }
+
+  @Override
+  public String getLinkTarget(String path) throws AccessControlException,
+      FileNotFoundException, IOException {
+    return rpcProxy.getLinkTarget(path);
+  }
+
+  @Override
+  public LocatedBlock updateBlockForPipeline(ExtendedBlock block,
+      String clientName) throws IOException {
+    return LocatedBlockWritable.convertLocatedBlock(
+        rpcProxy.updateBlockForPipeline(
+            ExtendedBlockWritable.convertExtendedBlock(block), clientName));
+  }
+
+  @Override
+  public void updatePipeline(String clientName, ExtendedBlock oldBlock,
+      ExtendedBlock newBlock, DatanodeID[] newNodes) throws IOException {
+    rpcProxy.updatePipeline(clientName,
+        ExtendedBlockWritable.convertExtendedBlock(oldBlock),
+        ExtendedBlockWritable.convertExtendedBlock(newBlock),
+        DatanodeIDWritable.convertDatanodeID(newNodes));
+
+  }
+
+  @Override
+  public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer)
+      throws IOException {
+    return rpcProxy.getDelegationToken(renewer);
+  }
+
+  @Override
+  public long renewDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException {
+    return rpcProxy.renewDelegationToken(token);
+  }
+
+  @Override
+  public void cancelDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException {
+    rpcProxy.cancelDelegationToken(token);
+  }
+
+  @Override
+  public void setBalancerBandwidth(long bandwidth) throws IOException {
+    rpcProxy.setBalancerBandwidth(bandwidth);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ClientNamenodeWireProtocol.java

@@ -0,0 +1,482 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+import org.apache.avro.reflect.Nullable;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.CreateFlag;
+import org.apache.hadoop.fs.Options;
+import org.apache.hadoop.fs.FileAlreadyExistsException;
+import org.apache.hadoop.fs.ParentNotDirectoryException;
+import org.apache.hadoop.fs.UnresolvedLinkException;
+import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
+import org.apache.hadoop.hdfs.protocol.DSQuotaExceededException;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.UpgradeAction;
+import org.apache.hadoop.hdfs.server.namenode.NotReplicatedYetException;
+import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
+import org.apache.hadoop.io.EnumSetWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.ipc.VersionedProtocol;
+import org.apache.hadoop.security.AccessControlException;
+import org.apache.hadoop.security.KerberosInfo;
+import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.security.token.TokenInfo;
+import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
+import org.apache.hadoop.ipc.ProtocolInfo;
+
+import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
+import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSelector;
+
+/**********************************************************************
+ * This class defines the actual protocol used to communicate with the
+ * NN via RPC using writable types.
+ * The parameters in the methods which are specified in the
+ * package are separate from those used internally in the NN and DFSClient
+ * and hence need to be converted using {@link ClientNamenodeProtocolTranslatorR23}
+ * and {@link ClientNamenodeProtocolServerSideTranslatorR23}.
+ *
+ **********************************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+@KerberosInfo(
+    serverPrincipal = DFSConfigKeys.DFS_NAMENODE_USER_NAME_KEY)
+@TokenInfo(DelegationTokenSelector.class)
+@ProtocolInfo(protocolName = HdfsConstants.CLIENT_NAMENODE_PROTOCOL_NAME)
+public interface ClientNamenodeWireProtocol extends VersionedProtocol {
+
+  /**
+   * Changes to the protocol:
+   * 
+   * Do NOT change a method's signature (ie name, parameters, parameter types
+   * or exceptions thrown). If you need to make changes then ADD new methods and
+   * new data types.
+   * Hence if you maintain compatibility you will NOT have to change
+   * the version number below. The version number is changed ONLY
+   * if you break compatibility (which is a big deal).
+   * Hence the version number is really a Major Version Number.
+   *
+   * The log of historical changes prior to 69 can be retrieved from the svn.
+   * ALL changes since version 69L are recorded.
+   * Version number is changed ONLY for Incompatible changes.
+   *  (note previously we used to change version number for both
+   *  compatible and incompatible changes).
+   * 69: Eliminate overloaded method names. (Compatible)
+   * 70: Separation of Datatypes - the client namenode protocol is implemented
+   *     in this class instead of in 
+   *           {@link org.apache.hadoop.hdfs.protocol.ClientProtocol}
+   *     as was done prior to version 70.
+   */
+  public static final long versionID = 70L;
+  
+  ///////////////////////////////////////
+  // File contents
+  ///////////////////////////////////////
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getBlockLocations}
+   */
+  @Nullable
+  public LocatedBlocksWritable getBlockLocations(String src,
+                                         long offset,
+                                         long length) 
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getServerDefaults()}
+   */
+  public FsServerDefaultsWritable getServerDefaults() throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#create(String, 
+   * org.apache.hadoop.fs.permission.FsPermission, String, 
+   * EnumSetWritable, boolean, short, long)}
+   */
+  public void create(String src, FsPermissionWritable masked, String clientName,
+      EnumSetWritable<CreateFlag> flag, boolean createParent,
+      short replication, long blockSize) throws AccessControlException,
+      AlreadyBeingCreatedException, DSQuotaExceededException,
+      FileAlreadyExistsException, FileNotFoundException,
+      NSQuotaExceededException, ParentNotDirectoryException, SafeModeException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#append(String, String)}
+   */
+  public LocatedBlockWritable append(String src, String clientName)
+      throws AccessControlException, DSQuotaExceededException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#setReplication(String, short)}
+   */
+  public boolean setReplication(String src, short replication)
+      throws AccessControlException, DSQuotaExceededException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#setPermission(String,
+   * org.apache.hadoop.fs.permission.FsPermission)}
+   */
+  public void setPermission(String src, FsPermissionWritable permission)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#setOwner(String, String, String)}
+   */
+  public void setOwner(String src, String username, String groupname)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#abandonBlock(
+   * org.apache.hadoop.hdfs.protocol.ExtendedBlock, String, String)}
+   */
+  public void abandonBlock(ExtendedBlockWritable b, String src, String holder)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#addBlock(String, 
+   * String, org.apache.hadoop.hdfs.protocol.ExtendedBlock, 
+   * org.apache.hadoop.hdfs.protocol.DatanodeInfo[])}
+   */
+  public LocatedBlockWritable addBlock(String src, String clientName,
+      @Nullable ExtendedBlockWritable previous, @Nullable DatanodeInfoWritable[] excludeNodes)
+      throws AccessControlException, FileNotFoundException,
+      NotReplicatedYetException, SafeModeException, UnresolvedLinkException,
+      IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getAdditionalDatanode}
+   */
+  public LocatedBlockWritable getAdditionalDatanode(
+      final String src, final ExtendedBlockWritable blk,
+      final DatanodeInfoWritable[] existings,
+      final DatanodeInfoWritable[] excludes,
+      final int numAdditionalNodes, final String clientName
+      ) throws AccessControlException, FileNotFoundException,
+          SafeModeException, UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#complete}
+   */
+  public boolean complete(
+      String src, String clientName, ExtendedBlockWritable last)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#reportBadBlocks}
+   */
+  public void reportBadBlocks(LocatedBlockWritable[] blocks) throws IOException;
+
+  ///////////////////////////////////////
+  // Namespace management
+  ///////////////////////////////////////
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#rename(String, String)}
+   */
+  public boolean rename(String src, String dst) 
+      throws UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#concat(String, String[])}
+   */
+  public void concat(String trg, String[] srcs) 
+      throws IOException, UnresolvedLinkException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#rename2}
+   */
+  public void rename2(String src, String dst, Options.Rename... options)
+      throws AccessControlException, DSQuotaExceededException,
+      FileAlreadyExistsException, FileNotFoundException,
+      NSQuotaExceededException, ParentNotDirectoryException, SafeModeException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#delete(String, boolean)}
+   */
+  public boolean delete(String src, boolean recursive)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#mkdirs}
+   */
+  public boolean mkdirs(
+      String src, FsPermissionWritable masked, boolean createParent)
+      throws AccessControlException, FileAlreadyExistsException,
+      FileNotFoundException, NSQuotaExceededException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getListing}
+   */
+  public DirectoryListingWritable getListing(String src,
+                                     byte[] startAfter,
+                                     boolean needLocation)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  ///////////////////////////////////////
+  // System issues and management
+  ///////////////////////////////////////
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#renewLease(String)}
+   */
+  public void renewLease(String clientName) throws AccessControlException,
+      IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#recoverLease(String, String)}
+   */
+  public boolean recoverLease(String src, String clientName) throws IOException;
+
+  public int GET_STATS_CAPACITY_IDX = 0;
+  public int GET_STATS_USED_IDX = 1;
+  public int GET_STATS_REMAINING_IDX = 2;
+  public int GET_STATS_UNDER_REPLICATED_IDX = 3;
+  public int GET_STATS_CORRUPT_BLOCKS_IDX = 4;
+  public int GET_STATS_MISSING_BLOCKS_IDX = 5;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getStats()}
+   */
+  public long[] getStats() throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getDatanodeReport}
+   */
+  public DatanodeInfoWritable[] getDatanodeReport(
+      HdfsConstants.DatanodeReportType type)
+      throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getPreferredBlockSize}
+   */
+  public long getPreferredBlockSize(String filename) 
+      throws IOException, UnresolvedLinkException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#setSafeMode(org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction)}
+   */
+  public boolean setSafeMode(HdfsConstants.SafeModeAction action) 
+      throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#saveNamespace()}
+   */
+  public void saveNamespace() throws AccessControlException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#restoreFailedStorage(String)}
+   */
+  public boolean restoreFailedStorage(String arg) throws AccessControlException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#refreshNodes()}
+   */
+  public void refreshNodes() throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#finalizeUpgrade()}
+   */
+  public void finalizeUpgrade() throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#distributedUpgradeProgress}
+   */
+  @Nullable
+  public UpgradeStatusReportWritable distributedUpgradeProgress(
+      UpgradeAction action) 
+      throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#listCorruptFileBlocks(String, String)}
+   */
+  public CorruptFileBlocksWritable
+    listCorruptFileBlocks(String path, String cookie)
+    throws IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#metaSave(String)}
+   */
+  public void metaSave(String filename) throws IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#setBalancerBandwidth(long)}
+   */
+  public void setBalancerBandwidth(long bandwidth) throws IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getFileInfo(String)}
+   */
+  @Nullable
+  public HdfsFileStatusWritable getFileInfo(String src)
+      throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getFileLinkInfo(String)}
+   */
+  public HdfsFileStatusWritable getFileLinkInfo(String src)
+      throws AccessControlException, UnresolvedLinkException, IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getContentSummary(String)}
+   */
+  public ContentSummaryWritable getContentSummary(String path)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#setQuota(String, long, long)}
+   */
+  public void setQuota(String path, long namespaceQuota, long diskspaceQuota)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#fsync(String, String)}
+   */
+  public void fsync(String src, String client) 
+      throws AccessControlException, FileNotFoundException, 
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#setTimes(String, long, long)}
+   */
+  public void setTimes(String src, long mtime, long atime)
+      throws AccessControlException, FileNotFoundException, 
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#createSymlink}
+   */
+  public void createSymlink(
+      String target, String link, FsPermissionWritable dirPerm,
+      boolean createParent) throws AccessControlException,
+      FileAlreadyExistsException, FileNotFoundException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getLinkTarget(String)}
+   */
+  public String getLinkTarget(String path) throws AccessControlException,
+      FileNotFoundException, IOException; 
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#updateBlockForPipeline}
+   */
+  public LocatedBlockWritable updateBlockForPipeline(
+      ExtendedBlockWritable block, String clientName) throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#updatePipeline}
+   */
+  public void updatePipeline(String clientName, ExtendedBlockWritable oldBlock, 
+      ExtendedBlockWritable newBlock, DatanodeIDWritable[] newNodes)
+      throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#getDelegationToken(Text)}
+   */
+  public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer) 
+      throws IOException;
+
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#renewDelegationToken(Token)}
+   */
+  public long renewDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException;
+  
+  /**
+   * The specification of this method matches that of
+   * {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#cancelDelegationToken(Token)}
+   */
+  public void cancelDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException;
+  
+  /**
+   * This method is defined to get the protocol signature using 
+   * the R23 protocol - hence we have added the suffix of 2 the method name
+   * to avoid conflict.
+   */
+  public org.apache.hadoop.hdfs.protocolR23Compatible.ProtocolSignatureWritable
+           getProtocolSignature2(String protocol, 
+      long clientVersion,
+      int clientMethodsHash) throws IOException;
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ContentSummaryWritable.java

@@ -0,0 +1,184 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+
+/** Store the summary of a content (a directory or a file). */
+@InterfaceAudience.Public
+@InterfaceStability.Stable
+public class ContentSummaryWritable implements Writable{
+  private long length;
+  private long fileCount;
+  private long directoryCount;
+  private long quota;
+  private long spaceConsumed;
+  private long spaceQuota;
+  
+  
+  public static org.apache.hadoop.fs.ContentSummary convert(ContentSummaryWritable cs) {
+    if (cs == null) return null;
+    return new org.apache.hadoop.fs.ContentSummary(
+      cs.getLength(), cs.getFileCount(), cs.getDirectoryCount(), cs.getQuota(),
+      cs.getSpaceConsumed(), cs.getSpaceQuota());
+  }
+  
+  public static ContentSummaryWritable convert(org.apache.hadoop.fs.ContentSummary cs) {
+    if (cs == null) return null;
+    return new  ContentSummaryWritable(
+      cs.getLength(), cs.getFileCount(), cs.getDirectoryCount(), cs.getQuota(),
+      cs.getSpaceConsumed(), cs.getSpaceQuota());
+  }
+
+  /** Constructor */
+  public ContentSummaryWritable() {}
+  
+  /** Constructor */
+  public ContentSummaryWritable(long length, long fileCount, long directoryCount) {
+    this(length, fileCount, directoryCount, -1L, length, -1L);
+  }
+
+  /** Constructor */
+  public ContentSummaryWritable(
+      long length, long fileCount, long directoryCount, long quota,
+      long spaceConsumed, long spaceQuota) {
+    this.length = length;
+    this.fileCount = fileCount;
+    this.directoryCount = directoryCount;
+    this.quota = quota;
+    this.spaceConsumed = spaceConsumed;
+    this.spaceQuota = spaceQuota;
+  }
+
+  /** @return the length */
+  public long getLength() {return length;}
+
+  /** @return the directory count */
+  public long getDirectoryCount() {return directoryCount;}
+
+  /** @return the file count */
+  public long getFileCount() {return fileCount;}
+  
+  /** Return the directory quota */
+  public long getQuota() {return quota;}
+  
+  /** Retuns (disk) space consumed */ 
+  public long getSpaceConsumed() {return spaceConsumed;}
+
+  /** Returns (disk) space quota */
+  public long getSpaceQuota() {return spaceQuota;}
+  
+  @InterfaceAudience.Private
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeLong(length);
+    out.writeLong(fileCount);
+    out.writeLong(directoryCount);
+    out.writeLong(quota);
+    out.writeLong(spaceConsumed);
+    out.writeLong(spaceQuota);
+  }
+
+  @InterfaceAudience.Private
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    this.length = in.readLong();
+    this.fileCount = in.readLong();
+    this.directoryCount = in.readLong();
+    this.quota = in.readLong();
+    this.spaceConsumed = in.readLong();
+    this.spaceQuota = in.readLong();
+  }
+  
+  /** 
+   * Output format:
+   * <----12----> <----12----> <-------18------->
+   *    DIR_COUNT   FILE_COUNT       CONTENT_SIZE FILE_NAME    
+   */
+  private static final String STRING_FORMAT = "%12d %12d %18d ";
+  /** 
+   * Output format:
+   * <----12----> <----15----> <----15----> <----15----> <----12----> <----12----> <-------18------->
+   *    QUOTA   REMAINING_QUATA SPACE_QUOTA SPACE_QUOTA_REM DIR_COUNT   FILE_COUNT   CONTENT_SIZE     FILE_NAME    
+   */
+  private static final String QUOTA_STRING_FORMAT = "%12s %15s ";
+  private static final String SPACE_QUOTA_STRING_FORMAT = "%15s %15s ";
+  
+  /** The header string */
+  private static final String HEADER = String.format(
+      STRING_FORMAT.replace('d', 's'), "directories", "files", "bytes");
+
+  private static final String QUOTA_HEADER = String.format(
+      QUOTA_STRING_FORMAT + SPACE_QUOTA_STRING_FORMAT, 
+      "quota", "remaining quota", "space quota", "reamaining quota") +
+      HEADER;
+  
+  /** Return the header of the output.
+   * if qOption is false, output directory count, file count, and content size;
+   * if qOption is true, output quota and remaining quota as well.
+   * 
+   * @param qOption a flag indicating if quota needs to be printed or not
+   * @return the header of the output
+   */
+  public static String getHeader(boolean qOption) {
+    return qOption ? QUOTA_HEADER : HEADER;
+  }
+  
+  @Override
+  public String toString() {
+    return toString(true);
+  }
+
+  /** Return the string representation of the object in the output format.
+   * if qOption is false, output directory count, file count, and content size;
+   * if qOption is true, output quota and remaining quota as well.
+   * 
+   * @param qOption a flag indicating if quota needs to be printed or not
+   * @return the string representation of the object
+   */
+  public String toString(boolean qOption) {
+    String prefix = "";
+    if (qOption) {
+      String quotaStr = "none";
+      String quotaRem = "inf";
+      String spaceQuotaStr = "none";
+      String spaceQuotaRem = "inf";
+      
+      if (quota>0) {
+        quotaStr = Long.toString(quota);
+        quotaRem = Long.toString(quota-(directoryCount+fileCount));
+      }
+      if (spaceQuota>0) {
+        spaceQuotaStr = Long.toString(spaceQuota);
+        spaceQuotaRem = Long.toString(spaceQuota - spaceConsumed);        
+      }
+      
+      prefix = String.format(QUOTA_STRING_FORMAT + SPACE_QUOTA_STRING_FORMAT, 
+                             quotaStr, quotaRem, spaceQuotaStr, spaceQuotaRem);
+    }
+    
+    return prefix + String.format(STRING_FORMAT, directoryCount, 
+                                  fileCount, length);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/CorruptFileBlocksWritable.java

@@ -0,0 +1,88 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.Text;
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+/**
+ * Contains a list of paths corresponding to corrupt files and a cookie
+ * used for iterative calls to NameNode.listCorruptFileBlocks.
+ *
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class CorruptFileBlocksWritable implements Writable {
+
+  private String[] files;
+  private String cookie;
+
+  static public org.apache.hadoop.hdfs.protocol.CorruptFileBlocks 
+    convertCorruptFileBlocks(CorruptFileBlocksWritable c) {
+    if (c == null) return null;
+    return new org.apache.hadoop.hdfs.protocol.CorruptFileBlocks(
+        c.getFiles(), c.getCookie());
+  }
+  
+  public static CorruptFileBlocksWritable convertCorruptFilesBlocks(
+      org.apache.hadoop.hdfs.protocol.CorruptFileBlocks c) {
+    if (c == null) return null;
+    return new CorruptFileBlocksWritable(c.getFiles(), c.getCookie());
+  }
+ 
+  public CorruptFileBlocksWritable() {
+    this(new String[0], "");
+  }
+
+  public CorruptFileBlocksWritable(String[] files, String cookie) {
+    this.files = files;
+    this.cookie = cookie;
+  }
+ 
+  public String[] getFiles() {
+    return files;
+  }
+
+  public String getCookie() {
+    return cookie;
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    int fileCount = in.readInt();
+    files = new String[fileCount];
+    for (int i = 0; i < fileCount; i++) {
+      files[i] = Text.readString(in);
+    }
+    cookie = Text.readString(in);
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeInt(files.length);
+    for (int i = 0; i < files.length; i++) {
+      Text.writeString(out, files[i]);
+    }
+    Text.writeString(out, cookie);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/DatanodeIDWritable.java

@@ -0,0 +1,209 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.DeprecatedUTF8;
+import org.apache.hadoop.io.Writable;
+
+/**
+ * DatanodeID is composed of the data node 
+ * name (hostname:portNumber) and the data storage ID, 
+ * which it currently represents.
+ * 
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class DatanodeIDWritable implements Writable {
+  public static final DatanodeIDWritable[] EMPTY_ARRAY = {}; 
+
+  public String name;      /// hostname:portNumber
+  public String storageID; /// unique per cluster storageID
+  protected int infoPort;     /// the port where the infoserver is running
+  public int ipcPort;     /// the port where the ipc server is running
+
+  
+  static public DatanodeIDWritable[] 
+      convertDatanodeID(org.apache.hadoop.hdfs.protocol.DatanodeID[] did) {
+    if (did == null) return null;
+    final int len = did.length;
+    DatanodeIDWritable[] result = new DatanodeIDWritable[len];
+    for (int i = 0; i < len; ++i) {
+      result[i] = convertDatanodeID(did[i]);
+    }
+    return result;
+  }
+  
+  static public org.apache.hadoop.hdfs.protocol.DatanodeID[] 
+      convertDatanodeID(DatanodeIDWritable[] did) {
+    if (did == null) return null;
+    final int len = did.length;
+    org.apache.hadoop.hdfs.protocol.DatanodeID[] result = new org.apache.hadoop.hdfs.protocol.DatanodeID[len];
+    for (int i = 0; i < len; ++i) {
+      result[i] = convertDatanodeID(did[i]);
+    }
+    return result;
+  }
+  
+  static public org.apache.hadoop.hdfs.protocol.DatanodeID convertDatanodeID(
+      DatanodeIDWritable did) {
+    if (did == null) return null;
+    return new org.apache.hadoop.hdfs.protocol.DatanodeID(
+        did.getName(), did.getStorageID(), did.getInfoPort(), did.getIpcPort());
+    
+  }
+  
+  public static DatanodeIDWritable convertDatanodeID(org.apache.hadoop.hdfs.protocol.DatanodeID from) {
+    return new DatanodeIDWritable(from.getName(),
+        from.getStorageID(),
+        from.getInfoPort(),
+        from.getIpcPort());
+  }
+  
+  /** Equivalent to DatanodeID(""). */
+  public DatanodeIDWritable() {this("");}
+
+  /** Equivalent to DatanodeID(nodeName, "", -1, -1). */
+  public DatanodeIDWritable(String nodeName) {this(nodeName, "", -1, -1);}
+
+  /**
+   * DatanodeID copy constructor
+   * 
+   * @param from
+   */
+  public DatanodeIDWritable(DatanodeIDWritable from) {
+    this(from.getName(),
+        from.getStorageID(),
+        from.getInfoPort(),
+        from.getIpcPort());
+  }
+  
+  /**
+   * Create DatanodeID
+   * @param nodeName (hostname:portNumber) 
+   * @param storageID data storage ID
+   * @param infoPort info server port 
+   * @param ipcPort ipc server port
+   */
+  public DatanodeIDWritable(String nodeName, String storageID,
+      int infoPort, int ipcPort) {
+    this.name = nodeName;
+    this.storageID = storageID;
+    this.infoPort = infoPort;
+    this.ipcPort = ipcPort;
+  }
+  
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public void setInfoPort(int infoPort) {
+    this.infoPort = infoPort;
+  }
+  
+  public void setIpcPort(int ipcPort) {
+    this.ipcPort = ipcPort;
+  }
+  
+  /**
+   * @return hostname:portNumber.
+   */
+  public String getName() {
+    return name;
+  }
+  
+  /**
+   * @return data storage ID.
+   */
+  public String getStorageID() {
+    return this.storageID;
+  }
+
+  /**
+   * @return infoPort (the port at which the HTTP server bound to)
+   */
+  public int getInfoPort() {
+    return infoPort;
+  }
+
+  /**
+   * @return ipcPort (the port at which the IPC server bound to)
+   */
+  public int getIpcPort() {
+    return ipcPort;
+  }
+
+  /**
+   * sets the data storage ID.
+   */
+  public void setStorageID(String storageID) {
+    this.storageID = storageID;
+  }
+
+  /**
+   * @return hostname and no :portNumber.
+   */
+  public String getHost() {
+    int colon = name.indexOf(":");
+    if (colon < 0) {
+      return name;
+    } else {
+      return name.substring(0, colon);
+    }
+  }
+  
+  public int getPort() {
+    int colon = name.indexOf(":");
+    if (colon < 0) {
+      return 50010; // default port.
+    }
+    return Integer.parseInt(name.substring(colon+1));
+  }
+
+  
+  public String toString() {
+    return name;
+  }    
+
+  /////////////////////////////////////////////////
+  // Writable
+  /////////////////////////////////////////////////
+  @Override
+  public void write(DataOutput out) throws IOException {
+    DeprecatedUTF8.writeString(out, name);
+    DeprecatedUTF8.writeString(out, storageID);
+    out.writeShort(infoPort);
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    name = DeprecatedUTF8.readString(in);
+    storageID = DeprecatedUTF8.readString(in);
+    // the infoPort read could be negative, if the port is a large number (more
+    // than 15 bits in storage size (but less than 16 bits).
+    // So chop off the first two bytes (and hence the signed bits) before 
+    // setting the field.
+    this.infoPort = in.readShort() & 0x0000ffff;
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/DatanodeInfoWritable.java

@@ -0,0 +1,328 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+import org.apache.hadoop.io.WritableUtils;
+import org.apache.hadoop.net.NetworkTopology;
+import org.apache.hadoop.net.NodeBase;
+import org.apache.hadoop.HadoopIllegalArgumentException;
+
+import org.apache.avro.reflect.Nullable;
+
+/** 
+ * DatanodeInfo represents the status of a DataNode.
+ * This object is used for communication in the
+ * Datanode Protocol and the Client Protocol.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class DatanodeInfoWritable extends DatanodeIDWritable  {
+  protected long capacity;
+  protected long dfsUsed;
+  protected long remaining;
+  protected long blockPoolUsed;
+  protected long lastUpdate;
+  protected int xceiverCount;
+  protected String location = NetworkTopology.DEFAULT_RACK;
+
+  /** HostName as supplied by the datanode during registration as its 
+   * name. Namenode uses datanode IP address as the name.
+   */
+  @Nullable
+  protected String hostName = null;
+  
+  // administrative states of a datanode
+  public enum AdminStates {
+    NORMAL(org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates.NORMAL.toString()), 
+    DECOMMISSION_INPROGRESS(org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates.DECOMMISSION_INPROGRESS.toString()), 
+    DECOMMISSIONED(org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates.DECOMMISSIONED.toString());
+
+    final String value;
+
+    AdminStates(final String v) {
+      this.value = v;
+    }
+
+    public String toString() {
+      return value;
+    }
+    
+    public static AdminStates fromValue(final String value) {
+      for (AdminStates as : AdminStates.values()) {
+        if (as.value.equals(value)) return as;
+      }
+      throw new HadoopIllegalArgumentException("Unknown Admin State" + value);
+    }
+  }
+
+  @Nullable
+  protected AdminStates adminState;
+  
+  static public org.apache.hadoop.hdfs.protocol.DatanodeInfo convertDatanodeInfo(DatanodeInfoWritable di) {
+    if (di == null) return null;
+    return new org.apache.hadoop.hdfs.protocol.DatanodeInfo(
+        new org.apache.hadoop.hdfs.protocol.DatanodeID(di.getName(), di.getStorageID(), di.getInfoPort(), di.getIpcPort()),
+        di.getNetworkLocation(), di.getHostName(),
+         di.getCapacity(),  di.getDfsUsed(),  di.getRemaining(),
+        di.getBlockPoolUsed()  ,  di.getLastUpdate() , di.getXceiverCount() ,
+        org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates.fromValue(di.getAdminState().value)); 
+  }
+  
+  
+  static public org.apache.hadoop.hdfs.protocol.DatanodeInfo[] convertDatanodeInfo(DatanodeInfoWritable di[]) {
+    if (di == null) return null;
+    org.apache.hadoop.hdfs.protocol.DatanodeInfo[] result = new org.apache.hadoop.hdfs.protocol.DatanodeInfo[di.length];
+    for (int i = 0; i < di.length; i++) {
+      result[i] = convertDatanodeInfo(di[i]);
+    }    
+    return result;
+  }
+  
+  static public DatanodeInfoWritable[] convertDatanodeInfo(org.apache.hadoop.hdfs.protocol.DatanodeInfo[] di) {
+    if (di == null) return null;
+    DatanodeInfoWritable[] result = new DatanodeInfoWritable[di.length];
+    for (int i = 0; i < di.length; i++) {
+      result[i] = new DatanodeInfoWritable(new DatanodeIDWritable(di[i].getName(), di[i].getStorageID(), di[i].getInfoPort(), di[i].getIpcPort()),
+          di[i].getNetworkLocation(), di[i].getHostName(),
+          di[i].getCapacity(),  di[i].getDfsUsed(),  di[i].getRemaining(),
+          di[i].getBlockPoolUsed()  ,  di[i].getLastUpdate() , di[i].getXceiverCount() ,
+          AdminStates.fromValue(di[i].getAdminState().toString()));
+    }    
+    return result;
+    
+  }
+
+  public DatanodeInfoWritable() {
+    super();
+    adminState = null;
+  }
+  
+  public DatanodeInfoWritable(DatanodeInfoWritable from) {
+    super(from);
+    this.capacity = from.getCapacity();
+    this.dfsUsed = from.getDfsUsed();
+    this.remaining = from.getRemaining();
+    this.blockPoolUsed = from.getBlockPoolUsed();
+    this.lastUpdate = from.getLastUpdate();
+    this.xceiverCount = from.getXceiverCount();
+    this.location = from.getNetworkLocation();
+    this.adminState = from.adminState;
+    this.hostName = from.hostName;
+  }
+
+  public DatanodeInfoWritable(DatanodeIDWritable nodeID) {
+    super(nodeID);
+    this.capacity = 0L;
+    this.dfsUsed = 0L;
+    this.remaining = 0L;
+    this.blockPoolUsed = 0L;
+    this.lastUpdate = 0L;
+    this.xceiverCount = 0;
+    this.adminState = null;    
+  }
+  
+  protected DatanodeInfoWritable(DatanodeIDWritable nodeID, String location, String hostName) {
+    this(nodeID);
+    this.location = location;
+    this.hostName = hostName;
+  }
+  
+  public DatanodeInfoWritable(DatanodeIDWritable nodeID, String location, String hostName,
+      final long capacity, final long dfsUsed, final long remaining,
+      final long blockPoolUsed, final long lastUpdate, final int xceiverCount,
+      final AdminStates adminState) {
+    this(nodeID, location, hostName);
+    this.capacity = capacity;
+    this.dfsUsed = dfsUsed;
+    this.remaining = remaining;
+    this.blockPoolUsed = blockPoolUsed;
+    this.lastUpdate = lastUpdate;
+    this.xceiverCount = xceiverCount;
+    this.adminState = adminState;
+  }
+  
+  /** The raw capacity. */
+  public long getCapacity() { return capacity; }
+  
+  /** The used space by the data node. */
+  public long getDfsUsed() { return dfsUsed; }
+
+  /** The used space by the block pool on data node. */
+  public long getBlockPoolUsed() { return blockPoolUsed; }
+
+  /** The used space by the data node. */
+  public long getNonDfsUsed() { 
+    long nonDFSUsed = capacity - dfsUsed - remaining;
+    return nonDFSUsed < 0 ? 0 : nonDFSUsed;
+  }
+
+  /** The used space by the data node as percentage of present capacity */
+  public float getDfsUsedPercent() { 
+    return DFSUtil.getPercentUsed(dfsUsed, capacity);
+  }
+
+  /** The raw free space. */
+  public long getRemaining() { return remaining; }
+
+  /** Used space by the block pool as percentage of present capacity */
+  public float getBlockPoolUsedPercent() {
+    return DFSUtil.getPercentUsed(blockPoolUsed, capacity);
+  }
+  
+  /** The remaining space as percentage of configured capacity. */
+  public float getRemainingPercent() { 
+    return DFSUtil.getPercentRemaining(remaining, capacity);
+  }
+
+  /** The time when this information was accurate. */
+  public long getLastUpdate() { return lastUpdate; }
+
+  /** number of active connections */
+  public int getXceiverCount() { return xceiverCount; }
+
+  /** Sets raw capacity. */
+  public void setCapacity(long capacity) { 
+    this.capacity = capacity; 
+  }
+  
+  /** Sets the used space for the datanode. */
+  public void setDfsUsed(long dfsUsed) {
+    this.dfsUsed = dfsUsed;
+  }
+
+  /** Sets raw free space. */
+  public void setRemaining(long remaining) { 
+    this.remaining = remaining; 
+  }
+
+  /** Sets block pool used space */
+  public void setBlockPoolUsed(long bpUsed) { 
+    this.blockPoolUsed = bpUsed; 
+  }
+
+  /** Sets time when this information was accurate. */
+  public void setLastUpdate(long lastUpdate) { 
+    this.lastUpdate = lastUpdate; 
+  }
+
+  /** Sets number of active connections */
+  public void setXceiverCount(int xceiverCount) { 
+    this.xceiverCount = xceiverCount; 
+  }
+
+  /** rack name */
+  public String getNetworkLocation() {return location;}
+    
+  /** Sets the rack name */
+  public void setNetworkLocation(String location) {
+    this.location = NodeBase.normalize(location);
+  }
+  
+  public String getHostName() {
+    return (hostName == null || hostName.length()==0) ? getHost() : hostName;
+  }
+  
+  public void setHostName(String host) {
+    hostName = host;
+  }
+
+  /**
+   * Retrieves the admin state of this node.
+   */
+  public AdminStates getAdminState() {
+    if (adminState == null) {
+      return AdminStates.NORMAL;
+    }
+    return adminState;
+  }
+
+  /**
+   * Sets the admin state of this node.
+   */
+  protected void setAdminState(AdminStates newState) {
+    if (newState == AdminStates.NORMAL) {
+      adminState = null;
+    }
+    else {
+      adminState = newState;
+    }
+  }
+
+  /////////////////////////////////////////////////
+  // Writable
+  /////////////////////////////////////////////////
+  static {                                      // register a ctor
+    WritableFactories.setFactory
+      (DatanodeInfoWritable.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new DatanodeInfoWritable(); }
+       });
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    super.write(out);
+
+    out.writeShort(ipcPort);
+
+    out.writeLong(capacity);
+    out.writeLong(dfsUsed);
+    out.writeLong(remaining);
+    out.writeLong(blockPoolUsed);
+    out.writeLong(lastUpdate);
+    out.writeInt(xceiverCount);
+    Text.writeString(out, location);
+    Text.writeString(out, hostName == null? "" : hostName);
+    WritableUtils.writeEnum(out, getAdminState());
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    super.readFields(in);
+
+    this.ipcPort = in.readShort() & 0x0000ffff;
+
+    this.capacity = in.readLong();
+    this.dfsUsed = in.readLong();
+    this.remaining = in.readLong();
+    this.blockPoolUsed = in.readLong();
+    this.lastUpdate = in.readLong();
+    this.xceiverCount = in.readInt();
+    this.location = Text.readString(in);
+    this.hostName = Text.readString(in);
+    setAdminState(WritableUtils.readEnum(in, AdminStates.class));
+  }
+
+  /** Read a DatanodeInfo */
+  public static DatanodeInfoWritable read(DataInput in) throws IOException {
+    final DatanodeInfoWritable d = new DatanodeInfoWritable();
+    d.readFields(in);
+    return d;
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/DirectoryListingWritable.java

@@ -0,0 +1,157 @@
+/* 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+/**
+ * This class defines a partial listing of a directory to support
+ * iterative directory listing.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class DirectoryListingWritable implements Writable {
+  static {                                      // register a ctor
+    WritableFactories.setFactory
+      (DirectoryListingWritable.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new DirectoryListingWritable(); }
+       });
+  }
+
+  private HdfsFileStatusWritable[] partialListing;
+  private int remainingEntries;
+  
+  public static org.apache.hadoop.hdfs.protocol.DirectoryListing 
+    convertDirectoryListing(DirectoryListingWritable dl) {
+    if (dl == null) return null;
+    return new org.apache.hadoop.hdfs.protocol.DirectoryListing(
+        HdfsFileStatusWritable.convertHdfsFileStatus(
+            dl.getPartialListing()), dl.getRemainingEntries());
+  }
+
+  public static DirectoryListingWritable convertDirectoryListing(
+      org.apache.hadoop.hdfs.protocol.DirectoryListing d) {
+    if (d == null) return null;
+    return new DirectoryListingWritable(
+        org.apache.hadoop.hdfs.protocolR23Compatible.HdfsFileStatusWritable.
+        convertHdfsFileStatus(d.getPartialListing()), d.getRemainingEntries());
+  } 
+  
+  /**
+   * default constructor
+   */
+  public DirectoryListingWritable() {
+  }
+  
+  /**
+   * constructor
+   * @param partialListing a partial listing of a directory
+   * @param remainingEntries number of entries that are left to be listed
+   */
+  public DirectoryListingWritable(HdfsFileStatusWritable[] partialListing, 
+      int remainingEntries) {
+    if (partialListing == null) {
+      throw new IllegalArgumentException("partial listing should not be null");
+    }
+    if (partialListing.length == 0 && remainingEntries != 0) {
+      throw new IllegalArgumentException("Partial listing is empty but " +
+          "the number of remaining entries is not zero");
+    }
+    this.partialListing = partialListing;
+    this.remainingEntries = remainingEntries;
+  }
+
+  /**
+   * Get the partial listing of file status
+   * @return the partial listing of file status
+   */
+  public HdfsFileStatusWritable[] getPartialListing() {
+    return partialListing;
+  }
+  
+  /**
+   * Get the number of remaining entries that are left to be listed
+   * @return the number of remaining entries that are left to be listed
+   */
+  public int getRemainingEntries() {
+    return remainingEntries;
+  }
+  
+  /**
+   * Check if there are more entries that are left to be listed
+   * @return true if there are more entries that are left to be listed;
+   *         return false otherwise.
+   */
+  public boolean hasMore() {
+    return remainingEntries != 0;
+  }
+  
+  /**
+   * Get the last name in this list
+   * @return the last name in the list if it is not empty; otherwise return null
+   */
+  public byte[] getLastName() {
+    if (partialListing.length == 0) {
+      return null;
+    }
+    return partialListing[partialListing.length-1].getLocalNameInBytes();
+  }
+
+  // Writable interface
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    int numEntries = in.readInt();
+    partialListing = new HdfsFileStatusWritable[numEntries];
+    if (numEntries !=0 ) {
+      boolean hasLocation = in.readBoolean();
+      for (int i=0; i<numEntries; i++) {
+        if (hasLocation) {
+          partialListing[i] = new HdfsLocatedFileStatusWritable();
+        } else {
+          partialListing[i] = new HdfsFileStatusWritable();
+        }
+        partialListing[i].readFields(in);
+      }
+    }
+    remainingEntries = in.readInt();
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeInt(partialListing.length);
+    if (partialListing.length != 0) { 
+       if (partialListing[0] instanceof HdfsLocatedFileStatusWritable) {
+         out.writeBoolean(true);
+       } else {
+         out.writeBoolean(false);
+       }
+       for (HdfsFileStatusWritable fileStatus : partialListing) {
+         fileStatus.write(out);
+       }
+    }
+    out.writeInt(remainingEntries);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ExtendedBlockWritable.java

@@ -0,0 +1,121 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.DeprecatedUTF8;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+/**
+ * Identifies a Block uniquely across the block pools
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class ExtendedBlockWritable implements Writable {
+  private String poolId;
+  private long blockId;
+  private long numBytes;
+  private long generationStamp;
+
+  static { // register a ctor
+    WritableFactories.setFactory(ExtendedBlockWritable.class, new WritableFactory() {
+      public Writable newInstance() {
+        return new ExtendedBlockWritable();
+      }
+    });
+  }
+
+  static public org.apache.hadoop.hdfs.protocol.ExtendedBlock convertExtendedBlock(ExtendedBlockWritable eb) {
+    if (eb == null) return null;
+    return new org.apache.hadoop.hdfs.protocol.ExtendedBlock( eb.getBlockPoolId(),  eb.getBlockId(),   eb.getNumBytes(),
+       eb.getGenerationStamp());
+  }
+  
+  public static ExtendedBlockWritable convertExtendedBlock(final org.apache.hadoop.hdfs.protocol.ExtendedBlock b) {
+    if (b == null) return null;
+    return new ExtendedBlockWritable(b.getBlockPoolId(), 
+        b.getBlockId(), b.getNumBytes(), b.getGenerationStamp());
+  }
+  
+  public ExtendedBlockWritable() {
+    this(null, 0, 0, 0);
+  }
+
+  public ExtendedBlockWritable(final ExtendedBlockWritable b) {
+    this(b.poolId, b.blockId, b.numBytes, b.generationStamp);
+  }
+  
+  public ExtendedBlockWritable(final String poolId, final long blockId) {
+    this(poolId, blockId, 0, 0);
+  }
+
+  public ExtendedBlockWritable(final String poolId, final long blkid, final long len,
+      final long genstamp) {
+    this.poolId = poolId;
+    this.blockId = blkid;
+    this.numBytes = len;
+    this.generationStamp = genstamp;
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    DeprecatedUTF8.writeString(out, poolId);
+    out.writeLong(blockId);
+    out.writeLong(numBytes);
+    out.writeLong(generationStamp);
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    this.poolId = DeprecatedUTF8.readString(in);
+    this.blockId = in.readLong();
+    this.numBytes = in.readLong();
+    this.generationStamp = in.readLong();
+    if (numBytes < 0) {
+      throw new IOException("Unexpected block size: " + numBytes);
+    }
+  }
+
+  public String getBlockPoolId() {
+    return poolId;
+  }
+
+  public long getNumBytes() {
+    return numBytes;
+  }
+
+  public long getBlockId() {
+    return blockId;
+  }
+
+  public long getGenerationStamp() {
+    return generationStamp;
+  }
+  
+  @Override // Object
+  public String toString() {
+    return poolId + ":" + (new org.apache.hadoop.hdfs.protocol.Block(blockId, numBytes, generationStamp));
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/FsPermissionWritable.java

@@ -0,0 +1,80 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class FsPermissionWritable  implements Writable {
+  static final WritableFactory FACTORY = new WritableFactory() {
+	public Writable newInstance() { return new FsPermissionWritable(); }
+  };
+  static {                                      // register a ctor
+    WritableFactories.setFactory(FsPermissionWritable.class, FACTORY);
+  }
+  //POSIX permission style
+  private short thePermissions = 0;
+  
+  public static FsPermissionWritable convertPermission(org.apache.hadoop.fs.permission.FsPermission p) {
+    if (p == null) return null;
+    return new FsPermissionWritable(p.toShort());
+  }
+  
+  public static org.apache.hadoop.fs.permission.FsPermission convertPermission(FsPermissionWritable p) {
+    if (p == null) return null;
+    return new org.apache.hadoop.fs.permission.FsPermission(p.thePermissions);
+  }
+  
+  public static FsPermissionWritable getDefault() {
+    return new FsPermissionWritable((short)00777);
+  }
+  
+  FsPermissionWritable() {
+  }
+	FsPermissionWritable(short p) {
+	  thePermissions = p;
+	}
+  
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeShort(thePermissions);
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    thePermissions = in.readShort();
+  }
+
+  /**
+   * Create and initialize a {@link FsPermissionWritable} from {@link DataInput}.
+   */
+  public static FsPermissionWritable read(DataInput in) throws IOException {
+    FsPermissionWritable p = new FsPermissionWritable();
+    p.readFields(in);
+    return p;
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/FsServerDefaultsWritable.java

@@ -0,0 +1,122 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+/****************************************************
+ * Provides server default configuration values to clients.
+ * 
+ ****************************************************/
+@InterfaceAudience.Public
+@InterfaceStability.Stable
+public class FsServerDefaultsWritable implements Writable {
+
+  static { // register a ctor
+    WritableFactories.setFactory(FsServerDefaultsWritable.class, new WritableFactory() {
+      public Writable newInstance() {
+        return new FsServerDefaultsWritable();
+      }
+    });
+  }
+
+  private long blockSize;
+  private int bytesPerChecksum;
+  private int writePacketSize;
+  private short replication;
+  private int fileBufferSize;
+  
+  public static org.apache.hadoop.fs.FsServerDefaults convert(
+      FsServerDefaultsWritable fs) {
+    if (fs == null) return null;
+    return new org.apache.hadoop.fs.FsServerDefaults(
+        fs.getBlockSize(), fs.getBytesPerChecksum(), 
+        fs.getWritePacketSize(), fs.getReplication(), fs.getFileBufferSize());
+  }
+  
+  public static FsServerDefaultsWritable convert(
+      org.apache.hadoop.fs.FsServerDefaults fs) {
+    if (fs == null) return null;
+    return new FsServerDefaultsWritable(
+        fs.getBlockSize(), fs.getBytesPerChecksum(), 
+        fs.getWritePacketSize(), fs.getReplication(), fs.getFileBufferSize());
+  }
+  
+  public FsServerDefaultsWritable() {
+  }
+
+  public FsServerDefaultsWritable(long blockSize, int bytesPerChecksum,
+      int writePacketSize, short replication, int fileBufferSize) {
+    this.blockSize = blockSize;
+    this.bytesPerChecksum = bytesPerChecksum;
+    this.writePacketSize = writePacketSize;
+    this.replication = replication;
+    this.fileBufferSize = fileBufferSize;
+  }
+
+  public long getBlockSize() {
+    return blockSize;
+  }
+
+  public int getBytesPerChecksum() {
+    return bytesPerChecksum;
+  }
+
+  public int getWritePacketSize() {
+    return writePacketSize;
+  }
+
+  public short getReplication() {
+    return replication;
+  }
+
+  public int getFileBufferSize() {
+    return fileBufferSize;
+  }
+
+  // /////////////////////////////////////////
+  // Writable
+  // /////////////////////////////////////////
+  @Override
+  @InterfaceAudience.Private
+  public void write(DataOutput out) throws IOException {
+    out.writeLong(blockSize);
+    out.writeInt(bytesPerChecksum);
+    out.writeInt(writePacketSize);
+    out.writeShort(replication);
+    out.writeInt(fileBufferSize);
+  }
+
+  @Override
+  @InterfaceAudience.Private
+  public void readFields(DataInput in) throws IOException {
+    blockSize = in.readLong();
+    bytesPerChecksum = in.readInt();
+    writePacketSize = in.readInt();
+    replication = in.readShort();
+    fileBufferSize = in.readInt();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/HdfsFileStatusWritable.java

@@ -0,0 +1,351 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+import org.apache.avro.reflect.Nullable;
+
+/** Interface that represents the over the wire information for a file.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class HdfsFileStatusWritable implements Writable {
+  static {                                      // register a ctor
+    WritableFactories.setFactory
+      (HdfsFileStatusWritable.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new HdfsFileStatusWritable(); }
+       });
+  }
+
+  private byte[] path;  // local name of the inode that's encoded in java UTF8
+  @Nullable
+  private byte[] symlink; // symlink target encoded in java UTF8 or null
+  private long length;
+  private boolean isdir;
+  private short block_replication;
+  private long blocksize;
+  private long modification_time;
+  private long access_time;
+  private FsPermissionWritable permission;
+  private String owner;
+  private String group;
+  
+  public static final byte[] EMPTY_NAME = new byte[0];
+
+  static public org.apache.hadoop.hdfs.protocol.HdfsFileStatus
+    convertHdfsFileStatus(HdfsFileStatusWritable fs) {
+    if (fs == null) return null;
+    return new org.apache.hadoop.hdfs.protocol.HdfsFileStatus(fs.getLen(),
+        fs.isDir(), fs.getReplication(), fs.getBlockSize(),
+        fs.getModificationTime(), fs.getAccessTime(), 
+        FsPermissionWritable.convertPermission(fs.getPermission()),
+        fs.getOwner(), fs.getGroup(), fs.getSymlinkInBytes(),
+        fs.getLocalNameInBytes());
+  }
+  
+  static public HdfsFileStatusWritable[] convertHdfsFileStatus(org.apache.hadoop.hdfs.protocol.HdfsFileStatus[] fs) {
+    if (fs == null) return null;
+    final int len = fs.length;
+    HdfsFileStatusWritable[] result = new HdfsFileStatusWritable[len];
+    for (int i = 0; i < len; ++i) {
+      if (fs[i] instanceof org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus) {
+        result[i] = 
+            HdfsLocatedFileStatusWritable.convertLocatedHdfsFileStatus(
+                (org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus)fs[i]);
+      } else {
+        result[i] = HdfsFileStatusWritable.convertHdfsFileStatus(fs[i]);
+      }
+    }
+    return result;
+  }
+  
+
+  public static org.apache.hadoop.hdfs.protocol.HdfsFileStatus[] convertHdfsFileStatus(
+      HdfsFileStatusWritable[] fs) {
+    if (fs == null) return null;
+    final int len = fs.length;
+    org.apache.hadoop.hdfs.protocol.HdfsFileStatus[] result = 
+        new org.apache.hadoop.hdfs.protocol.HdfsFileStatus[len];
+    for (int i = 0; i < len; ++i) {
+      if (fs[i] instanceof HdfsLocatedFileStatusWritable) {
+        result[i] = 
+            HdfsLocatedFileStatusWritable.convertLocatedHdfsFileStatus((HdfsLocatedFileStatusWritable)fs[i]);
+      } else {
+        result[i] = convertHdfsFileStatus(fs[i]);
+      }
+    }
+    return result;
+  }
+ 
+  public static HdfsFileStatusWritable convertHdfsFileStatus(org.apache.hadoop.hdfs.protocol.HdfsFileStatus fs) {
+    if (fs == null) return null;
+    return new HdfsFileStatusWritable(fs.getLen(), fs.isDir(), fs.getReplication(),
+       fs.getBlockSize(),  fs.getModificationTime(),  fs.getAccessTime(),
+       org.apache.hadoop.hdfs.protocolR23Compatible.FsPermissionWritable.
+         convertPermission(fs.getPermission()),
+       fs.getOwner(),  fs.getGroup(), 
+       fs.getSymlinkInBytes(), fs.getLocalNameInBytes());
+  }
+  
+  /**
+   * default constructor
+   */
+  public HdfsFileStatusWritable() { 
+    this(0, false, 0, 0, 0, 0, null, null, null, null, null); 
+  }
+  
+  /**
+   * Constructor
+   * @param length the number of bytes the file has
+   * @param isdir if the path is a directory
+   * @param block_replication the replication factor
+   * @param blocksize the block size
+   * @param modification_time modification time
+   * @param access_time access time
+   * @param permission permission
+   * @param owner the owner of the path
+   * @param group the group of the path
+   * @param path the local name in java UTF8 encoding the same as that in-memory
+   */
+  public HdfsFileStatusWritable(long length, boolean isdir, int block_replication,
+                    long blocksize, long modification_time, long access_time,
+                    FsPermissionWritable permission, String owner, String group, 
+                    byte[] symlink, byte[] path) {
+    this.length = length;
+    this.isdir = isdir;
+    this.block_replication = (short)block_replication;
+    this.blocksize = blocksize;
+    this.modification_time = modification_time;
+    this.access_time = access_time;
+    this.permission = (permission == null) ? FsPermissionWritable.getDefault() : permission;
+    this.owner = (owner == null) ? "" : owner;
+    this.group = (group == null) ? "" : group;
+    this.symlink = symlink;
+    this.path = path;
+  }
+
+  /**
+   * Get the length of this file, in bytes.
+   * @return the length of this file, in bytes.
+   */
+  final public long getLen() {
+    return length;
+  }
+
+  /**
+   * Is this a directory?
+   * @return true if this is a directory
+   */
+  final public boolean isDir() {
+    return isdir;
+  }
+
+  /**
+   * Is this a symbolic link?
+   * @return true if this is a symbolic link
+   */
+  public boolean isSymlink() {
+    return symlink != null;
+  }
+   
+  /**
+   * Get the block size of the file.
+   * @return the number of bytes
+   */
+  final public long getBlockSize() {
+    return blocksize;
+  }
+
+  /**
+   * Get the replication factor of a file.
+   * @return the replication factor of a file.
+   */
+  final public short getReplication() {
+    return block_replication;
+  }
+
+  /**
+   * Get the modification time of the file.
+   * @return the modification time of file in milliseconds since January 1, 1970 UTC.
+   */
+  final public long getModificationTime() {
+    return modification_time;
+  }
+
+  /**
+   * Get the access time of the file.
+   * @return the access time of file in milliseconds since January 1, 1970 UTC.
+   */
+  final public long getAccessTime() {
+    return access_time;
+  }
+
+  /**
+   * Get FsPermission associated with the file.
+   * @return permssion
+   */
+  final public FsPermissionWritable getPermission() {
+    return permission;
+  }
+  
+  /**
+   * Get the owner of the file.
+   * @return owner of the file
+   */
+  final public String getOwner() {
+    return owner;
+  }
+  
+  /**
+   * Get the group associated with the file.
+   * @return group for the file. 
+   */
+  final public String getGroup() {
+    return group;
+  }
+  
+  /**
+   * Check if the local name is empty
+   * @return true if the name is empty
+   */
+  final public boolean isEmptyLocalName() {
+    return path.length == 0;
+  }
+
+  /**
+   * Get the string representation of the local name
+   * @return the local name in string
+   */
+  final public String getLocalName() {
+    return DFSUtil.bytes2String(path);
+  }
+  
+  /**
+   * Get the Java UTF8 representation of the local name
+   * @return the local name in java UTF8
+   */
+  final public byte[] getLocalNameInBytes() {
+    return path;
+  }
+
+  /**
+   * Get the string representation of the full path name
+   * @param parent the parent path
+   * @return the full path in string
+   */
+  final public String getFullName(final String parent) {
+    if (isEmptyLocalName()) {
+      return parent;
+    }
+    
+    StringBuilder fullName = new StringBuilder(parent);
+    if (!parent.endsWith(Path.SEPARATOR)) {
+      fullName.append(Path.SEPARATOR);
+    }
+    fullName.append(getLocalName());
+    return fullName.toString();
+  }
+
+  /**
+   * Get the full path
+   * @param parent the parent path
+   * @return the full path
+   */
+  final public Path getFullPath(final Path parent) {
+    if (isEmptyLocalName()) {
+      return parent;
+    }
+    
+    return new Path(parent, getLocalName());
+  }
+
+  /**
+   * Get the string representation of the symlink.
+   * @return the symlink as a string.
+   */
+  final public String getSymlink() {
+    return DFSUtil.bytes2String(symlink);
+  }
+  
+  final public byte[] getSymlinkInBytes() {
+    return symlink;
+  }
+  
+
+  //////////////////////////////////////////////////
+  // Writable
+  //////////////////////////////////////////////////
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeInt(path.length);
+    out.write(path);
+    out.writeLong(length);
+    out.writeBoolean(isdir);
+    out.writeShort(block_replication);
+    out.writeLong(blocksize);
+    out.writeLong(modification_time);
+    out.writeLong(access_time);
+    permission.write(out);
+    Text.writeString(out, owner);
+    Text.writeString(out, group);
+    out.writeBoolean(isSymlink());
+    if (isSymlink()) {
+      out.writeInt(symlink.length);
+      out.write(symlink);
+    }
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    int numOfBytes = in.readInt();
+    if (numOfBytes == 0) {
+      this.path = EMPTY_NAME;
+    } else {
+      this.path = new byte[numOfBytes];
+      in.readFully(path);
+    }
+    this.length = in.readLong();
+    this.isdir = in.readBoolean();
+    this.block_replication = in.readShort();
+    blocksize = in.readLong();
+    modification_time = in.readLong();
+    access_time = in.readLong();
+    permission.readFields(in);
+    owner = Text.readString(in);
+    group = Text.readString(in);
+    if (in.readBoolean()) {
+      numOfBytes = in.readInt();
+      this.symlink = new byte[numOfBytes];
+      in.readFully(symlink);
+    }
+  }
+
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/HdfsLocatedFileStatusWritable.java

@@ -0,0 +1,116 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/** 
+ * Interface that represents the over the wire information
+ * including block locations for a file.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class HdfsLocatedFileStatusWritable extends HdfsFileStatusWritable {
+  private LocatedBlocksWritable locations;
+  
+  /**
+   * Default constructor
+   */
+  public HdfsLocatedFileStatusWritable() {
+  }
+  
+  /**
+   * Constructor
+   * 
+   * @param length size
+   * @param isdir if this is directory
+   * @param block_replication the file's replication factor
+   * @param blocksize the file's block size
+   * @param modification_time most recent modification time
+   * @param access_time most recent access time
+   * @param permission permission
+   * @param owner owner
+   * @param group group
+   * @param symlink symbolic link
+   * @param path local path name in java UTF8 format 
+   * @param locations block locations
+   */
+  public HdfsLocatedFileStatusWritable(long length, boolean isdir,
+      int block_replication,
+	    long blocksize, long modification_time, long access_time,
+	    FsPermissionWritable permission, String owner, String group, 
+	    byte[] symlink, byte[] path, LocatedBlocksWritable locations) {
+	  super(length, isdir, block_replication, blocksize, modification_time,
+		  access_time, permission, owner, group, symlink, path);
+    this.locations = locations;
+	}
+  
+  static public org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus
+  convertLocatedHdfsFileStatus(HdfsLocatedFileStatusWritable fs) {
+  if (fs == null) return null;
+  return new org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus(fs.getLen(),
+      fs.isDir(), fs.getReplication(), fs.getBlockSize(),
+      fs.getModificationTime(), fs.getAccessTime(), 
+      FsPermissionWritable.convertPermission(fs.getPermission()),
+      fs.getOwner(), fs.getGroup(), fs.getSymlinkInBytes(),
+      fs.getLocalNameInBytes(),
+      LocatedBlocksWritable.convertLocatedBlocks(fs.getBlockLocations()));
+}
+  
+  static public HdfsLocatedFileStatusWritable convertLocatedHdfsFileStatus(
+      org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus fs) {
+  if (fs == null) return null;
+  return new HdfsLocatedFileStatusWritable(fs.getLen(),
+      fs.isDir(), fs.getReplication(), fs.getBlockSize(),
+      fs.getModificationTime(), fs.getAccessTime(), 
+      org.apache.hadoop.hdfs.protocolR23Compatible.FsPermissionWritable.
+        convertPermission(fs.getPermission()),
+      fs.getOwner(), fs.getGroup(), fs.getSymlinkInBytes(),
+      fs.getLocalNameInBytes(), 
+      LocatedBlocksWritable.convertLocatedBlocks(fs.getBlockLocations()));
+}
+	
+	public LocatedBlocksWritable getBlockLocations() {
+		return locations;
+	}
+	
+  //////////////////////////////////////////////////
+  // Writable
+  //////////////////////////////////////////////////
+  @Override
+  public void write(DataOutput out) throws IOException {
+    super.write(out);
+    if (!isDir() && !isSymlink()) {
+      locations.write(out);
+    }
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    super.readFields(in);
+    if (!isDir() && !isSymlink()) {
+      locations = new LocatedBlocksWritable();
+      locations.readFields(in);
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/LocatedBlockWritable.java

@@ -0,0 +1,253 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
+import org.apache.hadoop.io.*;
+
+import java.io.*;
+import java.util.ArrayList;
+import java.util.List;
+
+/****************************************************
+ * A LocatedBlock is a pair of Block, DatanodeInfo[]
+ * objects.  It tells where to find a Block.
+ * 
+ ****************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class LocatedBlockWritable implements Writable {
+
+  static {                                      // register a ctor
+    WritableFactories.setFactory
+      (LocatedBlockWritable.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new LocatedBlockWritable(); }
+       });
+  }
+
+  private ExtendedBlockWritable b;
+  private long offset;  // offset of the first byte of the block in the file
+  private DatanodeInfoWritable[] locs;
+  // corrupt flag is true if all of the replicas of a block are corrupt.
+  // else false. If block has few corrupt replicas, they are filtered and 
+  // their locations are not part of this object
+  private boolean corrupt;
+  private TokenWritable blockToken = new TokenWritable();
+
+  
+  static public org.apache.hadoop.hdfs.protocol.LocatedBlock
+    convertLocatedBlock(LocatedBlockWritable lb) {
+    if (lb == null) return null;
+    org.apache.hadoop.hdfs.protocol.LocatedBlock result =  
+        new org.apache.hadoop.hdfs.protocol.LocatedBlock(ExtendedBlockWritable.
+            convertExtendedBlock(lb.getBlock()),
+        DatanodeInfoWritable.convertDatanodeInfo(
+            lb.getLocations()), lb.getStartOffset(), lb.isCorrupt());
+    
+    // Fill in the token
+    TokenWritable tok = lb.getBlockToken();
+    result.setBlockToken(
+        new org.apache.hadoop.security.token.Token<BlockTokenIdentifier>(
+            tok.getIdentifier(), tok.getPassword(), tok.getKind(),
+            tok.getService()));
+    return result;
+  }
+  
+  public static LocatedBlockWritable 
+    convertLocatedBlock(org.apache.hadoop.hdfs.protocol.LocatedBlock lb) {
+    if (lb == null) return null;
+    LocatedBlockWritable result =  
+        new LocatedBlockWritable(ExtendedBlockWritable.convertExtendedBlock(lb.getBlock()), 
+        DatanodeInfoWritable.convertDatanodeInfo(lb.getLocations()),
+        lb.getStartOffset(), lb.isCorrupt());
+    
+    // Fill in the token
+    org.apache.hadoop.security.token.Token<BlockTokenIdentifier> tok = 
+        lb.getBlockToken();
+    result.setBlockToken(new TokenWritable(tok.getIdentifier(), tok.getPassword(), 
+        tok.getKind(), tok.getService()));
+    return result;
+  }
+  
+  static public LocatedBlockWritable[] 
+      convertLocatedBlock(org.apache.hadoop.hdfs.protocol.LocatedBlock[] lb) {
+    if (lb == null) return null;
+    final int len = lb.length;
+    LocatedBlockWritable[] result = new LocatedBlockWritable[len];
+    for (int i = 0; i < len; ++i) {
+      result[i] = new LocatedBlockWritable(
+          ExtendedBlockWritable.convertExtendedBlock(lb[i].getBlock()),
+          DatanodeInfoWritable.convertDatanodeInfo(lb[i].getLocations()), 
+          lb[i].getStartOffset(), lb[i].isCorrupt());
+    }
+    return result;
+  }
+  
+  static public org.apache.hadoop.hdfs.protocol.LocatedBlock[] 
+      convertLocatedBlock(LocatedBlockWritable[] lb) {
+    if (lb == null) return null;
+    final int len = lb.length;
+    org.apache.hadoop.hdfs.protocol.LocatedBlock[] result = 
+        new org.apache.hadoop.hdfs.protocol.LocatedBlock[len];
+    for (int i = 0; i < len; ++i) {
+      result[i] = new org.apache.hadoop.hdfs.protocol.LocatedBlock(
+          ExtendedBlockWritable.convertExtendedBlock(lb[i].getBlock()),
+          DatanodeInfoWritable.convertDatanodeInfo(lb[i].getLocations()), 
+          lb[i].getStartOffset(), lb[i].isCorrupt());
+    }
+    return result;
+  }
+  
+  static public List<org.apache.hadoop.hdfs.protocol.LocatedBlock> 
+    convertLocatedBlock(
+        List<org.apache.hadoop.hdfs.protocolR23Compatible.LocatedBlockWritable> lb) {
+    if (lb == null) return null;
+    final int len = lb.size();
+    List<org.apache.hadoop.hdfs.protocol.LocatedBlock> result = 
+        new ArrayList<org.apache.hadoop.hdfs.protocol.LocatedBlock>(len);
+    for (int i = 0; i < len; ++i) {
+      result.add(LocatedBlockWritable.convertLocatedBlock(lb.get(i)));
+    }
+    return result;
+  }
+  
+  static public List<LocatedBlockWritable> 
+  convertLocatedBlock2(List<org.apache.hadoop.hdfs.protocol.LocatedBlock> lb) {
+    if (lb == null) return null;
+    final int len = lb.size();
+    List<LocatedBlockWritable> result = new ArrayList<LocatedBlockWritable>(len);
+    for (int i = 0; i < len; ++i) {
+      result.add(LocatedBlockWritable.convertLocatedBlock(lb.get(i)));
+    }
+    return result;
+  }
+  
+  public LocatedBlockWritable() {
+    this(new ExtendedBlockWritable(), new DatanodeInfoWritable[0], 0L, false);
+  }
+
+  public LocatedBlockWritable(ExtendedBlockWritable eb) {
+    this(eb, new DatanodeInfoWritable[0], 0L, false);
+  }
+  
+  public LocatedBlockWritable(ExtendedBlockWritable b, DatanodeInfoWritable[] locs) {
+    this(b, locs, -1, false); // startOffset is unknown
+  }
+
+  public LocatedBlockWritable(ExtendedBlockWritable b, DatanodeInfoWritable[] locs, long startOffset) {
+    this(b, locs, startOffset, false);
+  }
+
+  public LocatedBlockWritable(ExtendedBlockWritable b, DatanodeInfoWritable[] locs, long startOffset, 
+                      boolean corrupt) {
+    this.b = b;
+    this.offset = startOffset;
+    this.corrupt = corrupt;
+    if (locs==null) {
+      this.locs = new DatanodeInfoWritable[0];
+    } else {
+      this.locs = locs;
+    }
+  }
+
+  public TokenWritable getBlockToken() {
+    return blockToken;
+  }
+
+  public void setBlockToken(TokenWritable token) {
+    this.blockToken = token;
+  }
+
+  public ExtendedBlockWritable getBlock() {
+    return b;
+  }
+
+  public DatanodeInfoWritable[] getLocations() {
+    return locs;
+  }
+  
+  public long getStartOffset() {
+    return offset;
+  }
+  
+  public long getBlockSize() {
+    return b.getNumBytes();
+  }
+
+  void setStartOffset(long value) {
+    this.offset = value;
+  }
+
+  void setCorrupt(boolean corrupt) {
+    this.corrupt = corrupt;
+  }
+  
+  public boolean isCorrupt() {
+    return this.corrupt;
+  }
+
+  ///////////////////////////////////////////
+  // Writable
+  ///////////////////////////////////////////
+  @Override
+  public void write(DataOutput out) throws IOException {
+    blockToken.write(out);
+    out.writeBoolean(corrupt);
+    out.writeLong(offset);
+    b.write(out);
+    out.writeInt(locs.length);
+    for (int i = 0; i < locs.length; i++) {
+      locs[i].write(out);
+    }
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    blockToken.readFields(in);
+    this.corrupt = in.readBoolean();
+    offset = in.readLong();
+    this.b = new ExtendedBlockWritable();
+    b.readFields(in);
+    int count = in.readInt();
+    this.locs = new DatanodeInfoWritable[count];
+    for (int i = 0; i < locs.length; i++) {
+      locs[i] = new DatanodeInfoWritable();
+      locs[i].readFields(in);
+    }
+  }
+
+  /** Read LocatedBlock from in. */
+  public static LocatedBlockWritable read(DataInput in) throws IOException {
+    final LocatedBlockWritable lb = new LocatedBlockWritable();
+    lb.readFields(in);
+    return lb;
+  }
+
+  @Override
+  public String toString() {
+    return getClass().getSimpleName() + "{" + b
+        + "; getBlockSize()=" + getBlockSize()
+        + "; corrupt=" + corrupt
+        + "; offset=" + offset
+        + "; locs=" + java.util.Arrays.asList(locs)
+        + "}";
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/LocatedBlocksWritable.java

@@ -0,0 +1,200 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+import java.util.List;
+import java.util.ArrayList;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+import org.apache.avro.reflect.Nullable;
+
+/**
+ * Collection of blocks with their locations and the file length.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class LocatedBlocksWritable implements Writable {
+  private long fileLength;
+  private List<LocatedBlockWritable> blocks; // array of blocks with prioritized locations
+  private boolean underConstruction;
+  @Nullable
+  private LocatedBlockWritable lastLocatedBlock = null;
+  private boolean isLastBlockComplete = false;
+
+  public static org.apache.hadoop.hdfs.protocol.LocatedBlocks convertLocatedBlocks(
+      LocatedBlocksWritable lb) {
+    if (lb == null) {
+      return null;
+    }
+    return new org.apache.hadoop.hdfs.protocol.LocatedBlocks(
+        lb.getFileLength(), lb.isUnderConstruction(),
+        LocatedBlockWritable.convertLocatedBlock(lb.getLocatedBlocks()),
+        LocatedBlockWritable.convertLocatedBlock(lb.getLastLocatedBlock()),
+        lb.isLastBlockComplete());
+  }
+  
+  public static LocatedBlocksWritable convertLocatedBlocks(
+      org.apache.hadoop.hdfs.protocol.LocatedBlocks lb) {
+    if (lb == null) {
+      return null;
+    }
+    return new LocatedBlocksWritable(lb.getFileLength(), lb.isUnderConstruction(),
+        LocatedBlockWritable.convertLocatedBlock2(lb.getLocatedBlocks()),
+        LocatedBlockWritable.convertLocatedBlock(lb.getLastLocatedBlock()),
+        lb.isLastBlockComplete());
+  }
+  
+  public LocatedBlocksWritable() {
+    this(0, false, null, null, false);
+  }
+  
+  /** public Constructor */
+  public LocatedBlocksWritable(long flength, boolean isUnderConstuction,
+      List<LocatedBlockWritable> blks, 
+      LocatedBlockWritable lastBlock, boolean isLastBlockCompleted) {
+    fileLength = flength;
+    blocks = blks;
+    underConstruction = isUnderConstuction;
+    this.lastLocatedBlock = lastBlock;
+    this.isLastBlockComplete = isLastBlockCompleted;
+  }
+  
+  /**
+   * Get located blocks.
+   */
+  public List<LocatedBlockWritable> getLocatedBlocks() {
+    return blocks;
+  }
+  
+  /** Get the last located block. */
+  public LocatedBlockWritable getLastLocatedBlock() {
+    return lastLocatedBlock;
+  }
+  
+  /** Is the last block completed? */
+  public boolean isLastBlockComplete() {
+    return isLastBlockComplete;
+  }
+
+  /**
+   * Get located block.
+   */
+  public LocatedBlockWritable get(int index) {
+    return blocks.get(index);
+  }
+  
+  /**
+   * Get number of located blocks.
+   */
+  public int locatedBlockCount() {
+    return blocks == null ? 0 : blocks.size();
+  }
+
+  /**
+   * Get file length
+   */
+  public long getFileLength() {
+    return this.fileLength;
+  }
+
+  /**
+   * Return ture if file was under construction when 
+   * this LocatedBlocks was constructed, false otherwise.
+   */
+  public boolean isUnderConstruction() {
+    return underConstruction;
+  }
+
+  //////////////////////////////////////////////////
+  // Writable
+  //////////////////////////////////////////////////
+  static {                                      // register a ctor
+    WritableFactories.setFactory
+      (LocatedBlocksWritable.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new LocatedBlocksWritable(); }
+       });
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeLong(this.fileLength);
+    out.writeBoolean(underConstruction);
+
+    //write the last located block
+    final boolean isNull = lastLocatedBlock == null;
+    out.writeBoolean(isNull);
+    if (!isNull) {
+      lastLocatedBlock.write(out);
+    }
+    out.writeBoolean(isLastBlockComplete);
+
+    // write located blocks
+    int nrBlocks = locatedBlockCount();
+    out.writeInt(nrBlocks);
+    if (nrBlocks == 0) {
+      return;
+    }
+    for (LocatedBlockWritable blk : this.blocks) {
+      blk.write(out);
+    }
+  }
+  
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    this.fileLength = in.readLong();
+    underConstruction = in.readBoolean();
+
+    //read the last located block
+    final boolean isNull = in.readBoolean();
+    if (!isNull) {
+      lastLocatedBlock = LocatedBlockWritable.read(in);
+    }
+    isLastBlockComplete = in.readBoolean();
+
+    // read located blocks
+    int nrBlocks = in.readInt();
+    this.blocks = new ArrayList<LocatedBlockWritable>(nrBlocks);
+    for (int idx = 0; idx < nrBlocks; idx++) {
+      LocatedBlockWritable blk = new LocatedBlockWritable();
+      blk.readFields(in);
+      this.blocks.add(blk);
+    }
+  }
+
+  @Override
+  public String toString() {
+    final StringBuilder b = new StringBuilder(getClass().getSimpleName());
+    b.append("{")
+     .append("\n  fileLength=").append(fileLength)
+     .append("\n  underConstruction=").append(underConstruction)
+     .append("\n  blocks=").append(blocks)
+     .append("\n  lastLocatedBlock=").append(lastLocatedBlock)
+     .append("\n  isLastBlockComplete=").append(isLastBlockComplete)
+     .append("}");
+    return b.toString();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/ProtocolSignatureWritable.java

@@ -0,0 +1,110 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class ProtocolSignatureWritable implements Writable {
+  static {               // register a ctor
+    WritableFactories.setFactory
+      (ProtocolSignatureWritable.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new ProtocolSignatureWritable(); }
+       });
+  }
+
+  private long version;
+  private int[] methods = null; // an array of method hash codes
+  
+  public static org.apache.hadoop.ipc.ProtocolSignature convert(
+      final ProtocolSignatureWritable ps) {
+    if (ps == null) return null;
+    return new org.apache.hadoop.ipc.ProtocolSignature(
+        ps.getVersion(), ps.getMethods());
+  }
+  
+  public static ProtocolSignatureWritable convert(
+      final org.apache.hadoop.ipc.ProtocolSignature ps) {
+    if (ps == null) return null;
+    return new ProtocolSignatureWritable(ps.getVersion(), ps.getMethods());
+  }
+  
+  /**
+   * default constructor
+   */
+  public ProtocolSignatureWritable() {
+  }
+  
+  /**
+   * Constructor
+   * 
+   * @param version server version
+   * @param methodHashcodes hash codes of the methods supported by server
+   */
+  public ProtocolSignatureWritable(long version, int[] methodHashcodes) {
+    this.version = version;
+    this.methods = methodHashcodes;
+  }
+  
+  public long getVersion() {
+    return version;
+  }
+  
+  public int[] getMethods() {
+    return methods;
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    version = in.readLong();
+    boolean hasMethods = in.readBoolean();
+    if (hasMethods) {
+      int numMethods = in.readInt();
+      methods = new int[numMethods];
+      for (int i=0; i<numMethods; i++) {
+        methods[i] = in.readInt();
+      }
+    }
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeLong(version);
+    if (methods == null) {
+      out.writeBoolean(false);
+    } else {
+      out.writeBoolean(true);
+      out.writeInt(methods.length);
+      for (int method : methods) {
+        out.writeInt(method);
+      }
+    }
+  }
+}
+

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/TokenWritable.java

@@ -0,0 +1,208 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.commons.codec.binary.Base64;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.DataInputBuffer;
+import org.apache.hadoop.io.DataOutputBuffer;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableUtils;
+
+/**
+ * The client-side form of the token.
+ */
+@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
+@InterfaceStability.Stable
+public class TokenWritable implements Writable {
+  private byte[] identifier;
+  private byte[] password;
+  private Text kind;
+  private Text service;
+ 
+  /**
+   * Construct a token from the components.
+   * @param identifier the token identifier
+   * @param password the token's password
+   * @param kind the kind of token
+   * @param service the service for this token
+   */
+  public TokenWritable(byte[] identifier, byte[] password, Text kind, Text service) {
+    this.identifier = identifier;
+    this.password = password;
+    this.kind = kind;
+    this.service = service;
+  }
+
+  /**
+   * Default constructor
+   */
+  public TokenWritable() {
+    this(new byte[0], new byte[0], new Text(), new Text());
+  }
+
+  /**
+   * Get the token identifier
+   * @return the token identifier
+   */
+  public byte[] getIdentifier() {
+    return identifier;
+  }
+  
+  /**
+   * Get the token password/secret
+   * @return the token password/secret
+   */
+  public byte[] getPassword() {
+    return password;
+  }
+  
+  /**
+   * Get the token kind
+   * @return the kind of the token
+   */
+  public Text getKind() {
+    return kind;
+  }
+
+  /**
+   * Get the service on which the token is supposed to be used
+   * @return the service name
+   */
+  public Text getService() {
+    return service;
+  }
+  
+  /**
+   * Set the service on which the token is supposed to be used
+   * @param newService the service name
+   */
+  public void setService(Text newService) {
+    service = newService;
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    int len = WritableUtils.readVInt(in);
+    if (identifier == null || identifier.length != len) {
+      identifier = new byte[len];
+    }
+    in.readFully(identifier);
+    len = WritableUtils.readVInt(in);
+    if (password == null || password.length != len) {
+      password = new byte[len];
+    }
+    in.readFully(password);
+    kind.readFields(in);
+    service.readFields(in);
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    WritableUtils.writeVInt(out, identifier.length);
+    out.write(identifier);
+    WritableUtils.writeVInt(out, password.length);
+    out.write(password);
+    kind.write(out);
+    service.write(out);
+  }
+
+  /**
+   * Generate a string with the url-quoted base64 encoded serialized form
+   * of the Writable.
+   * @param obj the object to serialize
+   * @return the encoded string
+   * @throws IOException
+   */
+  private static String encodeWritable(Writable obj) throws IOException {
+    DataOutputBuffer buf = new DataOutputBuffer();
+    obj.write(buf);
+    Base64 encoder = new Base64(0, null, true);
+    byte[] raw = new byte[buf.getLength()];
+    System.arraycopy(buf.getData(), 0, raw, 0, buf.getLength());
+    return encoder.encodeToString(raw);
+  }
+  
+  /**
+   * Modify the writable to the value from the newValue
+   * @param obj the object to read into
+   * @param newValue the string with the url-safe base64 encoded bytes
+   * @throws IOException
+   */
+  private static void decodeWritable(Writable obj, 
+                                     String newValue) throws IOException {
+    Base64 decoder = new Base64(0, null, true);
+    DataInputBuffer buf = new DataInputBuffer();
+    byte[] decoded = decoder.decode(newValue);
+    buf.reset(decoded, decoded.length);
+    obj.readFields(buf);
+  }
+
+  /**
+   * Encode this token as a url safe string
+   * @return the encoded string
+   * @throws IOException
+   */
+  public String encodeToUrlString() throws IOException {
+    return encodeWritable(this);
+  }
+  
+  /**
+   * Decode the given url safe string into this token.
+   * @param newValue the encoded string
+   * @throws IOException
+   */
+  public void decodeFromUrlString(String newValue) throws IOException {
+    decodeWritable(this, newValue);
+  }
+  
+  private static void addBinaryBuffer(StringBuilder buffer, byte[] bytes) {
+    for (int idx = 0; idx < bytes.length; idx++) {
+      // if not the first, put a blank separator in
+      if (idx != 0) {
+        buffer.append(' ');
+      }
+      String num = Integer.toHexString(0xff & bytes[idx]);
+      // if it is only one digit, add a leading 0.
+      if (num.length() < 2) {
+        buffer.append('0');
+      }
+      buffer.append(num);
+    }
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder buffer = new StringBuilder();
+    buffer.append("Ident: ");
+    addBinaryBuffer(buffer, identifier);
+    buffer.append(", Kind: ");
+    buffer.append(kind.toString());
+    buffer.append(", Service: ");
+    buffer.append(service.toString());
+    return buffer.toString();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/UpgradeStatusReportWritable.java

@@ -0,0 +1,140 @@
+/**
+ * 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.hdfs.protocolR23Compatible;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+/**
+ * Base upgrade upgradeStatus class.
+ * 
+ * Describes status of current upgrade.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class UpgradeStatusReportWritable implements Writable {
+  protected int version;
+  protected short upgradeStatus;
+  protected boolean finalized;
+  
+  public static UpgradeStatusReportWritable convert(
+      org.apache.hadoop.hdfs.server.common.UpgradeStatusReport r) {
+    if (r == null) return null;
+    return new UpgradeStatusReportWritable(
+        r.getVersion(), r.getUpgradeStatus(), r.isFinalized());
+  }
+  
+  public static org.apache.hadoop.hdfs.server.common.UpgradeStatusReport 
+    convert(UpgradeStatusReportWritable r) {
+    if (r == null) return null;
+    return new org.apache.hadoop.hdfs.server.common.UpgradeStatusReport(
+        r.getVersion(), r.getUpgradeStatus(), r.isFinalized());
+  }
+  
+  public UpgradeStatusReportWritable() {
+    this(0, (short)0, false);
+  }
+
+  public UpgradeStatusReportWritable(int version, short status, boolean isFinalized) {
+    this.version = version;
+    this.upgradeStatus = status;
+    this.finalized = isFinalized;
+  }
+
+  /**
+   * Get the layout version of the currently running upgrade.
+   * @return layout version
+   */
+  public int getVersion() {
+    return this.version;
+  }
+
+  /**
+   * Get upgrade upgradeStatus as a percentage of the total upgrade done.
+   */ 
+  public short getUpgradeStatus() {
+    return upgradeStatus;
+  }
+
+  /**
+   * Is current upgrade finalized.
+   * @return true if finalized or false otherwise.
+   */
+  public boolean isFinalized() {
+    return this.finalized;
+  }
+
+  /**
+   * Get upgradeStatus data as a text for reporting.
+   * Should be overloaded for a particular upgrade specific upgradeStatus data.
+   * 
+   * @param details true if upgradeStatus details need to be included, 
+   *                false otherwise
+   * @return text
+   */
+  public String getStatusText(boolean details) {
+    return "Upgrade for version " + getVersion() 
+            + (upgradeStatus<100 ? 
+              " is in progress. Status = " + upgradeStatus + "%" : 
+              " has been completed."
+              + "\nUpgrade is " + (finalized ? "" : "not ")
+              + "finalized.");
+  }
+
+  /**
+   * Print basic upgradeStatus details.
+   */
+  @Override
+  public String toString() {
+    return getStatusText(false);
+  }
+
+  /////////////////////////////////////////////////
+  // Writable
+  /////////////////////////////////////////////////
+  static {                                      // register a ctor
+    WritableFactories.setFactory
+      (UpgradeStatusReportWritable.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new UpgradeStatusReportWritable(); }
+       });
+  }
+
+  
+  // Note when upgrade has been finalized then the NN always
+  // returns a null as the report. 
+  // hence the isFinalized is serialized (ugly)
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeInt(this.version);
+    out.writeShort(this.upgradeStatus);
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    this.version = in.readInt();
+    this.upgradeStatus = in.readShort();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolR23Compatible/overview.html

@@ -0,0 +1,44 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+<html>
+<!--
+   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.
+-->
+<head>
+   <title>Namenode Client Protocols Compatible with the version
+    of Hadoop Release 23</title>
+</head>
+<body>
+<p>
+This package is for ALL versions of HDFS protocols that use writable data types
+and are compatible with the version of the protocol that was
+ shipped with Release 23 of Hadoop.
+</p>
+
+Compatibility should be maintained:
+<ul>
+<li> Do NOT delete any methods </li>
+<li> Do NOT change the signatures of any method:
+ do not  change parameters, parameter types
+or exceptions thrown by the method.</li>
+</ul>
+<p>
+You can add new methods and new types. If you need to  change a method's
+signature, please add a new method instead.
+When you add new methods and new types do NOT change the version number.
+<p> 
+Version number is changed ONLY when compatibility is broken (which
+should be very rare and a big deal).
+</p>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java

@@ -105,6 +105,7 @@ import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtocol;
 import org.apache.hadoop.hdfs.protocol.datatransfer.Sender;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.DNTransferAckProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.Status;
+import org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeProtocolServerSideTranslatorR23;
 import org.apache.hadoop.hdfs.security.token.block.BlockPoolTokenSecretManager;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenSecretManager;
@@ -517,7 +518,12 @@ public class DataNode extends Configured
         conf.get("dfs.datanode.ipc.address"));
     
     // Add all the RPC protocols that the Datanode implements    
-    ipcServer = RPC.getServer(ClientDatanodeProtocol.class, this, ipcAddr.getHostName(),
+    ClientDatanodeProtocolServerSideTranslatorR23 
+        clientDatanodeProtocolServerTranslator = 
+          new ClientDatanodeProtocolServerSideTranslatorR23(this);
+    ipcServer = RPC.getServer(
+      org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol.class,
+      clientDatanodeProtocolServerTranslator, ipcAddr.getHostName(),
                               ipcAddr.getPort(), 
                               conf.getInt(DFS_DATANODE_HANDLER_COUNT_KEY, 
                                           DFS_DATANODE_HANDLER_COUNT_DEFAULT), 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java

@@ -57,6 +57,8 @@ import org.apache.hadoop.hdfs.protocol.UnresolvedPathException;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.UpgradeAction;
+import org.apache.hadoop.hdfs.protocolR23Compatible.ClientNamenodeWireProtocol;
+import org.apache.hadoop.hdfs.protocolR23Compatible.ClientNamenodeProtocolServerSideTranslatorR23;
 import org.apache.hadoop.hdfs.security.token.block.ExportedBlockKeys;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.server.common.IncorrectVersionException;
@@ -143,9 +145,12 @@ class NameNodeRpcServer implements NamenodeProtocols {
       serviceRPCAddress = null;
     }
     // Add all the RPC protocols that the namenode implements
-    this.server = RPC.getServer(ClientProtocol.class, this,
+    ClientNamenodeProtocolServerSideTranslatorR23 clientProtocolServerTranslator = 
-                                socAddr.getHostName(), socAddr.getPort(),
+        new ClientNamenodeProtocolServerSideTranslatorR23(this);
-                                handlerCount, false, conf, 
+    this.server = RPC.getServer(
+            org.apache.hadoop.hdfs.protocolR23Compatible.ClientNamenodeWireProtocol.class,
+            clientProtocolServerTranslator, socAddr.getHostName(),
+            socAddr.getPort(), handlerCount, false, conf,
             namesystem.getDelegationTokenSecretManager());
     this.server.addProtocol(DatanodeProtocol.class, this);
     this.server.addProtocol(NamenodeProtocol.class, this);
@@ -210,7 +215,8 @@ class NameNodeRpcServer implements NamenodeProtocols {
   public long getProtocolVersion(String protocol, 
                                  long clientVersion) throws IOException {
     if (protocol.equals(ClientProtocol.class.getName())) {
-      return ClientProtocol.versionID; 
+      throw new IOException("Old Namenode Client protocol is not supported:" + 
+      protocol + "Switch your clientside to " + ClientNamenodeWireProtocol.class); 
     } else if (protocol.equals(DatanodeProtocol.class.getName())){
       return DatanodeProtocol.versionID;
     } else if (protocol.equals(NamenodeProtocol.class.getName())){

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientRetries.java

@@ -96,7 +96,7 @@ public class TestDFSClientRetries extends TestCase {
     }
 
     @Override
-    public Writable call(Class<?> protocol, Writable param, long receiveTime)
+    public Writable call(String protocol, Writable param, long receiveTime)
         throws IOException {
       if (sleep) {
         // sleep a bit

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/security/token/block/TestBlockToken.java

@@ -51,12 +51,12 @@ import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.protocol.Block;
-import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
+import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
 import org.apache.hadoop.io.TestWritable;
 import org.apache.hadoop.ipc.Client;
 import org.apache.hadoop.ipc.ProtocolSignature;
@@ -120,7 +120,8 @@ public class TestBlockToken {
     public Long answer(InvocationOnMock invocation) throws IOException {
       Object args[] = invocation.getArguments();
       assertEquals(1, args.length);
-      ExtendedBlock block = (ExtendedBlock) args[0];
+      org.apache.hadoop.hdfs.protocolR23Compatible.ExtendedBlockWritable block = 
+          (org.apache.hadoop.hdfs.protocolR23Compatible.ExtendedBlockWritable) args[0];
       Set<TokenIdentifier> tokenIds = UserGroupInformation.getCurrentUser()
           .getTokenIdentifiers();
       assertEquals("Only one BlockTokenIdentifier expected", 1, tokenIds.size());
@@ -129,7 +130,9 @@ public class TestBlockToken {
         BlockTokenIdentifier id = (BlockTokenIdentifier) tokenId;
         LOG.info("Got: " + id.toString());
         assertTrue("Received BlockTokenIdentifier is wrong", ident.equals(id));
-        sm.checkAccess(id, null, block, BlockTokenSecretManager.AccessMode.WRITE);
+        sm.checkAccess(id, null, org.apache.hadoop.hdfs.protocolR23Compatible.
+            ExtendedBlockWritable.convertExtendedBlock(block),
+            BlockTokenSecretManager.AccessMode.WRITE);
         result = id.getBlockId();
       }
       return result;
@@ -137,7 +140,8 @@ public class TestBlockToken {
   }
 
   private BlockTokenIdentifier generateTokenId(BlockTokenSecretManager sm,
-      ExtendedBlock block, EnumSet<BlockTokenSecretManager.AccessMode> accessModes)
+      ExtendedBlock block,
+      EnumSet<BlockTokenSecretManager.AccessMode> accessModes)
       throws IOException {
     Token<BlockTokenIdentifier> token = sm.generateToken(block, accessModes);
     BlockTokenIdentifier id = sm.createIdentifier();
@@ -151,12 +155,12 @@ public class TestBlockToken {
     TestWritable.testWritable(new BlockTokenIdentifier());
     BlockTokenSecretManager sm = new BlockTokenSecretManager(true,
         blockKeyUpdateInterval, blockTokenLifetime);
-    TestWritable.testWritable(generateTokenId(sm, block1, EnumSet
+    TestWritable.testWritable(generateTokenId(sm, block1,
-        .allOf(BlockTokenSecretManager.AccessMode.class)));
+        EnumSet.allOf(BlockTokenSecretManager.AccessMode.class)));
-    TestWritable.testWritable(generateTokenId(sm, block2, EnumSet
+    TestWritable.testWritable(generateTokenId(sm, block2,
-        .of(BlockTokenSecretManager.AccessMode.WRITE)));
+        EnumSet.of(BlockTokenSecretManager.AccessMode.WRITE)));
-    TestWritable.testWritable(generateTokenId(sm, block3, EnumSet
+    TestWritable.testWritable(generateTokenId(sm, block3,
-        .noneOf(BlockTokenSecretManager.AccessMode.class)));
+        EnumSet.noneOf(BlockTokenSecretManager.AccessMode.class)));
   }
 
   private void tokenGenerationAndVerification(BlockTokenSecretManager master,
@@ -176,8 +180,8 @@ public class TestBlockToken {
       slave.checkAccess(token2, null, block2, mode);
     }
     // multi-mode tokens
-    Token<BlockTokenIdentifier> mtoken = master.generateToken(block3, EnumSet
+    Token<BlockTokenIdentifier> mtoken = master.generateToken(block3,
-        .allOf(BlockTokenSecretManager.AccessMode.class));
+        EnumSet.allOf(BlockTokenSecretManager.AccessMode.class));
     for (BlockTokenSecretManager.AccessMode mode : BlockTokenSecretManager.AccessMode
         .values()) {
       master.checkAccess(mtoken, null, block3, mode);
@@ -205,22 +209,25 @@ public class TestBlockToken {
 
   private Server createMockDatanode(BlockTokenSecretManager sm,
       Token<BlockTokenIdentifier> token) throws IOException {
-    ClientDatanodeProtocol mockDN = mock(ClientDatanodeProtocol.class);
+    org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol mockDN =
+        mock(org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol.class);
     when(mockDN.getProtocolVersion(anyString(), anyLong())).thenReturn(
-        ClientDatanodeProtocol.versionID);
+        org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol.versionID);
-    doReturn(ProtocolSignature.getProtocolSignature(
+    doReturn(
-        mockDN, ClientDatanodeProtocol.class.getName(),
+        ProtocolSignature.getProtocolSignature(mockDN,
-        ClientDatanodeProtocol.versionID, 0))
+            org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol.class.getName(),
-      .when(mockDN).getProtocolSignature(anyString(), anyLong(), anyInt());
+            org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol.versionID, 0)).when(mockDN)
+        .getProtocolSignature(anyString(), anyLong(), anyInt());
 
     BlockTokenIdentifier id = sm.createIdentifier();
     id.readFields(new DataInputStream(new ByteArrayInputStream(token
         .getIdentifier())));
     doAnswer(new getLengthAnswer(sm, id)).when(mockDN).getReplicaVisibleLength(
-        any(ExtendedBlock.class));
+        any(org.apache.hadoop.hdfs.protocolR23Compatible.ExtendedBlockWritable.class));
 
-    return RPC.getServer(ClientDatanodeProtocol.class, mockDN,
+    return RPC.getServer(org.apache.hadoop.hdfs.protocolR23Compatible.ClientDatanodeWireProtocol.class, 
-        ADDRESS, 0, 5, true, conf, sm);
+        mockDN, ADDRESS, 0, 5,
+        true, conf, sm);
   }
 
   @Test
@@ -241,9 +248,8 @@ public class TestBlockToken {
 
     ClientDatanodeProtocol proxy = null;
     try {
-      proxy = RPC.getProxy(
+      proxy = DFSUtil.createClientDatanodeProtocolProxy(addr, ticket, conf,
-          ClientDatanodeProtocol.class, ClientDatanodeProtocol.versionID, addr,
+          NetUtils.getDefaultSocketFactory(conf));
-          ticket, conf, NetUtils.getDefaultSocketFactory(conf));
       assertEquals(block3.getBlockId(), proxy.getReplicaVisibleLength(block3));
     } finally {
       server.stop();
@@ -255,8 +261,8 @@ public class TestBlockToken {
 
   /**
    * Test that fast repeated invocations of createClientDatanodeProtocolProxy
-   * will not end up using up thousands of sockets. This is a regression test for
+   * will not end up using up thousands of sockets. This is a regression test
-   * HDFS-1965.
+   * for HDFS-1965.
    */
   @Test
   public void testBlockTokenRpcLeak() throws Exception {
@@ -270,8 +276,8 @@ public class TestBlockToken {
     server.start();
 
     final InetSocketAddress addr = NetUtils.getConnectAddress(server);
-    DatanodeID fakeDnId = new DatanodeID(
+    DatanodeID fakeDnId = new DatanodeID("localhost:" + addr.getPort(),
-        "localhost:" + addr.getPort(), "fake-storage", 0, addr.getPort());
+        "fake-storage", 0, addr.getPort());
 
     ExtendedBlock b = new ExtendedBlock("fake-pool", new Block(12345L));
     LocatedBlock fakeBlock = new LocatedBlock(b, new DatanodeInfo[0]);
@@ -284,8 +290,8 @@ public class TestBlockToken {
     ClientDatanodeProtocol proxyToNoWhere = RPC.getProxy(
         ClientDatanodeProtocol.class, ClientDatanodeProtocol.versionID,
         new InetSocketAddress("1.1.1.1", 1),
-        UserGroupInformation.createRemoteUser("junk"),
+        UserGroupInformation.createRemoteUser("junk"), conf,
-        conf, NetUtils.getDefaultSocketFactory(conf));
+        NetUtils.getDefaultSocketFactory(conf));
 
     ClientDatanodeProtocol proxy = null;
 
@@ -293,8 +299,8 @@ public class TestBlockToken {
     try {
       long endTime = System.currentTimeMillis() + 3000;
       while (System.currentTimeMillis() < endTime) {
-        proxy = DFSUtil.createClientDatanodeProtocolProxy(
+        proxy = DFSUtil.createClientDatanodeProtocolProxy(fakeDnId, conf, 1000,
-            fakeDnId, conf, 1000, fakeBlock);
+            fakeBlock);
         assertEquals(block3.getBlockId(), proxy.getReplicaVisibleLength(block3));
         if (proxy != null) {
           RPC.stopProxy(proxy);
@@ -315,8 +321,7 @@ public class TestBlockToken {
   }
 
   /**
-   * @return the current number of file descriptors open by this
+   * @return the current number of file descriptors open by this process.
-   * process.
    */
   private static int countOpenFileDescriptors() throws IOException {
     return FD_DIR.list().length;
@@ -338,7 +343,6 @@ public class TestBlockToken {
           blockKeyUpdateInterval, blockTokenLifetime);
       bpMgr.addBlockPool(bpid, slaveHandler);
 
-      
       ExportedBlockKeys keys = masterHandler.exportKeys();
       bpMgr.setKeys(bpid, keys);
       tokenGenerationAndVerification(masterHandler, bpMgr.get(bpid));
@@ -353,9 +357,10 @@ public class TestBlockToken {
   }
 
   /**
-   * This test writes a file and gets the block locations without closing
+   * This test writes a file and gets the block locations without closing the
-   * the file, and tests the block token in the last block. Block token is
+   * file, and tests the block token in the last block. Block token is verified
-   * verified by ensuring it is of correct kind.
+   * by ensuring it is of correct kind.
+   * 
    * @throws IOException
    * @throws InterruptedException
    */

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestInterDatanodeProtocol.java

@@ -81,7 +81,7 @@ public class TestInterDatanodeProtocol {
     }
 
     @Override
-    public Writable call(Class<?> protocol, Writable param, long receiveTime)
+    public Writable call(String protocol, Writable param, long receiveTime)
         throws IOException {
       if (sleep) {
         // sleep a bit