HDFS-6259. Support extended attributes via WebHDFS. Contributed by Yi Liu.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2006@1596104 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES-HDFS-2006.txt

@@ -38,6 +38,8 @@ HDFS-2006 (Unreleased)
     HDFS-6412. Interface audience and stability annotations missing from
     several new classes related to xattrs. (wang)
 
+    HDFS-6259. Support extended attributes via WebHDFS. (yliu)
+
   OPTIMIZATIONS
 
     HDFS-6346. Optimize OP_SET_XATTRS by persisting single Xattr entry per setXattr/removeXattr api call

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/web/resources/NamenodeWebHdfsMethods.java

@@ -28,6 +28,7 @@ import java.net.URISyntaxException;
 import java.security.PrivilegedExceptionAction;
 import java.util.ArrayList;
 import java.util.EnumSet;
+import java.util.List;
 
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
@@ -53,8 +54,10 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.ContentSummary;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.Options;
+import org.apache.hadoop.fs.XAttr;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.hdfs.StorageType;
+import org.apache.hadoop.hdfs.XAttrHelper;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
@@ -101,6 +104,10 @@ import org.apache.hadoop.hdfs.web.resources.ReplicationParam;
 import org.apache.hadoop.hdfs.web.resources.TokenArgumentParam;
 import org.apache.hadoop.hdfs.web.resources.UriFsPathParam;
 import org.apache.hadoop.hdfs.web.resources.UserParam;
+import org.apache.hadoop.hdfs.web.resources.XAttrEncodingParam;
+import org.apache.hadoop.hdfs.web.resources.XAttrNameParam;
+import org.apache.hadoop.hdfs.web.resources.XAttrSetFlagParam;
+import org.apache.hadoop.hdfs.web.resources.XAttrValueParam;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.ipc.Server;
 import org.apache.hadoop.net.NetworkTopology.InvalidTopologyException;
@@ -341,12 +348,19 @@ public class NamenodeWebHdfsMethods {
       @QueryParam(TokenArgumentParam.NAME) @DefaultValue(TokenArgumentParam.DEFAULT)
           final TokenArgumentParam delegationTokenArgument,
       @QueryParam(AclPermissionParam.NAME) @DefaultValue(AclPermissionParam.DEFAULT) 
-          final AclPermissionParam aclPermission
+          final AclPermissionParam aclPermission,
+      @QueryParam(XAttrNameParam.NAME) @DefaultValue(XAttrNameParam.DEFAULT)
+          final XAttrNameParam xattrName,
+      @QueryParam(XAttrValueParam.NAME) @DefaultValue(XAttrValueParam.DEFAULT)
+          final XAttrValueParam xattrValue,
+      @QueryParam(XAttrSetFlagParam.NAME) @DefaultValue(XAttrSetFlagParam.DEFAULT)
+          final XAttrSetFlagParam xattrSetFlag
           )throws IOException, InterruptedException {
     return put(ugi, delegation, username, doAsUser, ROOT, op, destination,
         owner, group, permission, overwrite, bufferSize, replication,
         blockSize, modificationTime, accessTime, renameOptions, createParent,
-        delegationTokenArgument,aclPermission);
+        delegationTokenArgument,aclPermission, xattrName, xattrValue,
+        xattrSetFlag);
   }
 
   /** Handle HTTP PUT request. */
@@ -392,12 +406,19 @@ public class NamenodeWebHdfsMethods {
       @QueryParam(TokenArgumentParam.NAME) @DefaultValue(TokenArgumentParam.DEFAULT)
           final TokenArgumentParam delegationTokenArgument,
       @QueryParam(AclPermissionParam.NAME) @DefaultValue(AclPermissionParam.DEFAULT) 
-          final AclPermissionParam aclPermission
+          final AclPermissionParam aclPermission,
+      @QueryParam(XAttrNameParam.NAME) @DefaultValue(XAttrNameParam.DEFAULT)
+          final XAttrNameParam xattrName,
+      @QueryParam(XAttrValueParam.NAME) @DefaultValue(XAttrValueParam.DEFAULT)
+          final XAttrValueParam xattrValue,
+      @QueryParam(XAttrSetFlagParam.NAME) @DefaultValue(XAttrSetFlagParam.DEFAULT)
+          final XAttrSetFlagParam xattrSetFlag
       ) throws IOException, InterruptedException {
 
     init(ugi, delegation, username, doAsUser, path, op, destination, owner,
         group, permission, overwrite, bufferSize, replication, blockSize,
-        modificationTime, accessTime, renameOptions, delegationTokenArgument,aclPermission);
+        modificationTime, accessTime, renameOptions, delegationTokenArgument,aclPermission, 
+        xattrName, xattrValue, xattrSetFlag);
 
     return ugi.doAs(new PrivilegedExceptionAction<Response>() {
       @Override
@@ -407,7 +428,8 @@ public class NamenodeWebHdfsMethods {
               path.getAbsolutePath(), op, destination, owner, group,
               permission, overwrite, bufferSize, replication, blockSize,
               modificationTime, accessTime, renameOptions, createParent,
-              delegationTokenArgument,aclPermission);
+              delegationTokenArgument,aclPermission, xattrName, 
+              xattrValue, xattrSetFlag);
         } finally {
           reset();
         }
@@ -435,7 +457,10 @@ public class NamenodeWebHdfsMethods {
       final RenameOptionSetParam renameOptions,
       final CreateParentParam createParent,
       final TokenArgumentParam delegationTokenArgument,
-      final AclPermissionParam aclPermission
+      final AclPermissionParam aclPermission,
+      final XAttrNameParam xattrName,
+      final XAttrValueParam xattrValue,
+      final XAttrSetFlagParam xattrSetFlag
       ) throws IOException, URISyntaxException {
 
     final Configuration conf = (Configuration)context.getAttribute(JspHelper.CURRENT_CONF);
@@ -535,6 +560,15 @@ public class NamenodeWebHdfsMethods {
       np.setAcl(fullpath, aclPermission.getAclPermission(true));
       return Response.ok().type(MediaType.APPLICATION_OCTET_STREAM).build();
     }
+    case SETXATTR: {
+      np.setXAttr(fullpath, XAttrHelper.buildXAttr(xattrName.getXAttrName(), 
+          xattrValue.getXAttrValue()), xattrSetFlag.getFlag());
+      return Response.ok().type(MediaType.APPLICATION_OCTET_STREAM).build();
+    }
+    case REMOVEXATTR: {
+      np.removeXAttr(fullpath, XAttrHelper.buildXAttr(xattrName.getXAttrName()));
+      return Response.ok().type(MediaType.APPLICATION_OCTET_STREAM).build();
+    }
     default:
       throw new UnsupportedOperationException(op + " is not supported");
     }
@@ -650,10 +684,14 @@ public class NamenodeWebHdfsMethods {
       @QueryParam(RenewerParam.NAME) @DefaultValue(RenewerParam.DEFAULT)
           final RenewerParam renewer,
       @QueryParam(BufferSizeParam.NAME) @DefaultValue(BufferSizeParam.DEFAULT)
-          final BufferSizeParam bufferSize
+          final BufferSizeParam bufferSize,
+      @QueryParam(XAttrNameParam.NAME) @DefaultValue(XAttrNameParam.DEFAULT)
+          final XAttrNameParam xattrName,
+      @QueryParam(XAttrEncodingParam.NAME) @DefaultValue(XAttrEncodingParam.DEFAULT)
+          final XAttrEncodingParam xattrEncoding
       ) throws IOException, InterruptedException {
     return get(ugi, delegation, username, doAsUser, ROOT, op,
-        offset, length, renewer, bufferSize);
+        offset, length, renewer, bufferSize, xattrName, xattrEncoding);
   }
 
   /** Handle HTTP GET request. */
@@ -678,18 +716,23 @@ public class NamenodeWebHdfsMethods {
       @QueryParam(RenewerParam.NAME) @DefaultValue(RenewerParam.DEFAULT)
           final RenewerParam renewer,
       @QueryParam(BufferSizeParam.NAME) @DefaultValue(BufferSizeParam.DEFAULT)
-          final BufferSizeParam bufferSize
+          final BufferSizeParam bufferSize,
+      @QueryParam(XAttrNameParam.NAME) @DefaultValue(XAttrNameParam.DEFAULT)
+          final XAttrNameParam xattrName,
+      @QueryParam(XAttrEncodingParam.NAME) @DefaultValue(XAttrEncodingParam.DEFAULT)
+          final XAttrEncodingParam xattrEncoding
       ) throws IOException, InterruptedException {
 
     init(ugi, delegation, username, doAsUser, path, op,
-        offset, length, renewer, bufferSize);
+        offset, length, renewer, bufferSize, xattrName, xattrEncoding);
 
     return ugi.doAs(new PrivilegedExceptionAction<Response>() {
       @Override
       public Response run() throws IOException, URISyntaxException {
         try {
           return get(ugi, delegation, username, doAsUser,
-              path.getAbsolutePath(), op, offset, length, renewer, bufferSize);
+              path.getAbsolutePath(), op, offset, length, renewer, bufferSize,
+              xattrName, xattrEncoding);
         } finally {
           reset();
         }
@@ -707,7 +750,9 @@ public class NamenodeWebHdfsMethods {
       final OffsetParam offset,
       final LengthParam length,
       final RenewerParam renewer,
-      final BufferSizeParam bufferSize
+      final BufferSizeParam bufferSize,
+      final XAttrNameParam xattrName,
+      final XAttrEncodingParam xattrEncoding
       ) throws IOException, URISyntaxException {
     final NameNode namenode = (NameNode)context.getAttribute("name.node");
     final NamenodeProtocols np = getRPCServer(namenode);
@@ -782,6 +827,17 @@ public class NamenodeWebHdfsMethods {
       final String js = JsonUtil.toJsonString(status);
       return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
     }
+    case GETXATTR: {
+      XAttr xAttr = XAttrHelper.getFirstXAttr(np.getXAttrs(fullpath, 
+          XAttrHelper.buildXAttrAsList(xattrName.getXAttrName())));
+      final String js = JsonUtil.toJsonString(xAttr, xattrEncoding.getEncoding());
+      return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
+    }
+    case GETXATTRS: {
+      List<XAttr> xAttrs = np.getXAttrs(fullpath, null);
+      final String js = JsonUtil.toJsonString(xAttrs, xattrEncoding.getEncoding());
+      return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
+    }
     default:
       throw new UnsupportedOperationException(op + " is not supported");
     }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/JsonUtil.java

@@ -22,6 +22,7 @@ import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.hdfs.XAttrHelper;
 import org.apache.hadoop.hdfs.protocol.*;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
@@ -34,6 +35,8 @@ import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.StringUtils;
 import org.mortbay.util.ajax.JSON;
 
+import com.google.common.collect.Maps;
+
 import java.io.ByteArrayInputStream;
 import java.io.DataInputStream;
 import java.io.IOException;
@@ -661,4 +664,125 @@ public class JsonUtil {
     aclStatusBuilder.addEntries(aclEntryList);
     return aclStatusBuilder.build();
   }
+  
+  public static String toJsonString(final XAttr xAttr, 
+      final XAttrCodec encoding) throws IOException {
+    if (xAttr == null) {
+      return "{}";
+    }
+    final Map<String, Object> m = new TreeMap<String, Object>();
+    m.put("name", XAttrHelper.getPrefixName(xAttr));
+    m.put("value", xAttr.getValue() != null ? 
+        XAttrCodec.encodeValue(xAttr.getValue(), encoding) : null);
+    final Map<String, Map<String, Object>> finalMap =
+        new TreeMap<String, Map<String, Object>>();
+    finalMap.put(XAttr.class.getSimpleName(), m);
+    return JSON.toString(finalMap);
+  }
+  
+  private static Map<String, Object> toJsonMap(final XAttr xAttr,
+      final XAttrCodec encoding) throws IOException {
+    if (xAttr == null) {
+      return null;
+    }
+ 
+    final Map<String, Object> m = new TreeMap<String, Object>();
+    m.put("name", XAttrHelper.getPrefixName(xAttr));
+    m.put("value", xAttr.getValue() != null ? 
+        XAttrCodec.encodeValue(xAttr.getValue(), encoding) : null);
+    return m;
+  }
+  
+  private static Object[] toJsonArray(final List<XAttr> array,
+      final XAttrCodec encoding) throws IOException {
+    if (array == null) {
+      return null;
+    } else if (array.size() == 0) {
+      return EMPTY_OBJECT_ARRAY;
+    } else {
+      final Object[] a = new Object[array.size()];
+      for(int i = 0; i < array.size(); i++) {
+        a[i] = toJsonMap(array.get(i), encoding);
+      }
+      return a;
+    }
+  }
+  
+  public static String toJsonString(final List<XAttr> xAttrs, 
+      final XAttrCodec encoding) throws IOException {
+    final Map<String, Object> finalMap = new TreeMap<String, Object>();
+    finalMap.put("XAttrs", toJsonArray(xAttrs, encoding));
+    return JSON.toString(finalMap);
+  }
+  
+  public static XAttr toXAttr(final Map<?, ?> json) throws IOException {
+    if (json == null) {
+      return null;
+    }
+    
+    Map<?, ?> m = (Map<?, ?>) json.get(XAttr.class.getSimpleName());
+    if (m == null) {
+      return null;
+    }
+    String name = (String) m.get("name");
+    String value = (String) m.get("value");
+    return XAttrHelper.buildXAttr(name, decodeXAttrValue(value));
+  }
+  
+  public static Map<String, byte[]> toXAttrs(final Map<?, ?> json) 
+      throws IOException {
+    if (json == null) {
+      return null;
+    }
+    
+    return toXAttrMap((Object[])json.get("XAttrs"));
+  }
+  
+  public static Map<String, byte[]> toXAttrs(final Map<?, ?> json, 
+      List<String> names) throws IOException {
+    if (json == null || names == null) {
+      return null;
+    }
+    if (names.isEmpty()) {
+      return Maps.newHashMap();
+    }
+    Map<String, byte[]> xAttrs = toXAttrs(json);
+    if (xAttrs == null || xAttrs.isEmpty()) {
+      return xAttrs;
+    }
+    
+    Map<String, byte[]> result = Maps.newHashMap();
+    for (String name : names) {
+      if (xAttrs.containsKey(name)) {
+        result.put(name, xAttrs.get(name));
+      }
+    }
+    return result;
+  }
+  
+  private static Map<String, byte[]> toXAttrMap(final Object[] objects) 
+      throws IOException {
+    if (objects == null) {
+      return null;
+    } else if (objects.length == 0) {
+      return Maps.newHashMap();
+    } else {
+      final Map<String, byte[]> xAttrs = Maps.newHashMap();
+      for(int i = 0; i < objects.length; i++) {
+        Map<?, ?> m = (Map<?, ?>) objects[i];
+        String name = (String) m.get("name");
+        String value = (String) m.get("value");
+        xAttrs.put(name, decodeXAttrValue(value));
+      }
+      return xAttrs;
+    }
+  }
+  
+  private static byte[] decodeXAttrValue(String value) throws IOException {
+    if (value != null) {
+      return XAttrCodec.decodeValue(value);
+    } else {
+      return new byte[0];
+    }
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

@@ -30,6 +30,7 @@ import java.net.URI;
 import java.net.URL;
 import java.security.PrivilegedExceptionAction;
 import java.util.ArrayList;
+import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
 import java.util.StringTokenizer;
@@ -49,6 +50,9 @@ import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.MD5MD5CRC32FileChecksum;
 import org.apache.hadoop.fs.Options;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.XAttr;
+import org.apache.hadoop.fs.XAttrCodec;
+import org.apache.hadoop.fs.XAttrSetFlag;
 import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -813,6 +817,66 @@ public class WebHdfsFileSystem extends FileSystem
         new RenameOptionSetParam(options)
     ).run();
   }
+  
+  @Override
+  public void setXAttr(Path p, String name, byte[] value, 
+      EnumSet<XAttrSetFlag> flag) throws IOException {
+    statistics.incrementWriteOps(1);
+    final HttpOpParam.Op op = PutOpParam.Op.SETXATTR;
+    if (value != null) {
+      new FsPathRunner(op, p, new XAttrNameParam(name), new XAttrValueParam(
+          XAttrCodec.encodeValue(value, XAttrCodec.HEX)), 
+          new XAttrSetFlagParam(flag)).run();
+    } else {
+      new FsPathRunner(op, p, new XAttrNameParam(name), 
+          new XAttrSetFlagParam(flag)).run();
+    }
+  }
+  
+  @Override
+  public byte[] getXAttr(Path p, String name) throws IOException {
+    final HttpOpParam.Op op = GetOpParam.Op.GETXATTR;
+    return new FsPathResponseRunner<byte[]>(op, p, new XAttrNameParam(name), 
+        new XAttrEncodingParam(XAttrCodec.HEX)) {
+      @Override
+      byte[] decodeResponse(Map<?, ?> json) throws IOException {
+        XAttr xAttr = JsonUtil.toXAttr(json);
+        return xAttr != null ? xAttr.getValue() : null;
+      }
+    }.run();
+  }
+  
+  @Override
+  public Map<String, byte[]> getXAttrs(Path p) throws IOException {
+    final HttpOpParam.Op op = GetOpParam.Op.GETXATTRS;
+    return new FsPathResponseRunner<Map<String, byte[]>>(op, p, 
+        new XAttrEncodingParam(XAttrCodec.HEX)) {
+      @Override
+      Map<String, byte[]> decodeResponse(Map<?, ?> json) throws IOException {
+        return JsonUtil.toXAttrs(json);
+      }
+    }.run();
+  }
+  
+  @Override
+  public Map<String, byte[]> getXAttrs(Path p, final List<String> names) 
+      throws IOException {
+    final HttpOpParam.Op op = GetOpParam.Op.GETXATTRS;
+    return new FsPathResponseRunner<Map<String, byte[]>>(op, p, 
+        new XAttrEncodingParam(XAttrCodec.HEX)) {
+      @Override
+      Map<String, byte[]> decodeResponse(Map<?, ?> json) throws IOException {
+        return JsonUtil.toXAttrs(json, names);
+      }
+    }.run();
+  }
+  
+  @Override
+  public void removeXAttr(Path p, String name) throws IOException {
+    statistics.incrementWriteOps(1);
+    final HttpOpParam.Op op = PutOpParam.Op.REMOVEXATTR;
+    new FsPathRunner(op, p, new XAttrNameParam(name)).run();
+  }
 
   @Override
   public void setOwner(final Path p, final String owner, final String group

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/GetOpParam.java

@@ -36,6 +36,8 @@ public class GetOpParam extends HttpOpParam<GetOpParam.Op> {
     /** GET_BLOCK_LOCATIONS is a private unstable op. */
     GET_BLOCK_LOCATIONS(false, HttpURLConnection.HTTP_OK),
     GETACLSTATUS(false, HttpURLConnection.HTTP_OK),
+    GETXATTR(false, HttpURLConnection.HTTP_OK),
+    GETXATTRS(false, HttpURLConnection.HTTP_OK),
 
     NULL(false, HttpURLConnection.HTTP_NOT_IMPLEMENTED);
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/PutOpParam.java

@@ -42,6 +42,8 @@ public class PutOpParam extends HttpOpParam<PutOpParam.Op> {
     REMOVEDEFAULTACL(false, HttpURLConnection.HTTP_OK),
     REMOVEACL(false, HttpURLConnection.HTTP_OK),
     SETACL(false, HttpURLConnection.HTTP_OK),
+    SETXATTR(false, HttpURLConnection.HTTP_OK),
+    REMOVEXATTR(false, HttpURLConnection.HTTP_OK),
     
     NULL(false, HttpURLConnection.HTTP_NOT_IMPLEMENTED);
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/XAttrEncodingParam.java

@@ -0,0 +1,56 @@
+/**
+ * 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.web.resources;
+
+import org.apache.hadoop.fs.XAttrCodec;
+
+public class XAttrEncodingParam extends EnumParam<XAttrCodec> {
+  /** Parameter name. */
+  public static final String NAME = "encoding";
+  /** Default parameter value. */
+  public static final String DEFAULT = "";
+  
+  private static final Domain<XAttrCodec> DOMAIN = 
+      new Domain<XAttrCodec>(NAME, XAttrCodec.class);
+  
+  public XAttrEncodingParam(final XAttrCodec encoding) {
+    super(DOMAIN, encoding);
+  }
+  
+  /**
+   * Constructor.
+   * @param str a string representation of the parameter value.
+   */
+  public XAttrEncodingParam(final String str) {
+    super(DOMAIN, str != null && !str.isEmpty() ? DOMAIN.parse(str) : null);
+  }
+
+  @Override
+  public String getName() {
+    return NAME;
+  }
+  
+  @Override
+  public String getValueString() {
+    return value.toString();
+  }
+  
+  public XAttrCodec getEncoding() {
+    return getValue();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/XAttrNameParam.java

@@ -0,0 +1,44 @@
+/**
+ * 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.web.resources;
+
+import java.util.regex.Pattern;
+
+public class XAttrNameParam extends StringParam {
+  /** Parameter name. **/
+  public static final String NAME = "xattr.name";
+  /** Default parameter value. **/
+  public static final String DEFAULT = "";
+  
+  private static Domain DOMAIN = new Domain(NAME, 
+      Pattern.compile("^(user\\.|trusted\\.|system\\.|security\\.).+"));
+  
+  public XAttrNameParam(final String str) {
+    super(DOMAIN, str == null || str.equals(DEFAULT) ? null : str);
+  }
+
+  @Override
+  public String getName() {
+    return NAME;
+  }
+  
+  public String getXAttrName() {
+    final String v = getValue();
+    return v;
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/XAttrSetFlagParam.java

@@ -0,0 +1,53 @@
+/**
+ * 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.web.resources;
+
+import java.util.EnumSet;
+
+import org.apache.hadoop.fs.XAttrSetFlag;
+
+public class XAttrSetFlagParam extends EnumSetParam<XAttrSetFlag> {
+  /** Parameter name. */
+  public static final String NAME = "flag";
+  /** Default parameter value. */
+  public static final String DEFAULT = "";
+
+  private static final Domain<XAttrSetFlag> DOMAIN = new Domain<XAttrSetFlag>(
+      NAME, XAttrSetFlag.class);
+
+  public XAttrSetFlagParam(final EnumSet<XAttrSetFlag> flag) {
+    super(DOMAIN, flag);
+  }
+  
+  /**
+   * Constructor.
+   * @param str a string representation of the parameter value.
+   */
+  public XAttrSetFlagParam(final String str) {
+    super(DOMAIN, DOMAIN.parse(str));
+  }
+
+  @Override
+  public String getName() {
+    return NAME;
+  }
+  
+  public EnumSet<XAttrSetFlag> getFlag() {
+    return getValue();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/XAttrValueParam.java

@@ -0,0 +1,45 @@
+/**
+ * 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.web.resources;
+
+import java.io.IOException;
+
+import org.apache.hadoop.fs.XAttrCodec;
+
+public class XAttrValueParam extends StringParam {
+  /** Parameter name. **/
+  public static final String NAME = "xattr.value";
+  /** Default parameter value. **/
+  public static final String DEFAULT = "";
+  
+  private static Domain DOMAIN = new Domain(NAME, null);
+  
+  public XAttrValueParam(final String str) {
+    super(DOMAIN, str == null || str.equals(DEFAULT) ? null : str);
+  }
+
+  @Override
+  public String getName() {
+    return NAME;
+  }
+  
+  public byte[] getXAttrValue() throws IOException {
+    final String v = getValue();
+    return XAttrCodec.decodeValue(v);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/FSXAttrBaseTest.java

@@ -32,6 +32,7 @@ import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.io.IOUtils;
+import org.apache.hadoop.ipc.RemoteException;
 import org.apache.hadoop.test.GenericTestUtils;
 import org.junit.After;
 import org.junit.AfterClass;
@@ -231,6 +232,8 @@ public class FSXAttrBaseTest {
       Assert.fail("Setting xattr with null name should fail.");
     } catch (NullPointerException e) {
       GenericTestUtils.assertExceptionContains("XAttr name cannot be null", e);
+    } catch (RemoteException e) {
+      GenericTestUtils.assertExceptionContains("XAttr name cannot be null", e);
     }
     
     // Set xattr with empty name: "user."
@@ -240,6 +243,9 @@ public class FSXAttrBaseTest {
       Assert.fail("Setting xattr with empty name should fail.");
     } catch (HadoopIllegalArgumentException e) {
       GenericTestUtils.assertExceptionContains("XAttr name cannot be empty", e);
+    } catch (IllegalArgumentException e) {
+      GenericTestUtils.assertExceptionContains("Invalid value: \"user.\" does " + 
+          "not belong to the domain ^(user\\.|trusted\\.|system\\.|security\\.).+", e);
     }
     
     // Set xattr with invalid name: "a1"
@@ -250,6 +256,9 @@ public class FSXAttrBaseTest {
           "name prefix should fail.");
     } catch (HadoopIllegalArgumentException e) {
       GenericTestUtils.assertExceptionContains("XAttr name must be prefixed", e);
+    } catch (IllegalArgumentException e) {
+      GenericTestUtils.assertExceptionContains("Invalid value: \"a1\" does " + 
+          "not belong to the domain ^(user\\.|trusted\\.|system\\.|security\\.).+", e);
     }
     
     // Set xattr without XAttrSetFlag

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestJsonUtil.java

@@ -22,16 +22,22 @@ import static org.apache.hadoop.fs.permission.AclEntryType.*;
 import static org.apache.hadoop.fs.permission.FsAction.*;
 import static org.apache.hadoop.hdfs.server.namenode.AclTestHelpers.*;
 
+import java.io.IOException;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
 
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.XAttr;
+import org.apache.hadoop.fs.XAttrCodec;
 import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.hdfs.XAttrHelper;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.server.namenode.INodeId;
@@ -186,6 +192,48 @@ public class TestJsonUtil {
         JsonUtil.toJsonString(aclStatusBuilder.build()));
 
   }
+  
+  @Test
+  public void testToJsonFromXAttrs() throws IOException {
+    String jsonString = 
+        "{\"XAttrs\":[{\"name\":\"user.a1\",\"value\":\"0x313233\"}," +
+        "{\"name\":\"user.a2\",\"value\":\"0x313131\"}]}";
+    XAttr xAttr1 = (new XAttr.Builder()).setNameSpace(XAttr.NameSpace.USER).
+        setName("a1").setValue(XAttrCodec.decodeValue("0x313233")).build();
+    XAttr xAttr2 = (new XAttr.Builder()).setNameSpace(XAttr.NameSpace.USER).
+        setName("a2").setValue(XAttrCodec.decodeValue("0x313131")).build();
+    List<XAttr> xAttrs = Lists.newArrayList();
+    xAttrs.add(xAttr1);
+    xAttrs.add(xAttr2);
+    
+    Assert.assertEquals(jsonString, JsonUtil.toJsonString(xAttrs, 
+        XAttrCodec.HEX));
+  }
+  
+  @Test
+  public void testToXAttrMap() throws IOException {
+    String jsonString = 
+        "{\"XAttrs\":[{\"name\":\"user.a1\",\"value\":\"0x313233\"}," +
+        "{\"name\":\"user.a2\",\"value\":\"0x313131\"}]}";
+    Map<?, ?> json = (Map<?, ?>)JSON.parse(jsonString);
+    XAttr xAttr1 = (new XAttr.Builder()).setNameSpace(XAttr.NameSpace.USER).
+        setName("a1").setValue(XAttrCodec.decodeValue("0x313233")).build();
+    XAttr xAttr2 = (new XAttr.Builder()).setNameSpace(XAttr.NameSpace.USER).
+        setName("a2").setValue(XAttrCodec.decodeValue("0x313131")).build();
+    List<XAttr> xAttrs = Lists.newArrayList();
+    xAttrs.add(xAttr1);
+    xAttrs.add(xAttr2);
+    Map<String, byte[]> xAttrMap = XAttrHelper.buildXAttrMap(xAttrs);
+    Map<String, byte[]> parsedXAttrMap = JsonUtil.toXAttrs(json);
+    
+    Assert.assertEquals(xAttrMap.size(), parsedXAttrMap.size());
+    Iterator<Entry<String, byte[]>> iter = xAttrMap.entrySet().iterator();
+    while(iter.hasNext()) {
+      Entry<String, byte[]> entry = iter.next();
+      Assert.assertArrayEquals(entry.getValue(), 
+          parsedXAttrMap.get(entry.getKey()));
+    }
+  }
 
   private void checkDecodeFailure(Map<String, Object> map) {
     try {

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHDFSXAttr.java

@@ -0,0 +1,36 @@
+/**
+ * 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.web;
+
+import org.apache.hadoop.hdfs.server.namenode.FSXAttrBaseTest;
+
+/**
+ * Tests XAttr APIs via WebHDFS.
+ */
+public class TestWebHDFSXAttr extends FSXAttrBaseTest {
+  /**
+   * Overridden to provide a WebHdfsFileSystem wrapper for the super-user.
+   *
+   * @return WebHdfsFileSystem for super-user
+   * @throws Exception if creation fails
+   */
+  @Override
+  protected WebHdfsFileSystem createFileSystem() throws Exception {
+    return WebHdfsTestUtil.getWebHdfsFileSystem(conf, WebHdfsFileSystem.SCHEME);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/resources/TestParam.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.hdfs.web.resources;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 
+import java.io.IOException;
 import java.util.Arrays;
 import java.util.EnumSet;
 import java.util.List;
@@ -30,6 +31,8 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
 import org.apache.hadoop.fs.Options;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.XAttrCodec;
+import org.apache.hadoop.fs.XAttrSetFlag;
 import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
@@ -348,6 +351,43 @@ public class TestParam {
     }
   }
  
+  @Test
+  public void testXAttrNameParam() {
+    final XAttrNameParam p = new XAttrNameParam("user.a1");
+    Assert.assertEquals(p.getXAttrName(), "user.a1");
+    try {
+      new XAttrNameParam("a1");
+      Assert.fail();
+    } catch (IllegalArgumentException e) {
+      LOG.info("EXPECTED: " + e);
+    }
+  }
+  
+  @Test
+  public void testXAttrValueParam() throws IOException {
+    final XAttrValueParam p = new XAttrValueParam("0x313233");
+    Assert.assertArrayEquals(p.getXAttrValue(), 
+        XAttrCodec.decodeValue("0x313233"));
+  }
+  
+  @Test
+  public void testXAttrEncodingParam() {
+    final XAttrEncodingParam p = new XAttrEncodingParam(XAttrCodec.BASE64);
+    Assert.assertEquals(p.getEncoding(), XAttrCodec.BASE64);
+    final XAttrEncodingParam p1 = new XAttrEncodingParam(p.getValueString());
+    Assert.assertEquals(p1.getEncoding(), XAttrCodec.BASE64);
+  }
+  
+  @Test
+  public void testXAttrSetFlagParam() {
+    EnumSet<XAttrSetFlag> flag = EnumSet.of(
+        XAttrSetFlag.CREATE, XAttrSetFlag.REPLACE);
+    final XAttrSetFlagParam p = new XAttrSetFlagParam(flag);
+    Assert.assertEquals(p.getFlag(), flag);
+    final XAttrSetFlagParam p1 = new XAttrSetFlagParam(p.getValueString());
+    Assert.assertEquals(p1.getFlag(), flag);
+  }
+  
   @Test
   public void testRenameOptionSetParam() {
     final RenameOptionSetParam p = new RenameOptionSetParam(