HDFS-9951. Use string constants for XML tags in OfflineImageReconstructor (Lin Yiqun via cmccabe)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/OfflineImageReconstructor.java

@@ -22,6 +22,7 @@ import static org.apache.hadoop.hdfs.server.namenode.FSImageFormatPBINode.XATTR_
 import static org.apache.hadoop.hdfs.server.namenode.FSImageFormatPBINode.XATTR_NAMESPACE_OFFSET;
 import static org.apache.hadoop.hdfs.server.namenode.FSImageFormatPBINode.XATTR_NAMESPACE_EXT_OFFSET;
 import static org.apache.hadoop.hdfs.server.namenode.FSImageFormatPBINode.XATTR_NAMESPACE_EXT_MASK;
+import static org.apache.hadoop.hdfs.tools.offlineImageViewer.PBImageXmlWriter.*;
 
 import java.io.BufferedOutputStream;
 import java.io.File;
@@ -434,36 +435,38 @@ class OfflineImageReconstructor {
       Node node = new Node();
       loadNodeChildren(node, "NameSection fields");
       NameSystemSection.Builder b =  NameSystemSection.newBuilder();
-      Integer namespaceId = node.removeChildInt("namespaceId");
+      Integer namespaceId = node.removeChildInt(NAME_SECTION_NAMESPACE_ID);
       if (namespaceId == null)  {
         throw new IOException("<NameSection> is missing <namespaceId>");
       }
       b.setNamespaceId(namespaceId);
-      Long lval = node.removeChildLong("genstampV1");
+      Long lval = node.removeChildLong(NAME_SECTION_GENSTAMPV1);
       if (lval != null)  {
         b.setGenstampV1(lval);
       }
-      lval = node.removeChildLong("genstampV2");
+      lval = node.removeChildLong(NAME_SECTION_GENSTAMPV2);
       if (lval != null)  {
         b.setGenstampV2(lval);
       }
-      lval = node.removeChildLong("genstampV1Limit");
+      lval = node.removeChildLong(NAME_SECTION_GENSTAMPV1_LIMIT);
       if (lval != null)  {
         b.setGenstampV1Limit(lval);
       }
-      lval = node.removeChildLong("lastAllocatedBlockId");
+      lval = node.removeChildLong(NAME_SECTION_LAST_ALLOCATED_BLOCK_ID);
       if (lval != null)  {
         b.setLastAllocatedBlockId(lval);
       }
-      lval = node.removeChildLong("txid");
+      lval = node.removeChildLong(NAME_SECTION_TXID);
       if (lval != null)  {
         b.setTransactionId(lval);
       }
-      lval = node.removeChildLong("rollingUpgradeStartTime");
+      lval = node.removeChildLong(
+          NAME_SECTION_ROLLING_UPGRADE_START_TIME);
       if (lval != null)  {
         b.setRollingUpgradeStartTime(lval);
       }
-      lval = node.removeChildLong("lastAllocatedStripedBlockId");
+      lval = node.removeChildLong(
+          NAME_SECTION_LAST_ALLOCATED_STRIPED_BLOCK_ID);
       if (lval != null)  {
         b.setLastAllocatedStripedBlockId(lval);
       }
@@ -486,11 +489,12 @@ class OfflineImageReconstructor {
       Node headerNode = new Node();
       loadNodeChildren(headerNode, "INodeSection fields", "inode");
       INodeSection.Builder b =  INodeSection.newBuilder();
-      Long lval = headerNode.removeChildLong("lastInodeId");
+      Long lval = headerNode.removeChildLong(INODE_SECTION_LAST_INODE_ID);
       if (lval != null)  {
         b.setLastInodeId(lval);
       }
-      Integer expectedNumINodes = headerNode.removeChildInt("numInodes");
+      Integer expectedNumINodes =
+          headerNode.removeChildInt(INODE_SECTION_NUM_INODES);
       if (expectedNumINodes == null) {
         throw new IOException("Failed to find <numInodes> in INodeSection.");
       }
@@ -501,7 +505,7 @@ class OfflineImageReconstructor {
       int actualNumINodes = 0;
       while (actualNumINodes < expectedNumINodes) {
         try {
-          expectTag("inode", false);
+          expectTag(INODE_SECTION_INODE, false);
         } catch (IOException e) {
           throw new IOException("Only found " + actualNumINodes +
               " <inode> entries out of " + expectedNumINodes, e);
@@ -512,24 +516,24 @@ class OfflineImageReconstructor {
         INodeSection.INode.Builder inodeBld = processINodeXml(inode);
         inodeBld.build().writeDelimitedTo(out);
       }
-      expectTagEnd("INodeSection");
+      expectTagEnd(INODE_SECTION_NAME);
       recordSectionLength(SectionName.INODE.name());
     }
   }
 
   private INodeSection.INode.Builder processINodeXml(Node node)
       throws IOException {
-    String type = node.removeChildStr("type");
+    String type = node.removeChildStr(INODE_SECTION_TYPE);
     if (type == null) {
       throw new IOException("INode XML found with no <type> tag.");
     }
     INodeSection.INode.Builder inodeBld = INodeSection.INode.newBuilder();
-    Long id = node.removeChildLong("id");
+    Long id = node.removeChildLong(SECTION_ID);
     if (id == null) {
       throw new IOException("<inode> found without <id>");
     }
     inodeBld.setId(id);
-    String name = node.removeChildStr("name");
+    String name = node.removeChildStr(SECTION_NAME);
     if (name != null) {
       inodeBld.setName(ByteString.copyFrom(name, "UTF8"));
     }
@@ -555,46 +559,46 @@ class OfflineImageReconstructor {
       throws IOException {
     inodeBld.setType(INodeSection.INode.Type.FILE);
     INodeSection.INodeFile.Builder bld = INodeSection.INodeFile.newBuilder();
-    Integer ival = node.removeChildInt("replication");
+    Integer ival = node.removeChildInt(SECTION_REPLICATION);
     if (ival != null) {
       bld.setReplication(ival);
     }
-    Long lval = node.removeChildLong("mtime");
+    Long lval = node.removeChildLong(INODE_SECTION_MTIME);
     if (lval != null) {
       bld.setModificationTime(lval);
     }
-    lval = node.removeChildLong("atime");
+    lval = node.removeChildLong(INODE_SECTION_ATIME);
     if (lval != null) {
       bld.setAccessTime(lval);
     }
-    lval = node.removeChildLong("preferredBlockSize");
+    lval = node.removeChildLong(INODE_SECTION_PREFERRED_BLOCK_SIZE);
     if (lval != null) {
       bld.setPreferredBlockSize(lval);
     }
-    String perm = node.removeChildStr("permission");
+    String perm = node.removeChildStr(INODE_SECTION_PERMISSION);
     if (perm != null) {
       bld.setPermission(permissionXmlToU64(perm));
     }
-    Node blocks = node.removeChild("blocks");
+    Node blocks = node.removeChild(INODE_SECTION_BLOCKS);
     if (blocks != null) {
       while (true) {
-        Node block = blocks.removeChild("block");
+        Node block = blocks.removeChild(INODE_SECTION_BLOCK);
         if (block == null) {
           break;
         }
         HdfsProtos.BlockProto.Builder blockBld =
             HdfsProtos.BlockProto.newBuilder();
-        Long id = block.removeChildLong("id");
+        Long id = block.removeChildLong(SECTION_ID);
         if (id == null) {
           throw new IOException("<block> found without <id>");
         }
         blockBld.setBlockId(id);
-        Long genstamp = block.removeChildLong("genstamp");
+        Long genstamp = block.removeChildLong(INODE_SECTION_GEMSTAMP);
         if (genstamp == null) {
           throw new IOException("<block> found without <genstamp>");
         }
         blockBld.setGenStamp(genstamp);
-        Long numBytes = block.removeChildLong("numBytes");
+        Long numBytes = block.removeChildLong(INODE_SECTION_NUM_BYTES);
         if (numBytes == null) {
           throw new IOException("<block> found without <numBytes>");
         }
@@ -602,19 +606,21 @@ class OfflineImageReconstructor {
         bld.addBlocks(blockBld);
       }
     }
-    Node fileUnderConstruction = node.removeChild("file-under-construction");
+    Node fileUnderConstruction =
+        node.removeChild(INODE_SECTION_FILE_UNDER_CONSTRUCTION);
     if (fileUnderConstruction != null) {
       INodeSection.FileUnderConstructionFeature.Builder fb =
           INodeSection.FileUnderConstructionFeature.newBuilder();
       String clientName =
-          fileUnderConstruction.removeChildStr("clientName");
+          fileUnderConstruction.removeChildStr(INODE_SECTION_CLIENT_NAME);
       if (clientName == null) {
         throw new IOException("<file-under-construction> found without " +
             "<clientName>");
       }
       fb.setClientName(clientName);
       String clientMachine =
-          fileUnderConstruction.removeChildStr("clientMachine");
+          fileUnderConstruction
+                  .removeChildStr(INODE_SECTION_CLIENT_MACHINE);
       if (clientMachine == null) {
         throw new IOException("<file-under-construction> found without " +
             "<clientMachine>");
@@ -622,19 +628,19 @@ class OfflineImageReconstructor {
       fb.setClientMachine(clientMachine);
       bld.setFileUC(fb);
     }
-    Node acls = node.removeChild("acls");
+    Node acls = node.removeChild(INODE_SECTION_ACLS);
     if (acls != null) {
       bld.setAcl(aclXmlToProto(acls));
     }
-    Node xattrs = node.removeChild("xattrs");
+    Node xattrs = node.removeChild(INODE_SECTION_XATTRS);
     if (xattrs != null) {
       bld.setXAttrs(xattrsXmlToProto(xattrs));
     }
-    ival = node.removeChildInt("storagePolicyId");
+    ival = node.removeChildInt(INODE_SECTION_STORAGE_POLICY_ID);
     if (ival != null) {
       bld.setStoragePolicyID(ival);
     }
-    Boolean bval = node.removeChildBool("isStriped");
+    Boolean bval = node.removeChildBool(INODE_SECTION_IS_STRIPED);
     bld.setIsStriped(bval);
     inodeBld.setFile(bld);
     // Will check remaining keys and serialize in processINodeXml
@@ -645,40 +651,40 @@ class OfflineImageReconstructor {
     inodeBld.setType(INodeSection.INode.Type.DIRECTORY);
     INodeSection.INodeDirectory.Builder bld =
         INodeSection.INodeDirectory.newBuilder();
-    Long lval = node.removeChildLong("mtime");
+    Long lval = node.removeChildLong(INODE_SECTION_MTIME);
     if (lval != null) {
       bld.setModificationTime(lval);
     }
-    lval = node.removeChildLong("nsquota");
+    lval = node.removeChildLong(INODE_SECTION_NS_QUOTA);
     if (lval != null) {
       bld.setNsQuota(lval);
     }
-    lval = node.removeChildLong("dsquota");
+    lval = node.removeChildLong(INODE_SECTION_DS_QUOTA);
     if (lval != null) {
       bld.setDsQuota(lval);
     }
-    String perm = node.removeChildStr("permission");
+    String perm = node.removeChildStr(INODE_SECTION_PERMISSION);
     if (perm != null) {
       bld.setPermission(permissionXmlToU64(perm));
     }
-    Node acls = node.removeChild("acls");
+    Node acls = node.removeChild(INODE_SECTION_ACLS);
     if (acls != null) {
       bld.setAcl(aclXmlToProto(acls));
     }
-    Node xattrs = node.removeChild("xattrs");
+    Node xattrs = node.removeChild(INODE_SECTION_XATTRS);
     if (xattrs != null) {
       bld.setXAttrs(xattrsXmlToProto(xattrs));
     }
     INodeSection.QuotaByStorageTypeFeatureProto.Builder qf =
         INodeSection.QuotaByStorageTypeFeatureProto.newBuilder();
     while (true) {
-      Node typeQuota = node.removeChild("typeQuota");
+      Node typeQuota = node.removeChild(INODE_SECTION_TYPE_QUOTA);
       if (typeQuota == null) {
         break;
       }
       INodeSection.QuotaByStorageTypeEntryProto.Builder qbld =
           INodeSection.QuotaByStorageTypeEntryProto.newBuilder();
-      String type = typeQuota.removeChildStr("type");
+      String type = typeQuota.removeChildStr(INODE_SECTION_TYPE);
       if (type == null) {
         throw new IOException("<typeQuota> was missing <type>");
       }
@@ -688,7 +694,7 @@ class OfflineImageReconstructor {
         throw new IOException("<typeQuota> had unknown <type> " + type);
       }
       qbld.setStorageType(storageType);
-      Long quota = typeQuota.removeChildLong("quota");
+      Long quota = typeQuota.removeChildLong(INODE_SECTION_QUOTA);
       if (quota == null) {
         throw new IOException("<typeQuota> was missing <quota>");
       }
@@ -705,19 +711,19 @@ class OfflineImageReconstructor {
     inodeBld.setType(INodeSection.INode.Type.SYMLINK);
     INodeSection.INodeSymlink.Builder bld =
         INodeSection.INodeSymlink.newBuilder();
-    String perm = node.removeChildStr("permission");
+    String perm = node.removeChildStr(INODE_SECTION_PERMISSION);
     if (perm != null) {
       bld.setPermission(permissionXmlToU64(perm));
     }
-    String target = node.removeChildStr("target");
+    String target = node.removeChildStr(INODE_SECTION_TARGET);
     if (target != null) {
       bld.setTarget(ByteString.copyFrom(target, "UTF8"));
     }
-    Long lval = node.removeChildLong("mtime");
+    Long lval = node.removeChildLong(INODE_SECTION_MTIME);
     if (lval != null) {
       bld.setModificationTime(lval);
     }
-    lval = node.removeChildLong("atime");
+    lval = node.removeChildLong(INODE_SECTION_ATIME);
     if (lval != null) {
       bld.setAccessTime(lval);
     }
@@ -736,23 +742,23 @@ class OfflineImageReconstructor {
     INodeSection.XAttrFeatureProto.Builder bld =
         INodeSection.XAttrFeatureProto.newBuilder();
     while (true) {
-      Node xattr = xattrs.removeChild("xattr");
+      Node xattr = xattrs.removeChild(INODE_SECTION_XATTR);
       if (xattr == null) {
         break;
       }
       INodeSection.XAttrCompactProto.Builder b =
           INodeSection.XAttrCompactProto.newBuilder();
-      String ns = xattr.removeChildStr("ns");
+      String ns = xattr.removeChildStr(INODE_SECTION_NS);
       if (ns == null) {
         throw new IOException("<xattr> had no <ns> entry.");
       }
       int nsIdx = XAttrProtos.XAttrProto.
           XAttrNamespaceProto.valueOf(ns).ordinal();
-      String name = xattr.removeChildStr("name");
-      String valStr = xattr.removeChildStr("val");
+      String name = xattr.removeChildStr(SECTION_NAME);
+      String valStr = xattr.removeChildStr(INODE_SECTION_VAL);
       byte[] val = null;
       if (valStr == null) {
-        String valHex = xattr.removeChildStr("valHex");
+        String valHex = xattr.removeChildStr(INODE_SECTION_VAL_HEX);
         if (valHex == null) {
           throw new IOException("<xattr> had no <val> or <valHex> entry.");
         }
@@ -787,24 +793,28 @@ class OfflineImageReconstructor {
       loadNodeChildren(secretHeader, "SecretManager fields",
           "delegationKey", "token");
       SecretManagerSection.Builder b =  SecretManagerSection.newBuilder();
-      Integer currentId = secretHeader.removeChildInt("currentId");
+      Integer currentId =
+          secretHeader.removeChildInt(SECRET_MANAGER_SECTION_CURRENT_ID);
       if (currentId == null) {
         throw new IOException("SecretManager section had no <currentId>");
       }
       b.setCurrentId(currentId);
-      Integer tokenSequenceNumber = secretHeader.removeChildInt("tokenSequenceNumber");
+      Integer tokenSequenceNumber = secretHeader.removeChildInt(
+          SECRET_MANAGER_SECTION_TOKEN_SEQUENCE_NUMBER);
       if (tokenSequenceNumber == null) {
         throw new IOException("SecretManager section had no " +
             "<tokenSequenceNumber>");
       }
       b.setTokenSequenceNumber(tokenSequenceNumber);
-      Integer expectedNumKeys = secretHeader.removeChildInt("numDelegationKeys");
+      Integer expectedNumKeys = secretHeader.removeChildInt(
+          SECRET_MANAGER_SECTION_NUM_DELEGATION_KEYS);
       if (expectedNumKeys == null) {
         throw new IOException("SecretManager section had no " +
             "<numDelegationKeys>");
       }
       b.setNumKeys(expectedNumKeys);
-      Integer expectedNumTokens = secretHeader.removeChildInt("numTokens");
+      Integer expectedNumTokens =
+          secretHeader.removeChildInt(SECRET_MANAGER_SECTION_NUM_TOKENS);
       if (expectedNumTokens == null) {
         throw new IOException("SecretManager section had no " +
             "<numTokens>");
@@ -815,7 +825,7 @@ class OfflineImageReconstructor {
       for (int actualNumKeys = 0; actualNumKeys < expectedNumKeys;
            actualNumKeys++) {
         try {
-          expectTag("delegationKey", false);
+          expectTag(SECRET_MANAGER_SECTION_DELEGATION_KEY, false);
         } catch (IOException e) {
           throw new IOException("Only read " + actualNumKeys +
               " delegation keys out of " + expectedNumKeys, e);
@@ -824,32 +834,32 @@ class OfflineImageReconstructor {
             SecretManagerSection.DelegationKey.newBuilder();
         Node dkey = new Node();
         loadNodeChildren(dkey, "Delegation key fields");
-        Integer id = dkey.removeChildInt("id");
+        Integer id = dkey.removeChildInt(SECTION_ID);
         if (id == null) {
           throw new IOException("Delegation key stanza <delegationKey> " +
               "lacked an <id> field.");
         }
         dbld.setId(id);
-        String expiry = dkey.removeChildStr("expiry");
+        String expiry = dkey.removeChildStr(SECRET_MANAGER_SECTION_EXPIRY);
         if (expiry == null) {
           throw new IOException("Delegation key stanza <delegationKey> " +
               "lacked an <expiry> field.");
         }
         dbld.setExpiryDate(dateStrToLong(expiry));
-        String keyHex = dkey.removeChildStr("key");
+        String keyHex = dkey.removeChildStr(SECRET_MANAGER_SECTION_KEY);
         if (keyHex == null) {
           throw new IOException("Delegation key stanza <delegationKey> " +
               "lacked a <key> field.");
         }
         byte[] key = new HexBinaryAdapter().unmarshal(keyHex);
-        dkey.verifyNoRemainingKeys("delegationKey");
+        dkey.verifyNoRemainingKeys(SECRET_MANAGER_SECTION_DELEGATION_KEY);
         dbld.setKey(ByteString.copyFrom(key));
         dbld.build().writeDelimitedTo(out);
       }
       for (int actualNumTokens = 0; actualNumTokens < expectedNumTokens;
            actualNumTokens++) {
         try {
-          expectTag("token", false);
+          expectTag(SECRET_MANAGER_SECTION_TOKEN, false);
         } catch (IOException e) {
           throw new IOException("Only read " + actualNumTokens +
               " tokens out of " + expectedNumTokens, e);
@@ -858,46 +868,54 @@ class OfflineImageReconstructor {
             SecretManagerSection.PersistToken.newBuilder();
         Node token = new Node();
         loadNodeChildren(token, "PersistToken key fields");
-        Integer version = token.removeChildInt("version");
+        Integer version =
+            token.removeChildInt(SECRET_MANAGER_SECTION_VERSION);
         if (version != null) {
           tbld.setVersion(version);
         }
-        String owner = token.removeChildStr("owner");
+        String owner = token.removeChildStr(SECRET_MANAGER_SECTION_OWNER);
         if (owner != null) {
           tbld.setOwner(owner);
         }
-        String renewer = token.removeChildStr("renewer");
+        String renewer =
+            token.removeChildStr(SECRET_MANAGER_SECTION_RENEWER);
         if (renewer != null) {
           tbld.setRenewer(renewer);
         }
-        String realUser = token.removeChildStr("realUser");
+        String realUser =
+            token.removeChildStr(SECRET_MANAGER_SECTION_REAL_USER);
         if (realUser != null) {
           tbld.setRealUser(realUser);
         }
-        String issueDateStr = token.removeChildStr("issueDate");
+        String issueDateStr =
+            token.removeChildStr(SECRET_MANAGER_SECTION_ISSUE_DATE);
         if (issueDateStr != null) {
           tbld.setIssueDate(dateStrToLong(issueDateStr));
         }
-        String maxDateStr = token.removeChildStr("maxDate");
+        String maxDateStr =
+            token.removeChildStr(SECRET_MANAGER_SECTION_MAX_DATE);
         if (maxDateStr != null) {
           tbld.setMaxDate(dateStrToLong(maxDateStr));
         }
-        Integer seqNo = token.removeChildInt("sequenceNumber");
+        Integer seqNo =
+            token.removeChildInt(SECRET_MANAGER_SECTION_SEQUENCE_NUMBER);
         if (seqNo != null) {
           tbld.setSequenceNumber(seqNo);
         }
-        Integer masterKeyId = token.removeChildInt("masterKeyId");
+        Integer masterKeyId =
+            token.removeChildInt(SECRET_MANAGER_SECTION_MASTER_KEY_ID);
         if (masterKeyId != null) {
           tbld.setMasterKeyId(masterKeyId);
         }
-        String expiryDateStr = token.removeChildStr("expiryDate");
+        String expiryDateStr =
+            token.removeChildStr(SECRET_MANAGER_SECTION_EXPIRY_DATE);
         if (expiryDateStr != null) {
           tbld.setExpiryDate(dateStrToLong(expiryDateStr));
         }
         token.verifyNoRemainingKeys("token");
         tbld.build().writeDelimitedTo(out);
       }
-      expectTagEnd("SecretManagerSection");
+      expectTagEnd(SECRET_MANAGER_SECTION_NAME);
       recordSectionLength(SectionName.SECRET_MANAGER.name());
     }
 
@@ -919,17 +937,20 @@ class OfflineImageReconstructor {
       Node node = new Node();
       loadNodeChildren(node, "CacheManager fields", "pool", "directive");
       CacheManagerSection.Builder b =  CacheManagerSection.newBuilder();
-      Long nextDirectiveId = node.removeChildLong("nextDirectiveId");
+      Long nextDirectiveId =
+          node.removeChildLong(CACHE_MANAGER_SECTION_NEXT_DIRECTIVE_ID);
       if (nextDirectiveId == null) {
         throw new IOException("CacheManager section had no <nextDirectiveId>");
       }
       b.setNextDirectiveId(nextDirectiveId);
-      Integer expectedNumPools = node.removeChildInt("numPools");
+      Integer expectedNumPools =
+          node.removeChildInt(CACHE_MANAGER_SECTION_NUM_POOLS);
       if (expectedNumPools == null) {
         throw new IOException("CacheManager section had no <numPools>");
       }
       b.setNumPools(expectedNumPools);
-      Integer expectedNumDirectives = node.removeChildInt("numDirectives");
+      Integer expectedNumDirectives =
+          node.removeChildInt(CACHE_MANAGER_SECTION_NUM_DIRECTIVES);
       if (expectedNumDirectives == null) {
         throw new IOException("CacheManager section had no <numDirectives>");
       }
@@ -938,7 +959,7 @@ class OfflineImageReconstructor {
       long actualNumPools = 0;
       while (actualNumPools < expectedNumPools) {
         try {
-          expectTag("pool", false);
+          expectTag(CACHE_MANAGER_SECTION_POOL, false);
         } catch (IOException e) {
           throw new IOException("Only read " + actualNumPools +
               " cache pools out of " + expectedNumPools, e);
@@ -951,7 +972,7 @@ class OfflineImageReconstructor {
       long actualNumDirectives = 0;
       while (actualNumDirectives < expectedNumDirectives) {
         try {
-          expectTag("directive", false);
+          expectTag(CACHE_MANAGER_SECTION_DIRECTIVE, false);
         } catch (IOException e) {
           throw new IOException("Only read " + actualNumDirectives +
               " cache pools out of " + expectedNumDirectives, e);
@@ -961,38 +982,42 @@ class OfflineImageReconstructor {
         loadNodeChildren(pool, "directive fields", "");
         processDirectiveXml(node);
       }
-      expectTagEnd("CacheManagerSection");
+      expectTagEnd(CACHE_MANAGER_SECTION_NAME);
       recordSectionLength(SectionName.CACHE_MANAGER.name());
     }
 
     private void processPoolXml(Node pool) throws IOException {
       CachePoolInfoProto.Builder bld = CachePoolInfoProto.newBuilder();
-      String poolName = pool.removeChildStr("poolName");
+      String poolName =
+          pool.removeChildStr(CACHE_MANAGER_SECTION_POOL_NAME);
       if (poolName == null) {
         throw new IOException("<pool> found without <poolName>");
       }
       bld.setPoolName(poolName);
-      String ownerName = pool.removeChildStr("ownerName");
+      String ownerName =
+          pool.removeChildStr(CACHE_MANAGER_SECTION_OWNER_NAME);
       if (ownerName == null) {
         throw new IOException("<pool> found without <ownerName>");
       }
       bld.setOwnerName(ownerName);
-      String groupName = pool.removeChildStr("groupName");
+      String groupName =
+          pool.removeChildStr(CACHE_MANAGER_SECTION_GROUP_NAME);
       if (groupName == null) {
         throw new IOException("<pool> found without <groupName>");
       }
       bld.setGroupName(groupName);
-      Integer mode = pool.removeChildInt("mode");
+      Integer mode = pool.removeChildInt(CACHE_MANAGER_SECTION_MODE);
       if (mode == null) {
         throw new IOException("<pool> found without <mode>");
       }
       bld.setMode(mode);
-      Long limit = pool.removeChildLong("limit");
+      Long limit = pool.removeChildLong(CACHE_MANAGER_SECTION_LIMIT);
       if (limit == null) {
         throw new IOException("<pool> found without <limit>");
       }
       bld.setLimit(limit);
-      Long maxRelativeExpiry = pool.removeChildLong("maxRelativeExpiry");
+      Long maxRelativeExpiry =
+          pool.removeChildLong(CACHE_MANAGER_SECTION_MAX_RELATIVE_EXPIRY);
       if (maxRelativeExpiry == null) {
         throw new IOException("<pool> found without <maxRelativeExpiry>");
       }
@@ -1004,37 +1029,39 @@ class OfflineImageReconstructor {
     private void processDirectiveXml(Node directive) throws IOException {
       CacheDirectiveInfoProto.Builder bld =
           CacheDirectiveInfoProto.newBuilder();
-      Long id = directive.removeChildLong("id");
+      Long id = directive.removeChildLong(SECTION_ID);
       if (id == null) {
         throw new IOException("<directive> found without <id>");
       }
       bld.setId(id);
-      String path = directive.removeChildStr("path");
+      String path = directive.removeChildStr(SECTION_PATH);
       if (path == null) {
         throw new IOException("<directive> found without <path>");
       }
       bld.setPath(path);
-      Integer replication = directive.removeChildInt("replication");
+      Integer replication = directive.removeChildInt(SECTION_REPLICATION);
       if (replication == null) {
         throw new IOException("<directive> found without <replication>");
       }
       bld.setReplication(replication);
-      String pool = directive.removeChildStr("pool");
+      String pool = directive.removeChildStr(CACHE_MANAGER_SECTION_POOL);
       if (path == null) {
         throw new IOException("<directive> found without <pool>");
       }
       bld.setPool(pool);
-      Node expiration = directive.removeChild("expiration");
+      Node expiration =
+          directive.removeChild(CACHE_MANAGER_SECTION_EXPIRATION);
       if (expiration != null) {
         CacheDirectiveInfoExpirationProto.Builder ebld =
             CacheDirectiveInfoExpirationProto.newBuilder();
-        Long millis = expiration.removeChildLong("millis");
+        Long millis =
+            expiration.removeChildLong(CACHE_MANAGER_SECTION_MILLIS);
         if (millis == null) {
           throw new IOException("cache directive <expiration> found " +
               "without <millis>");
         }
         ebld.setMillis(millis);
-        if (expiration.removeChildBool("relative")) {
+        if (expiration.removeChildBool(CACHE_MANAGER_SECTION_RELATIVE)) {
           ebld.setIsRelative(true);
         } else {
           ebld.setIsRelative(false);
@@ -1054,7 +1081,7 @@ class OfflineImageReconstructor {
       // There is no header for this section.
       // We process the repeated <ref> elements.
       while (true) {
-        XMLEvent ev = expectTag("ref", true);
+        XMLEvent ev = expectTag(INODE_REFERENCE_SECTION_REF, true);
         if (ev.isEndElement()) {
           break;
         }
@@ -1062,7 +1089,8 @@ class OfflineImageReconstructor {
         FsImageProto.INodeReferenceSection.INodeReference.Builder bld =
             FsImageProto.INodeReferenceSection.INodeReference.newBuilder();
         loadNodeChildren(inodeRef, "INodeReference");
-        Long referredId = inodeRef.removeChildLong("referredId");
+        Long referredId =
+            inodeRef.removeChildLong(INODE_REFERENCE_SECTION_REFERRED_ID);
         if (referredId != null) {
           bld.setReferredId(referredId);
         }
@@ -1070,11 +1098,13 @@ class OfflineImageReconstructor {
         if (name != null) {
           bld.setName(ByteString.copyFrom(name, "UTF8"));
         }
-        Integer dstSnapshotId = inodeRef.removeChildInt("dstSnapshotId");
+        Integer dstSnapshotId = inodeRef.removeChildInt(
+            INODE_REFERENCE_SECTION_DST_SNAPSHOT_ID);
         if (dstSnapshotId != null) {
           bld.setDstSnapshotId(dstSnapshotId);
         }
-        Integer lastSnapshotId = inodeRef.removeChildInt("lastSnapshotId");
+        Integer lastSnapshotId = inodeRef.removeChildInt(
+            INODE_REFERENCE_SECTION_LAST_SNAPSHOT_ID);
         if (lastSnapshotId != null) {
           bld.setLastSnapshotId(lastSnapshotId);
         }
@@ -1093,7 +1123,7 @@ class OfflineImageReconstructor {
       // No header for this section
       // Process the repeated <directory> elements.
       while (true) {
-        XMLEvent ev = expectTag("directory", true);
+        XMLEvent ev = expectTag(INODE_DIRECTORY_SECTION_DIRECTORY, true);
         if (ev.isEndElement()) {
           break;
         }
@@ -1101,19 +1131,22 @@ class OfflineImageReconstructor {
         FsImageProto.INodeDirectorySection.DirEntry.Builder bld =
             FsImageProto.INodeDirectorySection.DirEntry.newBuilder();
         loadNodeChildren(directory, "directory");
-        Long parent = directory.removeChildLong("parent");
+        Long parent = directory.removeChildLong(
+            INODE_DIRECTORY_SECTION_PARENT);
         if (parent != null) {
           bld.setParent(parent);
         }
         while (true) {
-          Node child = directory.removeChild("child");
+          Node child = directory.removeChild(
+              INODE_DIRECTORY_SECTION_CHILD);
           if (child == null) {
             break;
           }
           bld.addChildren(Long.parseLong(child.getVal()));
         }
         while (true) {
-          Node refChild = directory.removeChild("refChild");
+          Node refChild = directory.removeChild(
+              INODE_DIRECTORY_SECTION_REF_CHILD);
           if (refChild == null) {
             break;
           }
@@ -1135,7 +1168,7 @@ class OfflineImageReconstructor {
       // No header for this section type.
       // Process the repeated files under construction elements.
       while (true) {
-        XMLEvent ev = expectTag("inode", true);
+        XMLEvent ev = expectTag(INODE_SECTION_INODE, true);
         if (ev.isEndElement()) {
           break;
         }
@@ -1143,11 +1176,12 @@ class OfflineImageReconstructor {
         loadNodeChildren(fileUnderConstruction, "file under construction");
         FileUnderConstructionEntry.Builder bld =
             FileUnderConstructionEntry.newBuilder();
-        Long id = fileUnderConstruction.removeChildLong("id");
+        Long id = fileUnderConstruction.removeChildLong(SECTION_ID);
         if (id != null) {
           bld.setInodeId(id);
         }
-        String fullpath = fileUnderConstruction.removeChildStr("path");
+        String fullpath =
+            fileUnderConstruction.removeChildStr(SECTION_PATH);
         if (fullpath != null) {
           bld.setFullPath(fullpath);
         }
@@ -1167,24 +1201,26 @@ class OfflineImageReconstructor {
           FsImageProto.SnapshotSection.newBuilder();
       Node header = new Node();
       loadNodeChildren(header, "SnapshotSection fields", "snapshot");
-      Integer snapshotCounter = header.removeChildInt("snapshotCounter");
+      Integer snapshotCounter = header.removeChildInt(
+          SNAPSHOT_SECTION_SNAPSHOT_COUNTER);
       if (snapshotCounter == null) {
         throw new IOException("No <snapshotCounter> entry found in " +
             "SnapshotSection header");
       }
       bld.setSnapshotCounter(snapshotCounter);
-      Integer expectedNumSnapshots = header.removeChildInt("numSnapshots");
+      Integer expectedNumSnapshots = header.removeChildInt(
+          SNAPSHOT_SECTION_NUM_SNAPSHOTS);
       if (expectedNumSnapshots == null) {
         throw new IOException("No <numSnapshots> entry found in " +
             "SnapshotSection header");
       }
       bld.setNumSnapshots(expectedNumSnapshots);
       while (true) {
-        Node sd = header.removeChild("snapshottableDir");
+        Node sd = header.removeChild(SNAPSHOT_SECTION_SNAPSHOT_TABLE_DIR);
         if (sd == null) {
           break;
         }
-        Long dir = sd.removeChildLong("dir");
+        Long dir = sd.removeChildLong(SNAPSHOT_SECTION_DIR);
         sd.verifyNoRemainingKeys("<dir>");
         bld.addSnapshottableDir(dir);
       }
@@ -1193,7 +1229,7 @@ class OfflineImageReconstructor {
       int actualNumSnapshots = 0;
       while (actualNumSnapshots < expectedNumSnapshots) {
         try {
-          expectTag("snapshot", false);
+          expectTag(SNAPSHOT_SECTION_SNAPSHOT, false);
         } catch (IOException e) {
           throw new IOException("Only read " + actualNumSnapshots +
               " <snapshot> entries out of " + expectedNumSnapshots, e);
@@ -1203,17 +1239,17 @@ class OfflineImageReconstructor {
         loadNodeChildren(snapshot, "snapshot fields");
         FsImageProto.SnapshotSection.Snapshot.Builder s =
             FsImageProto.SnapshotSection.Snapshot.newBuilder();
-        Integer snapshotId = snapshot.removeChildInt("id");
+        Integer snapshotId = snapshot.removeChildInt(SECTION_ID);
         if (snapshotId == null) {
           throw new IOException("<snapshot> section was missing <id>");
         }
         s.setSnapshotId(snapshotId);
-        Node snapshotRoot = snapshot.removeChild("root");
+        Node snapshotRoot = snapshot.removeChild(SNAPSHOT_SECTION_ROOT);
         INodeSection.INode.Builder inodeBld = processINodeXml(snapshotRoot);
         s.setRoot(inodeBld);
         s.build().writeDelimitedTo(out);
       }
-      expectTagEnd("SnapshotSection");
+      expectTagEnd(SNAPSHOT_SECTION_NAME);
       recordSectionLength(SectionName.SNAPSHOT.name());
     }
   }
@@ -1229,15 +1265,15 @@ class OfflineImageReconstructor {
         XMLEvent ev = expectTag("[diff start tag]", true);
         if (ev.isEndElement()) {
           String name = ev.asEndElement().getName().getLocalPart();
-          if (name.equals("SnapshotDiffSection")) {
+          if (name.equals(SNAPSHOT_DIFF_SECTION_NAME)) {
             break;
           }
           throw new IOException("Got unexpected end tag for " + name);
         }
         String tagName = ev.asStartElement().getName().getLocalPart();
-        if (tagName.equals("dirDiffEntry")) {
+        if (tagName.equals(SNAPSHOT_DIFF_SECTION_DIR_DIFF_ENTRY)) {
           processDirDiffEntry();
-        } else if (tagName.equals("fileDiffEntry")) {
+        } else if (tagName.equals(SNAPSHOT_DIFF_SECTION_FILE_DIFF_ENTRY)) {
           processFileDiffEntry();
         } else {
           throw new IOException("SnapshotDiffSection contained unexpected " +
@@ -1253,12 +1289,14 @@ class OfflineImageReconstructor {
       headerBld.setType(DiffEntry.Type.DIRECTORYDIFF);
       Node dirDiffHeader = new Node();
       loadNodeChildren(dirDiffHeader, "dirDiffEntry fields", "dirDiff");
-      Long inodeId = dirDiffHeader.removeChildLong("inodeId");
+      Long inodeId = dirDiffHeader.removeChildLong(
+          SNAPSHOT_DIFF_SECTION_INODE_ID);
       if (inodeId == null) {
         throw new IOException("<dirDiffEntry> contained no <inodeId> entry.");
       }
       headerBld.setInodeId(inodeId);
-      Integer expectedDiffs = dirDiffHeader.removeChildInt("count");
+      Integer expectedDiffs = dirDiffHeader.removeChildInt(
+          SNAPSHOT_DIFF_SECTION_COUNT);
       if (expectedDiffs == null) {
         throw new IOException("<dirDiffEntry> contained no <count> entry.");
       }
@@ -1267,7 +1305,7 @@ class OfflineImageReconstructor {
       headerBld.build().writeDelimitedTo(out);
       for (int actualDiffs = 0; actualDiffs < expectedDiffs; actualDiffs++) {
         try {
-          expectTag("dirDiff", false);
+          expectTag(SNAPSHOT_DIFF_SECTION_DIR_DIFF, false);
         } catch (IOException e) {
           throw new IOException("Only read " + (actualDiffs + 1) +
               " diffs out of " + expectedDiffs, e);
@@ -1276,38 +1314,43 @@ class OfflineImageReconstructor {
         loadNodeChildren(dirDiff, "dirDiff fields");
         FsImageProto.SnapshotDiffSection.DirectoryDiff.Builder bld =
             FsImageProto.SnapshotDiffSection.DirectoryDiff.newBuilder();
-        Integer snapshotId = dirDiff.removeChildInt("snapshotId");
+        Integer snapshotId = dirDiff.removeChildInt(
+            SNAPSHOT_DIFF_SECTION_SNAPSHOT_ID);
         if (snapshotId != null) {
           bld.setSnapshotId(snapshotId);
         }
-        Integer childrenSize = dirDiff.removeChildInt("childrenSize");
+        Integer childrenSize = dirDiff.removeChildInt(
+            SNAPSHOT_DIFF_SECTION_CHILDREN_SIZE);
         if (childrenSize == null) {
           throw new IOException("Expected to find <childrenSize> in " +
               "<dirDiff> section.");
         }
-        bld.setIsSnapshotRoot(dirDiff.removeChildBool("isSnapshotRoot"));
+        bld.setIsSnapshotRoot(dirDiff.removeChildBool(
+            SNAPSHOT_DIFF_SECTION_IS_SNAPSHOT_ROOT));
         bld.setChildrenSize(childrenSize);
-        String name = dirDiff.removeChildStr("name");
+        String name = dirDiff.removeChildStr(SECTION_NAME);
         if (name != null) {
           bld.setName(ByteString.copyFrom(name, "UTF8"));
         }
         // TODO: add missing snapshotCopy field to XML
-        Integer expectedCreatedListSize =
-            dirDiff.removeChildInt("createdListSize");
+        Integer expectedCreatedListSize = dirDiff.removeChildInt(
+            SNAPSHOT_DIFF_SECTION_CREATED_LIST_SIZE);
         if (expectedCreatedListSize == null) {
           throw new IOException("Expected to find <createdListSize> in " +
               "<dirDiff> section.");
         }
         bld.setCreatedListSize(expectedCreatedListSize);
         while (true) {
-          Node deleted = dirDiff.removeChild("deletedInode");
+          Node deleted = dirDiff.removeChild(
+              SNAPSHOT_DIFF_SECTION_DELETED_INODE);
           if (deleted == null){
             break;
           }
           bld.addDeletedINode(Long.parseLong(deleted.getVal()));
         }
         while (true) {
-          Node deleted = dirDiff.removeChild("deletedInoderef");
+          Node deleted = dirDiff.removeChild(
+              SNAPSHOT_DIFF_SECTION_DELETED_INODE_REF);
           if (deleted == null){
             break;
           }
@@ -1317,11 +1360,12 @@ class OfflineImageReconstructor {
         // After the DirectoryDiff header comes a list of CreatedListEntry PBs.
         int actualCreatedListSize = 0;
         while (true) {
-          Node created = dirDiff.removeChild("created");
+          Node created = dirDiff.removeChild(
+              SNAPSHOT_DIFF_SECTION_CREATED);
           if (created == null){
             break;
           }
-          String cleName = created.removeChildStr("name");
+          String cleName = created.removeChildStr(SECTION_NAME);
           if (cleName == null) {
             throw new IOException("Expected <created> entry to have " +
                 "a <name> field");
@@ -1339,7 +1383,7 @@ class OfflineImageReconstructor {
         }
         dirDiff.verifyNoRemainingKeys("dirDiff");
       }
-      expectTagEnd("dirDiffEntry");
+      expectTagEnd(SNAPSHOT_DIFF_SECTION_DIR_DIFF_ENTRY);
     }
 
     private void processFileDiffEntry() throws IOException {
@@ -1348,12 +1392,14 @@ class OfflineImageReconstructor {
       headerBld.setType(DiffEntry.Type.FILEDIFF);
       Node fileDiffHeader = new Node();
       loadNodeChildren(fileDiffHeader, "fileDiffEntry fields", "fileDiff");
-      Long inodeId = fileDiffHeader.removeChildLong("inodeid");
+      Long inodeId = fileDiffHeader.removeChildLong(
+          SNAPSHOT_DIFF_SECTION_INODE_ID);
       if (inodeId == null) {
         throw new IOException("<fileDiffEntry> contained no <inodeid> entry.");
       }
       headerBld.setInodeId(inodeId);
-      Integer expectedDiffs = fileDiffHeader.removeChildInt("count");
+      Integer expectedDiffs = fileDiffHeader.removeChildInt(
+          SNAPSHOT_DIFF_SECTION_COUNT);
       if (expectedDiffs == null) {
         throw new IOException("<fileDiffEntry> contained no <count> entry.");
       }
@@ -1362,7 +1408,7 @@ class OfflineImageReconstructor {
       headerBld.build().writeDelimitedTo(out);
       for (int actualDiffs = 0; actualDiffs < expectedDiffs; actualDiffs++) {
         try {
-          expectTag("fileDiff", false);
+          expectTag(SNAPSHOT_DIFF_SECTION_FILE_DIFF, false);
         } catch (IOException e) {
           throw new IOException("Only read " + (actualDiffs + 1) +
               " diffs out of " + expectedDiffs, e);
@@ -1371,15 +1417,17 @@ class OfflineImageReconstructor {
         loadNodeChildren(fileDiff, "fileDiff fields");
         FsImageProto.SnapshotDiffSection.FileDiff.Builder bld =
             FsImageProto.SnapshotDiffSection.FileDiff.newBuilder();
-        Integer snapshotId = fileDiff.removeChildInt("snapshotId");
+        Integer snapshotId = fileDiff.removeChildInt(
+            SNAPSHOT_DIFF_SECTION_SNAPSHOT_ID);
         if (snapshotId != null) {
           bld.setSnapshotId(snapshotId);
         }
-        Long size = fileDiff.removeChildLong("size");
+        Long size = fileDiff.removeChildLong(
+            SNAPSHOT_DIFF_SECTION_SIZE);
         if (size != null) {
           bld.setFileSize(size);
         }
-        String name = fileDiff.removeChildStr("name");
+        String name = fileDiff.removeChildStr(SECTION_NAME);
         if (name != null) {
           bld.setName(ByteString.copyFrom(name, "UTF8"));
         }
@@ -1388,7 +1436,7 @@ class OfflineImageReconstructor {
         fileDiff.verifyNoRemainingKeys("fileDiff");
         bld.build().writeDelimitedTo(out);
       }
-      expectTagEnd("fileDiffEntry");
+      expectTagEnd(SNAPSHOT_DIFF_SECTION_FILE_DIFF_ENTRY);
     }
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/PBImageXmlWriter.java

@@ -77,6 +77,154 @@ import static org.apache.hadoop.hdfs.server.namenode.FSImageFormatPBINode.XATTR_
  */
 @InterfaceAudience.Private
 public final class PBImageXmlWriter {
+  public static final String NAME_SECTION_NAME = "NameSection";
+  public static final String INODE_SECTION_NAME = "INodeSection";
+  public static final String SECRET_MANAGER_SECTION_NAME =
+      "SecretManagerSection";
+  public static final String CACHE_MANAGER_SECTION_NAME = "CacheManagerSection";
+  public static final String SNAPSHOT_DIFF_SECTION_NAME = "SnapshotDiffSection";
+  public static final String INODE_REFERENCE_SECTION_NAME =
+      "INodeReferenceSection";
+  public static final String INODE_DIRECTORY_SECTION_NAME =
+      "INodeDirectorySection";
+  public static final String FILE_UNDER_CONSTRUCTION_SECTION_NAME =
+      "FileUnderConstructionSection";
+  public static final String SNAPSHOT_SECTION_NAME = "SnapshotSection";
+
+  public static final String SECTION_ID = "id";
+  public static final String SECTION_REPLICATION = "replication";
+  public static final String SECTION_PATH = "path";
+  public static final String SECTION_NAME = "name";
+
+  public static final String NAME_SECTION_NAMESPACE_ID = "namespaceId";
+  public static final String NAME_SECTION_GENSTAMPV1 = "genstampV1";
+  public static final String NAME_SECTION_GENSTAMPV2 = "genstampV2";
+  public static final String NAME_SECTION_GENSTAMPV1_LIMIT = "genstampV1Limit";
+  public static final String NAME_SECTION_LAST_ALLOCATED_BLOCK_ID =
+      "lastAllocatedBlockId";
+  public static final String NAME_SECTION_TXID = "txid";
+  public static final String NAME_SECTION_ROLLING_UPGRADE_START_TIME =
+      "rollingUpgradeStartTime";
+  public static final String NAME_SECTION_LAST_ALLOCATED_STRIPED_BLOCK_ID =
+      "lastAllocatedStripedBlockId";
+
+  public static final String INODE_SECTION_LAST_INODE_ID = "lastInodeId";
+  public static final String INODE_SECTION_NUM_INODES = "numInodes";
+  public static final String INODE_SECTION_TYPE = "type";
+  public static final String INODE_SECTION_MTIME = "mtime";
+  public static final String INODE_SECTION_ATIME = "atime";
+  public static final String INODE_SECTION_PREFERRED_BLOCK_SIZE =
+      "preferredBlockSize";
+  public static final String INODE_SECTION_PERMISSION = "permission";
+  public static final String INODE_SECTION_BLOCKS = "blocks";
+  public static final String INODE_SECTION_BLOCK = "block";
+  public static final String INODE_SECTION_GEMSTAMP = "genstamp";
+  public static final String INODE_SECTION_NUM_BYTES = "numBytes";
+  public static final String INODE_SECTION_FILE_UNDER_CONSTRUCTION =
+      "file-under-construction";
+  public static final String INODE_SECTION_CLIENT_NAME = "clientName";
+  public static final String INODE_SECTION_CLIENT_MACHINE = "clientMachine";
+  public static final String INODE_SECTION_ACL = "acl";
+  public static final String INODE_SECTION_ACLS = "acls";
+  public static final String INODE_SECTION_XATTR = "xattr";
+  public static final String INODE_SECTION_XATTRS = "xattrs";
+  public static final String INODE_SECTION_STORAGE_POLICY_ID =
+      "storagePolicyId";
+  public static final String INODE_SECTION_IS_STRIPED = "isStriped";
+  public static final String INODE_SECTION_NS_QUOTA = "nsquota";
+  public static final String INODE_SECTION_DS_QUOTA = "dsquota";
+  public static final String INODE_SECTION_TYPE_QUOTA = "typeQuota";
+  public static final String INODE_SECTION_QUOTA = "quota";
+  public static final String INODE_SECTION_TARGET = "target";
+  public static final String INODE_SECTION_NS = "ns";
+  public static final String INODE_SECTION_VAL = "val";
+  public static final String INODE_SECTION_VAL_HEX = "valHex";
+  public static final String INODE_SECTION_INODE = "inode";
+
+  public static final String SECRET_MANAGER_SECTION_CURRENT_ID = "currentId";
+  public static final String SECRET_MANAGER_SECTION_TOKEN_SEQUENCE_NUMBER =
+      "tokenSequenceNumber";
+  public static final String SECRET_MANAGER_SECTION_NUM_DELEGATION_KEYS =
+      "numDelegationKeys";
+  public static final String SECRET_MANAGER_SECTION_NUM_TOKENS = "numTokens";
+  public static final String SECRET_MANAGER_SECTION_EXPIRY = "expiry";
+  public static final String SECRET_MANAGER_SECTION_KEY = "key";
+  public static final String SECRET_MANAGER_SECTION_DELEGATION_KEY =
+      "delegationKey";
+  public static final String SECRET_MANAGER_SECTION_VERSION = "version";
+  public static final String SECRET_MANAGER_SECTION_OWNER = "owner";
+  public static final String SECRET_MANAGER_SECTION_RENEWER = "renewer";
+  public static final String SECRET_MANAGER_SECTION_REAL_USER = "realUser";
+  public static final String SECRET_MANAGER_SECTION_ISSUE_DATE = "issueDate";
+  public static final String SECRET_MANAGER_SECTION_MAX_DATE = "maxDate";
+  public static final String SECRET_MANAGER_SECTION_SEQUENCE_NUMBER =
+      "sequenceNumber";
+  public static final String SECRET_MANAGER_SECTION_MASTER_KEY_ID =
+      "masterKeyId";
+  public static final String SECRET_MANAGER_SECTION_EXPIRY_DATE = "expiryDate";
+  public static final String SECRET_MANAGER_SECTION_TOKEN = "token";
+
+  public static final String CACHE_MANAGER_SECTION_NEXT_DIRECTIVE_ID =
+      "nextDirectiveId";
+  public static final String CACHE_MANAGER_SECTION_NUM_POOLS = "numPools";
+  public static final String CACHE_MANAGER_SECTION_NUM_DIRECTIVES =
+      "numDirectives";
+  public static final String CACHE_MANAGER_SECTION_POOL_NAME = "poolName";
+  public static final String CACHE_MANAGER_SECTION_OWNER_NAME = "ownerName";
+  public static final String CACHE_MANAGER_SECTION_GROUP_NAME = "groupName";
+  public static final String CACHE_MANAGER_SECTION_MODE = "mode";
+  public static final String CACHE_MANAGER_SECTION_LIMIT = "limit";
+  public static final String CACHE_MANAGER_SECTION_MAX_RELATIVE_EXPIRY =
+      "maxRelativeExpiry";
+  public static final String CACHE_MANAGER_SECTION_POOL = "pool";
+  public static final String CACHE_MANAGER_SECTION_EXPIRATION = "expiration";
+  public static final String CACHE_MANAGER_SECTION_MILLIS = "millis";
+  public static final String CACHE_MANAGER_SECTION_RELATIVE = "relative";
+  public static final String CACHE_MANAGER_SECTION_DIRECTIVE = "directive";
+
+  public static final String SNAPSHOT_DIFF_SECTION_INODE_ID = "inodeId";
+  public static final String SNAPSHOT_DIFF_SECTION_COUNT = "count";
+  public static final String SNAPSHOT_DIFF_SECTION_SNAPSHOT_ID = "snapshotId";
+  public static final String SNAPSHOT_DIFF_SECTION_CHILDREN_SIZE =
+      "childrenSize";
+  public static final String SNAPSHOT_DIFF_SECTION_IS_SNAPSHOT_ROOT =
+      "isSnapshotRoot";
+  public static final String SNAPSHOT_DIFF_SECTION_CREATED_LIST_SIZE =
+      "createdListSize";
+  public static final String SNAPSHOT_DIFF_SECTION_DELETED_INODE =
+      "deletedInode";
+  public static final String SNAPSHOT_DIFF_SECTION_DELETED_INODE_REF =
+      "deletedInoderef";
+  public static final String SNAPSHOT_DIFF_SECTION_CREATED = "created";
+  public static final String SNAPSHOT_DIFF_SECTION_SIZE = "size";
+  public static final String SNAPSHOT_DIFF_SECTION_FILE_DIFF_ENTRY =
+      "fileDiffEntry";
+  public static final String SNAPSHOT_DIFF_SECTION_DIR_DIFF_ENTRY =
+      "dirDiffEntry";
+  public static final String SNAPSHOT_DIFF_SECTION_FILE_DIFF = "fileDiff";
+  public static final String SNAPSHOT_DIFF_SECTION_DIR_DIFF = "dirDiff";
+
+  public static final String INODE_REFERENCE_SECTION_REFERRED_ID = "referredId";
+  public static final String INODE_REFERENCE_SECTION_DST_SNAPSHOT_ID =
+      "dstSnapshotId";
+  public static final String INODE_REFERENCE_SECTION_LAST_SNAPSHOT_ID =
+      "lastSnapshotId";
+  public static final String INODE_REFERENCE_SECTION_REF = "ref";
+
+  public static final String INODE_DIRECTORY_SECTION_PARENT = "parent";
+  public static final String INODE_DIRECTORY_SECTION_CHILD = "child";
+  public static final String INODE_DIRECTORY_SECTION_REF_CHILD = "refChild";
+  public static final String INODE_DIRECTORY_SECTION_DIRECTORY = "directory";
+
+  public static final String SNAPSHOT_SECTION_SNAPSHOT_COUNTER =
+      "snapshotCounter";
+  public static final String SNAPSHOT_SECTION_NUM_SNAPSHOTS = "numSnapshots";
+  public static final String SNAPSHOT_SECTION_SNAPSHOT_TABLE_DIR =
+      "snapshottableDir";
+  public static final String SNAPSHOT_SECTION_DIR = "dir";
+  public static final String SNAPSHOT_SECTION_ROOT = "root";
+  public static final String SNAPSHOT_SECTION_SNAPSHOT = "snapshot";
+
   private final Configuration conf;
   private final PrintStream out;
   private final SimpleDateFormat isoDateFormat;
@@ -177,98 +325,106 @@ public final class PBImageXmlWriter {
   }
 
   private void dumpCacheManagerSection(InputStream is) throws IOException {
-    out.print("<CacheManagerSection>");
+    out.print("<" + CACHE_MANAGER_SECTION_NAME + ">");
     CacheManagerSection s = CacheManagerSection.parseDelimitedFrom(is);
-    o("nextDirectiveId", s.getNextDirectiveId());
-    o("numDirectives", s.getNumDirectives());
-    o("numPools", s.getNumPools());
+    o(CACHE_MANAGER_SECTION_NEXT_DIRECTIVE_ID, s.getNextDirectiveId());
+    o(CACHE_MANAGER_SECTION_NUM_DIRECTIVES, s.getNumDirectives());
+    o(CACHE_MANAGER_SECTION_NUM_POOLS, s.getNumPools());
     for (int i = 0; i < s.getNumPools(); ++i) {
       CachePoolInfoProto p = CachePoolInfoProto.parseDelimitedFrom(is);
-      out.print("<pool>");
-      o("poolName", p.getPoolName()).o("ownerName", p.getOwnerName())
-          .o("groupName", p.getGroupName()).o("mode", p.getMode())
-          .o("limit", p.getLimit())
-          .o("maxRelativeExpiry", p.getMaxRelativeExpiry());
-      out.print("</pool>\n");
+      out.print("<" + CACHE_MANAGER_SECTION_POOL +">");
+      o(CACHE_MANAGER_SECTION_POOL_NAME, p.getPoolName()).
+          o(CACHE_MANAGER_SECTION_OWNER_NAME, p.getOwnerName())
+          .o(CACHE_MANAGER_SECTION_GROUP_NAME, p.getGroupName())
+          .o(CACHE_MANAGER_SECTION_MODE, p.getMode())
+          .o(CACHE_MANAGER_SECTION_LIMIT, p.getLimit())
+          .o(CACHE_MANAGER_SECTION_MAX_RELATIVE_EXPIRY,
+              p.getMaxRelativeExpiry());
+      out.print("</" + CACHE_MANAGER_SECTION_POOL + ">\n");
     }
     for (int i = 0; i < s.getNumDirectives(); ++i) {
       CacheDirectiveInfoProto p = CacheDirectiveInfoProto
           .parseDelimitedFrom(is);
-      out.print("<directive>");
-      o("id", p.getId()).o("path", p.getPath())
-          .o("replication", p.getReplication()).o("pool", p.getPool());
-      out.print("<expiration>");
+      out.print("<" + CACHE_MANAGER_SECTION_DIRECTIVE + ">");
+      o(SECTION_ID, p.getId()).o(SECTION_PATH, p.getPath())
+          .o(SECTION_REPLICATION, p.getReplication())
+          .o(CACHE_MANAGER_SECTION_POOL, p.getPool());
+      out.print("<" + CACHE_MANAGER_SECTION_EXPIRATION +">");
       CacheDirectiveInfoExpirationProto e = p.getExpiration();
-      o("millis", e.getMillis()).o("relative", e.getIsRelative());
-      out.print("</expiration>\n");
-      out.print("</directive>\n");
+      o(CACHE_MANAGER_SECTION_MILLIS, e.getMillis())
+          .o(CACHE_MANAGER_SECTION_RELATIVE, e.getIsRelative());
+      out.print("</" + CACHE_MANAGER_SECTION_EXPIRATION+ ">\n");
+      out.print("</" + CACHE_MANAGER_SECTION_DIRECTIVE + ">\n");
     }
-    out.print("</CacheManagerSection>\n");
+    out.print("</" + CACHE_MANAGER_SECTION_NAME + ">\n");
 
   }
 
   private void dumpFileUnderConstructionSection(InputStream in)
       throws IOException {
-    out.print("<FileUnderConstructionSection>");
+    out.print("<" + FILE_UNDER_CONSTRUCTION_SECTION_NAME + ">");
     while (true) {
       FileUnderConstructionEntry e = FileUnderConstructionEntry
           .parseDelimitedFrom(in);
       if (e == null) {
         break;
       }
-      out.print("<inode>");
-      o("id", e.getInodeId()).o("path", e.getFullPath());
-      out.print("</inode>\n");
+      out.print("<" + INODE_SECTION_INODE + ">");
+      o(SECTION_ID, e.getInodeId())
+          .o(SECTION_PATH, e.getFullPath());
+      out.print("</" + INODE_SECTION_INODE + ">\n");
     }
-    out.print("</FileUnderConstructionSection>\n");
+    out.print("</" + FILE_UNDER_CONSTRUCTION_SECTION_NAME + ">\n");
   }
 
   private void dumpXattrs(INodeSection.XAttrFeatureProto xattrs) {
-    out.print("<xattrs>");
+    out.print("<" + INODE_SECTION_XATTRS + ">");
     for (INodeSection.XAttrCompactProto xattr : xattrs.getXAttrsList()) {
-      out.print("<xattr>");
+      out.print("<" + INODE_SECTION_XATTR + ">");
       int encodedName = xattr.getName();
       int ns = (XATTR_NAMESPACE_MASK & (encodedName >> XATTR_NAMESPACE_OFFSET)) |
           ((XATTR_NAMESPACE_EXT_MASK & (encodedName >> XATTR_NAMESPACE_EXT_OFFSET)) << 2);
-      o("ns", XAttrProtos.XAttrProto.
+      o(INODE_SECTION_NS, XAttrProtos.XAttrProto.
           XAttrNamespaceProto.valueOf(ns).toString());
-      o("name", stringTable[XATTR_NAME_MASK & (encodedName >> XATTR_NAME_OFFSET)]);
+      o(SECTION_NAME,
+          stringTable[XATTR_NAME_MASK & (encodedName >> XATTR_NAME_OFFSET)]);
       ByteString val = xattr.getValue();
       if (val.isValidUtf8()) {
-        o("val", val.toStringUtf8());
+        o(INODE_SECTION_VAL, val.toStringUtf8());
       } else {
-        o("valHex", Hex.encodeHexString(val.toByteArray()));
+        o(INODE_SECTION_VAL_HEX, Hex.encodeHexString(val.toByteArray()));
       }
-      out.print("</xattr>");
+      out.print("</" + INODE_SECTION_XATTR + ">");
     }
-    out.print("</xattrs>");
+    out.print("</" + INODE_SECTION_XATTRS + ">");
   }
 
   private void dumpINodeDirectory(INodeDirectory d) {
-    o("mtime", d.getModificationTime()).o("permission",
-        dumpPermission(d.getPermission()));
+    o(INODE_SECTION_MTIME, d.getModificationTime())
+        .o(INODE_SECTION_PERMISSION, dumpPermission(d.getPermission()));
     if (d.hasXAttrs()) {
       dumpXattrs(d.getXAttrs());
     }
     dumpAcls(d.getAcl());
     if (d.hasDsQuota() && d.hasNsQuota()) {
-      o("nsquota", d.getNsQuota()).o("dsquota", d.getDsQuota());
+      o(INODE_SECTION_NS_QUOTA, d.getNsQuota())
+        .o(INODE_SECTION_DS_QUOTA, d.getDsQuota());
     }
     INodeSection.QuotaByStorageTypeFeatureProto typeQuotas =
       d.getTypeQuotas();
     if (typeQuotas != null) {
       for (INodeSection.QuotaByStorageTypeEntryProto entry:
             typeQuotas.getQuotasList()) {
-        out.print("<typeQuota>");
-        o("type", entry.getStorageType().toString());
-        o("quota", entry.getQuota());
-        out.print("</typeQuota>");
+        out.print("<" + INODE_SECTION_TYPE_QUOTA + ">");
+        o(INODE_SECTION_TYPE, entry.getStorageType().toString());
+        o(INODE_SECTION_QUOTA, entry.getQuota());
+        out.print("</" + INODE_SECTION_TYPE_QUOTA + ">");
       }
     }
   }
 
   private void dumpINodeDirectorySection(InputStream in) throws IOException {
-    out.print("<INodeDirectorySection>");
+    out.print("<" + INODE_DIRECTORY_SECTION_NAME + ">");
     while (true) {
       INodeDirectorySection.DirEntry e = INodeDirectorySection.DirEntry
           .parseDelimitedFrom(in);
@@ -276,21 +432,21 @@ public final class PBImageXmlWriter {
       if (e == null) {
         break;
       }
-      out.print("<directory>");
-      o("parent", e.getParent());
+      out.print("<" + INODE_DIRECTORY_SECTION_DIRECTORY + ">");
+      o(INODE_DIRECTORY_SECTION_PARENT, e.getParent());
       for (long id : e.getChildrenList()) {
-        o("child", id);
+        o(INODE_DIRECTORY_SECTION_CHILD, id);
       }
       for (int refId : e.getRefChildrenList()) {
-        o("refChild", refId);
+        o(INODE_DIRECTORY_SECTION_REF_CHILD, refId);
       }
-      out.print("</directory>\n");
+      out.print("</" + INODE_DIRECTORY_SECTION_DIRECTORY + ">\n");
     }
-    out.print("</INodeDirectorySection>\n");
+    out.print("</" + INODE_DIRECTORY_SECTION_NAME + ">\n");
   }
 
   private void dumpINodeReferenceSection(InputStream in) throws IOException {
-    out.print("<INodeReferenceSection>");
+    out.print("<" + INODE_REFERENCE_SECTION_NAME + ">");
     while (true) {
       INodeReferenceSection.INodeReference e = INodeReferenceSection
           .INodeReference.parseDelimitedFrom(in);
@@ -299,49 +455,53 @@ public final class PBImageXmlWriter {
       }
       dumpINodeReference(e);
     }
-    out.print("</INodeReferenceSection>");
+    out.print("</" + INODE_REFERENCE_SECTION_NAME + ">");
   }
 
   private void dumpINodeReference(INodeReferenceSection.INodeReference r) {
-    out.print("<ref>");
-    o("referredId", r.getReferredId()).o("name", r.getName().toStringUtf8())
-        .o("dstSnapshotId", r.getDstSnapshotId())
-        .o("lastSnapshotId", r.getLastSnapshotId());
-    out.print("</ref>\n");
+    out.print("<" + INODE_REFERENCE_SECTION_REF + ">");
+    o(INODE_REFERENCE_SECTION_REFERRED_ID, r.getReferredId())
+        .o(SECTION_NAME, r.getName().toStringUtf8())
+            .o(INODE_REFERENCE_SECTION_DST_SNAPSHOT_ID, r.getDstSnapshotId())
+            .o(INODE_REFERENCE_SECTION_LAST_SNAPSHOT_ID,
+            r.getLastSnapshotId());
+    out.print("</" + INODE_REFERENCE_SECTION_REF + ">\n");
   }
 
   private void dumpINodeFile(INodeSection.INodeFile f) {
-    o("replication", f.getReplication()).o("mtime", f.getModificationTime())
-        .o("atime", f.getAccessTime())
-        .o("preferredBlockSize", f.getPreferredBlockSize())
-        .o("permission", dumpPermission(f.getPermission()));
+    o(SECTION_REPLICATION, f.getReplication())
+        .o(INODE_SECTION_MTIME, f.getModificationTime())
+        .o(INODE_SECTION_ATIME, f.getAccessTime())
+        .o(INODE_SECTION_PREFERRED_BLOCK_SIZE, f.getPreferredBlockSize())
+        .o(INODE_SECTION_PERMISSION, dumpPermission(f.getPermission()));
     if (f.hasXAttrs()) {
       dumpXattrs(f.getXAttrs());
     }
     dumpAcls(f.getAcl());
     if (f.getBlocksCount() > 0) {
-      out.print("<blocks>");
+      out.print("<" + INODE_SECTION_BLOCKS + ">");
       for (BlockProto b : f.getBlocksList()) {
-        out.print("<block>");
-        o("id", b.getBlockId()).o("genstamp", b.getGenStamp()).o("numBytes",
-            b.getNumBytes());
-        out.print("</block>\n");
+        out.print("<" + INODE_SECTION_BLOCK + ">");
+        o(SECTION_ID, b.getBlockId())
+            .o(INODE_SECTION_GEMSTAMP, b.getGenStamp())
+            .o(INODE_SECTION_NUM_BYTES, b.getNumBytes());
+        out.print("</" + INODE_SECTION_BLOCK + ">\n");
       }
-      out.print("</blocks>\n");
+      out.print("</" + INODE_SECTION_BLOCKS + ">\n");
     }
     if (f.hasStoragePolicyID()) {
-      o("storagePolicyId", f.getStoragePolicyID());
+      o(INODE_SECTION_STORAGE_POLICY_ID, f.getStoragePolicyID());
     }
     if (f.getIsStriped()) {
-      out.print("<isStriped/>");
+      out.print("<" + INODE_SECTION_IS_STRIPED + "/>");
     }
 
     if (f.hasFileUC()) {
       INodeSection.FileUnderConstructionFeature u = f.getFileUC();
-      out.print("<file-under-construction>");
-      o("clientName", u.getClientName()).o("clientMachine",
-          u.getClientMachine());
-      out.print("</file-under-construction>\n");
+      out.print("<" + INODE_SECTION_FILE_UNDER_CONSTRUCTION + ">");
+      o(INODE_SECTION_CLIENT_NAME, u.getClientName())
+          .o(INODE_SECTION_CLIENT_MACHINE, u.getClientMachine());
+      out.print("</" + INODE_SECTION_FILE_UNDER_CONSTRUCTION + ">\n");
     }
   }
 
@@ -349,31 +509,31 @@ public final class PBImageXmlWriter {
     ImmutableList<AclEntry> aclEntryList = FSImageFormatPBINode.Loader
         .loadAclEntries(aclFeatureProto, stringTable);
     if (aclEntryList.size() > 0) {
-      out.print("<acls>");
+      out.print("<" + INODE_SECTION_ACLS + ">");
       for (AclEntry aclEntry : aclEntryList) {
-        o("acl", aclEntry.toString());
+        o(INODE_SECTION_ACL, aclEntry.toString());
       }
-      out.print("</acls>");
+      out.print("</" + INODE_SECTION_ACLS + ">");
     }
   }
 
   private void dumpINodeSection(InputStream in) throws IOException {
     INodeSection s = INodeSection.parseDelimitedFrom(in);
-    out.print("<INodeSection>");
-    o("lastInodeId", s.getLastInodeId());
-    o("numInodes", s.getNumInodes());
+    out.print("<" + INODE_SECTION_NAME + ">");
+    o(INODE_SECTION_LAST_INODE_ID, s.getLastInodeId());
+    o(INODE_SECTION_NUM_INODES, s.getNumInodes());
     for (int i = 0; i < s.getNumInodes(); ++i) {
       INodeSection.INode p = INodeSection.INode.parseDelimitedFrom(in);
-      out.print("<inode>");
+      out.print("<" + INODE_SECTION_INODE + ">");
       dumpINodeFields(p);
-      out.print("</inode>\n");
+      out.print("</" + INODE_SECTION_INODE + ">\n");
     }
-    out.print("</INodeSection>\n");
+    out.print("</" + INODE_SECTION_NAME + ">\n");
   }
 
   private void dumpINodeFields(INodeSection.INode p) {
-    o("id", p.getId()).o("type", p.getType()).o("name",
-        p.getName().toStringUtf8());
+    o(SECTION_ID, p.getId()).o(INODE_SECTION_TYPE, p.getType())
+            .o(SECTION_NAME, p.getName().toStringUtf8());
     if (p.hasFile()) {
       dumpINodeFile(p.getFile());
     } else if (p.hasDirectory()) {
@@ -384,20 +544,23 @@ public final class PBImageXmlWriter {
   }
 
   private void dumpINodeSymlink(INodeSymlink s) {
-    o("permission", dumpPermission(s.getPermission()))
-        .o("target", s.getTarget().toStringUtf8())
-        .o("mtime", s.getModificationTime()).o("atime", s.getAccessTime());
+    o(INODE_SECTION_PERMISSION, dumpPermission(s.getPermission()))
+        .o(INODE_SECTION_TARGET, s.getTarget().toStringUtf8())
+        .o(INODE_SECTION_MTIME, s.getModificationTime())
+        .o(INODE_SECTION_ATIME, s.getAccessTime());
   }
 
   private void dumpNameSection(InputStream in) throws IOException {
     NameSystemSection s = NameSystemSection.parseDelimitedFrom(in);
-    out.print("<NameSection>");
-    o("namespaceId", s.getNamespaceId());
-    o("genstampV1", s.getGenstampV1()).o("genstampV2", s.getGenstampV2())
-        .o("genstampV1Limit", s.getGenstampV1Limit())
-        .o("lastAllocatedBlockId", s.getLastAllocatedBlockId())
-        .o("txid", s.getTransactionId());
-    out.print("</NameSection>\n");
+    out.print("<" + NAME_SECTION_NAME + ">");
+    o(NAME_SECTION_NAMESPACE_ID, s.getNamespaceId());
+    o(NAME_SECTION_GENSTAMPV1, s.getGenstampV1())
+        .o(NAME_SECTION_GENSTAMPV2, s.getGenstampV2())
+        .o(NAME_SECTION_GENSTAMPV1_LIMIT, s.getGenstampV1Limit())
+        .o(NAME_SECTION_LAST_ALLOCATED_BLOCK_ID,
+            s.getLastAllocatedBlockId())
+        .o(NAME_SECTION_TXID, s.getTransactionId());
+    out.print("</" + NAME_SECTION_NAME + ">\n");
   }
 
   private String dumpPermission(long permission) {
@@ -408,59 +571,63 @@ public final class PBImageXmlWriter {
   }
 
   private void dumpSecretManagerSection(InputStream is) throws IOException {
-    out.print("<SecretManagerSection>");
+    out.print("<" + SECRET_MANAGER_SECTION_NAME + ">");
     SecretManagerSection s = SecretManagerSection.parseDelimitedFrom(is);
     int expectedNumDelegationKeys = s.getNumKeys();
     int expectedNumTokens = s.getNumTokens();
-    o("currentId", s.getCurrentId()).o("tokenSequenceNumber",
-        s.getTokenSequenceNumber()).
-        o("numDelegationKeys", expectedNumDelegationKeys).
-        o("numTokens", expectedNumTokens);
+    o(SECRET_MANAGER_SECTION_CURRENT_ID, s.getCurrentId())
+        .o(SECRET_MANAGER_SECTION_TOKEN_SEQUENCE_NUMBER,
+            s.getTokenSequenceNumber()).
+        o(SECRET_MANAGER_SECTION_NUM_DELEGATION_KEYS,
+            expectedNumDelegationKeys).
+        o(SECRET_MANAGER_SECTION_NUM_TOKENS, expectedNumTokens);
     for (int i = 0; i < expectedNumDelegationKeys; i++) {
       SecretManagerSection.DelegationKey dkey =
           SecretManagerSection.DelegationKey.parseDelimitedFrom(is);
-      out.print("<delegationKey>");
-      o("id", dkey.getId());
-      o("key", Hex.encodeHexString(dkey.getKey().toByteArray()));
+      out.print("<" + SECRET_MANAGER_SECTION_DELEGATION_KEY + ">");
+      o(SECTION_ID, dkey.getId());
+      o(SECRET_MANAGER_SECTION_KEY,
+          Hex.encodeHexString(dkey.getKey().toByteArray()));
       if (dkey.hasExpiryDate()) {
-        dumpDate("expiry", dkey.getExpiryDate());
+        dumpDate(SECRET_MANAGER_SECTION_EXPIRY, dkey.getExpiryDate());
       }
-      out.print("</delegationKey>");
+      out.print("</" + SECRET_MANAGER_SECTION_DELEGATION_KEY + ">");
     }
     for (int i = 0; i < expectedNumTokens; i++) {
       SecretManagerSection.PersistToken token =
           SecretManagerSection.PersistToken.parseDelimitedFrom(is);
-      out.print("<token>");
+      out.print("<" + SECRET_MANAGER_SECTION_TOKEN + ">");
       if (token.hasVersion()) {
-        o("version", token.getVersion());
+        o(SECRET_MANAGER_SECTION_VERSION, token.getVersion());
       }
       if (token.hasOwner()) {
-        o("owner", token.getOwner());
+        o(SECRET_MANAGER_SECTION_OWNER, token.getOwner());
       }
       if (token.hasRenewer()) {
-        o("renewer", token.getRenewer());
+        o(SECRET_MANAGER_SECTION_RENEWER, token.getRenewer());
       }
       if (token.hasRealUser()) {
-        o("realUser", token.getRealUser());
+        o(SECRET_MANAGER_SECTION_REAL_USER, token.getRealUser());
       }
       if (token.hasIssueDate()) {
-        dumpDate("issueDate", token.getIssueDate());
+        dumpDate(SECRET_MANAGER_SECTION_ISSUE_DATE, token.getIssueDate());
       }
       if (token.hasMaxDate()) {
-        dumpDate("maxDate", token.getMaxDate());
+        dumpDate(SECRET_MANAGER_SECTION_MAX_DATE, token.getMaxDate());
       }
       if (token.hasSequenceNumber()) {
-        o("sequenceNumber", token.getSequenceNumber());
+        o(SECRET_MANAGER_SECTION_SEQUENCE_NUMBER,
+            token.getSequenceNumber());
       }
       if (token.hasMasterKeyId()) {
-        o("masterKeyId", token.getMasterKeyId());
+        o(SECRET_MANAGER_SECTION_MASTER_KEY_ID, token.getMasterKeyId());
       }
       if (token.hasExpiryDate()) {
-        dumpDate("expiryDate", token.getExpiryDate());
+        dumpDate(SECRET_MANAGER_SECTION_EXPIRY_DATE, token.getExpiryDate());
       }
-      out.print("</token>");
+      out.print("</" + SECRET_MANAGER_SECTION_TOKEN + ">");
     }
-    out.print("</SecretManagerSection>");
+    out.print("</" + SECRET_MANAGER_SECTION_NAME + ">");
   }
 
   private void dumpDate(String tag, long date) {
@@ -469,7 +636,7 @@ public final class PBImageXmlWriter {
   }
 
   private void dumpSnapshotDiffSection(InputStream in) throws IOException {
-    out.print("<SnapshotDiffSection>");
+    out.print("<" + SNAPSHOT_DIFF_SECTION_NAME + ">");
     while (true) {
       SnapshotDiffSection.DiffEntry e = SnapshotDiffSection.DiffEntry
           .parseDelimitedFrom(in);
@@ -478,52 +645,54 @@ public final class PBImageXmlWriter {
       }
       switch (e.getType()) {
       case FILEDIFF:
-        out.print("<fileDiffEntry>");
+        out.print("<" + SNAPSHOT_DIFF_SECTION_FILE_DIFF_ENTRY + ">");
         break;
       case DIRECTORYDIFF:
-        out.print("<dirDiffEntry>");
+        out.print("<" + SNAPSHOT_DIFF_SECTION_DIR_DIFF_ENTRY + ">");
         break;
       default:
         throw new IOException("unknown DiffEntry type " + e.getType());
       }
-      o("inodeId", e.getInodeId());
-      o("count", e.getNumOfDiff());
+      o(SNAPSHOT_DIFF_SECTION_INODE_ID, e.getInodeId());
+      o(SNAPSHOT_DIFF_SECTION_COUNT, e.getNumOfDiff());
       switch (e.getType()) {
       case FILEDIFF: {
         for (int i = 0; i < e.getNumOfDiff(); ++i) {
-          out.print("<fileDiff>");
+          out.print("<" + SNAPSHOT_DIFF_SECTION_FILE_DIFF + ">");
           SnapshotDiffSection.FileDiff f = SnapshotDiffSection.FileDiff
               .parseDelimitedFrom(in);
-          o("snapshotId", f.getSnapshotId()).o("size", f.getFileSize()).o(
-              "name", f.getName().toStringUtf8());
-          out.print("</fileDiff>\n");
+          o(SNAPSHOT_DIFF_SECTION_SNAPSHOT_ID, f.getSnapshotId())
+              .o(SNAPSHOT_DIFF_SECTION_SIZE, f.getFileSize())
+              .o(SECTION_NAME, f.getName().toStringUtf8());
+          out.print("</" + SNAPSHOT_DIFF_SECTION_FILE_DIFF + ">\n");
         }
       }
         break;
       case DIRECTORYDIFF: {
         for (int i = 0; i < e.getNumOfDiff(); ++i) {
-          out.print("<dirDiff>");
+          out.print("<" + SNAPSHOT_DIFF_SECTION_DIR_DIFF + ">");
           SnapshotDiffSection.DirectoryDiff d = SnapshotDiffSection.DirectoryDiff
               .parseDelimitedFrom(in);
-          o("snapshotId", d.getSnapshotId())
-              .o("childrenSize", d.getChildrenSize())
-              .o("isSnapshotRoot", d.getIsSnapshotRoot())
-              .o("name", d.getName().toStringUtf8())
-              .o("createdListSize", d.getCreatedListSize());
+          o(SNAPSHOT_DIFF_SECTION_SNAPSHOT_ID, d.getSnapshotId())
+              .o(SNAPSHOT_DIFF_SECTION_CHILDREN_SIZE, d.getChildrenSize())
+              .o(SNAPSHOT_DIFF_SECTION_IS_SNAPSHOT_ROOT, d.getIsSnapshotRoot())
+              .o(SECTION_NAME, d.getName().toStringUtf8())
+              .o(SNAPSHOT_DIFF_SECTION_CREATED_LIST_SIZE,
+                  d.getCreatedListSize());
           for (long did : d.getDeletedINodeList()) {
-            o("deletedInode", did);
+            o(SNAPSHOT_DIFF_SECTION_DELETED_INODE, did);
           }
           for (int dRefid : d.getDeletedINodeRefList()) {
-            o("deletedInoderef", dRefid);
+            o(SNAPSHOT_DIFF_SECTION_DELETED_INODE_REF, dRefid);
           }
           for (int j = 0; j < d.getCreatedListSize(); ++j) {
             SnapshotDiffSection.CreatedListEntry ce = SnapshotDiffSection.CreatedListEntry
                 .parseDelimitedFrom(in);
-            out.print("<created>");
-            o("name", ce.getName().toStringUtf8());
-            out.print("</created>\n");
+            out.print("<" + SNAPSHOT_DIFF_SECTION_CREATED + ">");
+            o(SECTION_NAME, ce.getName().toStringUtf8());
+            out.print("</" + SNAPSHOT_DIFF_SECTION_CREATED + ">\n");
           }
-          out.print("</dirDiff>\n");
+          out.print("</" + SNAPSHOT_DIFF_SECTION_DIR_DIFF + ">\n");
         }
         break;
       }
@@ -532,41 +701,41 @@ public final class PBImageXmlWriter {
       }
       switch (e.getType()) {
       case FILEDIFF:
-        out.print("</fileDiffEntry>");
+        out.print("</" + SNAPSHOT_DIFF_SECTION_FILE_DIFF_ENTRY + ">");
         break;
       case DIRECTORYDIFF:
-        out.print("</dirDiffEntry>");
+        out.print("</" + SNAPSHOT_DIFF_SECTION_DIR_DIFF_ENTRY + ">");
         break;
       default:
         throw new IOException("unknown DiffEntry type " + e.getType());
       }
     }
-    out.print("</SnapshotDiffSection>\n");
+    out.print("</" + SNAPSHOT_DIFF_SECTION_NAME + ">\n");
   }
 
   private void dumpSnapshotSection(InputStream in) throws IOException {
-    out.print("<SnapshotSection>");
+    out.print("<" + SNAPSHOT_SECTION_NAME + ">");
     SnapshotSection s = SnapshotSection.parseDelimitedFrom(in);
-    o("snapshotCounter", s.getSnapshotCounter());
-    o("numSnapshots", s.getNumSnapshots());
+    o(SNAPSHOT_SECTION_SNAPSHOT_COUNTER, s.getSnapshotCounter());
+    o(SNAPSHOT_SECTION_NUM_SNAPSHOTS, s.getNumSnapshots());
     if (s.getSnapshottableDirCount() > 0) {
-      out.print("<snapshottableDir>");
+      out.print("<" + SNAPSHOT_SECTION_SNAPSHOT_TABLE_DIR + ">");
       for (long id : s.getSnapshottableDirList()) {
-        o("dir", id);
+        o(SNAPSHOT_SECTION_DIR, id);
       }
-      out.print("</snapshottableDir>\n");
+      out.print("</" + SNAPSHOT_SECTION_SNAPSHOT_TABLE_DIR + ">\n");
     }
     for (int i = 0; i < s.getNumSnapshots(); ++i) {
       SnapshotSection.Snapshot pbs = SnapshotSection.Snapshot
           .parseDelimitedFrom(in);
-      out.print("<snapshot>");
-      o("id", pbs.getSnapshotId());
-      out.print("<root>");
+      out.print("<" + SNAPSHOT_SECTION_SNAPSHOT + ">");
+      o(SECTION_ID, pbs.getSnapshotId());
+      out.print("<" + SNAPSHOT_SECTION_ROOT + ">");
       dumpINodeFields(pbs.getRoot());
-      out.print("</root>");
-      out.print("</snapshot>");
+      out.print("</" + SNAPSHOT_SECTION_ROOT + ">");
+      out.print("</" + SNAPSHOT_SECTION_SNAPSHOT + ">");
     }
-    out.print("</SnapshotSection>\n");
+    out.print("</" + SNAPSHOT_SECTION_NAME + ">\n");
   }
 
   private void loadStringTable(InputStream in) throws IOException {