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Posted to common-commits@hadoop.apache.org by ha...@apache.org on 2018/02/23 19:44:56 UTC

[15/50] [abbrv] hadoop git commit: YARN-7919. Refactor timelineservice-hbase module into submodules. Contributed by Haibo Chen.

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/SubApplicationEntityReader.java
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diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/SubApplicationEntityReader.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/SubApplicationEntityReader.java
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+/**
+ * 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.yarn.server.timelineservice.storage.reader;
+
+import java.io.IOException;
+import java.util.EnumSet;
+import java.util.Set;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.client.Connection;
+import org.apache.hadoop.hbase.client.Query;
+import org.apache.hadoop.hbase.client.Result;
+import org.apache.hadoop.hbase.client.ResultScanner;
+import org.apache.hadoop.hbase.client.Scan;
+import org.apache.hadoop.hbase.filter.BinaryComparator;
+import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp;
+import org.apache.hadoop.hbase.filter.FamilyFilter;
+import org.apache.hadoop.hbase.filter.FilterList;
+import org.apache.hadoop.hbase.filter.FilterList.Operator;
+import org.apache.hadoop.hbase.filter.PageFilter;
+import org.apache.hadoop.hbase.filter.QualifierFilter;
+import org.apache.hadoop.yarn.api.records.timelineservice.TimelineEntity;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineDataToRetrieve;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineEntityFilters;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineReaderContext;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineReaderUtils;
+import org.apache.hadoop.yarn.server.timelineservice.reader.filter.TimelineFilterList;
+import org.apache.hadoop.yarn.server.timelineservice.reader.filter.TimelineFilterUtils;
+import org.apache.hadoop.yarn.server.timelineservice.storage.TimelineReader.Field;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.BaseTableRW;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnRWHelper;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.HBaseTimelineStorageUtils;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.RowKeyPrefix;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.TimelineStorageUtils;
+import org.apache.hadoop.yarn.server.timelineservice.storage.subapplication.SubApplicationColumn;
+import org.apache.hadoop.yarn.server.timelineservice.storage.subapplication.SubApplicationColumnFamily;
+import org.apache.hadoop.yarn.server.timelineservice.storage.subapplication.SubApplicationColumnPrefix;
+import org.apache.hadoop.yarn.server.timelineservice.storage.subapplication.SubApplicationRowKey;
+import org.apache.hadoop.yarn.server.timelineservice.storage.subapplication.SubApplicationRowKeyPrefix;
+import org.apache.hadoop.yarn.server.timelineservice.storage.subapplication.SubApplicationTableRW;
+import org.apache.hadoop.yarn.webapp.BadRequestException;
+
+import com.google.common.base.Preconditions;
+
+class SubApplicationEntityReader extends GenericEntityReader {
+  private static final SubApplicationTableRW SUB_APPLICATION_TABLE =
+      new SubApplicationTableRW();
+
+  SubApplicationEntityReader(TimelineReaderContext ctxt,
+      TimelineEntityFilters entityFilters, TimelineDataToRetrieve toRetrieve) {
+    super(ctxt, entityFilters, toRetrieve);
+  }
+
+  SubApplicationEntityReader(TimelineReaderContext ctxt,
+      TimelineDataToRetrieve toRetrieve) {
+    super(ctxt, toRetrieve);
+  }
+
+  /**
+   * Uses the {@link SubApplicationTableRW}.
+   */
+  protected BaseTableRW<?> getTable() {
+    return SUB_APPLICATION_TABLE;
+  }
+
+  @Override
+  protected FilterList constructFilterListBasedOnFilters() throws IOException {
+    // Filters here cannot be null for multiple entity reads as they are set in
+    // augmentParams if null.
+    FilterList listBasedOnFilters = new FilterList();
+    TimelineEntityFilters filters = getFilters();
+    // Create filter list based on created time range and add it to
+    // listBasedOnFilters.
+    long createdTimeBegin = filters.getCreatedTimeBegin();
+    long createdTimeEnd = filters.getCreatedTimeEnd();
+    if (createdTimeBegin != 0 || createdTimeEnd != Long.MAX_VALUE) {
+      listBasedOnFilters.addFilter(TimelineFilterUtils
+          .createSingleColValueFiltersByRange(SubApplicationColumn.CREATED_TIME,
+              createdTimeBegin, createdTimeEnd));
+    }
+    // Create filter list based on metric filters and add it to
+    // listBasedOnFilters.
+    TimelineFilterList metricFilters = filters.getMetricFilters();
+    if (metricFilters != null && !metricFilters.getFilterList().isEmpty()) {
+      listBasedOnFilters.addFilter(TimelineFilterUtils.createHBaseFilterList(
+          SubApplicationColumnPrefix.METRIC, metricFilters));
+    }
+    // Create filter list based on config filters and add it to
+    // listBasedOnFilters.
+    TimelineFilterList configFilters = filters.getConfigFilters();
+    if (configFilters != null && !configFilters.getFilterList().isEmpty()) {
+      listBasedOnFilters.addFilter(TimelineFilterUtils.createHBaseFilterList(
+          SubApplicationColumnPrefix.CONFIG, configFilters));
+    }
+    // Create filter list based on info filters and add it to listBasedOnFilters
+    TimelineFilterList infoFilters = filters.getInfoFilters();
+    if (infoFilters != null && !infoFilters.getFilterList().isEmpty()) {
+      listBasedOnFilters.addFilter(TimelineFilterUtils
+          .createHBaseFilterList(SubApplicationColumnPrefix.INFO, infoFilters));
+    }
+    return listBasedOnFilters;
+  }
+
+  /**
+   * Add {@link QualifierFilter} filters to filter list for each column of
+   * entity table.
+   *
+   * @param list filter list to which qualifier filters have to be added.
+   */
+  protected void updateFixedColumns(FilterList list) {
+    for (SubApplicationColumn column : SubApplicationColumn.values()) {
+      list.addFilter(new QualifierFilter(CompareOp.EQUAL,
+          new BinaryComparator(column.getColumnQualifierBytes())));
+    }
+  }
+
+  /**
+   * Creates a filter list which indicates that only some of the column
+   * qualifiers in the info column family will be returned in result.
+   *
+   * @param isApplication If true, it means operations are to be performed for
+   *          application table, otherwise for entity table.
+   * @return filter list.
+   * @throws IOException if any problem occurs while creating filter list.
+   */
+  private FilterList createFilterListForColsOfInfoFamily() throws IOException {
+    FilterList infoFamilyColsFilter = new FilterList(Operator.MUST_PASS_ONE);
+    // Add filters for each column in entity table.
+    updateFixedColumns(infoFamilyColsFilter);
+    EnumSet<Field> fieldsToRetrieve = getDataToRetrieve().getFieldsToRetrieve();
+    // If INFO field has to be retrieved, add a filter for fetching columns
+    // with INFO column prefix.
+    if (hasField(fieldsToRetrieve, Field.INFO)) {
+      infoFamilyColsFilter.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.EQUAL,
+              SubApplicationColumnPrefix.INFO));
+    }
+    TimelineFilterList relatesTo = getFilters().getRelatesTo();
+    if (hasField(fieldsToRetrieve, Field.RELATES_TO)) {
+      // If RELATES_TO field has to be retrieved, add a filter for fetching
+      // columns with RELATES_TO column prefix.
+      infoFamilyColsFilter.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.EQUAL,
+              SubApplicationColumnPrefix.RELATES_TO));
+    } else if (relatesTo != null && !relatesTo.getFilterList().isEmpty()) {
+      // Even if fields to retrieve does not contain RELATES_TO, we still
+      // need to have a filter to fetch some of the column qualifiers if
+      // relatesTo filters are specified. relatesTo filters will then be
+      // matched after fetching rows from HBase.
+      Set<String> relatesToCols =
+          TimelineFilterUtils.fetchColumnsFromFilterList(relatesTo);
+      infoFamilyColsFilter.addFilter(createFiltersFromColumnQualifiers(
+          SubApplicationColumnPrefix.RELATES_TO, relatesToCols));
+    }
+    TimelineFilterList isRelatedTo = getFilters().getIsRelatedTo();
+    if (hasField(fieldsToRetrieve, Field.IS_RELATED_TO)) {
+      // If IS_RELATED_TO field has to be retrieved, add a filter for fetching
+      // columns with IS_RELATED_TO column prefix.
+      infoFamilyColsFilter.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.EQUAL,
+              SubApplicationColumnPrefix.IS_RELATED_TO));
+    } else if (isRelatedTo != null && !isRelatedTo.getFilterList().isEmpty()) {
+      // Even if fields to retrieve does not contain IS_RELATED_TO, we still
+      // need to have a filter to fetch some of the column qualifiers if
+      // isRelatedTo filters are specified. isRelatedTo filters will then be
+      // matched after fetching rows from HBase.
+      Set<String> isRelatedToCols =
+          TimelineFilterUtils.fetchColumnsFromFilterList(isRelatedTo);
+      infoFamilyColsFilter.addFilter(createFiltersFromColumnQualifiers(
+          SubApplicationColumnPrefix.IS_RELATED_TO, isRelatedToCols));
+    }
+    TimelineFilterList eventFilters = getFilters().getEventFilters();
+    if (hasField(fieldsToRetrieve, Field.EVENTS)) {
+      // If EVENTS field has to be retrieved, add a filter for fetching columns
+      // with EVENT column prefix.
+      infoFamilyColsFilter.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.EQUAL,
+              SubApplicationColumnPrefix.EVENT));
+    } else if (eventFilters != null
+        && !eventFilters.getFilterList().isEmpty()) {
+      // Even if fields to retrieve does not contain EVENTS, we still need to
+      // have a filter to fetch some of the column qualifiers on the basis of
+      // event filters specified. Event filters will then be matched after
+      // fetching rows from HBase.
+      Set<String> eventCols =
+          TimelineFilterUtils.fetchColumnsFromFilterList(eventFilters);
+      infoFamilyColsFilter.addFilter(createFiltersFromColumnQualifiers(
+          SubApplicationColumnPrefix.EVENT, eventCols));
+    }
+    return infoFamilyColsFilter;
+  }
+
+  /**
+   * Exclude column prefixes via filters which are not required(based on fields
+   * to retrieve) from info column family. These filters are added to filter
+   * list which contains a filter for getting info column family.
+   *
+   * @param infoColFamilyList filter list for info column family.
+   */
+  private void excludeFieldsFromInfoColFamily(FilterList infoColFamilyList) {
+    EnumSet<Field> fieldsToRetrieve = getDataToRetrieve().getFieldsToRetrieve();
+    // Events not required.
+    if (!hasField(fieldsToRetrieve, Field.EVENTS)) {
+      infoColFamilyList.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.NOT_EQUAL,
+              SubApplicationColumnPrefix.EVENT));
+    }
+    // info not required.
+    if (!hasField(fieldsToRetrieve, Field.INFO)) {
+      infoColFamilyList.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.NOT_EQUAL,
+              SubApplicationColumnPrefix.INFO));
+    }
+    // is related to not required.
+    if (!hasField(fieldsToRetrieve, Field.IS_RELATED_TO)) {
+      infoColFamilyList.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.NOT_EQUAL,
+              SubApplicationColumnPrefix.IS_RELATED_TO));
+    }
+    // relates to not required.
+    if (!hasField(fieldsToRetrieve, Field.RELATES_TO)) {
+      infoColFamilyList.addFilter(
+          TimelineFilterUtils.createHBaseQualifierFilter(CompareOp.NOT_EQUAL,
+              SubApplicationColumnPrefix.RELATES_TO));
+    }
+  }
+
+  /**
+   * Updates filter list based on fields for confs and metrics to retrieve.
+   *
+   * @param listBasedOnFields filter list based on fields.
+   * @throws IOException if any problem occurs while updating filter list.
+   */
+  private void updateFilterForConfsAndMetricsToRetrieve(
+      FilterList listBasedOnFields) throws IOException {
+    TimelineDataToRetrieve dataToRetrieve = getDataToRetrieve();
+    // Please note that if confsToRetrieve is specified, we would have added
+    // CONFS to fields to retrieve in augmentParams() even if not specified.
+    if (dataToRetrieve.getFieldsToRetrieve().contains(Field.CONFIGS)) {
+      // Create a filter list for configs.
+      listBasedOnFields.addFilter(
+          TimelineFilterUtils.createFilterForConfsOrMetricsToRetrieve(
+              dataToRetrieve.getConfsToRetrieve(),
+              SubApplicationColumnFamily.CONFIGS,
+              SubApplicationColumnPrefix.CONFIG));
+    }
+
+    // Please note that if metricsToRetrieve is specified, we would have added
+    // METRICS to fields to retrieve in augmentParams() even if not specified.
+    if (dataToRetrieve.getFieldsToRetrieve().contains(Field.METRICS)) {
+      // Create a filter list for metrics.
+      listBasedOnFields.addFilter(
+          TimelineFilterUtils.createFilterForConfsOrMetricsToRetrieve(
+              dataToRetrieve.getMetricsToRetrieve(),
+              SubApplicationColumnFamily.METRICS,
+              SubApplicationColumnPrefix.METRIC));
+    }
+  }
+
+  @Override
+  protected FilterList constructFilterListBasedOnFields() throws IOException {
+    if (!needCreateFilterListBasedOnFields()) {
+      // Fetch all the columns. No need of a filter.
+      return null;
+    }
+    FilterList listBasedOnFields = new FilterList(Operator.MUST_PASS_ONE);
+    FilterList infoColFamilyList = new FilterList();
+    // By default fetch everything in INFO column family.
+    FamilyFilter infoColumnFamily = new FamilyFilter(CompareOp.EQUAL,
+        new BinaryComparator(SubApplicationColumnFamily.INFO.getBytes()));
+    infoColFamilyList.addFilter(infoColumnFamily);
+    if (fetchPartialColsFromInfoFamily()) {
+      // We can fetch only some of the columns from info family.
+      infoColFamilyList.addFilter(createFilterListForColsOfInfoFamily());
+    } else {
+      // Exclude column prefixes in info column family which are not required
+      // based on fields to retrieve.
+      excludeFieldsFromInfoColFamily(infoColFamilyList);
+    }
+    listBasedOnFields.addFilter(infoColFamilyList);
+    updateFilterForConfsAndMetricsToRetrieve(listBasedOnFields);
+    return listBasedOnFields;
+  }
+
+  @Override
+  protected void validateParams() {
+    Preconditions.checkNotNull(getContext(), "context shouldn't be null");
+    Preconditions.checkNotNull(getDataToRetrieve(),
+        "data to retrieve shouldn't be null");
+    Preconditions.checkNotNull(getContext().getClusterId(),
+        "clusterId shouldn't be null");
+    Preconditions.checkNotNull(getContext().getDoAsUser(),
+        "DoAsUser shouldn't be null");
+    Preconditions.checkNotNull(getContext().getEntityType(),
+        "entityType shouldn't be null");
+  }
+
+  @Override
+  protected void augmentParams(Configuration hbaseConf, Connection conn)
+      throws IOException {
+    getDataToRetrieve().addFieldsBasedOnConfsAndMetricsToRetrieve();
+    createFiltersIfNull();
+  }
+
+  private void setMetricsTimeRange(Query query) {
+    // Set time range for metric values.
+    HBaseTimelineStorageUtils.setMetricsTimeRange(query,
+        SubApplicationColumnFamily.METRICS.getBytes(),
+        getDataToRetrieve().getMetricsTimeBegin(),
+        getDataToRetrieve().getMetricsTimeEnd());
+  }
+
+  @Override
+  protected ResultScanner getResults(Configuration hbaseConf, Connection conn,
+      FilterList filterList) throws IOException {
+
+    // Scan through part of the table to find the entities belong to one app
+    // and one type
+    Scan scan = new Scan();
+    TimelineReaderContext context = getContext();
+    if (context.getDoAsUser() == null) {
+      throw new BadRequestException("Invalid user!");
+    }
+
+    RowKeyPrefix<SubApplicationRowKey> subApplicationRowKeyPrefix = null;
+    // default mode, will always scans from beginning of entity type.
+    if (getFilters() == null || getFilters().getFromId() == null) {
+      subApplicationRowKeyPrefix = new SubApplicationRowKeyPrefix(
+          context.getDoAsUser(), context.getClusterId(),
+          context.getEntityType(), null, null, null);
+      scan.setRowPrefixFilter(subApplicationRowKeyPrefix.getRowKeyPrefix());
+    } else { // pagination mode, will scan from given entityIdPrefix!enitityId
+
+      SubApplicationRowKey entityRowKey = null;
+      try {
+        entityRowKey = SubApplicationRowKey
+            .parseRowKeyFromString(getFilters().getFromId());
+      } catch (IllegalArgumentException e) {
+        throw new BadRequestException("Invalid filter fromid is provided.");
+      }
+      if (!context.getClusterId().equals(entityRowKey.getClusterId())) {
+        throw new BadRequestException(
+            "fromid doesn't belong to clusterId=" + context.getClusterId());
+      }
+
+      // set start row
+      scan.setStartRow(entityRowKey.getRowKey());
+
+      // get the bytes for stop row
+      subApplicationRowKeyPrefix = new SubApplicationRowKeyPrefix(
+          context.getDoAsUser(), context.getClusterId(),
+          context.getEntityType(), null, null, null);
+
+      // set stop row
+      scan.setStopRow(
+          HBaseTimelineStorageUtils.calculateTheClosestNextRowKeyForPrefix(
+              subApplicationRowKeyPrefix.getRowKeyPrefix()));
+
+      // set page filter to limit. This filter has to set only in pagination
+      // mode.
+      filterList.addFilter(new PageFilter(getFilters().getLimit()));
+    }
+    setMetricsTimeRange(scan);
+    scan.setMaxVersions(getDataToRetrieve().getMetricsLimit());
+    if (filterList != null && !filterList.getFilters().isEmpty()) {
+      scan.setFilter(filterList);
+    }
+    return getTable().getResultScanner(hbaseConf, conn, scan);
+  }
+
+  @Override
+  protected Result getResult(Configuration hbaseConf, Connection conn,
+      FilterList filterList) throws IOException {
+    throw new UnsupportedOperationException(
+        "we don't support a single entity query");
+  }
+
+  @Override
+  protected TimelineEntity parseEntity(Result result) throws IOException {
+    if (result == null || result.isEmpty()) {
+      return null;
+    }
+    TimelineEntity entity = new TimelineEntity();
+    SubApplicationRowKey parseRowKey =
+        SubApplicationRowKey.parseRowKey(result.getRow());
+    entity.setType(parseRowKey.getEntityType());
+    entity.setId(parseRowKey.getEntityId());
+    entity.setIdPrefix(parseRowKey.getEntityIdPrefix().longValue());
+
+    TimelineEntityFilters filters = getFilters();
+    // fetch created time
+    Long createdTime = (Long) ColumnRWHelper.readResult(result,
+        SubApplicationColumn.CREATED_TIME);
+    entity.setCreatedTime(createdTime);
+
+    EnumSet<Field> fieldsToRetrieve = getDataToRetrieve().getFieldsToRetrieve();
+    // fetch is related to entities and match isRelatedTo filter. If isRelatedTo
+    // filters do not match, entity would be dropped. We have to match filters
+    // locally as relevant HBase filters to filter out rows on the basis of
+    // isRelatedTo are not set in HBase scan.
+    boolean checkIsRelatedTo =
+        filters.getIsRelatedTo() != null
+            && filters.getIsRelatedTo().getFilterList().size() > 0;
+    if (hasField(fieldsToRetrieve, Field.IS_RELATED_TO) || checkIsRelatedTo) {
+      readRelationship(entity, result, SubApplicationColumnPrefix.IS_RELATED_TO,
+          true);
+      if (checkIsRelatedTo && !TimelineStorageUtils.matchIsRelatedTo(entity,
+          filters.getIsRelatedTo())) {
+        return null;
+      }
+      if (!hasField(fieldsToRetrieve, Field.IS_RELATED_TO)) {
+        entity.getIsRelatedToEntities().clear();
+      }
+    }
+
+    // fetch relates to entities and match relatesTo filter. If relatesTo
+    // filters do not match, entity would be dropped. We have to match filters
+    // locally as relevant HBase filters to filter out rows on the basis of
+    // relatesTo are not set in HBase scan.
+    boolean checkRelatesTo =
+        !isSingleEntityRead() && filters.getRelatesTo() != null
+            && filters.getRelatesTo().getFilterList().size() > 0;
+    if (hasField(fieldsToRetrieve, Field.RELATES_TO) || checkRelatesTo) {
+      readRelationship(entity, result, SubApplicationColumnPrefix.RELATES_TO,
+          false);
+      if (checkRelatesTo && !TimelineStorageUtils.matchRelatesTo(entity,
+          filters.getRelatesTo())) {
+        return null;
+      }
+      if (!hasField(fieldsToRetrieve, Field.RELATES_TO)) {
+        entity.getRelatesToEntities().clear();
+      }
+    }
+
+    // fetch info if fieldsToRetrieve contains INFO or ALL.
+    if (hasField(fieldsToRetrieve, Field.INFO)) {
+      readKeyValuePairs(entity, result, SubApplicationColumnPrefix.INFO, false);
+    }
+
+    // fetch configs if fieldsToRetrieve contains CONFIGS or ALL.
+    if (hasField(fieldsToRetrieve, Field.CONFIGS)) {
+      readKeyValuePairs(entity, result, SubApplicationColumnPrefix.CONFIG,
+          true);
+    }
+
+    // fetch events and match event filters if they exist. If event filters do
+    // not match, entity would be dropped. We have to match filters locally
+    // as relevant HBase filters to filter out rows on the basis of events
+    // are not set in HBase scan.
+    boolean checkEvents =
+        !isSingleEntityRead() && filters.getEventFilters() != null
+            && filters.getEventFilters().getFilterList().size() > 0;
+    if (hasField(fieldsToRetrieve, Field.EVENTS) || checkEvents) {
+      readEvents(entity, result, SubApplicationColumnPrefix.EVENT);
+      if (checkEvents && !TimelineStorageUtils.matchEventFilters(entity,
+          filters.getEventFilters())) {
+        return null;
+      }
+      if (!hasField(fieldsToRetrieve, Field.EVENTS)) {
+        entity.getEvents().clear();
+      }
+    }
+
+    // fetch metrics if fieldsToRetrieve contains METRICS or ALL.
+    if (hasField(fieldsToRetrieve, Field.METRICS)) {
+      readMetrics(entity, result, SubApplicationColumnPrefix.METRIC);
+    }
+
+    entity.getInfo().put(TimelineReaderUtils.FROMID_KEY,
+        parseRowKey.getRowKeyAsString());
+    return entity;
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReader.java
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diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReader.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReader.java
new file mode 100644
index 0000000..3168163
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReader.java
@@ -0,0 +1,464 @@
+/**
+ * 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.yarn.server.timelineservice.storage.reader;
+
+import java.io.IOException;
+import java.util.EnumSet;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.NavigableMap;
+import java.util.Set;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.client.Connection;
+import org.apache.hadoop.hbase.client.Result;
+import org.apache.hadoop.hbase.client.ResultScanner;
+import org.apache.hadoop.hbase.filter.BinaryPrefixComparator;
+import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp;
+import org.apache.hadoop.hbase.filter.FilterList;
+import org.apache.hadoop.hbase.filter.FilterList.Operator;
+import org.apache.hadoop.hbase.filter.QualifierFilter;
+import org.apache.hadoop.yarn.api.records.timelineservice.TimelineEntity;
+import org.apache.hadoop.yarn.api.records.timelineservice.TimelineEvent;
+import org.apache.hadoop.yarn.api.records.timelineservice.TimelineMetric;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineDataToRetrieve;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineEntityFilters;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineReaderContext;
+import org.apache.hadoop.yarn.server.timelineservice.storage.TimelineReader.Field;
+import org.apache.hadoop.yarn.server.timelineservice.storage.application.ApplicationColumnPrefix;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.BaseTable;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.BaseTableRW;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnPrefix;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnRWHelper;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.EventColumnName;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.EventColumnNameConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.KeyConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.Separator;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.StringKeyConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.entity.EntityColumnPrefix;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * The base class for reading and deserializing timeline entities from the
+ * HBase storage. Different types can be defined for different types of the
+ * entities that are being requested.
+ */
+public abstract class TimelineEntityReader extends
+    AbstractTimelineStorageReader {
+  private static final Logger LOG =
+      LoggerFactory.getLogger(TimelineEntityReader.class);
+
+  private final boolean singleEntityRead;
+  private TimelineDataToRetrieve dataToRetrieve;
+  // used only for multiple entity read mode
+  private TimelineEntityFilters filters;
+
+  /**
+   * Main table the entity reader uses.
+   */
+  private BaseTableRW<?> table;
+
+  /**
+   * Used to convert strings key components to and from storage format.
+   */
+  private final KeyConverter<String> stringKeyConverter =
+      new StringKeyConverter();
+
+  /**
+   * Instantiates a reader for multiple-entity reads.
+   *
+   * @param ctxt Reader context which defines the scope in which query has to be
+   *     made.
+   * @param entityFilters Filters which limit the entities returned.
+   * @param toRetrieve Data to retrieve for each entity.
+   */
+  protected TimelineEntityReader(TimelineReaderContext ctxt,
+      TimelineEntityFilters entityFilters, TimelineDataToRetrieve toRetrieve) {
+    super(ctxt);
+    this.singleEntityRead = false;
+    this.dataToRetrieve = toRetrieve;
+    this.filters = entityFilters;
+
+    this.setTable(getTable());
+  }
+
+  /**
+   * Instantiates a reader for single-entity reads.
+   *
+   * @param ctxt Reader context which defines the scope in which query has to be
+   *     made.
+   * @param toRetrieve Data to retrieve for each entity.
+   */
+  protected TimelineEntityReader(TimelineReaderContext ctxt,
+      TimelineDataToRetrieve toRetrieve) {
+    super(ctxt);
+    this.singleEntityRead = true;
+    this.dataToRetrieve = toRetrieve;
+
+    this.setTable(getTable());
+  }
+
+  /**
+   * Creates a {@link FilterList} based on fields, confs and metrics to
+   * retrieve. This filter list will be set in Scan/Get objects to trim down
+   * results fetched from HBase back-end storage. This is called only for
+   * multiple entity reads.
+   *
+   * @return a {@link FilterList} object.
+   * @throws IOException if any problem occurs while creating filter list.
+   */
+  protected abstract FilterList constructFilterListBasedOnFields()
+      throws IOException;
+
+  /**
+   * Creates a {@link FilterList} based on info, config and metric filters. This
+   * filter list will be set in HBase Get to trim down results fetched from
+   * HBase back-end storage.
+   *
+   * @return a {@link FilterList} object.
+   * @throws IOException if any problem occurs while creating filter list.
+   */
+  protected abstract FilterList constructFilterListBasedOnFilters()
+      throws IOException;
+
+  /**
+   * Combines filter lists created based on fields and based on filters.
+   *
+   * @return a {@link FilterList} object if it can be constructed. Returns null,
+   * if filter list cannot be created either on the basis of filters or on the
+   * basis of fields.
+   * @throws IOException if any problem occurs while creating filter list.
+   */
+  private FilterList createFilterList() throws IOException {
+    FilterList listBasedOnFilters = constructFilterListBasedOnFilters();
+    boolean hasListBasedOnFilters = listBasedOnFilters != null &&
+        !listBasedOnFilters.getFilters().isEmpty();
+    FilterList listBasedOnFields = constructFilterListBasedOnFields();
+    boolean hasListBasedOnFields = listBasedOnFields != null &&
+        !listBasedOnFields.getFilters().isEmpty();
+    // If filter lists based on both filters and fields can be created,
+    // combine them in a new filter list and return it.
+    // If either one of them has been created, return that filter list.
+    // Return null, if none of the filter lists can be created. This indicates
+    // that no filter list needs to be added to HBase Scan as filters are not
+    // specified for the query or only the default view of entity needs to be
+    // returned.
+    if (hasListBasedOnFilters && hasListBasedOnFields) {
+      FilterList list = new FilterList();
+      list.addFilter(listBasedOnFilters);
+      list.addFilter(listBasedOnFields);
+      return list;
+    } else if (hasListBasedOnFilters) {
+      return listBasedOnFilters;
+    } else if (hasListBasedOnFields) {
+      return listBasedOnFields;
+    }
+    return null;
+  }
+
+  protected TimelineDataToRetrieve getDataToRetrieve() {
+    return dataToRetrieve;
+  }
+
+  protected TimelineEntityFilters getFilters() {
+    return filters;
+  }
+
+  /**
+   * Create a {@link TimelineEntityFilters} object with default values for
+   * filters.
+   */
+  protected void createFiltersIfNull() {
+    if (filters == null) {
+      filters = new TimelineEntityFilters.Builder().build();
+    }
+  }
+
+  /**
+   * Reads and deserializes a single timeline entity from the HBase storage.
+   *
+   * @param hbaseConf HBase Configuration.
+   * @param conn HBase Connection.
+   * @return A <cite>TimelineEntity</cite> object.
+   * @throws IOException if there is any exception encountered while reading
+   *     entity.
+   */
+  public TimelineEntity readEntity(Configuration hbaseConf, Connection conn)
+      throws IOException {
+    validateParams();
+    augmentParams(hbaseConf, conn);
+
+    FilterList filterList = constructFilterListBasedOnFields();
+    if (LOG.isDebugEnabled() && filterList != null) {
+      LOG.debug("FilterList created for get is - " + filterList);
+    }
+    Result result = getResult(hbaseConf, conn, filterList);
+    if (result == null || result.isEmpty()) {
+      // Could not find a matching row.
+      LOG.info("Cannot find matching entity of type " +
+          getContext().getEntityType());
+      return null;
+    }
+    return parseEntity(result);
+  }
+
+  /**
+   * Reads and deserializes a set of timeline entities from the HBase storage.
+   * It goes through all the results available, and returns the number of
+   * entries as specified in the limit in the entity's natural sort order.
+   *
+   * @param hbaseConf HBase Configuration.
+   * @param conn HBase Connection.
+   * @return a set of <cite>TimelineEntity</cite> objects.
+   * @throws IOException if any exception is encountered while reading entities.
+   */
+  public Set<TimelineEntity> readEntities(Configuration hbaseConf,
+      Connection conn) throws IOException {
+    validateParams();
+    augmentParams(hbaseConf, conn);
+
+    Set<TimelineEntity> entities = new LinkedHashSet<>();
+    FilterList filterList = createFilterList();
+    if (LOG.isDebugEnabled() && filterList != null) {
+      LOG.debug("FilterList created for scan is - " + filterList);
+    }
+    ResultScanner results = getResults(hbaseConf, conn, filterList);
+    try {
+      for (Result result : results) {
+        TimelineEntity entity = parseEntity(result);
+        if (entity == null) {
+          continue;
+        }
+        entities.add(entity);
+        if (entities.size() == filters.getLimit()) {
+          break;
+        }
+      }
+      return entities;
+    } finally {
+      results.close();
+    }
+  }
+
+  /**
+   * Returns the main table to be used by the entity reader.
+   *
+   * @return A reference to the table.
+   */
+  protected BaseTableRW<?> getTable() {
+    return table;
+  }
+
+  /**
+   * Fetches a {@link Result} instance for a single-entity read.
+   *
+   * @param hbaseConf HBase Configuration.
+   * @param conn HBase Connection.
+   * @param filterList filter list which will be applied to HBase Get.
+   * @return the {@link Result} instance or null if no such record is found.
+   * @throws IOException if any exception is encountered while getting result.
+   */
+  protected abstract Result getResult(Configuration hbaseConf, Connection conn,
+      FilterList filterList) throws IOException;
+
+  /**
+   * Fetches a {@link ResultScanner} for a multi-entity read.
+   *
+   * @param hbaseConf HBase Configuration.
+   * @param conn HBase Connection.
+   * @param filterList filter list which will be applied to HBase Scan.
+   * @return the {@link ResultScanner} instance.
+   * @throws IOException if any exception is encountered while getting results.
+   */
+  protected abstract ResultScanner getResults(Configuration hbaseConf,
+      Connection conn, FilterList filterList) throws IOException;
+
+  /**
+   * Parses the result retrieved from HBase backend and convert it into a
+   * {@link TimelineEntity} object.
+   *
+   * @param result Single row result of a Get/Scan.
+   * @return the <cite>TimelineEntity</cite> instance or null if the entity is
+   *     filtered.
+   * @throws IOException if any exception is encountered while parsing entity.
+   */
+  protected abstract TimelineEntity parseEntity(Result result)
+      throws IOException;
+
+  /**
+   * Helper method for reading and deserializing {@link TimelineMetric} objects
+   * using the specified column prefix. The timeline metrics then are added to
+   * the given timeline entity.
+   *
+   * @param entity {@link TimelineEntity} object.
+   * @param result {@link Result} object retrieved from backend.
+   * @param columnPrefix Metric column prefix
+   * @throws IOException if any exception is encountered while reading metrics.
+   */
+  protected void readMetrics(TimelineEntity entity, Result result,
+      ColumnPrefix<?> columnPrefix) throws IOException {
+    NavigableMap<String, NavigableMap<Long, Number>> metricsResult =
+        ColumnRWHelper.readResultsWithTimestamps(
+            result, columnPrefix, stringKeyConverter);
+    for (Map.Entry<String, NavigableMap<Long, Number>> metricResult:
+        metricsResult.entrySet()) {
+      TimelineMetric metric = new TimelineMetric();
+      metric.setId(metricResult.getKey());
+      // Simply assume that if the value set contains more than 1 elements, the
+      // metric is a TIME_SERIES metric, otherwise, it's a SINGLE_VALUE metric
+      TimelineMetric.Type metricType = metricResult.getValue().size() > 1 ?
+          TimelineMetric.Type.TIME_SERIES : TimelineMetric.Type.SINGLE_VALUE;
+      metric.setType(metricType);
+      metric.addValues(metricResult.getValue());
+      entity.addMetric(metric);
+    }
+  }
+
+  /**
+   * Checks whether the reader has been created to fetch single entity or
+   * multiple entities.
+   *
+   * @return true, if query is for single entity, false otherwise.
+   */
+  public boolean isSingleEntityRead() {
+    return singleEntityRead;
+  }
+
+  protected void setTable(BaseTableRW<?> baseTable) {
+    this.table = baseTable;
+  }
+
+  /**
+   * Check if we have a certain field amongst fields to retrieve. This method
+   * checks against {@link Field#ALL} as well because that would mean field
+   * passed needs to be matched.
+   *
+   * @param fieldsToRetrieve fields to be retrieved.
+   * @param requiredField fields to be checked in fieldsToRetrieve.
+   * @return true if has the required field, false otherwise.
+   */
+  protected boolean hasField(EnumSet<Field> fieldsToRetrieve,
+      Field requiredField) {
+    return fieldsToRetrieve.contains(Field.ALL) ||
+        fieldsToRetrieve.contains(requiredField);
+  }
+
+  /**
+   * Create a filter list of qualifier filters based on passed set of columns.
+   *
+   * @param <T> Describes the type of column prefix.
+   * @param colPrefix Column Prefix.
+   * @param columns set of column qualifiers.
+   * @return filter list.
+   */
+  protected <T extends BaseTable<T>> FilterList
+      createFiltersFromColumnQualifiers(
+          ColumnPrefix<T> colPrefix, Set<String> columns) {
+    FilterList list = new FilterList(Operator.MUST_PASS_ONE);
+    for (String column : columns) {
+      // For columns which have compound column qualifiers (eg. events), we need
+      // to include the required separator.
+      byte[] compoundColQual = createColQualifierPrefix(colPrefix, column);
+      list.addFilter(new QualifierFilter(CompareOp.EQUAL,
+          new BinaryPrefixComparator(colPrefix
+              .getColumnPrefixBytes(compoundColQual))));
+    }
+    return list;
+  }
+
+  protected <T extends BaseTable<T>> byte[] createColQualifierPrefix(
+      ColumnPrefix<T> colPrefix, String column) {
+    if (colPrefix == ApplicationColumnPrefix.EVENT
+        || colPrefix == EntityColumnPrefix.EVENT) {
+      return new EventColumnName(column, null, null).getColumnQualifier();
+    } else {
+      return stringKeyConverter.encode(column);
+    }
+  }
+
+  /**
+   * Helper method for reading relationship.
+   *
+   * @param <T> Describes the type of column prefix.
+   * @param entity entity to fill.
+   * @param result result from HBase.
+   * @param prefix column prefix.
+   * @param isRelatedTo if true, means relationship is to be added to
+   *          isRelatedTo, otherwise its added to relatesTo.
+   * @throws IOException if any problem is encountered while reading result.
+   */
+  protected <T extends BaseTable<T>> void readRelationship(
+      TimelineEntity entity, Result result,
+      ColumnPrefix<T> prefix, boolean isRelatedTo) throws IOException {
+    // isRelatedTo and relatesTo are of type Map<String, Set<String>>
+    Map<String, Object> columns = ColumnRWHelper.readResults(
+        result, prefix, stringKeyConverter);
+    for (Map.Entry<String, Object> column : columns.entrySet()) {
+      for (String id : Separator.VALUES.splitEncoded(column.getValue()
+          .toString())) {
+        if (isRelatedTo) {
+          entity.addIsRelatedToEntity(column.getKey(), id);
+        } else {
+          entity.addRelatesToEntity(column.getKey(), id);
+        }
+      }
+    }
+  }
+
+  /**
+   * Read events from the entity table or the application table. The column name
+   * is of the form "eventId=timestamp=infoKey" where "infoKey" may be omitted
+   * if there is no info associated with the event.
+   *
+   * @param <T> Describes the type of column prefix.
+   * @param entity entity to fill.
+   * @param result HBase Result.
+   * @param prefix column prefix.
+   * @throws IOException if any problem is encountered while reading result.
+   */
+  protected static <T extends BaseTable<T>> void readEvents(
+      TimelineEntity entity, Result result,
+      ColumnPrefix<T> prefix) throws IOException {
+    Map<String, TimelineEvent> eventsMap = new HashMap<>();
+    Map<EventColumnName, Object> eventsResult = ColumnRWHelper.readResults(
+        result, prefix, new EventColumnNameConverter());
+    for (Map.Entry<EventColumnName, Object>
+             eventResult : eventsResult.entrySet()) {
+      EventColumnName eventColumnName = eventResult.getKey();
+      String key = eventColumnName.getId() +
+          Long.toString(eventColumnName.getTimestamp());
+      // Retrieve previously seen event to add to it
+      TimelineEvent event = eventsMap.get(key);
+      if (event == null) {
+        // First time we're seeing this event, add it to the eventsMap
+        event = new TimelineEvent();
+        event.setId(eventColumnName.getId());
+        event.setTimestamp(eventColumnName.getTimestamp());
+        eventsMap.put(key, event);
+      }
+      if (eventColumnName.getInfoKey() != null) {
+        event.addInfo(eventColumnName.getInfoKey(), eventResult.getValue());
+      }
+    }
+    Set<TimelineEvent> eventsSet = new HashSet<>(eventsMap.values());
+    entity.addEvents(eventsSet);
+  }
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReaderFactory.java
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReaderFactory.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReaderFactory.java
new file mode 100644
index 0000000..fa16077
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/TimelineEntityReaderFactory.java
@@ -0,0 +1,105 @@
+/**
+ * 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.yarn.server.timelineservice.storage.reader;
+
+import org.apache.hadoop.yarn.api.records.timelineservice.TimelineEntityType;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineDataToRetrieve;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineEntityFilters;
+import org.apache.hadoop.yarn.server.timelineservice.reader.TimelineReaderContext;
+
+/**
+ * Factory methods for instantiating a timeline entity reader.
+ */
+public final class TimelineEntityReaderFactory {
+  private TimelineEntityReaderFactory() {
+  }
+
+  /**
+   * Creates a timeline entity reader instance for reading a single entity with
+   * the specified input.
+   *
+   * @param context Reader context which defines the scope in which query has to
+   *     be made.
+   * @param dataToRetrieve Data to retrieve for each entity.
+   * @return An implementation of <cite>TimelineEntityReader</cite> object
+   *     depending on entity type.
+   */
+  public static TimelineEntityReader createSingleEntityReader(
+      TimelineReaderContext context, TimelineDataToRetrieve dataToRetrieve) {
+    // currently the types that are handled separate from the generic entity
+    // table are application, flow run, and flow activity entities
+    if (TimelineEntityType.YARN_APPLICATION.matches(context.getEntityType())) {
+      return new ApplicationEntityReader(context, dataToRetrieve);
+    } else if (TimelineEntityType.
+        YARN_FLOW_RUN.matches(context.getEntityType())) {
+      return new FlowRunEntityReader(context, dataToRetrieve);
+    } else if (TimelineEntityType.
+        YARN_FLOW_ACTIVITY.matches(context.getEntityType())) {
+      return new FlowActivityEntityReader(context, dataToRetrieve);
+    } else {
+      // assume we're dealing with a generic entity read
+      return new GenericEntityReader(context, dataToRetrieve);
+    }
+  }
+
+  /**
+   * Creates a timeline entity reader instance for reading set of entities with
+   * the specified input and predicates.
+   *
+   * @param context Reader context which defines the scope in which query has to
+   *     be made.
+   * @param filters Filters which limit the entities returned.
+   * @param dataToRetrieve Data to retrieve for each entity.
+   * @return An implementation of <cite>TimelineEntityReader</cite> object
+   *     depending on entity type.
+   */
+  public static TimelineEntityReader createMultipleEntitiesReader(
+      TimelineReaderContext context, TimelineEntityFilters filters,
+      TimelineDataToRetrieve dataToRetrieve) {
+    // currently the types that are handled separate from the generic entity
+    // table are application, flow run, and flow activity entities
+    if (TimelineEntityType.YARN_APPLICATION.matches(context.getEntityType())) {
+      return new ApplicationEntityReader(context, filters, dataToRetrieve);
+    } else if (TimelineEntityType.
+        YARN_FLOW_ACTIVITY.matches(context.getEntityType())) {
+      return new FlowActivityEntityReader(context, filters, dataToRetrieve);
+    } else if (TimelineEntityType.
+        YARN_FLOW_RUN.matches(context.getEntityType())) {
+      return new FlowRunEntityReader(context, filters, dataToRetrieve);
+    } else {
+      if (context.getDoAsUser() != null) {
+        return new SubApplicationEntityReader(context, filters, dataToRetrieve);
+      }
+      // assume we're dealing with a generic entity read
+      return new GenericEntityReader(context, filters, dataToRetrieve);
+    }
+  }
+
+  /**
+   * Creates a timeline entity type reader that will read all available entity
+   * types within the specified context.
+   *
+   * @param context Reader context which defines the scope in which query has to
+   *                be made. Limited to application level only.
+   * @return an <cite>EntityTypeReader</cite> object
+   */
+  public static EntityTypeReader createEntityTypeReader(
+      TimelineReaderContext context) {
+    return new EntityTypeReader(context);
+  }
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/package-info.java
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/package-info.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/package-info.java
new file mode 100644
index 0000000..9814d6d
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/reader/package-info.java
@@ -0,0 +1,28 @@
+/*
+ * 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.yarn.server.timelineservice.storage.reader
+ * contains classes used to read entities from backend based on query type.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+package org.apache.hadoop.yarn.server.timelineservice.storage.reader;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
\ No newline at end of file

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/SubApplicationTableRW.java
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/SubApplicationTableRW.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/SubApplicationTableRW.java
new file mode 100644
index 0000000..256b24b
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/SubApplicationTableRW.java
@@ -0,0 +1,137 @@
+/**
+ * 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.yarn.server.timelineservice.storage.subapplication;
+
+import java.io.IOException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HColumnDescriptor;
+import org.apache.hadoop.hbase.HTableDescriptor;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.Admin;
+import org.apache.hadoop.hbase.regionserver.BloomType;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.BaseTableRW;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.TimelineHBaseSchemaConstants;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Create, read and write to the SubApplication table.
+ */
+public class SubApplicationTableRW extends BaseTableRW<SubApplicationTable> {
+  /** sub app prefix. */
+  private static final String PREFIX =
+      YarnConfiguration.TIMELINE_SERVICE_PREFIX + "subapplication";
+
+  /** config param name that specifies the subapplication table name. */
+  public static final String TABLE_NAME_CONF_NAME = PREFIX + ".table.name";
+
+  /**
+   * config param name that specifies the TTL for metrics column family in
+   * subapplication table.
+   */
+  private static final String METRICS_TTL_CONF_NAME = PREFIX
+      + ".table.metrics.ttl";
+
+  /**
+   * config param name that specifies max-versions for
+   * metrics column family in subapplication table.
+   */
+  private static final String METRICS_MAX_VERSIONS =
+      PREFIX + ".table.metrics.max-versions";
+
+  /** default value for subapplication table name. */
+  public static final String DEFAULT_TABLE_NAME =
+      "timelineservice.subapplication";
+
+  /** default TTL is 30 days for metrics timeseries. */
+  private static final int DEFAULT_METRICS_TTL = 2592000;
+
+  /** default max number of versions. */
+  private static final int DEFAULT_METRICS_MAX_VERSIONS = 10000;
+
+  private static final Logger LOG = LoggerFactory.getLogger(
+      SubApplicationTableRW.class);
+
+  public SubApplicationTableRW() {
+    super(TABLE_NAME_CONF_NAME, DEFAULT_TABLE_NAME);
+  }
+
+  /*
+   * (non-Javadoc)
+   *
+   * @see
+   * org.apache.hadoop.yarn.server.timelineservice.storage.BaseTableRW#
+   * createTable(org.apache.hadoop.hbase.client.Admin,
+   * org.apache.hadoop.conf.Configuration)
+   */
+  public void createTable(Admin admin, Configuration hbaseConf)
+      throws IOException {
+
+    TableName table = getTableName(hbaseConf);
+    if (admin.tableExists(table)) {
+      // do not disable / delete existing table
+      // similar to the approach taken by map-reduce jobs when
+      // output directory exists
+      throw new IOException("Table " + table.getNameAsString()
+          + " already exists.");
+    }
+
+    HTableDescriptor subAppTableDescp = new HTableDescriptor(table);
+    HColumnDescriptor infoCF =
+        new HColumnDescriptor(SubApplicationColumnFamily.INFO.getBytes());
+    infoCF.setBloomFilterType(BloomType.ROWCOL);
+    subAppTableDescp.addFamily(infoCF);
+
+    HColumnDescriptor configCF =
+        new HColumnDescriptor(SubApplicationColumnFamily.CONFIGS.getBytes());
+    configCF.setBloomFilterType(BloomType.ROWCOL);
+    configCF.setBlockCacheEnabled(true);
+    subAppTableDescp.addFamily(configCF);
+
+    HColumnDescriptor metricsCF =
+        new HColumnDescriptor(SubApplicationColumnFamily.METRICS.getBytes());
+    subAppTableDescp.addFamily(metricsCF);
+    metricsCF.setBlockCacheEnabled(true);
+    // always keep 1 version (the latest)
+    metricsCF.setMinVersions(1);
+    metricsCF.setMaxVersions(
+        hbaseConf.getInt(METRICS_MAX_VERSIONS, DEFAULT_METRICS_MAX_VERSIONS));
+    metricsCF.setTimeToLive(hbaseConf.getInt(METRICS_TTL_CONF_NAME,
+        DEFAULT_METRICS_TTL));
+    subAppTableDescp.setRegionSplitPolicyClassName(
+        "org.apache.hadoop.hbase.regionserver.KeyPrefixRegionSplitPolicy");
+    subAppTableDescp.setValue("KeyPrefixRegionSplitPolicy.prefix_length",
+        TimelineHBaseSchemaConstants.USERNAME_SPLIT_KEY_PREFIX_LENGTH);
+    admin.createTable(subAppTableDescp,
+        TimelineHBaseSchemaConstants.getUsernameSplits());
+    LOG.info("Status of table creation for " + table.getNameAsString() + "="
+        + admin.tableExists(table));
+  }
+
+  /**
+   * @param metricsTTL time to live parameter for the metricss in this table.
+   * @param hbaseConf configururation in which to set the metrics TTL config
+   *          variable.
+   */
+  public void setMetricsTTL(int metricsTTL, Configuration hbaseConf) {
+    hbaseConf.setInt(METRICS_TTL_CONF_NAME, metricsTTL);
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/package-info.java
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/package-info.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/package-info.java
new file mode 100644
index 0000000..52cc399
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/subapplication/package-info.java
@@ -0,0 +1,28 @@
+/*
+ * 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.yarn.server.timelineservice.storage.subapplication
+ * contains classes related to implementation for subapplication table.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+package org.apache.hadoop.yarn.server.timelineservice.storage.subapplication;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/test/java/org/apache/hadoop/yarn/server/timelineservice/storage/common/TestHBaseTimelineStorageUtils.java
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/test/java/org/apache/hadoop/yarn/server/timelineservice/storage/common/TestHBaseTimelineStorageUtils.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/test/java/org/apache/hadoop/yarn/server/timelineservice/storage/common/TestHBaseTimelineStorageUtils.java
new file mode 100644
index 0000000..402a89b
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-client/src/test/java/org/apache/hadoop/yarn/server/timelineservice/storage/common/TestHBaseTimelineStorageUtils.java
@@ -0,0 +1,33 @@
+/**
+ * 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.yarn.server.timelineservice.storage.common;
+
+import org.junit.Test;
+
+/**
+ * Unit tests for HBaseTimelineStorageUtils static methos.
+ */
+public class TestHBaseTimelineStorageUtils {
+
+  @Test(expected=NullPointerException.class)
+  public void testGetTimelineServiceHBaseConfNullArgument() throws Exception {
+    HBaseTimelineStorageUtils.getTimelineServiceHBaseConf(null);
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/pom.xml
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/pom.xml b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/pom.xml
new file mode 100644
index 0000000..cb0d6e2
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/pom.xml
@@ -0,0 +1,132 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+   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.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
+                      http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <parent>
+    <artifactId>hadoop-yarn-server-timelineservice-hbase</artifactId>
+    <groupId>org.apache.hadoop</groupId>
+    <version>3.2.0-SNAPSHOT</version>
+  </parent>
+  <modelVersion>4.0.0</modelVersion>
+
+  <artifactId>hadoop-yarn-server-timelineservice-hbase-common</artifactId>
+  <name>Apache Hadoop YARN TimelineService HBase Common</name>
+  <version>3.2.0-SNAPSHOT</version>
+
+  <properties>
+    <!-- Needed for generating FindBugs warnings using parent pom -->
+    <yarn.basedir>${project.parent.parent.parent.basedir}</yarn.basedir>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-annotations</artifactId>
+      <scope>provided</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-yarn-api</artifactId>
+      <scope>provided</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-yarn-server-timelineservice</artifactId>
+    </dependency>
+
+    <!-- This is needed for GenericObjectMapper in GenericConverter -->
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-yarn-server-applicationhistoryservice</artifactId>
+      <scope>provided</scope>
+    </dependency>
+
+    <!-- 'mvn dependency:analyze' fails to detect use of this direct
+        dependency -->
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-common</artifactId>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>org.apache.hbase</groupId>
+      <artifactId>hbase-common</artifactId>
+      <exclusions>
+        <exclusion>
+          <groupId>org.apache.hadoop</groupId>
+          <artifactId>hadoop-mapreduce-client-core</artifactId>
+        </exclusion>
+        <exclusion>
+          <groupId>org.mortbay.jetty</groupId>
+          <artifactId>jetty-util</artifactId>
+        </exclusion>
+      </exclusions>
+    </dependency>
+
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <scope>test</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <artifactId>maven-jar-plugin</artifactId>
+        <executions>
+          <execution>
+            <goals>
+              <goal>test-jar</goal>
+            </goals>
+            <phase>test-compile</phase>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-dependency-plugin</artifactId>
+        <executions>
+          <execution>
+            <phase>package</phase>
+            <goals>
+              <goal>copy-dependencies</goal>
+            </goals>
+            <configuration>
+              <includeScope>runtime</includeScope>
+              <excludeGroupIds>org.slf4j,org.apache.hadoop,com.github.stephenc.findbugs</excludeGroupIds>
+              <outputDirectory>${project.build.directory}/lib</outputDirectory>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>
\ No newline at end of file

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumn.java
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumn.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumn.java
new file mode 100644
index 0000000..c3d6a52
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumn.java
@@ -0,0 +1,101 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.yarn.server.timelineservice.storage.application;
+
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.Column;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnFamily;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.GenericConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.LongConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.Separator;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ValueConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.flow.Attribute;
+
+/**
+ * Identifies fully qualified columns for the {@link ApplicationTable}.
+ */
+public enum ApplicationColumn implements Column<ApplicationTable> {
+
+  /**
+   * App id.
+   */
+  ID(ApplicationColumnFamily.INFO, "id"),
+
+  /**
+   * When the application was created.
+   */
+  CREATED_TIME(ApplicationColumnFamily.INFO, "created_time",
+      new LongConverter()),
+
+  /**
+   * The version of the flow that this app belongs to.
+   */
+  FLOW_VERSION(ApplicationColumnFamily.INFO, "flow_version");
+
+  private final ColumnFamily<ApplicationTable> columnFamily;
+  private final String columnQualifier;
+  private final byte[] columnQualifierBytes;
+  private final ValueConverter valueConverter;
+
+  private ApplicationColumn(ColumnFamily<ApplicationTable> columnFamily,
+      String columnQualifier) {
+    this(columnFamily, columnQualifier, GenericConverter.getInstance());
+  }
+
+  private ApplicationColumn(ColumnFamily<ApplicationTable> columnFamily,
+      String columnQualifier, ValueConverter converter) {
+    this.columnFamily = columnFamily;
+    this.columnQualifier = columnQualifier;
+    // Future-proof by ensuring the right column prefix hygiene.
+    this.columnQualifierBytes =
+        Bytes.toBytes(Separator.SPACE.encode(columnQualifier));
+    this.valueConverter = converter;
+  }
+
+  /**
+   * @return the column name value
+   */
+  private String getColumnQualifier() {
+    return columnQualifier;
+  }
+
+  @Override
+  public byte[] getColumnQualifierBytes() {
+    return columnQualifierBytes.clone();
+  }
+
+  @Override
+  public byte[] getColumnFamilyBytes() {
+    return columnFamily.getBytes();
+  }
+
+  @Override
+  public ValueConverter getValueConverter() {
+    return valueConverter;
+  }
+
+  @Override
+  public Attribute[] getCombinedAttrsWithAggr(Attribute... attributes) {
+    return attributes;
+  }
+
+  @Override
+  public boolean supplementCellTimestamp() {
+    return false;
+  }
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnFamily.java
----------------------------------------------------------------------
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnFamily.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnFamily.java
new file mode 100644
index 0000000..97e5f7b
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnFamily.java
@@ -0,0 +1,65 @@
+/**
+ * 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.yarn.server.timelineservice.storage.application;
+
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnFamily;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.Separator;
+
+/**
+ * Represents the application table column families.
+ */
+public enum ApplicationColumnFamily implements ColumnFamily<ApplicationTable> {
+
+  /**
+   * Info column family houses known columns, specifically ones included in
+   * columnfamily filters.
+   */
+  INFO("i"),
+
+  /**
+   * Configurations are in a separate column family for two reasons: a) the size
+   * of the config values can be very large and b) we expect that config values
+   * are often separately accessed from other metrics and info columns.
+   */
+  CONFIGS("c"),
+
+  /**
+   * Metrics have a separate column family, because they have a separate TTL.
+   */
+  METRICS("m");
+
+  /**
+   * Byte representation of this column family.
+   */
+  private final byte[] bytes;
+
+  /**
+   * @param value create a column family with this name. Must be lower case and
+   *          without spaces.
+   */
+  private ApplicationColumnFamily(String value) {
+    // column families should be lower case and not contain any spaces.
+    this.bytes = Bytes.toBytes(Separator.SPACE.encode(value));
+  }
+
+  public byte[] getBytes() {
+    return Bytes.copy(bytes);
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/9af30d46/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnPrefix.java
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diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnPrefix.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnPrefix.java
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+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-timelineservice-hbase/hadoop-yarn-server-timelineservice-hbase-common/src/main/java/org/apache/hadoop/yarn/server/timelineservice/storage/application/ApplicationColumnPrefix.java
@@ -0,0 +1,150 @@
+/**
+ * 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.yarn.server.timelineservice.storage.application;
+
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnFamily;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnHelper;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnPrefix;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.GenericConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.LongConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.Separator;
+import org.apache.hadoop.yarn.server.timelineservice.storage.common.ValueConverter;
+import org.apache.hadoop.yarn.server.timelineservice.storage.flow.Attribute;
+
+/**
+ * Identifies partially qualified columns for the application table.
+ */
+public enum ApplicationColumnPrefix implements ColumnPrefix<ApplicationTable> {
+
+  /**
+   * To store TimelineEntity getIsRelatedToEntities values.
+   */
+  IS_RELATED_TO(ApplicationColumnFamily.INFO, "s"),
+
+  /**
+   * To store TimelineEntity getRelatesToEntities values.
+   */
+  RELATES_TO(ApplicationColumnFamily.INFO, "r"),
+
+  /**
+   * To store TimelineEntity info values.
+   */
+  INFO(ApplicationColumnFamily.INFO, "i"),
+
+  /**
+   * Lifecycle events for an application.
+   */
+  EVENT(ApplicationColumnFamily.INFO, "e"),
+
+  /**
+   * Config column stores configuration with config key as the column name.
+   */
+  CONFIG(ApplicationColumnFamily.CONFIGS, null),
+
+  /**
+   * Metrics are stored with the metric name as the column name.
+   */
+  METRIC(ApplicationColumnFamily.METRICS, null, new LongConverter());
+
+  private final ColumnFamily<ApplicationTable> columnFamily;
+
+  /**
+   * Can be null for those cases where the provided column qualifier is the
+   * entire column name.
+   */
+  private final String columnPrefix;
+  private final byte[] columnPrefixBytes;
+  private final ValueConverter valueConverter;
+
+  /**
+   * Private constructor, meant to be used by the enum definition.
+   *
+   * @param columnFamily that this column is stored in.
+   * @param columnPrefix for this column.
+   */
+  private ApplicationColumnPrefix(ColumnFamily<ApplicationTable> columnFamily,
+      String columnPrefix) {
+    this(columnFamily, columnPrefix, GenericConverter.getInstance());
+  }
+
+  /**
+   * Private constructor, meant to be used by the enum definition.
+   *
+   * @param columnFamily that this column is stored in.
+   * @param columnPrefix for this column.
+   * @param converter used to encode/decode values to be stored in HBase for
+   * this column prefix.
+   */
+  private ApplicationColumnPrefix(ColumnFamily<ApplicationTable> columnFamily,
+      String columnPrefix, ValueConverter converter) {
+    this.valueConverter = converter;
+    this.columnFamily = columnFamily;
+    this.columnPrefix = columnPrefix;
+    if (columnPrefix == null) {
+      this.columnPrefixBytes = null;
+    } else {
+      // Future-proof by ensuring the right column prefix hygiene.
+      this.columnPrefixBytes =
+          Bytes.toBytes(Separator.SPACE.encode(columnPrefix));
+    }
+  }
+
+  /**
+   * @return the column name value
+   */
+  private String getColumnPrefix() {
+    return columnPrefix;
+  }
+
+  @Override
+  public byte[] getColumnPrefixBytes(byte[] qualifierPrefix) {
+    return ColumnHelper.getColumnQualifier(
+        this.columnPrefixBytes, qualifierPrefix);
+  }
+
+  @Override
+  public byte[] getColumnPrefixBytes(String qualifierPrefix) {
+    return ColumnHelper.getColumnQualifier(
+        this.columnPrefixBytes, qualifierPrefix);
+  }
+
+  @Override
+  public byte[] getColumnFamilyBytes() {
+    return columnFamily.getBytes();
+  }
+
+  @Override
+  public byte[] getColumnPrefixInBytes() {
+    return columnPrefixBytes != null ? columnPrefixBytes.clone() : null;
+  }
+
+  @Override
+  public Attribute[] getCombinedAttrsWithAggr(Attribute... attributes) {
+    return attributes;
+  }
+
+  @Override
+  public boolean supplementCellTimeStamp() {
+    return false;
+  }
+
+  public ValueConverter getValueConverter() {
+    return valueConverter;
+  }
+}


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