ColumnManagerForHBaseGist.java

package org.commonvox.hbase_column_manager_gist;

import java.io.File;
import java.io.IOException;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.NamespaceDescriptor;
import org.apache.hadoop.hbase.NamespaceNotFoundException;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.util.Bytes;
import org.commonvox.hbase_column_manager.ChangeEventMonitor;
import org.commonvox.hbase_column_manager.MConnectionFactory;
import org.commonvox.hbase_column_manager.RepositoryAdmin;

/**
 * THIS GIST DEMONSTRATES BASIC USAGE OF THE ColumnManagerForHBase API FOR
 *  (1) REPORTING ON COLUMN QUALIFIERS
 *  (2) EXPORTING HBASE SCHEMA, and
 *  (3) EXPORTING AN AUDIT-TRAIL OF SCHEMA CHANGES ("change events")
 * 
 * Successful running of this application requires access to an active instance
 * of HBase. For install instructions for a standalone instance of HBase, please
 * refer to:
 *        https://hbase.apache.org/book.html#quickstart
 *
 * For all available versions of hbase-column-manager, please consult Maven Central Repository:
 *        http://bit.ly/ColumnManagerMaven
 *
 * FULL INSTRUCTIONS for installation and activation of ColumnManager for HBase available here:
 *        http://bit.ly/ColumnManagerJavadocs
 * 
 */
public final class ColumnManagerForHBaseGist {

  protected static final String MY_NAMESPACE_NAME = "myTestNamespace";
  static final TableName MY_TABLE_NAME = TableName.valueOf(MY_NAMESPACE_NAME, "myTestTable");
  static final byte[] MY_COLUMN_FAMILY_NAME = Bytes.toBytes("cf");
  static final byte[] MY_FIRST_COLUMN_QUALIFIER = Bytes.toBytes("myFirstColumn");
  static final byte[] MY_SECOND_COLUMN_QUALIFIER = Bytes.toBytes("mySecondColumn");
  static final byte[] MY_ROW_ID01 = Bytes.toBytes("rowId01");
  static final byte[] MY_ROW_ID02 = Bytes.toBytes("rowId02");

  public static void main(final String[] args) throws Exception {

    try (Connection connection = MConnectionFactory.createConnection();
            Admin admin = connection.getAdmin()) {

      // use standard hbase-client API to create namepace/table & add rows
      if (!namespaceExists(admin, MY_NAMESPACE_NAME)) {
        admin.createNamespace(NamespaceDescriptor
                .create(MY_NAMESPACE_NAME).build());
      }
      if (!admin.tableExists(MY_TABLE_NAME)) {
        admin.createTable(new HTableDescriptor(MY_TABLE_NAME)
                .addFamily(new HColumnDescriptor(MY_COLUMN_FAMILY_NAME)));
      }

      try (Table table = connection.getTable(MY_TABLE_NAME)) {

        table.put(new Put(MY_ROW_ID01)
                .addColumn(MY_COLUMN_FAMILY_NAME, MY_FIRST_COLUMN_QUALIFIER,
                    Bytes.toBytes("Hello"))
                .addColumn(MY_COLUMN_FAMILY_NAME, MY_SECOND_COLUMN_QUALIFIER,
                    Bytes.toBytes("World!")));
        table.put(new Put(MY_ROW_ID02)
                .addColumn(MY_COLUMN_FAMILY_NAME, MY_FIRST_COLUMN_QUALIFIER,
                    Bytes.toBytes("Hello"))
                .addColumn(MY_COLUMN_FAMILY_NAME, MY_SECOND_COLUMN_QUALIFIER,
                    Bytes.toBytes("ColumnManager!")));
      }

      // INVOKE methods to query the ColumnManager repository
      RepositoryAdmin repositoryAdmin = new RepositoryAdmin(connection);
      repositoryAdmin.outputReportOnColumnQualifiers(new File("colQualifierReport.csv"), MY_TABLE_NAME);
      repositoryAdmin.exportSchema(new File("exportedHBaseSchema.xml"), MY_NAMESPACE_NAME);
      ChangeEventMonitor changeEventMonitor = repositoryAdmin.getChangeEventMonitor();
      ChangeEventMonitor.exportChangeEventListToCsvFile(
              changeEventMonitor.getAllChangeEvents(), new File("changeEventsReport.csv"));

      // use standard hbase-client API to delete table & namespace
      admin.disableTable(MY_TABLE_NAME); // Disable a table before deleting it!
      admin.deleteTable(MY_TABLE_NAME);
      admin.deleteNamespace(MY_NAMESPACE_NAME);
    }
  }

  /**
   * Checks to see whether a namespace exists.
   *
   * @param admin Standard Admin object
   * @param namespaceName Name of namespace
   * @return true If namespace exists
   * @throws IOException If IO problem encountered
   */
  static boolean namespaceExists(final Admin admin, final String namespaceName)
          throws IOException {
    try {
      admin.getNamespaceDescriptor(namespaceName);
    } catch (NamespaceNotFoundException e) {
      return false;
    }
    return true;
  }
}