Create a connection object

To connect to Bigtable using the Cloud Bigtable HBase client for Java, you'll need to set configuration properties, then create a Connection object. Creating a Connection object is a heavyweight operation, so create as few of these objects as possible:

If you use replication, or if you use app profiles to identify different types of traffic to your instance, create one Connection object per app profile and share the objects among threads in your application.
If you don't use replication or app profiles, create a single Connection object and share it among threads in your application.

There are a few ways to specify the configuration settings for a Connection object:

Include the settings in your code. If your application uses multiple app profiles (for example, if it performs several different functions, with a separate app profile for each function), you must use this option.

You can also use this option if you prefer to keep configuration settings in your application's code, or if it's not practical to include an external configuration file as a resource in your application.
Use an hbase-site.xml file to store settings. Use this option if your application uses both HBase and Bigtable, or if you prefer to keep your Bigtable configuration settings in a standalone file.

The following sections explain each way to configure and create a Connection object.

Including settings in your code

The following example shows how you might create a Connection object in your own application. Replace [VALUES_IN_BRACKETS] with the correct values for your instance:

package com.example.helloworld;

import com.google.cloud.bigtable.hbase.BigtableConfiguration;
import com.google.cloud.bigtable.hbase.BigtableOptionsFactory;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.client.Connection;

public class BigtableHelper {
  private static final String PROJECT_ID = "[YOUR_PROJECT_ID]";
  private static final String INSTANCE_ID = "[YOUR_INSTANCE_ID]";
  // Include the following line if you are using app profiles.
  // If you do not include the following line, the connection uses the
  // default app profile.
  private static final STRING APP_PROFILE_ID = "[YOUR_APP_PROFILE_ID]";

  private static Connection connection = null;

  public static void connect() throws IOException {
    Configuration config = BigtableConfiguration.configure(PROJECT_ID, INSTANCE_ID);
    // Include the following line if you are using app profiles.
    // If you do not include the following line, the connection uses the
    // default app profile.
    config.set(BigtableOptionsFactory.APP_PROFILE_ID_KEY, APP_PROFILE_ID);

    connection = BigtableConfiguration.connect(config);
  }
}

Using an hbase-site.xml file

This section explains how to create a Connection object by including the configuration settings in an hbase-site.xml file.

Sample code

The following example shows how you might configure and create a Connection object in your own application:

package com.example.helloworld;

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;

public class BigtableHelper {
  private static Connection connection = null;

  public static void connect() throws IOException {
    Configuration config = HBaseConfiguration.create();
    connection = ConnectionFactory.createConnection(config);
  }
}

A separate hbase-site.xml file is included in the JAR file's resources. When you create the Configuration object, the Cloud Bigtable HBase client for Java automatically reads the settings from the hbase-site.xml file.

The following sections explain how to implement this method in your application.

Creating the hbase-site.xml file

In your project's src/main/resources directory, create a file called hbase-site.xml. The file should contain all of the properties shown in the following example. Replace [VALUES_IN_BRACKETS] with the correct values for your instance:

<configuration>
  <property>
    <name>hbase.client.connection.impl</name>
    <value>com.google.cloud.bigtable.hbase1_x.BigtableConnection</value>
  </property>
  <property>
    <name>google.bigtable.project.id</name>
    <value>[YOUR_PROJECT_ID]</value>
  </property>
  <property>
    <name>google.bigtable.instance.id</name>
    <value>[YOUR_INSTANCE_ID]</value>
  </property>
  <!--
    Include the following property if you are using app profiles.
    If you do not include the following property, the connection uses the
    default app profile.
  -->
  <property>
    <name>google.bigtable.app_profile.id</name>
    <value>[YOUR_APP_PROFILE_ID]</value>
  </property>
</configuration>

Adding hbase-site.xml to the JAR file

After you create the hbase-site.xml file, you'll need to update your build script to include the src/main/resources directory in your project's JAR file.

If you're using Maven, edit the <build> element of your pom.xml file to copy the resources to your JAR file:

<build>
  <resources>
    <resource>
      <directory>src/main/resources</directory>
      <filtering>true</filtering>
    </resource>
  </resources>
</build>

Creating the Connection object

Now you can update your code to create a Configuration object. When you create this object, the Cloud Bigtable HBase client for Java automatically reads the settings from the hbase-site.xml file. You can then use these settings to create a Connection object:

Configuration config = HBaseConfiguration.create();
connection = ConnectionFactory.createConnection(config);