HBase connection pool in Tomcat?

Question

I have a small HBase cluster running with a Java frontend. I have it working successfully with test code that establishes a connection, runs test data, and disconnects, but I need to extend it into a webapp as part of a larger project. It was suggested that I use Tomcat as the HTTP service to interface with the database, and as part of this I need to set up a connection pool.

I understand connection pools on a conceptual level (a pile of persistent connections to the DB handed out to clients as needed and returned to the pool when discarded), but I've never written a webapp before and Tomcat is vexxing me. I can find loads of documentation on how to setup a connection pool to a SQL server using JDBC , but nothing on HBase (or, for that matter, anything BUT SQL ) and nothing on how to (or whether I can or should) write a custom interface to get it working with Tomcat . Is this doable, or even possible, or should I be taking a different approach?

Answer 1

I think it would be hard to find something that is made for Tomcat , I don't think that such thing exist. Most people are probably using custom classes. That being said, you should probably build something around the HTablePool that comes with HBase .

Here an example of something you can use in your project :

public class HTableManager {

    public static int HTABLE_POOL_SIZE = 15;

    private static HTableManager instance;
    private static HTablePool hTablePool;

    /**
     * Private Constructor
     */
    private HTableManager() {
        try {
            Configuration config = HBaseConfiguration.create();
            config.set("hbase.defaults.for.version.skip", "false");

            hTablePool = new HTablePool(config, HTABLE_POOL_SIZE);
        } catch (IOException ex) {
            // Error handling
        }
    }

    /**
     * @return The HbaseTableManager instance
     */
    public static HTableManager getInstance() {
        if (instance == null) {
            instance = new HTableManager();
        }
        return instance;
    }

    /**
     * Method used to retrieve a HTable instance.
     * 
     * @param tableName The table name
     * @return The HTableInterface instance
     * @throws IOException 
     */
    public synchronized HTableInterface getHTable(String tableName) throws IOException {
        return hTablePool.getTable(tableName);
    }
}

And then you can use it like this :

HTableManager hTableManager = htableManager.getInstance();
HTableInterface hTable = hTableManager.getHTable("yourTableName");
...
// Work with the hTable instance
...
// A call to the close method returns it to the pool
hTable.close();