The first class we're going to implement is the ConnectionManager in the src/main/java/com/couchbase/beersample directory. This is a ServletContextListener which starts the CouchbaseClient on startup and closes the connection when the application is shut down. Here is the full class, the discussion follows afterwards (the comments and imports have been removed to shorten the listing a bit).

package com.couchbase.beersample;

public class ConnectionManager implements ServletContextListener {

  private static CouchbaseClient client;

  private static final Logger logger = Logger.getLogger(
    ConnectionManager.class.getName());

  @Override
  public void contextInitialized(ServletContextEvent sce) {
    logger.log(Level.INFO, "Connecting to Couchbase Cluster");
    ArrayList<URI> nodes = new ArrayList<URI>();
    nodes.add(URI.create("http://127.0.0.1:8091/pools"));
    try {
      client = new CouchbaseClient(nodes, "beer-sample", "");
    } catch (IOException ex) {
      logger.log(Level.SEVERE, ex.getMessage());
    }
  }

  @Override
  public void contextDestroyed(ServletContextEvent sce) {
    logger.log(Level.INFO, "Disconnecting from Couchbase Cluster");
    client.shutdown();
  }

  public static CouchbaseClient getInstance() {
    return client;
  }

}

The contextInitialized and the contextDestroyed method are called on startup and shutdown. When the application starts, the CouchbaseClient is initialized with the list of nodes, the bucket name and the password (empty). Note that in a production deployment, you want to fetch these environment-dependent settings from a config file. The getInstance() method will be called from the servlets to obtain the CouchbaseClient instance.

When you publish your application, you should see in the server logs that Couchbase is correctly connecting to the bucket. If an exception is raised during this phase, it means that your settings are wrong or you don't have no Couchbase Server running at the given nodes.

INFO: Connecting to Couchbase Cluster
SEVERE: 2012-12-05 14:39:00.419 INFO com.couchbase.client.CouchbaseConnection:  Added {QA sa=/127.0.0.1:11210, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0} to connect queue
SEVERE: 2012-12-05 14:39:00.426 INFO com.couchbase.client.CouchbaseConnection:  Connection state changed for sun.nio.ch.SelectionKeyImpl@1b554a4
SEVERE: 2012-12-05 14:39:00.458 INFO net.spy.memcached.auth.AuthThread:  Authenticated to localhost/127.0.0.1:11210
SEVERE: 2012-12-05 14:39:00.487 INFO com.couchbase.client.ViewConnection:  Added localhost to connect queue
SEVERE: 2012-12-05 14:39:00.489 INFO com.couchbase.client.CouchbaseClient:  viewmode property isn't defined. Setting viewmode to production mode
INFO: WEB0671: Loading application [com.couchbase_beersample-java_war_1.0-SNAPSHOT] at [/]
INFO: com.couchbase_beersample-java_war_1.0-SNAPSHOT was successfully deployed in 760 milliseconds.