Couchbase Client Library: Java 1.0 - Chapter 2. Tutorial

2.3. Connecting with the Server
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2.3. Connecting with the Server

The driver library contains a number of different ways to connect to a Couchbase server. First, I will begin with a discussion of these methods and then we will use one of those methods to make the chat room client application connect with your Couchbase installation.

There are more than one way of connecting with one or more Couchbase servers from the driver:

A direct connection can be made by creating an instance of the CouchbaseClient object and passing in one or more addresses. For example:
```
URI server = new URI(addresses);
                ArrayList<URI> serverList = new ArrayList<URI>();
                serverList.add(server);
                CouchbaseClient client = new CouchbaseClient(
                        serverList, "default", "");
```
It's recommended to provide more than one server address of all the servers participating in the Couchbase cluster since the client can recover easily if the original server goes down.

Use the connection factory CouchbaseConnectionFactoryconstructors to establish a connection with your server:

URI base = new URI(String.format(
         "http://%s:8091/pools", serverAddress));
    ArrayList<URI> serverList = new ArrayList<URI>();
    serverList.add(base);
    CouchbaseConnectionFactory cf = new CouchbaseConnectionFactory(serverList,
       "default", "");

Create a connection that is authenticated using SASL by using a CouchbaseConnectionFactory. Merely specifying the authenticated bucket will establish an authenticated connection. In the case of Couchbase, the username and password you use here are based on the buckets you have defined on the server. The username is the bucket name, and the password is the password used when creating the bucket. I will talk more about this later, in the meantime here is the code you will need to authenticate and start using a bucket with SASL authentication.
```
CouchbaseConnectionFactory cf = new CouchbaseConnectionFactory(baseURIs,
       "rags", "password");
    client = new CouchbaseClient((CouchbaseConnectionFactory) cf);
```

Let's start making modifications to the tutorial Main.java class in order to make our first connection. Here we will be making an unauthenticated ASCII protocol connection to the server. After you have the tutorial code working, you can easily go back and change the connect() method to use authentication.

First you modify your main() method as follows:

public static void main(String[] args) {

    if (args.length != 1) {
        System.err.println("usage: serveraddress");
        System.exit(1);
    }

    String serverAddress = args[0];

    System.out.println(String.format("Connecting to %s",serverAddress));

     try {

             connect(serverAddress);
             client.shutdown(1, TimeUnit.MINUTES);

    } catch (IOException ex) {
      	  ex.printStackTrace();
    }

}

Next, add the connect() method.

private void connect(String serverAddress) throws Exception {

        URI base = new URI(String.format("http://%s:8091/pools",serverAddress));
        List<URI> baseURIs = new ArrayList<URI>();
        baseURIs.add(base);
        CouchbaseConnectionFactory cf = new
                CouchbaseConnectionFactory(baseURIs, "default", "");

        client = new CouchbaseClient((CouchbaseConnectionFactory) cf);

You'll recognize this constructor as a single server connection. What if you want to know more about the current connection state such as when the connection has been gained, or lost? You can add a connection observer by modifying the connect method and adding the following lines:

public void connectionLost(SocketAddress sa) {
                System.out.println("Connection lost to " + sa.toString());
            }

            public void connectionEstablished(SocketAddress sa,
                    int reconnectCount) {
                System.out.println("Connection established with "
                        + sa.toString());
                System.out.println("Reconnected count: " + reconnectCount);
            }
        });

    }

You've only connected with one server, what if it goes offline? This can easily be fixed by changing the first three lines of the connect method:

URI fallback = new URI(
            String.format("http://%s:8091/pools",fallbackAddress));
        baseURIs.add(fallback);

This class will even work with colon-delimited IPv6 addresses.

Finally, you need to create the static member variable to store the client instance at the top of the class:

private static CouchbaseClient client;

Now you can try compiling and running the application.

You can see that the driver outputs some logging statements indicating that it is making two connections. You can also see that the connection observer you added to the connect() method is being called with the addresses of the two servers as they are connected and the reconnection count is 1 indicating that the network is in good shape. It's ready to get some work done.

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2.2. Building a Chat Room Application	Home	2.4. Logging in the Chat Application