My favorite technical book of all time has been the C Programming Language by Kernighan and Ritchie affectionately referred to as K&R. They popularized a term that will ever be in a developer parlance - Hello World.

#include <stdio.h>
main()
{
    printf("Hello World\n");
}

This innocous looking program has helped launch the careers of many a programmer and has been the basis of the wild success of many an API. Dennis Ritchie who passed away recently, or as some would refer to it as returned from main(), was also inspirational in creating the Unix Operating System.

So, without further ado, here's the Hello World for Couchbase.

import java.net.URI;
import java.util.List;
import java.util.ArrayList;
import com.couchbase.client.CouchbaseClient;

public class HelloCouchbase {
  public static void main(String args[]) {
    try {
      URI local = new URI("http://localhost:8091/pools");
      List<URI> baseURIs = new ArrayList<URI>();
      baseURIs.add(local);

      CouchbaseClient c = new CouchbaseClient(baseURIs, "default", "");
      c.set("key", 0, "Hello World");
      System.out.println(c.get("key"));
    } catch (Exception e) {
      System.err.println("Error connecting to Couchbase: "
          + e.getMessage());
     System.exit(0);
    }
  }
}

Admittedly a much longer program.

What the program does is very simply to get the value of a key that was just set. However, in a distributed system, there are no guarantees due to the inherent dynamic nature of the system. The eight fallacies of distributed computing goes into greater details on this. From a programmer's perspective, the Java client libraries for Couchbase abstract this dyamic nature of a cluster.  They provide a basic set of operations such as get and set which is available in either synchronous or asynchronous forms. It's possible to use these simple operations in conjunction with operations that help implement atomicity such as check and set(cas) to implement high performant and scalable systems for the real world.

Any more and I am deviating from the philosophy of the Hello World.

I will be contributing more towards using Couchbase with the Java client libraries, but in the meantime, here are a few useful links.