SimpleCluster.java

/*
 * Copyright 2009-2012 Amazon Technologies, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *    http://aws.amazon.com/apache2.0
 *
 * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
 * OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and
 * limitations under the License.
 */
package com.amazonaws.ec2.cluster;

import java.lang.reflect.Constructor;

import com.amazonaws.services.ec2.model.Instance;

/**
 * Simple cluster implementation suitable for basic clusters that don't need a
 * lot of customization. Callers can create a new BasicCluster object and pass
 * in an implementation of the application server class that they want
 * instantiated for every host in the cluster.
 */
public class SimpleCluster extends Cluster {

	/**
	 * The application server class that will be instantiated for any hosts
	 * added to this cluster and contains all the logic required for working
	 * with application servers in this cluster (publishing, initializing, etc)
	 */
	private final Class<? extends Ec2Server> appServerClass;

	/**
	 * Creates a new SimpleCluster object that will use the specified
	 * application server class for all members of this cluster.
	 *
	 * @param clusterConfiguration
	 *            The configuration details for this cluster instance, including
	 *            the security group it runs in, the key pair used to access it,
	 *            etc.
	 * @param appServerClass
	 *            The application server subclass that will be instantiated for
	 *            all servers that are added to this cluster. This class must
	 *            have a publicly accessible constructor taking a
	 *            Instance object, otherwise this class will fail when it
	 *            tries to instantiate objects of this class for any hosts added
	 *            to this cluster.
	 */
	public SimpleCluster(ClusterConfiguration clusterConfiguration, Class<? extends Ec2Server> appServerClass) {
		super(clusterConfiguration);
		this.appServerClass = appServerClass;
	}

	/**
	 * {@inheritDoc}
	 *
	 * Simple implementation of createApplicationServer that instantiates the
	 * application server class specified in the constructor for the specified
	 * Amazon EC2 instance.
	 *
	 * @throws RuntimeException
	 *             If there were any problems instantiating the application
	 *             server class specified in this class' constructor.
	 */
	@Override
	protected Ec2Server createApplicationServer(Instance instance) {
		try {
			Constructor<? extends Ec2Server> constructor = appServerClass.getConstructor(Instance.class);
			return constructor.newInstance(instance);
		} catch (Exception e) {
			throw new RuntimeException("Unable to create new application server object of type "
					+ appServerClass.getName());
		}
	}

}