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Cassandra library for Dropwizard
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/*
 * Copyright 2017 Composable Systems Limited
 *
 *    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://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License 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 systems.composable.dropwizard.cassandra;

import io.dropwizard.Configuration;
import io.dropwizard.ConfiguredBundle;
import io.dropwizard.setup.Bootstrap;
import io.dropwizard.setup.Environment;

/**
 * A reusable bundle of Cassandra functionality that initializes {@link javax.ws.rs.core.Context}-annotated
 * {@link com.datastax.driver.core.Cluster} and {@link com.datastax.driver.core.Session} object instances.
 * The main usage is following:
 * 

 *  In your main application class add the following code into your
 * {@link io.dropwizard.Application#initialize(Bootstrap)} method:
 *  * @Override
 * public void initialize(final Bootstrap<MyAppConfiguration> bootstrap) {
 *   //...
 *   bootstrap.addBundle(new CassandraBundle<MyAppConfiguration>() {
 *     @Override
 *     public CassandraFactory getCassandraFactory(MyAppConfiguration configuration) {
 *       return configuration.getCassandraFactory();
 *     }
 *   });
 *   //...
 * }
 * 
 * 
 * Now you may inject into your resources either {@link com.datastax.driver.core.Cluster}:
 *  * @Path("/test")
 * public class TestService {
 *   @Context Cluster cluster;
 *
 *   @Produces(MediaType.APPLICATION_JSON)
 *   @GET
 *   @Path("/users")
 *   public List<User> getUsers() {
 *     try (final Session session = cluster.connect("auth")) {
 *       final ResultSet resultSet = session.execute("SELECT * FROM users");
 *       //...
 *     }
 *   }
 * }
 * 
 * or {@link com.datastax.driver.core.Session} instance:
 *  * @Path("/test")
 * public class TestService {
 *   @Produces(MediaType.APPLICATION_JSON)
 *   @GET
 *   @Path("/users")
 *   public List<User> getUsers(@Context Session session) {
 *     final ResultSet resultSet = session.execute("SELECT * FROM users");
 *     //...
 *   }
 * }
 * 
 * 
 * 
 * If you use injected {@link com.datastax.driver.core.Session} instance, then session
 * is opened with keyspace that is defined in your application configuration for Cassandra
 * (see {@link CassandraFactory#getKeyspace()}).
 * If keyspace isn't specified in your configuration, then session will be opened with no
 * defined keyspace, so that you have to explicitly specify it in statements for tables/column families.
 *
 */
public abstract class CassandraBundle
		implements ConfiguredBundle, CassandraConfiguration {

	/**
	 * Initializes Cassandra in application bootstrap.
	 * Does nothing for now.
	 *
	 * @param bootstrap The application bootstrap
	 */
	@Override
	public void initialize(Bootstrap bootstrap) {}

	/**
	 * Initializes the Cassandra environment: registers context binder for
	 * {@link com.datastax.driver.core.Cluster} and {@link com.datastax.driver.core.Session} instances.
	 *
	 * @param configuration The configuration object
	 * @param environment The application's Environment
	 */
	@Override
	public void run(T configuration, Environment environment) throws Exception {
		environment.jersey().register(CassandraProvider.binder(getCassandraFactory(configuration), environment));
	}
}