Java tutorial
/** * Copyright (C) 2012 Ness Computing, 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://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 com.nesscomputing.service.discovery.client; import java.net.InetSocketAddress; import java.util.Iterator; import java.util.Map; import org.apache.commons.configuration.Configuration; import org.apache.commons.lang3.ArrayUtils; import org.apache.commons.lang3.StringUtils; import com.google.common.base.Preconditions; import com.google.common.collect.ImmutableMap; import com.google.common.collect.Maps; import com.google.inject.AbstractModule; import com.google.inject.Binder; import com.google.inject.Provides; import com.google.inject.Scopes; import com.google.inject.Singleton; import com.google.inject.binder.LinkedBindingBuilder; import com.google.inject.multibindings.Multibinder; import com.google.inject.name.Named; import com.google.inject.name.Names; import com.nesscomputing.config.Config; import com.nesscomputing.config.ConfigProvider; import com.nesscomputing.httpclient.guice.HttpClientModule; import com.nesscomputing.logging.Log; import com.nesscomputing.service.discovery.client.internal.DiscoveryClientImpl; import com.nesscomputing.service.discovery.client.internal.ReadOnlyDiscoveryClientImpl; /** * Module for the client side of service discovery. */ public class DiscoveryClientModule extends AbstractModule { public static final String ZOOKEEPER_CONNECT_NAME = "_zookeeper_connect"; public static final Named ZOOKEEPER_CONNECT_NAMED = Names.named(ZOOKEEPER_CONNECT_NAME); private static final Log LOG = Log.findLog(); private final boolean readOnly; /** * Installs a read/write discovery client. */ public DiscoveryClientModule() { this(false); } /** * Installs a read/write discovery client. * * @param readonly - True if the client should be read only (allow service lookup but no announcements. */ public DiscoveryClientModule(final boolean readOnly) { this.readOnly = readOnly; } @Override public void configure() { bind(DiscoveryClientConfig.class).toProvider(ConfigProvider.of(DiscoveryClientConfig.class)) .in(Scopes.SINGLETON); bind(ServiceURIConverter.class).in(Scopes.SINGLETON); if (readOnly) { bind(ReadOnlyDiscoveryClient.class).to(ReadOnlyDiscoveryClientImpl.class).in(Scopes.SINGLETON); } else { bind(DiscoveryClient.class).to(DiscoveryClientImpl.class).in(Scopes.SINGLETON); bind(ReadOnlyDiscoveryClient.class).to(DiscoveryClient.class).in(Scopes.SINGLETON); bind(ServiceAnnouncer.class).asEagerSingleton(); } HttpClientModule.bindNewObserver(binder()).to(DiscoveryServiceInterceptor.class); } /** * Register a new Announcement with service discovery. This will only work with the read/write Discovery client and * it requires binding the ServiceAnnouncer as an eager singleton. * @return the binding builder you should register with */ public static LinkedBindingBuilder<ServiceInformation> bindNewAnnouncement(final Binder binder) { return Multibinder.newSetBinder(binder, ServiceInformation.class).addBinding(); } @Provides @Singleton @Named(ZOOKEEPER_CONNECT_NAME) String getConnectString(@Named(ZOOKEEPER_CONNECT_NAME) final Map<Integer, InetSocketAddress> zookeeperServers, final DiscoveryClientConfig clientConfig) { final StringBuilder sb = new StringBuilder(); for (final InetSocketAddress address : zookeeperServers.values()) { if (sb.length() > 0) { sb.append(','); } sb.append(address.getAddress().getHostAddress()).append(':').append(address.getPort()); } if (sb.length() == 0) { if (clientConfig.isEnabled()) { throw new IllegalStateException("Service discovery is enabled but no servers found!"); } else { LOG.info("No servers found!"); } } return sb.toString(); } @Provides @Singleton @Named(ZOOKEEPER_CONNECT_NAME) Map<Integer, InetSocketAddress> getZookeeperServers(final Config config, final DiscoveryClientConfig clientConfig) { Map<Integer, InetSocketAddress> results = Maps.newHashMap(); if (!clientConfig.isEnabled()) { LOG.warn("Service Discovery is administratively disabled."); } else { final Configuration zookeeperConfig = config.getConfiguration("ness.zookeeper"); // This can be explicitly given to support the "Three servers, one host" configuration. final String[] servers = zookeeperConfig.getStringArray("clientConnect"); if (ArrayUtils.isNotEmpty(servers)) { LOG.debug("Found explicit 'ness.zookeeper.clientConnect' string (%s)", StringUtils.join(servers, ",")); int serverId = 1; for (String server : servers) { final String parts[] = StringUtils.split(server, ":"); InetSocketAddress serverAddress = new InetSocketAddress(parts[0], Integer.parseInt(parts[1])); results.put(serverId++, serverAddress); } } else { LOG.debug("Building connectString from server configuration."); final int clientPort = zookeeperConfig.getInt("clientPort"); LOG.debug("ness.zookeeper.clientPort is %d", clientPort); for (final Iterator<?> it = zookeeperConfig.getKeys("server"); it.hasNext();) { final String key = it.next().toString(); final String[] keyElements = StringUtils.split(key, "."); final String value = zookeeperConfig.getString(key); final Integer serverId = Integer.parseInt(keyElements[keyElements.length - 1]); final String parts[] = StringUtils.split(value, ":"); InetSocketAddress serverAddress = new InetSocketAddress(parts[0], clientPort); results.put(serverId, serverAddress); LOG.debug("Server # %d : %s", serverId, serverAddress); } // If there are less than two servers, this is running in standalone mode. In that case, // use the clientAddress, because that is what the server will be using. if (results.size() < 2) { LOG.info("Found less than two servers, falling back to clientPortAddress/clientPort!"); final String clientAddress = zookeeperConfig.getString("clientPortAddress"); Preconditions.checkState(clientAddress != null, "Client address must not be null!"); final InetSocketAddress serverAddress = new InetSocketAddress(clientAddress, clientPort); LOG.debug("Server: %s", serverAddress); results = ImmutableMap.of(1, serverAddress); } } if (LOG.isDebugEnabled()) { for (Map.Entry<Integer, InetSocketAddress> entry : results.entrySet()) { LOG.debug("Server # %d : %s", entry.getKey(), entry.getValue()); } } } return results; } }