SpringCloud - Ribbon负载均衡入门与实战

<dependencies>
    <dependency><!-- 自己定义的api -->
      <groupId>com.web.springcloud</groupId>
      <artifactId>microservicecloud-api</artifactId>
      <version>${project.version}</version>
    </dependency>
    <!-- Cloud-Ribbon相关 -->
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-ribbon</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
      <!-- Spring Boot相关 -->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- 修改后立即生效，热部署相关 -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>springloaded</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-devtools</artifactId>
    </dependency>
  </dependencies>

server:
  port: 80
spring:
  application:
    name: microservicecloud-consumer
eureka:
  instance:
    prefer-ip-address: true # 注册服务的时候使用服务的ip地址
  client:
    register-with-eureka: false # 不向服务注册中心注册自己
    service-url: 
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/  
#      defaultZone: http://localhost:7001/eureka/

@Configuration
public class ConfigBean {
  @LoadBalanced//开启负载均衡机制
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate(); // 用来进行HTTP通信
    }
}

@SpringBootApplication
@EnableEurekaClient
public class DeptConsumer80_App
{
  public static void main(String[] args)
  {
    SpringApplication.run(DeptConsumer80_App.class, args);
  }
}

@RestController
public class DeptController_Consumer
{
//  private static final String REST_URL_PREFIX = "http://localhost:8001";
  private static final String REST_URL_PREFIX = "http://MICROSERVICECLOUD-DEPT";
  //这里使用服务名，也就是服务提供者应用名大写
  @Autowired
  private RestTemplate restTemplate;
  //...
}

server:
  port: 8002
mybatis:
  config-location: classpath:mybatis/mybatis.cfg.xml        # mybatis配置文件所在路径
  type-aliases-package: com.web.springcloud.entities    # 所有Entity别名类所在包
  mapper-locations:
  - classpath:mybatis/mapper/**/*.xml                       # mapper映射文件
spring:
   application:
    name: microservicecloud-dept # 这里不能修改
   datasource:
    type: com.alibaba.druid.pool.DruidDataSource            # 当前数据源操作类型
    driver-class-name: com.mysql.jdbc.Driver              # mysql驱动包
#    driver-class-name: org.gjt.mm.mysql.Driver              # mysql驱动包
    url: jdbc:mysql://localhost:3306/clouddb02              # 数据库名称
    username: root
    password: 123456
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: true
    testOnReturn: false
    poolPreparedStatements: true
    #配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500
#    dbcp2:
#      min-idle: 5                                           # 数据库连接池的最小维持连接数
#      initial-size: 5                                       # 初始化连接数
#      max-total: 5                                          # 最大连接数
#      max-wait-millis: 200                                  # 等待连接获取的最大超时时间
eureka:
  client: #客户端注册进eureka服务列表内
    service-url: 
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/      
#      defaultZone: http://localhost:7001/eureka/
  instance:
    instance-id: microservicecloud-dept8002 # 自定义服务实例Id
    prefer-ip-address: true     #访问路径可以显示IP地址     
# http://192.168.2.100:8002/info优化显示
info: 
  app.name: web-microservicecloud
  company.name: www.web.com
  build.artifactId: $project.artifactId$
  build.version: $project.version$

/**
 * Interface that defines a "Rule" for a LoadBalancer. A Rule can be thought of
 * as a Strategy for loadbalacing. Well known loadbalancing strategies include
 * Round Robin, Response Time based etc.
 * 
 * @author stonse
 * 
 */
public interface IRule{
    /*
     * choose one alive server from lb.allServers or
     * lb.upServers according to key
     * 
     * @return choosen Server object. NULL is returned if none
     *  server is available 
     */
    public Server choose(Object key);
    public void setLoadBalancer(ILoadBalancer lb);
    public ILoadBalancer getLoadBalancer();    
}

/**
 * Annotation to mark a RestTemplate bean to be configured to use a LoadBalancerClient
 * @author Spencer Gibb
 */
@Target({ ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Qualifier
public @interface LoadBalanced {
}

/*
 * Copyright 2013-2015 the original author or authors.
 *
 * 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 org.springframework.cloud.netflix.ribbon;
import java.io.IOException;
import java.net.URI;
import java.util.Collections;
import java.util.Map;
import org.springframework.cloud.client.DefaultServiceInstance;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.cloud.client.loadbalancer.LoadBalancerRequest;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.Server;
/**
 * @author Spencer Gibb
 * @author Dave Syer
 * @author Ryan Baxter
 */
public class RibbonLoadBalancerClient implements LoadBalancerClient {
  private SpringClientFactory clientFactory;
  public RibbonLoadBalancerClient(SpringClientFactory clientFactory) {
    this.clientFactory = clientFactory;
  }
  @Override
  public URI reconstructURI(ServiceInstance instance, URI original) {
    Assert.notNull(instance, "instance can not be null");
    String serviceId = instance.getServiceId();
    RibbonLoadBalancerContext context = this.clientFactory
        .getLoadBalancerContext(serviceId);
    Server server = new Server(instance.getHost(), instance.getPort());
    IClientConfig clientConfig = clientFactory.getClientConfig(serviceId);
    ServerIntrospector serverIntrospector = serverIntrospector(serviceId);
    URI uri = RibbonUtils.updateToHttpsIfNeeded(original, clientConfig,
        serverIntrospector, server);
    return context.reconstructURIWithServer(server, uri);
  }
  @Override
  public ServiceInstance choose(String serviceId) {
    Server server = getServer(serviceId);
    if (server == null) {
      return null;
    }
    return new RibbonServer(serviceId, server, isSecure(server, serviceId),
        serverIntrospector(serviceId).getMetadata(server));
  }
  @Override
  public <T> T execute(String serviceId, LoadBalancerRequest<T> request) throws IOException {
    ILoadBalancer loadBalancer = getLoadBalancer(serviceId);
    Server server = getServer(loadBalancer);
    if (server == null) {
      throw new IllegalStateException("No instances available for " + serviceId);
    }
    RibbonServer ribbonServer = new RibbonServer(serviceId, server, isSecure(server,
        serviceId), serverIntrospector(serviceId).getMetadata(server));
    return execute(serviceId, ribbonServer, request);
  }
  @Override
  public <T> T execute(String serviceId, ServiceInstance serviceInstance, LoadBalancerRequest<T> request) throws IOException {
    Server server = null;
    if(serviceInstance instanceof RibbonServer) {
      server = ((RibbonServer)serviceInstance).getServer();
    }
    if (server == null) {
      throw new IllegalStateException("No instances available for " + serviceId);
    }
    RibbonLoadBalancerContext context = this.clientFactory
        .getLoadBalancerContext(serviceId);
    RibbonStatsRecorder statsRecorder = new RibbonStatsRecorder(context, server);
    try {
      T returnVal = request.apply(serviceInstance);
      statsRecorder.recordStats(returnVal);
      return returnVal;
    }
    // catch IOException and rethrow so RestTemplate behaves correctly
    catch (IOException ex) {
      statsRecorder.recordStats(ex);
      throw ex;
    }
    catch (Exception ex) {
      statsRecorder.recordStats(ex);
      ReflectionUtils.rethrowRuntimeException(ex);
    }
    return null;
  }
  private ServerIntrospector serverIntrospector(String serviceId) {
    ServerIntrospector serverIntrospector = this.clientFactory.getInstance(serviceId,
        ServerIntrospector.class);
    if (serverIntrospector == null) {
      serverIntrospector = new DefaultServerIntrospector();
    }
    return serverIntrospector;
  }
  private boolean isSecure(Server server, String serviceId) {
    IClientConfig config = this.clientFactory.getClientConfig(serviceId);
    ServerIntrospector serverIntrospector = serverIntrospector(serviceId);
    return RibbonUtils.isSecure(config, serverIntrospector, server);
  }
  protected Server getServer(String serviceId) {
    return getServer(getLoadBalancer(serviceId));
  }
  protected Server getServer(ILoadBalancer loadBalancer) {
    if (loadBalancer == null) {
      return null;
    }
    return loadBalancer.chooseServer("default"); // TODO: better handling of key
  }
  protected ILoadBalancer getLoadBalancer(String serviceId) {
    return this.clientFactory.getLoadBalancer(serviceId);
  }
  public static class RibbonServer implements ServiceInstance {
    private final String serviceId;
    private final Server server;
    private final boolean secure;
    private Map<String, String> metadata;
    public RibbonServer(String serviceId, Server server) {
      this(serviceId, server, false, Collections.<String, String> emptyMap());
    }
    public RibbonServer(String serviceId, Server server, boolean secure,
        Map<String, String> metadata) {
      this.serviceId = serviceId;
      this.server = server;
      this.secure = secure;
      this.metadata = metadata;
    }
    @Override
    public String getServiceId() {
      return this.serviceId;
    }
    @Override
    public String getHost() {
      return this.server.getHost();
    }
    @Override
    public int getPort() {
      return this.server.getPort();
    }
    @Override
    public boolean isSecure() {
      return this.secure;
    }
    @Override
    public URI getUri() {
      return DefaultServiceInstance.getUri(this);
    }
    @Override
    public Map<String, String> getMetadata() {
      return this.metadata;
    }
    public Server getServer() {
      return this.server;
    }
    @Override
    public String toString() {
      final StringBuffer sb = new StringBuffer("RibbonServer{");
      sb.append("serviceId='").append(serviceId).append('\'');
      sb.append(", server=").append(server);
      sb.append(", secure=").append(secure);
      sb.append(", metadata=").append(metadata);
      sb.append('}');
      return sb.toString();
    }
  }
}

  protected ILoadBalancer getLoadBalancer(String serviceId) {
    return this.clientFactory.getLoadBalancer(serviceId);
  }

protected Server getServer(ILoadBalancer loadBalancer) {
    if (loadBalancer == null) {
      return null;
    }
    return loadBalancer.chooseServer("default"); // TODO: better handling of key
  }

package com.netflix.loadbalancer;
import java.util.List;
/**
 * Interface that defines the operations for a software loadbalancer. A typical
 * loadbalancer minimally need a set of servers to loadbalance for, a method to
 * mark a particular server to be out of rotation and a call that will choose a
 * server from the existing list of server.
 * 
 * @author stonse
 * 
 */
public interface ILoadBalancer {
  /**
   * Initial list of servers.
   * This API also serves to add additional ones at a later time
   * The same logical server (host:port) could essentially be added multiple times
   * (helpful in cases where you want to give more "weightage" perhaps ..)
   * 
   * @param newServers new servers to add
   */
  public void addServers(List<Server> newServers);
  /**
   * Choose a server from load balancer.
   * 
   * @param key An object that the load balancer may use to determine which server to return. null if 
   *         the load balancer does not use this parameter.
   * @return server chosen
   */
  public Server chooseServer(Object key);
  /**
   * To be called by the clients of the load balancer to notify that a Server is down
   * else, the LB will think its still Alive until the next Ping cycle - potentially
   * (assuming that the LB Impl does a ping)
   * 
   * @param server Server to mark as down
   */
  public void markServerDown(Server server);
  /**
   * @deprecated 2016-01-20 This method is deprecated in favor of the
   * cleaner {@link #getReachableServers} (equivalent to availableOnly=true)
   * and {@link #getAllServers} API (equivalent to availableOnly=false).
   *
   * Get the current list of servers.
   *
   * @param availableOnly if true, only live and available servers should be returned
   */
  @Deprecated
  public List<Server> getServerList(boolean availableOnly);
  /**
   * @return Only the servers that are up and reachable.
     */
    public List<Server> getReachableServers();
    /**
     * @return All known servers, both reachable and unreachable.
     */
  public List<Server> getAllServers();
}

/**
 * A basic implementation of the load balancer where an arbitrary list of
 * servers can be set as the server pool. A ping can be set to determine the
 * liveness of a server. Internally, this class maintains an "all" server list
 * and an "up" server list and use them depending on what the caller asks for.
 * 
 * @author stonse
 * 
 */
public class BaseLoadBalancer extends AbstractLoadBalancer implements
        PrimeConnections.PrimeConnectionListener, IClientConfigAware {
    private static Logger logger = LoggerFactory
            .getLogger(BaseLoadBalancer.class);
    private final static IRule DEFAULT_RULE = new RoundRobinRule();
    // 这里这里这里！！！
    private final static SerialPingStrategy DEFAULT_PING_STRATEGY = new SerialPingStrategy();
    private static final String DEFAULT_NAME = "default";
    private static final String PREFIX = "LoadBalancer_";
    protected IRule rule = DEFAULT_RULE;
    protected IPingStrategy pingStrategy = DEFAULT_PING_STRATEGY;
    protected IPing ping = null;
    @Monitor(name = PREFIX + "AllServerList", type = DataSourceType.INFORMATIONAL)
    protected volatile List<Server> allServerList = Collections
            .synchronizedList(new ArrayList<Server>());
    @Monitor(name = PREFIX + "UpServerList", type = DataSourceType.INFORMATIONAL)
    protected volatile List<Server> upServerList = Collections
            .synchronizedList(new ArrayList<Server>());
    protected ReadWriteLock allServerLock = new ReentrantReadWriteLock();
    protected ReadWriteLock upServerLock = new ReentrantReadWriteLock();
    protected String name = DEFAULT_NAME;
    protected Timer lbTimer = null;
    protected int pingIntervalSeconds = 10;
    protected int maxTotalPingTimeSeconds = 5;
    protected Comparator<Server> serverComparator = new ServerComparator();
    protected AtomicBoolean pingInProgress = new AtomicBoolean(false);
    protected LoadBalancerStats lbStats;
    private volatile Counter counter = Monitors.newCounter("LoadBalancer_ChooseServer");
    private PrimeConnections primeConnections;
    private volatile boolean enablePrimingConnections = false;
    private IClientConfig config;
    private List<ServerListChangeListener> changeListeners = new CopyOnWriteArrayList<ServerListChangeListener>();
    private List<ServerStatusChangeListener> serverStatusListeners = new CopyOnWriteArrayList<ServerStatusChangeListener>();
    /**
     * Default constructor which sets name as "default", sets null ping, and
     * {@link RoundRobinRule} as the rule.
     * <p>
     * This constructor is mainly used by {@link ClientFactory}. Calling this
     * constructor must be followed by calling {@link #init()} or
     * {@link #initWithNiwsConfig(IClientConfig)} to complete initialization.
     * This constructor is provided for reflection. When constructing
     * programatically, it is recommended to use other constructors.
     */
    public BaseLoadBalancer() {
        this.name = DEFAULT_NAME;
        this.ping = null;
        setRule(DEFAULT_RULE);
        // 空参使用默认Rule
        setupPingTask();
        lbStats = new LoadBalancerStats(DEFAULT_NAME);
    }
    public BaseLoadBalancer(String lbName, IRule rule, LoadBalancerStats lbStats) {
        this(lbName, rule, lbStats, null);
    }
    //...
 }

 /* Ignore null rules */
    public void setRule(IRule rule) {
        if (rule != null) {
            this.rule = rule;
        } else {
            /* default rule */
            this.rule = new RoundRobinRule();
        }
        if (this.rule.getLoadBalancer() != this) {
            this.rule.setLoadBalancer(this);
        }
    }

@Configuration
public class ConfigBean {
  @LoadBalanced//开启负载均衡机制
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate(); // 用来进行HTTP通信
    }
}

/**
 * Auto configuration for Ribbon (client side load balancing).
 *
 * @author Spencer Gibb
 * @author Dave Syer
 * @author Will Tran
 */
@Configuration
@ConditionalOnClass(RestTemplate.class)
@ConditionalOnBean(LoadBalancerClient.class)
@EnableConfigurationProperties(LoadBalancerRetryProperties.class)
public class LoadBalancerAutoConfiguration {
  @LoadBalanced
  @Autowired(required = false)
  private List<RestTemplate> restTemplates = Collections.emptyList();
  @Bean
  public SmartInitializingSingleton loadBalancedRestTemplateInitializer(
      final List<RestTemplateCustomizer> customizers) {
    return new SmartInitializingSingleton() {
      @Override
      public void afterSingletonsInstantiated() {
        for (RestTemplate restTemplate : LoadBalancerAutoConfiguration.this.restTemplates) {
          for (RestTemplateCustomizer customizer : customizers) {
            customizer.customize(restTemplate);
          }
        }
      }
    };
  }
  @Autowired(required = false)
  private List<LoadBalancerRequestTransformer> transformers = Collections.emptyList();
  @Bean
  @ConditionalOnMissingBean
  public LoadBalancerRequestFactory loadBalancerRequestFactory(
      LoadBalancerClient loadBalancerClient) {
    return new LoadBalancerRequestFactory(loadBalancerClient, transformers);
  }
  @Configuration
  @ConditionalOnMissingClass("org.springframework.retry.support.RetryTemplate")
  static class LoadBalancerInterceptorConfig {
    @Bean
    public LoadBalancerInterceptor ribbonInterceptor(
        LoadBalancerClient loadBalancerClient,
        LoadBalancerRequestFactory requestFactory) {
      return new LoadBalancerInterceptor(loadBalancerClient, requestFactory);
    }
    @Bean
    @ConditionalOnMissingBean
    public RestTemplateCustomizer restTemplateCustomizer(
        final LoadBalancerInterceptor loadBalancerInterceptor) {
      return new RestTemplateCustomizer() {
        @Override
        public void customize(RestTemplate restTemplate) {
          List<ClientHttpRequestInterceptor> list = new ArrayList<>(
              restTemplate.getInterceptors());
          list.add(loadBalancerInterceptor);
          restTemplate.setInterceptors(list);
        }
      };
    }
  }
  @Configuration
  @ConditionalOnClass(RetryTemplate.class)
  static class RetryAutoConfiguration {
    @Bean
    public RetryTemplate retryTemplate() {
      RetryTemplate template =  new RetryTemplate();
      template.setThrowLastExceptionOnExhausted(true);
      return template;
    }
    @Bean
    @ConditionalOnMissingBean
    public LoadBalancedRetryPolicyFactory loadBalancedRetryPolicyFactory() {
      return new LoadBalancedRetryPolicyFactory.NeverRetryFactory();
    }
    @Bean
    public RetryLoadBalancerInterceptor ribbonInterceptor(
        LoadBalancerClient loadBalancerClient, LoadBalancerRetryProperties properties,
        LoadBalancedRetryPolicyFactory lbRetryPolicyFactory,
        LoadBalancerRequestFactory requestFactory) {
      return new RetryLoadBalancerInterceptor(loadBalancerClient, retryTemplate(), properties,
          lbRetryPolicyFactory, requestFactory);
    }
    @Bean
    @ConditionalOnMissingBean
    public RestTemplateCustomizer restTemplateCustomizer(
        final RetryLoadBalancerInterceptor loadBalancerInterceptor) {
      return new RestTemplateCustomizer() {
        @Override
        public void customize(RestTemplate restTemplate) {
          List<ClientHttpRequestInterceptor> list = new ArrayList<>(
              restTemplate.getInterceptors());
          list.add(loadBalancerInterceptor);
          restTemplate.setInterceptors(list);
        }
      };
    }
  }
}

@Configuration
public class ConfigBean {
  @LoadBalanced//开启负载均衡机制
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate(); // 用来进行HTTP通信
    }
  // 在容器中注册IRule即可
  @Bean
  public IRule myRule(){
    return new RandomRule();
  }
}

@SpringBootApplication
//在启动该微服务的时候就能去加载我们的自定义Ribbon配置类，从而使配置生效
@RibbonClient(name="MICROSERVICECLOUD-DEPT",configuration=MySelfRule.class)
@EnableDiscoveryClient //服务发现
public class DeptConsumer80_App
{
  public static void main(String[] args)
  {
    SpringApplication.run(DeptConsumer80_App.class, args);
  }
}

@Configuration
public class MySelfRule
{
  @Bean
  public IRule myRule()
  {
    //return new RandomRule();// Ribbon默认是轮询，我自定义为随机
    //return new RoundRobinRule();// Ribbon默认是轮询，我自定义为随机
    return new MyRoundRobinRule();// 我自定义为每台机器5次
  }
}

package com.web.myrule;
import java.util.List;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.Server;
public class MyRoundRobinRule extends AbstractLoadBalancerRule
{
  // total = 0 // 当total==5以后，我们指针才能往下走，
  // index = 0 // 当前对外提供服务的服务器地址，
  // total需要重新置为零，但是已经达到过一个5次，我们的index = 1
  // 分析：我们5次，但是微服务只有8001 8002 8003 三台，OK？
  // 
  private int total = 0;      // 总共被调用的次数，目前要求每台被调用5次
  private int currentIndex = 0; // 当前提供服务的机器号
  public Server choose(ILoadBalancer lb, Object key)
  {
    if (lb == null) {
      return null;
    }
    Server server = null;
    while (server == null) {
      if (Thread.interrupted()) {
        return null;
      }
      List<Server> upList = lb.getReachableServers();
      List<Server> allList = lb.getAllServers();
      int serverCount = allList.size();
      if (serverCount == 0) {
        /*
         * No servers. End regardless of pass, because subsequent passes only get more
         * restrictive.
         */
        return null;
      }
//      int index = rand.nextInt(serverCount);// java.util.Random().nextInt(3);
//      server = upList.get(index);
//      private int total = 0;      // 总共被调用的次数，目前要求每台被调用5次
//      private int currentIndex = 0; // 当前提供服务的机器号
            if(total < 5)
            {
              server = upList.get(currentIndex);
              total++;
            }else {
              total = 0;
              currentIndex++;
              if(currentIndex >= upList.size())
              {
                currentIndex = 0;
              }
            }     
      if (server == null) {
        /*
         * The only time this should happen is if the server list were somehow trimmed.
         * This is a transient condition. Retry after yielding.
         */
        Thread.yield();
        continue;
      }
      if (server.isAlive()) {
        return (server);
      }
      // Shouldn't actually happen.. but must be transient or a bug.
      server = null;
      Thread.yield();
    }
    return server;
  }
  @Override
  public Server choose(Object key)
  {
    return choose(getLoadBalancer(), key);
  }
  @Override
  public void initWithNiwsConfig(IClientConfig clientConfig)
  {
    // TODO Auto-generated method stub
  }
}