Ribbon 和 Eureka 的集成_JAVA_编程开发_程序员俱乐部

Ribbon 是 Netflix 发布的云中间层服务开源项目，其主要功能是提供客户侧软件负载均衡算法，将 Netflix 的中间层服务连接在一起。Eureka 是一个 RESTful 服务，用来定位运行在 AWS 域（Region）中的中间层服务。本文介绍 Eureka 和 Ribbon 的集成，附带 Ribbon 自定义负载均衡算法示例。
??????? Ribbon 和 Eureka 的集成，其实也就是让 Ribbon 充当 Eureka 架构中的 Application Client 角色。本文示例基于前边相关博客中的 demo 而写。阅读本文最好参考一下《云中间层服务 - 区域感知负载均衡器 Ribbon》、《Eureka 的 Application Client 客户端的运行示例》。
??????? Why Eureka need Ribbon？
??????? Eureka 附带客户端库，为何还要 Ribbon 呢？
??????? Ribbon 的负载均衡算法、区域感知负载均衡器久经考验，可以直接拿来使用。
??????? Why Ribbon need Eureka？
??????? 熟悉 Ribbon 的同学都知道，Ribbon 维护了一个服务器列表，如果服务器有宕机现象，Ribbon 能够自行将其剔除；但如果该服务器故障排除，重新启动，或者增加新的负载节点，我们需要手工调用 Ribbon 的接口将其动态添加进 Ribbon 的服务器列表。这样明显不够尽如人意。如何能够在服务节点启动时，自行添加服务列表？—— Eureka。Eureka 提供了 Application Service 客户端的自行注册的功能。此外，Eureka 的缓存机制能够防止大规模宕机带来的灾难性后果。
??????? 下面开始我们的集成。进行以下操作之前，请确保 Eureka Server 已启动，Eureka Application Service 客户端已注册到 Server(参考《Eureka 的 Application Client 客户端的运行示例》)。
??????? 1. 加入 ribbon-eureka 依赖包
??????? http://mvnrepository.com/artifact/com.netflix.ribbon/ribbon-eureka 选择合适的版本下载，作者下载的是 ribbon-eureka-0.3.12.jar。
??????? 2. 配置的初始化

??????? 配置文件基本采用《Eureka 的 Application Client 客户端的运行示例》Eureka Application Client 客户端配置。另外增添以下配置项：

??? 启用客户端负载均衡器并将其配置为 DynamicServerListLoadBalancer 或其子类(这个无须在配置中体现，因为这个是 Eureka 和 Ribbon 集成默认为 true 的)。
??? 将 ServerList 配置为 com.netflix.niws.loadbalancer.DiscoveryEnabledNIWSServerList。
??? 配置服务器(负载均衡节点)的刷新频率(可选。默认是为 30 秒)。
??? 为 Eureka 客户端配置服务器的虚拟地址(VIP 地址)，并确保这个地址匹配到服务器(Application Service)注册 Eureka Server 时所用到的那个。

??????? 总之就是在《Eureka 的 Application Client 客户端的运行示例》基础上添加了以下配置项：
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??? myclient.ribbon.NIWSServerListClassName=com.netflix.niws.loadbalancer.DiscoveryEnabledNIWSServerList?
?????
?????
??? # refresh every minute??
??? myclient.ribbon.ServerListRefreshInterval=60000?
?????
?????
??? # movieservice is the virtual address that the target server(s) uses to register with Eureka server?
??? myclient.ribbon.DeploymentContextBasedVipAddresses=movieservice?
??????????? 配置文件的初始化仍然采用《Eureka 的 Application Client 客户端的运行示例》中的配置初始化方法：?
??????????? // Register with Eureka?
??????????? DiscoveryManager.getInstance().initComponent(?
??????????????????? new MyDataCenterInstanceConfig(),?
??????????????????? new DefaultEurekaClientConfig());?
??????????? ApplicationInfoManager.getInstance().setInstanceStatus(?
??????????????????? InstanceStatus.UP);?


??????? 3. 自定义负载均衡算法
??????? 负载均衡算法，简单 demo 起见，使用随机算法，就用 ribbon-core 类库里的 com.netflix.loadbalancer.RandomRule 所提供的随机负载算法，拿到侍服主机：
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??? // get LoadBalancer instance from configuration, properties file?
??? DynamicServerListLoadBalancer lb = (DynamicServerListLoadBalancer) ClientFactory.getNamedLoadBalancer("myclient");?
??? // use RandomRule 's RandomRule algorithm to get a random server from lb 's server list?
??? RandomRule randomRule = new RandomRule();?
??? Server randomAlgorithmServer = randomRule.choose(lb, null);?
??? logger.debug("random algorithm server host:" + randomAlgorithmServer.getHost() + ";port:" + randomAlgorithmServer.getPort());?


??????? 4. Application Client 网络请求
??????? 请求代码和《Eureka 的 Application Client 客户端的运行示例》中的一般无二，在此不再赘述。
??????? 5. Application Client 关闭时取消注册
??????? 取消代码和《Eureka 的 Application Client 客户端的运行示例》中的一般无二，在此不再赘述。
??????? 6. 运行 demo
??????? 新建一个项目(不要和 Application Service 的 demo 跑在同一个项目下)，现在我们把完整的 Eureka Application Client 和 Ribbon Client 集成的代码整理一下。
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??? /*
???? * Copyright 2012 Netflix, 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.netflix.eureka;?
?????
?????
??? import java.io.BufferedReader;?
??? import java.io.IOException;?
??? import java.io.InputStreamReader;?
??? import java.io.PrintStream;?
??? import java.net.InetSocketAddress;?
??? import java.net.Socket;?
??? import java.util.Date;?
??? import java.util.Iterator;?
??? import java.util.List;?
?????
?????
??? import org.slf4j.Logger;?
??? import org.slf4j.LoggerFactory;?
?????
?????
??? import com.netflix.appinfo.ApplicationInfoManager;?
??? import com.netflix.appinfo.InstanceInfo.InstanceStatus;?
??? import com.netflix.appinfo.MyDataCenterInstanceConfig;?
??? import com.netflix.client.ClientFactory;?
??? import com.netflix.discovery.DefaultEurekaClientConfig;?
??? import com.netflix.discovery.DiscoveryManager;?
??? import com.netflix.loadbalancer.DynamicServerListLoadBalancer;?
??? import com.netflix.loadbalancer.RandomRule;?
??? import com.netflix.loadbalancer.Server;?
?????
?????
??? /**
???? * Sample Eureka client that discovers the service using Eureka and sends
???? * requests.
???? *
???? * @author Karthik Ranganathan
???? *
???? */?
??? public class SampleEurekaRibbonClient {?
??????? private static final Logger logger = LoggerFactory?
??????????????? .getLogger(SampleEurekaRibbonClient.class);?
?????
?????
??????? public void sendRequestToServiceUsingEureka() {?
?????
?????
??????????? // Register with Eureka?
??????????? DiscoveryManager.getInstance().initComponent(?
??????????????????? new MyDataCenterInstanceConfig(),?
??????????????????? new DefaultEurekaClientConfig());?
??????????? ApplicationInfoManager.getInstance().setInstanceStatus(?
??????????????????? InstanceStatus.UP);?
??????????? // get LoadBalancer instance from configuration, properties file?
??????????? DynamicServerListLoadBalancer lb = (DynamicServerListLoadBalancer) ClientFactory.getNamedLoadBalancer("myclient");?
??????????? // show all servers in the list?
??????????? List<Server> list = lb.getServerList(false);?
??????????? Iterator<Server> it = list.iterator();?
??????????? while (it.hasNext()) {?
??????????????? Server server = it.next();?
??????????????? logger.debug("application service host:" + server.getHost() + ";port=" + server.getPort());?
??????????? }?
??????????? // use RandomRule 's RandomRule algorithm to get a random server from lb 's server list?
??????????? RandomRule randomRule = new RandomRule();?
??????????? Server randomAlgorithmServer = randomRule.choose(lb, null);?
??????????? logger.debug("random algorithm server host:" + randomAlgorithmServer.getHost() + ";port:" + randomAlgorithmServer.getPort());?
??????????? // communicate with the server?
??????????? Socket s = new Socket();?
??????????? try {?
??????????????? s.connect(new InetSocketAddress(randomAlgorithmServer.getHost(), randomAlgorithmServer.getPort()));?
??????????? } catch (IOException e) {?
??????????????? logger.error("Could not connect to the server :"?
??????????????????????? + randomAlgorithmServer.getHost() + " at port " + randomAlgorithmServer.getPort());?
??????????? }?
??????????? try {?
??????????????? logger.debug("Connected to server. Sending a sample request");?
??????????????? PrintStream out = new PrintStream(s.getOutputStream());?
??????????????? out.println("Sample request " + new Date());?
??????????????? String str = null;?
??????????????? logger.debug("Waiting for server response..");?
??????????????? BufferedReader rd = new BufferedReader(new InputStreamReader(?
??????????????????????? s.getInputStream()));?
??????????????? str = rd.readLine();?
??????????????? if (str != null) {?
??????????????????? logger.debug("Received response from server. Communication all fine using Eureka :");?
??????????????????? logger.debug("Exiting the client. Demo over..");?
??????????????? }?
??????????????? rd.close();?
??????????? } catch (IOException e) {?
??????????????? e.printStackTrace();?
??????????????? logger.error(e.getMessage(), e);?
??????????? }?
??????????? this.unRegisterWithEureka();?
??????? }?
?????
?????
??????? public void unRegisterWithEureka() {?
??????????? // Un register from eureka.?
??????????? DiscoveryManager.getInstance().shutdownComponent();?
??????? }?
?????
?????
??????? public static void main(String[] args) {?
??????????? SampleEurekaRibbonClient sampleEurekaRibbonClient = new SampleEurekaRibbonClient();?
??????????? sampleEurekaRibbonClient.sendRequestToServiceUsingEureka();?
?????
?????
??????? }?
??? }?


??????? 之后是把配置文件、log4j 文件整理一下，运行 SampleEurekaRibbonClient，日志显示 demo 成功。
??????? 参考资料

??? https://github.com/Netflix/ribbon/wiki/Programmers-Guide

本文来源：http://blog.csdn.net/defonds/article/details/38016301