dubbo和zikkeper的使用

1、先來一段異常看看：No provider available for the service

16:05:25.755 [localhost-startStop-1] WARN o.s.w.c.s.XmlWebApplicationContext - Exception encountered during context initialization - cancelling refresh attempt org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'quartz': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.test.rpc.OrgRPC com.xinping.crm.until.taglib.Quartz.orgRPC; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'orgRPC': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalStateException: Failed to check the status of the service com.test.rpc.OrgRPC. No provider available for the service com.test.rpc.OrgRPC from the url zookeeper://zookeeper-ip:2181/com.alibaba.dubbo.registry.RegistryService?anyhost=true&application=TEST_CRMWH_HELPER&check=false&dubbo=2.5.3&generic=false&interface=com.test.rpc.OrgRPC&methods=getOrgListByIdOrParentIdOrUpdateTime,getOrgById&pid=7916&revision=1.0.1-api&side=consumer&timeout=60000&timestamp=1471853122008 to the consumer consumer-ip use dubbo version 2.5.3 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1202) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:762) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757) ~[spring-context-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480) ~[spring-context-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403) [spring-web-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306) [spring-web-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) [spring-web-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5016) [catalina.jar:7.0.61] at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5528) [catalina.jar:7.0.61] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) [catalina.jar:7.0.61] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575) [catalina.jar:7.0.61] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565) [catalina.jar:7.0.61] at java.util.concurrent.FutureTask.run(FutureTask.java:262) [na:1.7.0_79] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_79] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_79] at java.lang.Thread.run(Thread.java:745) [na:1.7.0_79] Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.test.rpc.OrgRPC com.xinping.crm.until.taglib.Quartz.orgRPC; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'orgRPC': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalStateException: Failed to check the status of the service com.test.rpc.OrgRPC. No provider available for the service com.test.rpc.OrgRPC from the url zookeeper://zookeeper-ip:2181/com.alibaba.dubbo.registry.RegistryService?anyhost=true&application=TEST_CRMWH_HELPER&check=false&dubbo=2.5.3&generic=false&interface=com.test.rpc.OrgRPC&methods=getOrgListByIdOrParentIdOrUpdateTime,getOrgById&pid=7916&revision=1.0.1-api&side=consumer&timeout=60000&timestamp=1471853122008 to the consumer consumer-ip use dubbo version 2.5.3 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:558) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] ... 22 common frames omitted Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'orgRPC': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalStateException: Failed to check the status of the service com.test.rpc.OrgRPC. No provider available for the service com.test.rpc.OrgRPC from the url zookeeper://zookeeper-ip:2181/com.alibaba.dubbo.registry.RegistryService?anyhost=true&application=TEST_CRMWH_HELPER&check=false&dubbo=2.5.3&generic=false&interface=com.test.rpc.OrgRPC&methods=getOrgListByIdOrParentIdOrUpdateTime,getOrgById&pid=7916&revision=1.0.1-api&side=consumer&timeout=60000&timestamp=1471853122008 to the consumer consumer-ip use dubbo version 2.5.3 at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:175) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:103) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getObjectForBeanInstance(AbstractBeanFactory.java:1506) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:250) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1127) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1051) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:949) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:530) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] ... 24 common frames omitted Caused by: java.lang.IllegalStateException: Failed to check the status of the service com.test.rpc.OrgRPC. No provider available for the service com.test.rpc.OrgRPC from the url zookeeper://zookeeper-ip:2181/com.alibaba.dubbo.registry.RegistryService?anyhost=true&application=TEST_CRMWH_HELPER&check=false&dubbo=2.5.3&generic=false&interface=com.test.rpc.OrgRPC&methods=getOrgListByIdOrParentIdOrUpdateTime,getOrgById&pid=7916&revision=1.0.1-api&side=consumer&timeout=60000&timestamp=1471853122008 to the consumer consumer-ip use dubbo version 2.5.3 at com.alibaba.dubbo.config.ReferenceConfig.createProxy(ReferenceConfig.java:420) ~[dubbo-2.5.3.jar:2.5.3] at com.alibaba.dubbo.config.ReferenceConfig.init(ReferenceConfig.java:300) ~[dubbo-2.5.3.jar:2.5.3] at com.alibaba.dubbo.config.ReferenceConfig.get(ReferenceConfig.java:138) ~[dubbo-2.5.3.jar:2.5.3] at com.alibaba.dubbo.config.spring.ReferenceBean.getObject(ReferenceBean.java:65) ~[dubbo-2.5.3.jar:2.5.3] at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:168) ~[spring-beans-4.1.3.RELEASE.jar:4.1.3.RELEASE] ... 32 common frames omitted 16:05:25.755 [localhost-startStop-1] ERROR o.s.web.context.ContextLoader - Context initialization failed 八月 22, 2016 4:05:25 下午 org.apache.catalina.core.StandardContext startInternal 嚴重: Error listenerStart 八月 22, 2016 4:05:25 下午 org.apache.catalina.core.StandardContext startInternal 嚴重: Context [/crm] startup failed due to previous errors 八月 22, 2016 4:05:25 下午 org.apache.catalina.core.ApplicationContext log 信息: Closing Spring root WebApplicationContext

異常分析： 

上面的異常，Caused by的前半部分有的說bean創建失敗，有的說屬性自動裝配失敗，但后半部分都比較統一，都是：No provider available for the service ……，服務沒有可以使用的提供者，完整意思就是：對於消費者(consumer-ip)而言，在zookeeper注冊中心(zookeeper-url)沒有可用的提供者(No provider available for the service com.test.rpc.OrgRPC)，消費者訪問提供者的時候失敗了； 

因為消費者沒有變，變化的是向注冊中心注冊的提供者由開發服務器變更為測試服務器，同時由於之前處理過因為【No route to host】引起的異常，所以想到可能是提供者端口不通造成的，然后從消費者服務器telnet 提供者ip 20880端口，果然如此。

解決辦法： 

將提供者服務器的20880端口開放給消費者服務器ip，重新啟動消費者服務器，正常啟動。

2、dubbo+zookeeper與提供者provider、消費者consumer之間通信過程

先說一下整個系統框架的基本構造：

• zookeeper作為注冊中心，使用單獨服務器，占用2181端口

• dubbo-admin作為監控中心，與zookeeper使用相同服務器，tomcat部署占用8080端口

• provider作為提供者，使用單獨服務器，tomcat部署占用8080端口，使用dubbo協議開放20880端口

• consumer作為消費者，使用單獨服務器，tomcat部署占用8080端口

再看上面的異常，雖然解決了，是不是有人和我一樣有一些問題想不通：

• provider服務器端口是8080，為什么telnet測試以及解決方案中開放的端口卻是20880？

• 要說dubbo協議開放了20880端口，那8080端口應該也開放啊？

• zookeeper、provider、consumer之間端口開放和屏蔽情況到底是怎么回事？

帶着這些問題，進行了相關的驗證，最終得出如下結論，先看圖，再解釋：

 

1)、用dubbo協議在20880端口暴露服務

 

在提供者的dubbo配置文件中，一般都配置了<dubbo:protocol name="dubbo" port="20880"/>，表明用dubbo協議在20880端口暴露服務，當然如果你不配置，dubbo默認使用20880端口暴露服務，所有消費者都是通過20880端口進行，對於消費者而言，提供者服務器8080端口是透明的，也就是說提供者服務器端口號可以任意改變，服務也不會有任何影響，消費者無需關心。 

所以上面的異常解決辦法是開放20880端口給消費者，而不是8080端口給消費者。

從監控中心可以看到如圖：

除了在指定端口上暴露服務之外，還可以在指定ip上暴露服務，配置如下：

<dubbo:protocol name="dubbo" host="10.1.22.2" port="20880" />

 

2)、端口開放情況

 

zookeeper作為注冊中心，provider注冊服務、consumer訂閱服務、dubbo-admin監控服務，所以zookeeper注冊中心的2181端口需要向provider、consumer、dubbo-admin開放；

一般情況下，dubbo-admin監控中心與zookeeper注冊中心部署在相同的服務器上，zookeeper可以不考慮端口開放給dubbo-admin的情況；

consumer訂閱服務，即拿到了provider在20880端口暴露的服務，當consumer請求服務時，直接從consumer跳到provider，而不是consumer到zookeeper再到provider，所以provider的20880無需開放給zookeeper；

同理，provider響應服務時，也是直接從provider到consumer，而不是provider到zookeeper再到consumer，所以consumer的8080無需開放給zookeeper；

zookeeper注冊中心是完全被動的。

總結一下： 

- zookeeper的2181開放給provider、consumer、dubbo-admin 

- provider的20880開放給所有consumer，但8080服務器端口可以完全屏蔽 

- consumer的8080開放給所有provider 

- dubbo-admin的8080開放給管理員用戶，便於通過瀏覽器監控注冊中心服務的情況 

- 總結：注冊中心只負責服務注冊和目錄發布，安全授權，實際的服務訪問仍然是兩個組件之間的點對點連接完成，這種方式下整個架構下獲取更高的性能，同時服務管理平台也不容易成為大並發服務訪問下的單點瓶頸