Dubbo+Nacos系列专题二：Dubbo服务注册到Nacos(上篇)
一、Dubbo服务注册过程
先从下面这个demo开始：
@EnableDubbo(scanBasePackages = "com.alibaba.dubbo.demo.service")
@PropertySource(value = "classpath:/provider-config.properties")
public class DemoServiceProviderBootstrap {
public static void main(String[] args) throws IOException {
// AnnotationConfigApplicationContext 该类可以实现基于Java的配置类加载自定义在Spring的应用上下文的bean。
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
// 通过使用register方法具体到注册哪个配置类，最后刷新。
context.register(DemoServiceProviderBootstrap.class);
context.refresh();
System.out.println("DemoService provider is starting...");
System.in.read();
}
}
从context.refresh中，
通过event事件的方式，最后来到dubbo源码定义的：com.alibaba.dubbo.config.spring.ServiceBean#onApplicationEvent
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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.alibaba.dubbo.config.spring; import com.alibaba.dubbo.config.ApplicationConfig; import com.alibaba.dubbo.config.ModuleConfig; import com.alibaba.dubbo.config.MonitorConfig; import com.alibaba.dubbo.config.ProtocolConfig; import com.alibaba.dubbo.config.ProviderConfig; import com.alibaba.dubbo.config.RegistryConfig; import com.alibaba.dubbo.config.ServiceConfig; import com.alibaba.dubbo.config.annotation.Service; import com.alibaba.dubbo.config.spring.context.event.ServiceBeanExportedEvent; import com.alibaba.dubbo.config.spring.extension.SpringExtensionFactory; import org.springframework.aop.support.AopUtils; import org.springframework.beans.factory.BeanFactoryUtils; import org.springframework.beans.factory.BeanNameAware; import org.springframework.beans.factory.DisposableBean; import org.springframework.beans.factory.InitializingBean; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.context.ApplicationEventPublisher; import org.springframework.context.ApplicationEventPublisherAware; import org.springframework.context.ApplicationListener; import org.springframework.context.event.ContextRefreshedEvent; import java.util.ArrayList; import java.util.List; import java.util.Map; import static com.alibaba.dubbo.config.spring.util.BeanFactoryUtils.addApplicationListener; /** * ServiceFactoryBean * * @export */ public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean, DisposableBean, ApplicationContextAware, ApplicationListener<ContextRefreshedEvent>, BeanNameAware, ApplicationEventPublisherAware { private static final long serialVersionUID = 213195494150089726L; private final transient Service service; private transient ApplicationContext applicationContext; private transient String beanName; private transient boolean supportedApplicationListener; private ApplicationEventPublisher applicationEventPublisher; public ServiceBean() { super(); this.service = null; } public ServiceBean(Service service) { super(service); this.service = service; } @Override public void setApplicationContext(ApplicationContext applicationContext) { this.applicationContext = applicationContext; SpringExtensionFactory.addApplicationContext(applicationContext); supportedApplicationListener = addApplicationListener(applicationContext, this); } @Override public void setBeanName(String name) { this.beanName = name; } /** * Gets associated {@link Service} * * @return associated {@link Service} */ public Service getService() { return service; } @Override public void onApplicationEvent(ContextRefreshedEvent event) { if (isDelay() && !isExported() && !isUnexported()) { if (logger.isInfoEnabled()) { logger.info("The service ready on spring started. service: " + getInterface()); } export(); } } private boolean isDelay() { Integer delay = getDelay(); ProviderConfig provider = getProvider(); if (delay == null && provider != null) { delay = provider.getDelay(); } return supportedApplicationListener && (delay == null || delay == -1); } @Override @SuppressWarnings({"unchecked", "deprecation"}) public void afterPropertiesSet() throws Exception { if (getProvider() == null) { Map<String, ProviderConfig> providerConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProviderConfig.class, false, false); if (providerConfigMap != null && providerConfigMap.size() > 0) { Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false); if ((protocolConfigMap == null || protocolConfigMap.size() == 0) && providerConfigMap.size() > 1) { // backward compatibility List<ProviderConfig> providerConfigs = new ArrayList<ProviderConfig>(); for (ProviderConfig config : providerConfigMap.values()) { if (config.isDefault() != null && config.isDefault().booleanValue()) { providerConfigs.add(config); } } if (!providerConfigs.isEmpty()) { setProviders(providerConfigs); } } else { ProviderConfig providerConfig = null; for (ProviderConfig config : providerConfigMap.values()) { if (config.isDefault() == null || config.isDefault().booleanValue()) { if (providerConfig != null) { throw new IllegalStateException("Duplicate provider configs: " + providerConfig + " and " + config); } providerConfig = config; } } if (providerConfig != null) { setProvider(providerConfig); } } } } if (getApplication() == null && (getProvider() == null || getProvider().getApplication() == null)) { Map<String, ApplicationConfig> applicationConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ApplicationConfig.class, false, false); if (applicationConfigMap != null && applicationConfigMap.size() > 0) { ApplicationConfig applicationConfig = null; for (ApplicationConfig config : applicationConfigMap.values()) { if (config.isDefault() == null || config.isDefault().booleanValue()) { if (applicationConfig != null) { throw new IllegalStateException("Duplicate application configs: " + applicationConfig + " and " + config); } applicationConfig = config; } } if (applicationConfig != null) { setApplication(applicationConfig); } } } if (getModule() == null && (getProvider() == null || getProvider().getModule() == null)) { Map<String, ModuleConfig> moduleConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ModuleConfig.class, false, false); if (moduleConfigMap != null && moduleConfigMap.size() > 0) { ModuleConfig moduleConfig = null; for (ModuleConfig config : moduleConfigMap.values()) { if (config.isDefault() == null || config.isDefault().booleanValue()) { if (moduleConfig != null) { throw new IllegalStateException("Duplicate module configs: " + moduleConfig + " and " + config); } moduleConfig = config; } } if (moduleConfig != null) { setModule(moduleConfig); } } } if ((getRegistries() == null || getRegistries().isEmpty()) && (getProvider() == null || getProvider().getRegistries() == null || getProvider().getRegistries().isEmpty()) && (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().isEmpty())) { Map<String, RegistryConfig> registryConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RegistryConfig.class, false, false); if (registryConfigMap != null && registryConfigMap.size() > 0) { List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>(); for (RegistryConfig config : registryConfigMap.values()) { if (config.isDefault() == null || config.isDefault().booleanValue()) { registryConfigs.add(config); } } if (registryConfigs != null && !registryConfigs.isEmpty()) { super.setRegistries(registryConfigs); } } } if (getMonitor() == null && (getProvider() == null || getProvider().getMonitor() == null) && (getApplication() == null || getApplication().getMonitor() == null)) { Map<String, MonitorConfig> monitorConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, MonitorConfig.class, false, false); if (monitorConfigMap != null && monitorConfigMap.size() > 0) { MonitorConfig monitorConfig = null; for (MonitorConfig config : monitorConfigMap.values()) { if (config.isDefault() == null || config.isDefault().booleanValue()) { if (monitorConfig != null) { throw new IllegalStateException("Duplicate monitor configs: " + monitorConfig + " and " + config); } monitorConfig = config; } } if (monitorConfig != null) { setMonitor(monitorConfig); } } } if ((getProtocols() == null || getProtocols().isEmpty()) && (getProvider() == null || getProvider().getProtocols() == null || getProvider().getProtocols().isEmpty())) { Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false); if (protocolConfigMap != null && protocolConfigMap.size() > 0) { List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>(); for (ProtocolConfig config : protocolConfigMap.values()) { if (config.isDefault() == null || config.isDefault().booleanValue()) { protocolConfigs.add(config); } } if (protocolConfigs != null && !protocolConfigs.isEmpty()) { super.setProtocols(protocolConfigs); } } } if (getPath() == null || getPath().length() == 0) { if (beanName != null && beanName.length() > 0 && getInterface() != null && getInterface().length() > 0 && beanName.startsWith(getInterface())) { setPath(beanName); } } if (!isDelay()) { export(); } } /** * Get the name of {@link ServiceBean} * * @return {@link ServiceBean}'s name * @since 2.6.5 */ public String getBeanName() { return this.beanName; } /** * @since 2.6.5 */ @Override public void export() { super.export(); // Publish ServiceBeanExportedEvent publishExportEvent(); } /** * @since 2.6.5 */ private void publishExportEvent() { ServiceBeanExportedEvent exportEvent = new ServiceBeanExportedEvent(this); applicationEventPublisher.publishEvent(exportEvent); } @Override public void destroy() throws Exception { // no need to call unexport() here, see // org.apache.dubbo.config.spring.extension.SpringExtensionFactory.ShutdownHookListener } // merged from dubbox @Override protected Class getServiceClass(T ref) { if (AopUtils.isAopProxy(ref)) { return AopUtils.getTargetClass(ref); } return super.getServiceClass(ref); } /** * @param applicationEventPublisher * @since 2.6.5 */ @Override public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) { this.applicationEventPublisher = applicationEventPublisher; } }
关注这里重写的onApplicationEvent方法，进一步跟踪：export()：
先来看方法super.export() --> com/alibaba/dubbo/config/ServiceConfig.java
dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/integration/RegistryProtocol.java
Nacos的NameSpace,命名空间，用于进行租户粒度的配置隔离。不同的命名空间下，可以相同的Group和DataId。NameSpace的常用场景之一是不同环境的配置的区分隔离。例如开发测试和生产环境的资源的配置或者服务的隔离。Dubbo源码中通过调用NamingService发送HTTP请求，把服务注册到注册中心。
这个过程中有一个重要的类：com.alibaba.dubbo.registry.integration.RegistryProtocol。来看着这个方法：
@Override
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
//export invoker
final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker);
URL registryUrl = getRegistryUrl(originInvoker);
//registry provider
final Registry registry = getRegistry(originInvoker);
final URL registeredProviderUrl = getRegisteredProviderUrl(originInvoker);
//to judge to delay publish whether or not
boolean register = registeredProviderUrl.getParameter("register", true);
ProviderConsumerRegTable.registerProvider(originInvoker, registryUrl, registeredProviderUrl);
if (register) {
register(registryUrl, registeredProviderUrl);
ProviderConsumerRegTable.getProviderWrapper(originInvoker).setReg(true);
}
// Subscribe the override data
// FIXME When the provider subscribes, it will affect the scene : a certain JVM exposes the service and call the same service. Because the subscribed is cached key with the name of the service, it causes the subscription information to cover.
final URL overrideSubscribeUrl = getSubscribedOverrideUrl(registeredProviderUrl);
final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);
overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
//Ensure that a new exporter instance is returned every time export
return new DestroyableExporter<T>(exporter, originInvoker, overrideSubscribeUrl, registeredProviderUrl);
}
这里面有一个重要的方法：
private Registry getRegistry(final Invoker<?> originInvoker) {
URL registryUrl = getRegistryUrl(originInvoker);
return registryFactory.getRegistry(registryUrl);
}
这个地方很重要：使用NamingFactory 这个工厂创建出来一个NamingService（NacosNamingService）
public static NamingService createNamingService(Properties properties) throws NacosException {
try {
Class<?> driverImplClass = Class.forName("com.alibaba.nacos.client.naming.NacosNamingService");
Constructor constructor = driverImplClass.getConstructor(Properties.class);
NamingService vendorImpl = (NamingService) constructor.newInstance(properties);
return vendorImpl;
} catch (Throwable e) {
throw new NacosException(NacosException.CLIENT_INVALID_PARAM, e);
}
}
接下来，我们就需要关注：NamingService 创建的时候，里面都初始化了哪些组件？
public NacosNamingService(Properties properties) throws NacosException {
init(properties);
}
private void init(Properties properties) throws NacosException {
ValidatorUtils.checkInitParam(properties);
// 获取NameSpace
this.namespace = InitUtils.initNamespaceForNaming(properties);
InitUtils.initSerialization();
// 加载ServerList
initServerAddr(properties);
InitUtils.initWebRootContext(properties);
// 初始化缓存地址
initCacheDir();
initLogName(properties);
// serverProxy
this.serverProxy = new NamingProxy(this.namespace, this.endpoint, this.serverList, properties);
// 心跳：用于发送心跳的
this.beatReactor = new BeatReactor(this.serverProxy, initClientBeatThreadCount(properties));
// host refator：维护本地订阅的服务注册表信息
this.hostReactor = new HostReactor(this.serverProxy, beatReactor, this.cacheDir, isLoadCacheAtStart(properties),
isPushEmptyProtect(properties), initPollingThreadCount(properties));
}
其次，关注注册这个方法：
public void register(URL registryUrl, URL registedProviderUrl) {
Registry registry = registryFactory.getRegistry(registryUrl);
registry.register(registedProviderUrl);
}
--> dubbo-registry/dubbo-registry-nacos/src/main/java/com/alibaba/dubbo/registry/nacos/NacosRegistry.java
dubbo中，所有的服务都被封装成了URL，对应nacos中的服务实例Instance，
所以服务注册时，只需要简单的将URL转换成Instance就可以注册到nacos中。
protected void doRegister(URL url) { final String serviceName = getServiceName(url); final Instance instance = createInstance(url); execute(new NamingServiceCallback() { public void callback(NamingService namingService) throws NacosException { namingService.registerInstance(serviceName, instance); } }); }
二、Nacos
client/src/main/java/com/alibaba/nacos/client/naming/NacosNamingService.java
@Override
public void registerInstance(String serviceName, String ip, int port) throws NacosException {
registerInstance(serviceName, ip, port, Constants.DEFAULT_CLUSTER_NAME);
}
注册实例的时候，会判断是否临时实例，临时实例加入beatReactor心跳列表nacos把服务分为两类，临时和永久性服务。（永久性如数据库、缓存服务，客户端不会也没法发送心跳，通过TCP端口检测来反向探活）。
groupedServiceName其实就是groupName@@serviceName
@Override
public void registerInstance(String serviceName, String groupName, Instance instance) throws NacosException {
NamingUtils.checkInstanceIsLegal(instance);
String groupedServiceName = NamingUtils.getGroupedName(serviceName, groupName);
if (instance.isEphemeral()) {
BeatInfo beatInfo = beatReactor.buildBeatInfo(groupedServiceName, instance);
beatReactor.addBeatInfo(groupedServiceName, beatInfo);
}
serverProxy.registerService(groupedServiceName, groupName, instance);
}
从addBeatInfo方法来看：Nacos通过任务的方式来保持心跳。而dom2Beat是定义的一个ConcurrentHashMap, 是一个存放需要心跳上报的临时实例的map容器。
public void addBeatInfo(String serviceName, BeatInfo beatInfo) { NAMING_LOGGER.info("[BEAT] adding beat: {} to beat map.", beatInfo); String key = buildKey(serviceName, beatInfo.getIp(), beatInfo.getPort()); BeatInfo existBeat = null; //fix #1733 if ((existBeat = dom2Beat.remove(key)) != null) { existBeat.setStopped(true); } dom2Beat.put(key, beatInfo); // 通过任务来保持心跳 executorService.schedule(new BeatTask(beatInfo), beatInfo.getPeriod(), TimeUnit.MILLISECONDS); MetricsMonitor.getDom2BeatSizeMonitor().set(dom2Beat.size()); }
紧接着，来看serverProxy.registerService，这里通过HTTP POST请求的方式，调用请求路径：/v1/ns/instance
public void registerService(String serviceName, String groupName, Instance instance) throws NacosException { NAMING_LOGGER.info("[REGISTER-SERVICE] {} registering service {} with instance: {}", namespaceId, serviceName, instance); final Map<String, String> params = new HashMap<String, String>(16); params.put(CommonParams.NAMESPACE_ID, namespaceId); params.put(CommonParams.SERVICE_NAME, serviceName); params.put(CommonParams.GROUP_NAME, groupName); params.put(CommonParams.CLUSTER_NAME, instance.getClusterName()); params.put("ip", instance.getIp()); params.put("port", String.valueOf(instance.getPort())); params.put("weight", String.valueOf(instance.getWeight())); params.put("enable", String.valueOf(instance.isEnabled())); params.put("healthy", String.valueOf(instance.isHealthy())); params.put("ephemeral", String.valueOf(instance.isEphemeral())); params.put("metadata", JacksonUtils.toJson(instance.getMetadata())); reqApi(UtilAndComs.nacosUrlInstance, params, HttpMethod.POST); }
如果是多台NacosServer怎么选择呢？可以看到，是随机选择的，如果请求异常了，就轮着下一个server，你有多少server 就重试多少次。
也就是nacos的InstanceController#register
@CanDistro
@PostMapping
@Secured(parser = NamingResourceParser.class, action = ActionTypes.WRITE)
public String register(HttpServletRequest request) throws Exception {
final String namespaceId = WebUtils
.optional(request, CommonParams.NAMESPACE_ID, Constants.DEFAULT_NAMESPACE_ID);
final String serviceName = WebUtils.required(request, CommonParams.SERVICE_NAME);
NamingUtils.checkServiceNameFormat(serviceName);
final Instance instance = parseInstance(request);
serviceManager.registerInstance(namespaceId, serviceName, instance);
return "ok";
}
以上过程简单绘制如下图：
本篇先到这里，下一篇继续探讨这个注册的过程。
