大纲
1.Dubbo 2.7和3.x版本的区别
2.Dubbo服务的基本流程和启动入口
3.Dubbo服务发布的主流程
4.服务发布时执行相关组件的初始化
5.服务发布时执行的服务实例刷新操作
6.服务发布时执行的服务实例初始化操作
7.服务发布时执行的服务实例发布操作
8.执行服务实例发布操作时的主流程
9.服务发布过程中ProxyFactory生成Invoker
10.服务发布过程中Protocol组件发布Invoker
11.服务发布过程中NettyServer的构造流程
12.服务发布过程中RegistryProtocol的服务注册
13.Dubbo服务发布的完整流程总结
1.Dubbo 2.7和3.x版本的区别
区别一：后者引入了ModuleDeployer组件专门做服务启动时的初始化工作。将原来的注册中心拆分为三大中心：注册中心、配置中心、元数据中心。
区别二：后者很多地方使用了Double Check来代替前者对方法加Synchronized锁，大量采用了Double Check + Volatile + Static来实现单例模式。
区别三：后者引入了MigrationRuleListener、MigrationRuleHandler、MigrationInvoker，引入DynamicDirectory代替RegistryDirectory。
2.Dubbo服务的基本流程和启动入口
(1)Dubbo服务的基本流程
(2)Provider启动入口
(3)Consumer启动入口
(1)Dubbo服务的基本流程
(2)Provider启动入口
public class Application {public static void main(String[] args) throws Exception {//Service和ServiceConfig是什么//Service是一个服务，每个服务可能会包含多个接口//ServiceConfig便是针对这个服务的一些配置//下面传入的泛型DemoServiceImpl便是服务接口的实现ServiceConfig<DemoServiceImpl> service = new ServiceConfig<>();//设置服务暴露出去的接口service.setInterface(DemoService.class);//设置暴露出去的接口的实现类service.setRef(new DemoServiceImpl());//服务名称，可以在服务框架里进行定位service.setApplication(new ApplicationConfig("dubbo-demo-api-provider"));//所有的RPC框架，必须要和注册中心配合使用，服务启动后必须向注册中心进行注册//注册中心可以知道每个服务有几个实例，每个实例在哪台服务器上//进行服务调用时，要先找注册中心咨询要调用的服务有几个实例，分别都在什么机器上//下面便是设置ZooKeeper作为注册中心的地址service.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));//设置元数据上报的地方//Dubbo服务实例启动后，会有自己的元数据，需要上报到一个地方进行管理，比如zookeeperservice.setMetadataReportConfig(new MetadataReportConfig("zookeeper://127.0.0.1:2181"));//配置完毕后，调用ServiceConfig的export()方法启动网络监听程序//当接收到调用请求时，该网络监听程序会建立网络连接进行通信//接收按照协议封装的请求数据，该网络监听程序会执行RPC调用//此外，ServiceConfig的export()方法还会把自己作为一个服务实例注册到zk里service.export();System.out.println("dubbo service started");new CountDownLatch(1).await();}
}(3)Consumer启动入口
public class Application {public static void main(String[] args) throws Exception {//Reference和ReferenceConfig是什么//Reference是一个引用，是对Provider端的一个服务实例的引用//ReferenceConfig这个服务实例的引用的一些配置//通过泛型传递了这个服务实例对外暴露的接口ReferenceConfig<DemoService> reference = new ReferenceConfig<>();//设置应用名称reference.setApplication(new ApplicationConfig("dubbo-demo-api-consumer"));//设置注册中心的地址，默认是ZooKeeperreference.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));//设置元数据上报地址reference.setMetadataReportConfig(new MetadataReportConfig("zookeeper://127.0.0.1:2181"));//设置要调用的服务的接口reference.setInterface(DemoService.class);//直接通过ReferenceConfig的get()方法来拿到一个DemoService接口//它是一个动态代理接口，只要被调用，便会通过底层调用Provider服务实例的对应接口DemoService service = reference.get();String message = service.sayHello("dubbo");System.out.println(message);Thread.sleep(10000000L);}
}
3.Dubbo服务发布的主流程
ServiceConfig的export()方法在进行服务发布时，首先会初始化相关组件，然后刷新服务实例，接着初始化服务实例，最后发布服务实例。
public class ServiceConfig<T> extends ServiceConfigBase<T> {...@Overridepublic void export() {if (this.exported) {return;}//prepare for export//对比Dubbo 2.6.x和2.7.x源码，Dubbo 3.0的变动还是有点大的，比如这里使用了ModuleDeployer组件//Dubbo服务实例内部会有很多的代码组件，通过ModuleDeployer便可以避免零零散散的去调用和初始化//1.执行相关组件的初始化//通过获取到的ModuleDeployer来对相关组件进行初始化//比如会对MetadataReport元数据上报组件进行构建和初始化，以及启动(建立跟zk的连接)getScopeModel().getDeployer().start();synchronized (this) {if (this.exported) {return;}//2.执行服务实例的刷新操作//也就是刷新ProviderConfig->MethodConfig->ArgumentConfigif (!this.isRefreshed()) {this.refresh();}if (this.shouldExport()) {//3.执行服务实例的初始化//也就是会把Metadata元数据给准备好，后续可以进行元数据上报this.init();//这是Dubbo服务实例的延迟发布的特性//如果设置了Dubbo服务实例是延迟发布的，当调用了export()方法后，就会进入这里//在延迟指定的时间后，再去进行服务的发布if (shouldDelay()) {//延迟发布doDelayExport();} else {//立即发布//4.执行服务实例的发布//这里可以作为服务发布的直接入口doExport();}}}}...
}
4.服务发布时执行相关组件的初始化
public class DefaultModuleDeployer extends AbstractDeployer<ModuleModel> implements ModuleDeployer {//已经完成发布的服务实例集合private List<ServiceConfigBase<?>> exportedServices = new ArrayList<>();//下面这些组件，本身都是跟model组件体系强关联的private ModuleModel moduleModel;//父级ApplicationDeployer组件private ApplicationDeployer applicationDeployer;...@Overridepublic Future start() throws IllegalStateException {//initialize，maybe deadlock applicationDeployer lock & moduleDeployer lock//调用DefaultApplicationDeployer的initialize()方法applicationDeployer.initialize();return startSync();}@Overridepublic void prepare() {//module这个层级是application层级的下层//application层级是framework层级的下层applicationDeployer.initialize();this.initialize();}...
}public class DefaultApplicationDeployer extends AbstractDeployer<ApplicationModel> implements ApplicationDeployer {private final DubboShutdownHook dubboShutdownHook;...@Overridepublic void initialize() {if (initialized) {return;}//ApplicationDeployer组件，可能会被多线程并发访问//Ensure that the initialization is completed when concurrent callssynchronized (startLock) {if (initialized) {return;}//注册退出时需要进行资源销毁的ShutdownHook//register shutdown hookregisterShutdownHook();//启动配置中心ConfigCenter//动配置中心是专门存放配置信息的startConfigCenter();//加载应用配置loadApplicationConfigs();//初始化ModuleDeployerinitModuleDeployers();//启动元数据中心MetadataCenter//元数据中心是专门存放发布d的服务实例信息的startMetadataCenter();initialized = true;if (logger.isInfoEnabled()) {logger.info(getIdentifier() + " has been initialized!");}}//老的Dubbo版本只有注册中心的概念//后来随着版本的迭代和演进，出现了配置中心、元数据中心等这些用于解耦的概念//虽然Dubbo的服务实例信息、配置信息、元数据信息，都可以放在zk里//但如果把一个服务实例的各种数据和信息都存储在zk里，那么这些数据和信息会严重耦合在一起//下面从扩展性和可用性两个层面来分析，如果把各种数据都耦合放在一个zk里可能会出现的问题//(1)扩展性//在一个大规模的微服务系统里，服务本身可能都有上百个，服务实例可能有几百上千个，所以服务实例数据可能就很多//但每个服务实例关联的配置数据，可能不是太多，尤其是元数据可能也不是太多//而这里的扩展性不是指功能上的扩展，而是指数据上的扩展//随着服务实例数据在膨胀，配置数据和元数据虽然可能也在增加，但是增加的速度可能比不上服务实例数据//此时就需要对注册中心进行扩容或者更换一个系统去存储//而在这个过程之中，由于所有数据耦合在一起了，牵一发而动全身，不好扩展了//这就是多种不同类型的数据耦合在一起时会出现的痛点，也就是数据耦合导致数据扩展性差的问题//(2)可用性//由于注册数据、配置数据、元数据都放在一个地方比如zk//那么一旦zk出现了故障，这三种数据就一起没了，这就是可用性问题//因此，Dubbo3的架构设计会对不同类型的数据进行分离，形成了三种数据：注册数据、元数据、配置数据//于是就有了三大中心：注册中心、配置中心、元数据中心，这样就可以把三种不同类型的数据，放到不同的地方去//在扩展性方面，当服务实例数据太多时要进行扩容或者切换存储技术，此时对另外两种数据是没有直接影响的//在可用性方面，一旦作为注册中心的zk突然挂了，此时配置中心可能是Nacos，对它来说也没有直接影响的}private void registerShutdownHook() {dubboShutdownHook.register();}...
}public class DefaultApplicationDeployer extends AbstractDeployer<ApplicationModel> implements ApplicationDeployer {...//启动元数据中心private void startMetadataCenter() {//先分析元数据中心是否需要用注册中心来做元数据中心useRegistryAsMetadataCenterIfNecessary();ApplicationConfig applicationConfig = getApplication();//获取元数据类型metadataTypeString metadataType = applicationConfig.getMetadataType();//进行元数据的配置，里面包含了MetadataReport的配置Collection<MetadataReportConfig> metadataReportConfigs = configManager.getMetadataConfigs();if (CollectionUtils.isEmpty(metadataReportConfigs)) {return;}//从applicationModel中获取一个BeanFactory//再根据BeanFactory获取一个元数据上报组件的实例MetadataReportInstanceMetadataReportInstance metadataReportInstance = applicationModel.getBeanFactory().getBean(MetadataReportInstance.class);List<MetadataReportConfig> validMetadataReportConfigs = new ArrayList<>(metadataReportConfigs.size());for (MetadataReportConfig metadataReportConfig : metadataReportConfigs) {ConfigValidationUtils.validateMetadataConfig(metadataReportConfig);validMetadataReportConfigs.add(metadataReportConfig);}//对于唯一的一个MetadataReport，会在这里进行初始化//把配置的metadataReport地址和config传递进init()方法进行初始化metadataReportInstance.init(validMetadataReportConfigs);if (!metadataReportInstance.inited()) {throw new IllegalStateException(String.format("%s MetadataConfigs found, but none of them is valid.", metadataReportConfigs.size()));}//所以MetadataReport的启动//其实就是根据配置去获取对应的BeanFactory，然后通过BeanFactory创建出对应的MetadataReport实例//最后根据配置对元数据上报组件的实例MetadataReportInstance进行初始化}...
}public class MetadataReportInstance implements Disposable {...public void init(List<MetadataReportConfig> metadataReportConfigs) {if (!init.compareAndSet(false, true)) {return;}this.metadataType = applicationModel.getApplicationConfigManager().getApplicationOrElseThrow().getMetadataType();if (metadataType == null) {this.metadataType = DEFAULT_METADATA_STORAGE_TYPE;}//在这里会通过SPI机制的adaptive自适应，生成一个代理类//底层会通过自适应的机制，根据url里的参数去拿到对应的实现类，来调用它的方法//如果使用zk作为元数据中心，那么拿到的应该是一个ZooKeeperMetadataReportFactoryMetadataReportFactory metadataReportFactory = applicationModel.getExtensionLoader(MetadataReportFactory.class).getAdaptiveExtension();for (MetadataReportConfig metadataReportConfig : metadataReportConfigs) {init(metadataReportConfig, metadataReportFactory);}}private void init(MetadataReportConfig config, MetadataReportFactory metadataReportFactory) {...//这种url一般来说是针对zk的url地址MetadataReport metadataReport = metadataReportFactory.getMetadataReport(url);if (metadataReport != null) {metadataReports.put(relatedRegistryId, metadataReport);}}...
}public abstract class AbstractMetadataReportFactory implements MetadataReportFactory {...@Overridepublic MetadataReport getMetadataReport(URL url) {...metadataReport = createMetadataReport(url);...}protected abstract MetadataReport createMetadataReport(URL url);...
}public class ZookeeperMetadataReportFactory extends AbstractMetadataReportFactory {...@Overridepublic MetadataReport createMetadataReport(URL url) {return new ZookeeperMetadataReport(url, zookeeperTransporter);}...
}public class ZookeeperMetadataReport extends AbstractMetadataReport {private final String root;ZookeeperClient zkClient;...public ZookeeperMetadataReport(URL url, ZookeeperTransporter zookeeperTransporter) {super(url);...zkClient = zookeeperTransporter.connect(url);}...
}
5.服务发布时执行的服务实例刷新操作
完成相关组件的初始化后，便会调用ServiceConfig的refresh()方法执行服务实例的刷新操作。
public class ServiceConfig<T> extends ServiceConfigBase<T> {...@Overridepublic void export() {...//1.执行相关组件的初始化//通过获取到的ModuleDeployer来对相关组件进行初始化//比如会对MetadataReport元数据上报组件进行构建和初始化，以及启动(建立跟zk的连接)getScopeModel().getDeployer().start();synchronized (this) {if (this.exported) {return;}//2.执行服务实例的刷新操作//也就是刷新ProviderConfig->MethodConfig->ArgumentConfigif (!this.isRefreshed()) {//执行AbstractConfig的refresh()方法this.refresh();}...}}...
}public abstract class AbstractConfig implements Serializable {...public void refresh() {//check and init before do refresh//调用AbstractConfig的子类ServiceConfigBase的preProcessRefresh()方法//初始化一个ProviderConfig，也就是Provider服务实例preProcessRefresh();//Model组件体系对Dubbo的运行很关键，可以认为它是SPI机制使用的入口//而ScopeModel是Model组件体系的一个基础，ScopeModel类型是可以转换为ModuleModel、ApplicationModel//比如像ModuleServiceRepository、ModelEnvironment、BeanFactory等很多通用的组件都可以通过ScopeModel去获取Environment environment = getScopeModel().getModelEnvironment();//获取Environment对象List<Map<String, String>> configurationMaps = environment.getConfigurationMaps();//Search props starts with PREFIX in order//接下来要获取和拼接preferredPrefixString preferredPrefix = null;List<String> prefixes = getPrefixes();for (String prefix : prefixes) {if (ConfigurationUtils.hasSubProperties(configurationMaps, prefix)) {preferredPrefix = prefix;break;}}if (preferredPrefix == null) {preferredPrefix = prefixes.get(0);}...//使用反射注入需要的方法assignProperties(this, environment, subProperties, subPropsConfiguration);//process extra refresh of subclass, e.g. refresh method configs//调用AbstractInterfaceConfig的processExtraRefresh()方法//该方法中preferredPrefix是关键，它的值可能是：dubbo.service.org.apache.dubbo.demo.DemoService//其中dubbo.service代表dubbo服务名称的一个固定前缀，属于固定拼接的//而中间的org.apache.dubbo.demo，则是从服务接口所在包名里截取出来的，并且最后会加上服务接口的接口名//所以preferredPrefix会作为当前dubbo服务的全限定的名字//而这段refresh的代码的作用，就是处理这个preferredPrefix以及其他相关的配置信息processExtraRefresh(preferredPrefix, subPropsConfiguration);postProcessRefresh();refreshed.set(true);}protected void preProcessRefresh() {// pre-process refresh}protected void processExtraRefresh(String preferredPrefix, InmemoryConfiguration subPropsConfiguration) {// process extra refresh}protected void postProcessRefresh() {// post-process refreshcheckDefault();}...
}public abstract class AbstractInterfaceConfig extends AbstractMethodConfig {private List<MethodConfig> methods;...//该方法会通过反射技术，对需要发布的服务的接口方法和参数封装成MethodConfig、ArgumentConfig@Overrideprotected void processExtraRefresh(String preferredPrefix, InmemoryConfiguration subPropsConfiguration) {if (StringUtils.hasText(interfaceName)) {//通过反射技术获取需要发布的服务的接口Class<?> interfaceClass;interfaceClass = ClassUtils.forName(interfaceName);...//Auto create MethodConfig/ArgumentConfig according to config propsMap<String, String> configProperties = subPropsConfiguration.getProperties();//获取需要发布的服务的接口的所有方法Method[] methods;methods = interfaceClass.getMethods();//接下来对需要发布的服务的接口方法进行处理//整理出MethodConfig对象及其对应的ArgumentConfig对象//接口里的每个方法都要创建一个MethodConfig//方法里的每一个参数都要创建一个ArgumentConfigfor (Method method : methods) {//因为服务端每次处理客户端调用时，不可能都通过反射来获取method和args的情况//所以在刚开始启动时就需要对接口进行解析，将所有的method和args整理到methods属性中if (ConfigurationUtils.hasSubProperties(configProperties, method.getName())) {MethodConfig methodConfig = getMethodByName(method.getName());//Add method config if not foundif (methodConfig == null) {//需要发布的的服务的每个方法，都创建一个MethodConfig对象methodConfig = new MethodConfig();methodConfig.setName(method.getName());//将MethodConfig对象添加到methods属性中this.addMethod(methodConfig);}//Add argument config//dubbo.service.{interfaceName}.{methodName}.{arg-index}.xxx=xxxjava.lang.reflect.Parameter[] arguments = method.getParameters();for (int i = 0; i < arguments.length; i++) {if (getArgumentByIndex(methodConfig, i) == null && hasArgumentConfigProps(configProperties, methodConfig.getName(), i)) {//方法里的每个args参数，都创建一个ArgumentConfig对象ArgumentConfig argumentConfig = new ArgumentConfig();argumentConfig.setIndex(i);//将ArgumentConfig对象添加到MethodConfig对象中methodConfig.addArgument(argumentConfig);}}}}//refresh MethodConfigs，刷新刚才解析出来的MethodConfig对象List<MethodConfig> methodConfigs = this.getMethods();if (methodConfigs != null && methodConfigs.size() > 0) {//whether ignore invalid method configObject ignoreInvalidMethodConfigVal = getEnvironment().getConfiguration().getProperty(ConfigKeys.DUBBO_CONFIG_IGNORE_INVALID_METHOD_CONFIG, "false");boolean ignoreInvalidMethodConfig = Boolean.parseBoolean(ignoreInvalidMethodConfigVal.toString());Class<?> finalInterfaceClass = interfaceClass;List<MethodConfig> validMethodConfigs = methodConfigs.stream().filter(methodConfig -> {methodConfig.setParentPrefix(preferredPrefix);//关联Model组件methodConfig.setScopeModel(getScopeModel());methodConfig.refresh();//verify method configreturn verifyMethodConfig(methodConfig, finalInterfaceClass, ignoreInvalidMethodConfig);}).collect(Collectors.toList());this.setMethods(validMethodConfigs);}}}public void addMethod(MethodConfig methodConfig) {if (this.methods == null) {this.methods = new ArrayList<>();}this.methods.add(methodConfig);}...
}
6.服务发布时执行的服务实例初始化操作
public class ServiceConfig<T> extends ServiceConfigBase<T> {...@Overridepublic void export() {...synchronized (this) {...if (this.shouldExport()) {//3.执行服务实例的初始化//也就是会把Metadata元数据给准备好，后续可以进行元数据上报this.init();...}}}public void init() {//通过SPI机制获取ServiceListener扩展点的所有实现类实例//然后添加到ServiceConfig的serviceListeners字段里if (this.initialized.compareAndSet(false, true)) {//load ServiceListeners from extensionExtensionLoader<ServiceListener> extensionLoader = this.getExtensionLoader(ServiceListener.class);this.serviceListeners.addAll(extensionLoader.getSupportedExtensionInstances());}//初始化ServiceMetadata，也就是服务元数据//这需要与前面设置的MetadataCenter元数据中心配合起来看//ServiceMetadata作为服务实例的元数据，会对服务实例做一些描述，比如版本号、实现类等initServiceMetadata(provider);serviceMetadata.setServiceType(getInterfaceClass());serviceMetadata.setTarget(getRef());serviceMetadata.generateServiceKey();}...
}
7.服务发布时执行的服务实例发布操作
首先调用ServiceConfig的doExportUrls()方法发布服务，然后再调用其exported()方法进行服务发布后的处理，比如打印日志和回调监听器。
public class ServiceConfig<T> extends ServiceConfigBase<T> {...@Overridepublic void export() {...//4.执行服务实例的发布//进行debug时，可以通过控制台打印的日志去分析运行流程//比如通过log日志可以发现服务发布的流程可能涉及：//一.export Dubbo Service，发布dubbo服务实例//二.register Dubbo Service，往zk进行注册//三.启动NettyServer，监听端口和请求处理//四.服务发现注册//五.MetadataReport：服务实例上报//六.关闭JVM时的逆向处理过程//这里可以作为一个服务发布的直接入口doExport();}protected synchronized void doExport() {...//发布服务doExportUrls();//服务发布完成后的处理，比如打印日志和回调监听器exported();}...
}
8.执行服务实例发布操作时的主流程
首先通过ScopeModel组件体系获取服务数据存储组件，然后将要发布的服务注册到服务数据存储组件里，接着把相关信息封装成一个服务提供者，并将该服务提供者也注册到服务数据存储组件中，然后生成注册的URL，最后根据协议和生成的注册的URL来发布服务。
public class ServiceConfig<T> extends ServiceConfigBase<T> {... @SuppressWarnings({"unchecked", "rawtypes"})private void doExportUrls() {//所谓的ScopeModel，真实的类型是ModuleModel//下面这行代码会通过AbstractMethodConfig的getScopeModel()方法获取ScopeModel//接着会通过ModuleModel的getServiceRepository()方法去获取ServiceRepository//事实上，Dubbo会把它的各个组件都集中在ScopeModel(ModuleModel)里，而ScopeModel就类似于设计模式里的门面模式//ScopeModel、ModuleModel、ApplicationModel、FrameworkModel等多个Model会组成一个Model组件体系//1.通过ScopeModel组件体系获取服务数据存储组件ModuleServiceRepositoryModuleServiceRepository repository = getScopeModel().getServiceRepository();//ServiceRepository是Dubbo服务的数据存储组件//一个系统可以发布多个Dubbo服务//每个Dubbo服务的核心就是一个接口和一个实现类//2.把当前要发布的服务注册到Dubbo的服务数据存储组件中ServiceDescriptor serviceDescriptor;final boolean serverService = ref instanceof ServerService;if (serverService) {serviceDescriptor = ((ServerService) ref).getServiceDescriptor();repository.registerService(serviceDescriptor);} else {serviceDescriptor = repository.registerService(getInterfaceClass());}//ProviderModel也就是服务提供者，由于这里是暴露服务出去的，所以属于Provider//3.把所有相关的信息封装成一个服务提供者ProviderModelproviderModel = new ProviderModel(serviceMetadata.getServiceKey(),ref,//ref代表的是实际实现的类，通过泛型传入serviceDescriptor,//表示服务实例相关的信息getScopeModel(),serviceMetadata, interfaceClassLoader);providerModel.setConfig(this);providerModel.setDestroyRunner(getDestroyRunner());//3.将服务提供者ProviderModel注册到服务数据存储组件中repository.registerProvider(providerModel);//4.生成注册的URL：包含2181的端口号、注册到zk中 //service-discovery-registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103 //registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103List<URL> registryURLs = ConfigValidationUtils.loadRegistries(this, true);for (ProtocolConfig protocolConfig : protocols) {String pathKey = URL.buildKey(getContextPath(protocolConfig).map(p -> p + "/" + path).orElse(path), group, version);//stub service will use generated service nameif (!serverService) {//In case user specified path, register service one more time to map it to path.//将接口注册到服务数据存储组件中repository.registerService(pathKey, interfaceClass);}//5.调用doExportUrlsFor1Protocol()方法，根据协议和注册的URL来发布服务doExportUrlsFor1Protocol(protocolConfig, registryURLs);}providerModel.setServiceUrls(urls);}private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {Map<String, String> map = buildAttributes(protocolConfig);//remove null key and null valuemap.keySet().removeIf(key -> StringUtils.isEmpty(key) || StringUtils.isEmpty(map.get(key)));//init serviceMetadata attachments//将map数据放入serviceMetadata中，这与元数据相关serviceMetadata.getAttachments().putAll(map);//根据ProtocolConfig构建URLURL url = buildUrl(protocolConfig, map);//发布服务exportUrl(url, registryURLs);}...
}//ScopeModel、ModuleModel、ApplicationModel、FrameworkModel等多个Model会组成一个Model组件体系
public class ModuleModel extends ScopeModel {public static final String NAME = "ModuleModel";//ApplicationModel内部封装了其他很多组件，在这里是一个引用关系，通过构造方法传入进来private final ApplicationModel applicationModel;//包含了ServiceModule环境相关的数据，里面封装的都是各种各样的配置信息private ModuleEnvironment moduleEnvironment;//serviceRepository是一个服务仓储组件，存储了一些服务相关的数据private ModuleServiceRepository serviceRepository;//这是module配置管理器，用于存放一些服务相关的配置数据private ModuleConfigManager moduleConfigManager;//这是ModuleDeployer组件，用于管理其他的一些组件和模块的生命周期private ModuleDeployer deployer;...
}public class ApplicationModel extends ScopeModel {...//包含了多个ModuleModelprivate final List<ModuleModel> moduleModels = new CopyOnWriteArrayList<>();private final List<ModuleModel> pubModuleModels = new CopyOnWriteArrayList<>();//环境变量、配置信息private Environment environment;//服务配置相关的一些信息private ConfigManager configManager;//服务数据相关的一些存储private ServiceRepository serviceRepository;//属于application层级的一些组件的生命周期管理private ApplicationDeployer deployer;//父级组件private final FrameworkModel frameworkModel;//内部的一个ModuleModel组件private ModuleModel internalModule;//默认的一个ModuleModel组件private volatile ModuleModel defaultModule;//internal module index is 0, default module index is 1private AtomicInteger moduleIndex = new AtomicInteger(0);//是一个锁private Object moduleLock = new Object();...
}public class FrameworkModel extends ScopeModel {...//它没有父层级了，所以只能通过static静态变量，类级别去引用自己的FrameworkModel集合private static List<FrameworkModel> allInstances = new CopyOnWriteArrayList<>();//包含了多个ApplicationModelprivate List<ApplicationModel> applicationModels = new CopyOnWriteArrayList<>();//通过Framework、Application、Module各个层级都可以获取到service相关的配置和数据private FrameworkServiceRepository serviceRepository;...
}public class ModuleServiceRepository {private final ModuleModel moduleModel;//services，代表服务相关的数据，StubServiceDescriptorprivate final ConcurrentMap<String, List<ServiceDescriptor>> services = new ConcurrentHashMap<>();//consumers(key - group/interface:version, value - consumerModel list)//代表服务的调用方(consumer即消费方/调用方)private final ConcurrentMap<String, List<ConsumerModel>> consumers = new ConcurrentHashMap<>();//providers，代表服务提供方private final ConcurrentMap<String, ProviderModel> providers = new ConcurrentHashMap<>();//FrameworkServiceRepository存储的也是一些服务相关的数据private final FrameworkServiceRepository frameworkServiceRepository;...
}public class ModuleServiceRepository {//services，代表服务相关的数据，StubServiceDescriptorprivate final ConcurrentMap<String, List<ServiceDescriptor>> services = new ConcurrentHashMap<>();...public ServiceDescriptor registerService(ServiceDescriptor serviceDescriptor) {return registerService(serviceDescriptor.getServiceInterfaceClass(), serviceDescriptor);}public ServiceDescriptor registerService(Class<?> interfaceClazz) {ServiceDescriptor serviceDescriptor = new ReflectionServiceDescriptor(interfaceClazz);return registerService(interfaceClazz, serviceDescriptor);}public ServiceDescriptor registerService(Class<?> interfaceClazz, ServiceDescriptor serviceDescriptor) {List<ServiceDescriptor> serviceDescriptors = services.computeIfAbsent(interfaceClazz.getName(), k -> new CopyOnWriteArrayList<>());synchronized (serviceDescriptors) {Optional<ServiceDescriptor> previous = serviceDescriptors.stream().filter(s -> s.getServiceInterfaceClass().equals(interfaceClazz)).findFirst();if (previous.isPresent()) {return previous.get();} else {serviceDescriptors.add(serviceDescriptor);return serviceDescriptor;}}}...
}
9.服务发布过程中ProxyFactory生成Invoker
public class ServiceConfig<T> extends ServiceConfigBase<T> {...private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {Map<String, String> map = buildAttributes(protocolConfig);//remove null key and null valuemap.keySet().removeIf(key -> StringUtils.isEmpty(key) || StringUtils.isEmpty(map.get(key)));//init serviceMetadata attachments//将map数据放入serviceMetadata中，这与元数据相关serviceMetadata.getAttachments().putAll(map);//根据ProtocolConfig构建URLURL url = buildUrl(protocolConfig, map);//发布服务exportUrl(url, registryURLs);}private URL buildUrl(ProtocolConfig protocolConfig, Map<String, String> params) {//获取协议名称String name = protocolConfig.getName();if (StringUtils.isEmpty(name)) {//默认使用Dubbo协议name = DUBBO;}//获取host值String host = findConfiguredHosts(protocolConfig, provider, params);//获取port值Integer port = findConfiguredPort(protocolConfig, provider, this.getExtensionLoader(Protocol.class), name, params);//根据上面获取的host、port以及前文获取的map集合组装URLURL url = new ServiceConfigURL(name, null, null, host, port, getContextPath(protocolConfig).map(p -> p + "/" + path).orElse(path), params);//通过Configurator覆盖或添加新的参数if (this.getExtensionLoader(ConfiguratorFactory.class).hasExtension(url.getProtocol())) {url = this.getExtensionLoader(ConfiguratorFactory.class).getExtension(url.getProtocol()).getConfigurator(url).configure(url);}url = url.setScopeModel(getScopeModel());url = url.setServiceModel(providerModel);return url;}private void exportUrl(URL url, List<URL> registryURLs) {//从URL中获取scope参数，其中可选值有none、remote、local三个，分别代表不发布、发布到本地以及发布到远端String scope = url.getParameter(SCOPE_KEY);//scope不为none，才进行发布if (!SCOPE_NONE.equalsIgnoreCase(scope)) {//scope为local，只发布到本地if (!SCOPE_REMOTE.equalsIgnoreCase(scope)) {exportLocal(url);}//export to remote if the config is not local (export to local only when config is local)//scope为remote，发布到远端的注册中心if (!SCOPE_LOCAL.equalsIgnoreCase(scope)) {//进行远程发布url = exportRemote(url, registryURLs);if (!isGeneric(generic) && !getScopeModel().isInternal()) {//通过MetadataUtils推送这个服务实例的元数据到元数据中心//元数据中心是一个动态的配置中心，可以从里面获取参数，也可以添加监听器监听配置项的变更MetadataUtils.publishServiceDefinition(url, providerModel.getServiceModel(), getApplicationModel());}}}this.urls.add(url);}private void exportLocal(URL url) {//创建新URLURL local = URLBuilder.from(url).setProtocol(LOCAL_PROTOCOL).setHost(LOCALHOST_VALUE).setPort(0).build();local = local.setScopeModel(getScopeModel()).setServiceModel(providerModel);//本地发布doExportUrl(local, false);//exportLocal，指的是发布到本地//具体就是在jvm内部完成了组件之间的一些交互关系和发布logger.info("Export dubbo service " + interfaceClass.getName() + " to local registry url : " + local);}private URL exportRemote(URL url, List<URL> registryURLs) {//如果当前配置了至少一个注册中心if (CollectionUtils.isNotEmpty(registryURLs)) {//URL里有很多的信息，比如协议、各种参数等//URL可以在后续代码运行过程中提供配置和信息//接下来会向每个注册中心发布服务for (URL registryURL : registryURLs) {//registryURL.getProtocol()会获取协议if (SERVICE_REGISTRY_PROTOCOL.equals(registryURL.getProtocol())) {url = url.addParameterIfAbsent(SERVICE_NAME_MAPPING_KEY, "true");}//injvm协议只在exportLocal()中有用，不会将服务发布到注册中心，所以这里忽略injvm协议if (LOCAL_PROTOCOL.equalsIgnoreCase(url.getProtocol())) {continue;}//设置服务URL的dynamic参数url = url.addParameterIfAbsent(DYNAMIC_KEY, registryURL.getParameter(DYNAMIC_KEY));//创建monitorUrl，并作为monitor参数添加到服务URL中URL monitorUrl = ConfigValidationUtils.loadMonitor(this, registryURL);if (monitorUrl != null) {url = url.putAttribute(MONITOR_KEY, monitorUrl);}//For providers, this is used to enable custom proxy to generate invoker//设置服务URL的proxy参数，即生成动态代理方式(jdk或是javassist)，作为参数添加到RegistryURL中String proxy = url.getParameter(PROXY_KEY);if (StringUtils.isNotEmpty(proxy)) {registryURL = registryURL.addParameter(PROXY_KEY, proxy);}doExportUrl(registryURL.putAttribute(EXPORT_KEY, url), true);}} else {//不存在注册中心，仅发布服务，不会将服务信息发布到注册中心doExportUrl(url, true);}return url;}private void doExportUrl(URL url, boolean withMetaData) {//动态代理技术有很多种，比如cglib，jdk//而动态代理就是：面向一个接口，动态生成该接口的一个实现类，然后根据这个实现类再动态生成对应的对象//这个对象就是动态代理的对象，所以该对象会代理自己背后的一个实现类//当这个对象被调用时，背后的实现类也会被调用//ProxyFactory，Proxy就是动态代理//下面传入的ref指的是实现类//下面传入的interfaceClass指的是接口//下面传入的url就是服务实例对外暴露出去的一些核心信息//proxyFactory.getInvoker()获取到的是Invoker调用组件//当Dubbo的NettyServer监听到网络连接进行请求处理时，需要有一个调用组件去根据请求进行调用//Invoker调用组件可以认为是ProxyFactory基于DemoService接口生成的动态代理//当需要根据请求调用接口时，底层就会回调自己写的实现类DemoServiceImpl//proxyFactory.getInvoker()会封装一个AbstractProxyInvoker，对本地实现类进行代理//默认情况下，会通过Javassist技术生成Wrapper，该Wrapper会将本地实现类包装进去//调用AbstractProxyInvoker的invoke方法时，最终就会基于Javassist动态生成的Wrapper进行调用//下面这一行代码是为服务实现类的对象创建相应的Invoker//其中传入的服务url会作为export参数添加到RegistryURL中//这里的proxyFactory就是ProxyFactory接口的适配器，会通过SPI机制进行初始化//比如下面就会调用JavassistProxyFactory.getInvoker()方法//proxyFactory.getInvoker()会获取到Invoker调用组件(生成Invoker动态代理)//所以下面这一行代码会为本地实现类的对象创建相应的Invoker(封装着AbstractProxyInvoker)Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);if (withMetaData) {//DelegateProviderMetaDataInvoker是个装饰类//它会将当前ServiceConfig和Invoker关联起来invoker = new DelegateProviderMetaDataInvoker(invoker, this);}//调用Protocol的实现进行发布，protocolSPI是Protocol接口的适配器//进行本地发布时，使用的是InjvmProtocol + InjvmExporter//进行远程发布时，使用的是RegistryProtocol，它会对DubboProtocol进行包装和装饰//RegistryProtocol会先执行来处理服务注册的一些事情//DubboProtocol会后执行来启动NettyServer网络服务器Exporter<?> exporter = protocolSPI.export(invoker);exporters.add(exporter);}...
}public class JavassistProxyFactory extends AbstractProxyFactory {...@Overridepublic <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) throws RpcException {//下面会通过Wrapper创建一个包装类对象//该对象是动态构建出来的，它属于Wrapper的一个子类，里面会拼接一个关键的方法invokeMethod()，拼接代码由javassist动态生成final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf('$') < 0 ? proxy.getClass() : type);//下面会创建一个实现了AbstractProxyInvoker的匿名内部类//其doInvoker()方法会直接委托给Wrapper对象的invokeMethod()方法return new AbstractProxyInvoker<T>(proxy, type, url) {@Overrideprotected Object doInvoke(T proxy, String methodName, Class<?>[] parameterTypes, Object[] arguments) throws Throwable {//当AbstractProxyInvoker.invoke()方法被调用时，便会执行到这里//这里会通过类似于JDK反射的技术，调用本地实现类如DemoServiceImpl.sayHello()//这个wrapper对象是由javassist技术动态生成的，已经对本地实现类进行包装//这个动态生成的wrapper对象会通过javassist技术自己特有的方法//在invokerMethod()方法被调用时执行本地实现类的目标方法return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments);}};}...
}public abstract class AbstractProxyInvoker<T> implements Invoker<T> {...//当Netty Server接受到了请求后，经过解析就会知道是要调用什么//然后会把解析出来的数据放入Invocation中，通过AbstractProxyInvoker的invoke()方法来进行调用@Overridepublic Result invoke(Invocation invocation) throws RpcException {...//执行doInvoke()方法，调用业务实现Object value = doInvoke(proxy, invocation.getMethodName(), invocation.getParameterTypes(), invocation.getArguments());...//将value值封装成CompletableFuture对象CompletableFuture<Object> future = wrapWithFuture(value, invocation);//再次转换，转换为CompletableFuture<AppResponse>类型CompletableFuture<AppResponse> appResponseFuture = future.handle((obj, t) -> {AppResponse result = new AppResponse(invocation);...//将CompletableFuture封装成AsyncRpcResult返回return new AsyncRpcResult(appResponseFuture, invocation);}protected abstract Object doInvoke(T proxy, String methodName, Class<?>[] parameterTypes, Object[] arguments) throws Throwable;...
}
10.服务发布过程中Protocol组件发布Invoker
(1)Protocol协议接口
(2)Protocol组件发布Invoker
(1)Protocol协议接口
@SPI(value = "dubbo", scope = ExtensionScope.FRAMEWORK)
public interface Protocol {//默认端口int getDefaultPort();//Protocol接收到一个请求之后，必须要记录请求的源地址//对同一个服务实例(url)发布一次和发布多次，是没有任何区别的//export()方法会将一个Invoker发布出去//export()方法的实现需要是幂等的，即同一个服务暴露多次和暴露一次的效果是相同的@Adaptive<T> Exporter<T> export(Invoker<T> invoker) throws RpcException;//Protocol必须根据一个url和接口类型，获取到对应的Invoker//refer()方法会引用一个Invoker//refer()方法会根据参数返回一个Invoker对象，Consumer端可以通过这个Invoker请求到Provider端的服务@Adaptive<T> Invoker<T> refer(Class<T> type, URL url) throws RpcException;//销毁export()方法以及refer()方法使用到的Invoker对象，释放当前Protocol对象底层占用的资源void destroy();//返回当前Protocol底层的全部ProtocolServerdefault List<ProtocolServer> getServers() {return Collections.emptyList();}
}(2)Protocol组件发布Invoker
本地发布时使用InjvmProtocol + InjvmExporter，远程发布时使用RegistryProtocol + DestroyableExporter。
RegistryProtocol的export()方法被远程发布调用的时候，会调用到DubboProtocol的export()方法，并最终调用到HeaderExchanger的bind()方法执行NettyTransporter的bind()方法构建Netty服务器。
public class ServiceConfig<T> extends ServiceConfigBase<T> {...private void doExportUrl(URL url, boolean withMetaData) {//动态代理技术有很多种，比如cglib，jdk//而动态代理就是：面向一个接口，动态生成该接口的一个实现类，然后根据这个实现类再动态生成对应的对象//这个对象就是动态代理的对象，所以该对象会代理自己背后的一个实现类//当这个对象被调用时，背后的实现类也会被调用//ProxyFactory，Proxy就是动态代理//下面传入的ref指的是实现类//下面传入的interfaceClass指的是接口//下面传入的url就是服务实例对外暴露出去的一些核心信息//proxyFactory.getInvoker()获取到的是Invoker调用组件//当Dubbo的NettyServer监听到网络连接进行请求处理时，需要有一个调用组件去根据请求进行调用//Invoker调用组件可以认为是ProxyFactory基于DemoService接口生成的动态代理//当需要根据请求调用接口时，底层就会回调自己写的实现类DemoServiceImpl//proxyFactory.getInvoker()会封装一个AbstractProxyInvoker，对本地实现类进行代理//默认情况下，会通过Javassist技术生成Wrapper，该Wrapper会将本地实现类包装进去//调用AbstractProxyInvoker的invoke方法时，最终就会基于Javassist动态生成的Wrapper进行调用//下面这一行代码是为服务实现类的对象创建相应的Invoker//其中传入的服务url会作为export参数添加到RegistryURL中//这里的proxyFactory就是ProxyFactory接口的适配器，会通过SPI机制进行初始化//比如下面就会调用JavassistProxyFactory.getInvoker()方法//proxyFactory.getInvoker()会获取到Invoker调用组件(生成Invoker动态代理)//所以下面这一行代码会为本地实现类的对象创建相应的Invoker(封装着AbstractProxyInvoker)Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);if (withMetaData) {//DelegateProviderMetaDataInvoker是个装饰类//它会将当前ServiceConfig和Invoker关联起来invoker = new DelegateProviderMetaDataInvoker(invoker, this);}//调用Protocol的实现进行发布，protocolSPI是Protocol接口的适配器//进行本地发布时，使用的是InjvmProtocol + InjvmExporter//进行远程发布时，使用的是RegistryProtocol，它会对DubboProtocol进行包装和装饰//RegistryProtocol会先执行来处理服务注册的一些事情//DubboProtocol会后执行来启动NettyServer网络服务器Exporter<?> exporter = protocolSPI.export(invoker);exporters.add(exporter);}...
}//-> Protocol$Adaptive.export()
//-> ProtocolSerializationWrapper.export()
//-> ProtocolFilterWrapper.export()
//-> ProtocolListenerWrapper.export()
//-> InjvmProtocol.export()
public class InjvmProtocol extends AbstractProtocol implements Protocol {...@Overridepublic <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {return new InjvmExporter<T>(invoker, invoker.getUrl().getServiceKey(), exporterMap);}...
}public class InjvmExporter<T> extends AbstractExporter<T> {private final String key;//这就是在JVM里存放了private final Map<String, Exporter<?>> exporterMap;InjvmExporter(Invoker<T> invoker, String key, Map<String, Exporter<?>> exporterMap) {super(invoker);this.key = key;this.exporterMap = exporterMap;exporterMap.put(key, this);}...
}//-> Protocol$Adaptive.export()
//-> ProtocolSerializationWrapper.export()
//-> ProtocolFilterWrapper.export()
//-> ProtocolListenerWrapper.export()
//-> RegistryProtocol.export()
//-> Protocol$Adaptive.export()
//-> ProtocolSerializationWrapper.export()
//-> ProtocolFilterWrapper.export()
//-> ProtocolListenerWrapper.export()
//-> DubboProtocol.export()
//-> DubboProtocol.openServer()
//-> DubboProtocol.createServer()
//-> Exchangers.bind()
//-> HeaderExchanger.bind()
//-> Transporters.bind()
//-> NettyTransporter.bind()
//-> NettyServer@Activate
public class ProtocolSerializationWrapper implements Protocol {private Protocol protocol;public ProtocolSerializationWrapper(Protocol protocol) {this.protocol = protocol;}@Overridepublic <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {getFrameworkModel(invoker.getUrl().getScopeModel()).getServiceRepository().registerProviderUrl(invoker.getUrl());//下面会调用ProtocolFilterWrapper.export()方法return protocol.export(invoker);}...
}@Activate(order = 100)
public class ProtocolFilterWrapper implements Protocol {private final Protocol protocol;public ProtocolFilterWrapper(Protocol protocol) {if (protocol == null) {throw new IllegalArgumentException("protocol == null");}this.protocol = protocol;}@Overridepublic <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {if (UrlUtils.isRegistry(invoker.getUrl())) {return protocol.export(invoker);}FilterChainBuilder builder = getFilterChainBuilder(invoker.getUrl());//下面会调用ProtocolListenerWrapper.export()方法return protocol.export(builder.buildInvokerChain(invoker, SERVICE_FILTER_KEY, CommonConstants.PROVIDER));}private <T> FilterChainBuilder getFilterChainBuilder(URL url) {return ScopeModelUtil.getExtensionLoader(FilterChainBuilder.class, url.getScopeModel()).getDefaultExtension();}...
}@Activate
public class DefaultFilterChainBuilder implements FilterChainBuilder {//build consumer/provider filter chain@Overridepublic <T> Invoker<T> buildInvokerChain(final Invoker<T> originalInvoker, String key, String group) {Invoker<T> last = originalInvoker;URL url = originalInvoker.getUrl();List<ModuleModel> moduleModels = getModuleModelsFromUrl(url);List<Filter> filters;//通过SPI机制来获取Filterif (moduleModels != null && moduleModels.size() == 1) {filters = ScopeModelUtil.getExtensionLoader(Filter.class, moduleModels.get(0)).getActivateExtension(url, key, group);} else if (moduleModels != null && moduleModels.size() > 1) {filters = new ArrayList<>();List<ExtensionDirector> directors = new ArrayList<>();for (ModuleModel moduleModel : moduleModels) {List<Filter> tempFilters = ScopeModelUtil.getExtensionLoader(Filter.class, moduleModel).getActivateExtension(url, key, group);filters.addAll(tempFilters);directors.add(moduleModel.getExtensionDirector());}filters = sortingAndDeduplication(filters, directors);} else {filters = ScopeModelUtil.getExtensionLoader(Filter.class, null).getActivateExtension(url, key, group);}//构建Filter链条if (!CollectionUtils.isEmpty(filters)) {for (int i = filters.size() - 1; i >= 0; i--) {final Filter filter = filters.get(i);final Invoker<T> next = last;last = new CopyOfFilterChainNode<>(originalInvoker, next, filter);}return new CallbackRegistrationInvoker<>(last, filters);}return last;}...
}@Activate(order = 200)
public class ProtocolListenerWrapper implements Protocol {private final Protocol protocol;public ProtocolListenerWrapper(Protocol protocol) {if (protocol == null) {throw new IllegalArgumentException("protocol == null");}this.protocol = protocol;}@Overridepublic <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {if (UrlUtils.isRegistry(invoker.getUrl())) {return protocol.export(invoker);}//下面会调用RegistryProtocol.export()return new ListenerExporterWrapper<T>(protocol.export(invoker),Collections.unmodifiableList(ScopeModelUtil.getExtensionLoader(ExporterListener.class, invoker.getUrl().getScopeModel()).getActivateExtension(invoker.getUrl(), EXPORTER_LISTENER_KEY)));}...
}public class RegistryProtocol implements Protocol, ScopeModelAware {...@Overridepublic <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {...//export invoker//下面进行导出服务，底层会通过会执行DubboProtocol.export()方法，启动对应的Server//也就是会涉及到对另外一个protocol组件的调用，远程发布服务时其实就是执行DubboProtocol的export方法final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);...}private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originInvoker, URL providerUrl) {String key = getCacheKey(originInvoker);return (ExporterChangeableWrapper<T>) bounds.computeIfAbsent(key, s -> {Invoker<?> invokerDelegate = new InvokerDelegate<>(originInvoker, providerUrl);//下面会调用DubboProtocol的export()方法return new ExporterChangeableWrapper<>((Exporter<T>) protocol.export(invokerDelegate), originInvoker);});}...
}public class DubboProtocol extends AbstractProtocol {...@Overridepublic <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {checkDestroyed();URL url = invoker.getUrl();//export service.//创建ServiceKeyString key = serviceKey(url);//exporter组件，代表了指定的invoker被发布出去//下面代码会将上层传入的Invoker对象封装成DubboExporter对象，然后记录到exporterMap集合中DubboExporter<T> exporter = new DubboExporter<T>(invoker, key, exporterMap);...//启动ProtocolServer，这个就是打开对外的网络服务器，可以对外提供网络请求处理openServer(url);//序列化的优化处理optimizeSerialization(url);return exporter;}private void openServer(URL url) {checkDestroyed();//find server.//获取host:port这个地址String key = url.getAddress();//client can export a service which only for server to invokeboolean isServer = url.getParameter(IS_SERVER_KEY, true);//只有Server端才能启动Server对象if (isServer) {ProtocolServer server = serverMap.get(key);//无ProtocolServer监听该地址if (server == null) {//DoubleCheck，防止并发问题synchronized (this) {server = serverMap.get(key);if (server == null) {//调用createServer()方法创建ProtocolServer对象serverMap.put(key, createServer(url));return;}}}//server supports reset, use together with overrideserver.reset(url);}}private ProtocolServer createServer(URL url) {...ExchangeServer server;//通过Exchangers门面类，创建ExchangeServer对象server = Exchangers.bind(url, requestHandler);...//将ExchangeServer封装成DubboProtocolServer返回DubboProtocolServer protocolServer = new DubboProtocolServer(server);loadServerProperties(protocolServer);return protocolServer;}...
}public class DubboExporter<T> extends AbstractExporter<T> {private final String key;private final Map<String, Exporter<?>> exporterMap;public DubboExporter(Invoker<T> invoker, String key, Map<String, Exporter<?>> exporterMap) {super(invoker);this.key = key;this.exporterMap = exporterMap;exporterMap.put(key, this);}...
}public class Exchangers {...public static ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {url = url.addParameterIfAbsent(Constants.CODEC_KEY, "exchange");//先获取到一个Exchanger组件，再用这个Exchanger组件去进行bind，拿到对应的ExchangeServer//getExchanger()会通过SPI机制，获取到HeaderExchanger，然后将DubboProtocol的requestHandler传入bind()方法中return getExchanger(url).bind(url, handler);}public static Exchanger getExchanger(URL url) {String type = url.getParameter(Constants.EXCHANGER_KEY, Constants.DEFAULT_EXCHANGER);//根据SPI机制，通过model组件体系去拿到对应的SPI扩展实现类实例return url.getOrDefaultFrameworkModel().getExtensionLoader(Exchanger.class).getExtension(type);}...
}public class HeaderExchanger implements Exchanger {...@Overridepublic ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {//Exchanger这一层的代码可以理解为是位于上层的代码，它会把一些RpcInvocation调用转为请求/响应的模型，以及进行同步转异步的处理//从Exchanger这层开始，便进入网络模型的范围，引入了请求的概念，并最终会通过底层的网络框架把请求发送出去//因此需要获取到网络框架底层的Server和Client，并将它们封装到Exchanger组件如HeaderExchangeServer/HeaderExchangeClient中//为什么需要不同的Transporter？//在Exchanger这一层里其实是可以使用不同的网络技术的，比如Netty、Mina这些网络通信框架//由于Netty、Mina这些不同的框架，它们的用法和API都是不同的，所以在Exchanger这一层，不能把Netty、Mina的API直接提供过来//为了把这些不同的网络框架技术进行统一的封装，需要做一层Transporter，由Transporter来实现抽象统一的底层网络框架的使用标准//所以Exchanger这一层是基于Transporter这一层提供的标准模型来实现请求/响应处理//下面的Transporters.bind()会返回一个NettyServerreturn new HeaderExchangeServer(Transporters.bind(url, new DecodeHandler(new HeaderExchangeHandler(handler))));}...
}public class Transporters {...public static RemotingServer bind(URL url, ChannelHandler... handlers) throws RemotingException {ChannelHandler handler;if (handlers.length == 1) {handler = handlers[0];} else {handler = new ChannelHandlerDispatcher(handlers);}return getTransporter(url).bind(url, handler);}public static Transporter getTransporter(URL url) {//下面使用了getAdaptiveExtension()的自适应机制，针对接口动态生成代码然后创建代理类//代理类的方法，会根据url的参数动态提取对应的实现类的name名称，以及获取真正的需要使用的实现类//有了真正的实现类后，就可以去调用实现类的extension实例的方法了//比如下面会获取到一个NettyTransporter实例return url.getOrDefaultFrameworkModel().getExtensionLoader(Transporter.class).getAdaptiveExtension();}...
}//不同的框架可以有不同的Transporter
//每个框架对应的Transporter可以创建自己的Server和Client
public class NettyTransporter implements Transporter {public static final String NAME = "netty";@Overridepublic RemotingServer bind(URL url, ChannelHandler handler) throws RemotingException {return new NettyServer(url, handler);}@Overridepublic Client connect(URL url, ChannelHandler handler) throws RemotingException {//传入的handler装饰了DubboProtocol的requestHandler，返回一个NettyClientreturn new NettyClient(url, handler);}
}
11.服务发布过程中NettyServer的构造流程
public abstract class AbstractServer extends AbstractEndpoint implements RemotingServer {...//业务线程池private Set<ExecutorService> executors = new ConcurrentHashSet<>();private InetSocketAddress localAddress;private InetSocketAddress bindAddress;private int accepts;private ExecutorRepository executorRepository;public AbstractServer(URL url, ChannelHandler handler) throws RemotingException {//调用父类的构造方法super(url, handler);//通过使用SPI机制，从applicationModel组件中根据扩展接口ExecutorRepository去获取ExtensionLoader，然后拿到其默认实现类this.executorRepository = url.getOrDefaultApplicationModel().getExtensionLoader(ExecutorRepository.class).getDefaultExtension();//根据传入的URL初始化localAddress和bindAddressthis.localAddress = getUrl().toInetSocketAddress();String bindIp = getUrl().getParameter(Constants.BIND_IP_KEY, getUrl().getHost());int bindPort = getUrl().getParameter(Constants.BIND_PORT_KEY, getUrl().getPort());if (url.getParameter(ANYHOST_KEY, false) || NetUtils.isInvalidLocalHost(bindIp)) {bindIp = ANYHOST_VALUE;}this.bindAddress = new InetSocketAddress(bindIp, bindPort);//初始化accepts等字段this.accepts = url.getParameter(ACCEPTS_KEY, DEFAULT_ACCEPTS);//调用doOpen()这个抽象方法，启动该ServerdoOpen();//获取该Server关联的线程池，通过DefaultExecutorRepository创建一个FixedThreadPool线程池出来this.executors.add(executorRepository.createExecutorIfAbsent(url));}protected abstract void doOpen() throws Throwable;...
}public class NettyServer extends AbstractServer {...private Map<String, Channel> channels;private ServerBootstrap bootstrap;private io.netty.channel.Channel channel;private EventLoopGroup bossGroup;private EventLoopGroup workerGroup;private final int serverShutdownTimeoutMills;//NettyServer在构建的过程中，会构建和打开真正的网络服务器//这里是基于netty4技术去实现了网络服务器构建和打开的//一旦打开后，Netty Server就开始监听指定的端口号//当发现有请求过来就可以去进行处理，也就是通过ProxyInvoker去调用本地实现类的目标方法//入参handler其实就是DubboProtocol中的requestHandlerpublic NettyServer(URL url, ChannelHandler handler) throws RemotingException {//you can customize name and type of client thread pool by THREAD_NAME_KEY and THREAD_POOL_KEY in CommonConstants.//the handler will be wrapped: MultiMessageHandler->HeartbeatHandler->handlersuper(ExecutorUtil.setThreadName(url, SERVER_THREAD_POOL_NAME), ChannelHandlers.wrap(handler, url));//read config before destroyserverShutdownTimeoutMills = ConfigurationUtils.getServerShutdownTimeout(getUrl().getOrDefaultModuleModel());}//Init and start netty server@Overrideprotected void doOpen() throws Throwable {//创建ServerBootstrapbootstrap = new ServerBootstrap();//EventLoop，也可以理解为网络服务器，它会监听一个本地的端口号//外部系统针对本地服务器端口号发起连接、通信、网络事件时，监听的端口号就会不停的产生网络事件//EventLoop网络服务器，还会不停轮询监听到的网络事件//boss的意思是负责监听端口号是否有外部系统的连接请求，它是一个EventLoopGroup线程池//如果发现了网络事件，就需要进行请求处理，可以通过workerGroup里的多个线程进行并发处理//创建boss EventLoopGroup，线程数是1bossGroup = createBossGroup();//创建worker EventLoopGroup，线程数是CPU核数+1，但最多不会超过32个线程workerGroup = createWorkerGroup();//创建NettyServerHandler//它是一个Netty中的ChannelHandler实现，不是Dubbo Remoting层的ChannelHandler接口的实现final NettyServerHandler nettyServerHandler = createNettyServerHandler();//获取当前NettyServer创建的所有Channel//channels集合中的Channel不是Netty中的Channel对象，而是Dubbo Remoting层的Channel对象channels = nettyServerHandler.getChannels();//初始化ServerBootstrap，指定boss和worker EventLoopGroupinitServerBootstrap(nettyServerHandler);//绑定指定的地址和端口ChannelFuture channelFuture = bootstrap.bind(getBindAddress());//等待bind操作完成channelFuture.syncUninterruptibly();channel = channelFuture.channel();}protected EventLoopGroup createBossGroup() {return NettyEventLoopFactory.eventLoopGroup(1, EVENT_LOOP_BOSS_POOL_NAME);}protected EventLoopGroup createWorkerGroup() {return NettyEventLoopFactory.eventLoopGroup(getUrl().getPositiveParameter(IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS), EVENT_LOOP_WORKER_POOL_NAME);}protected NettyServerHandler createNettyServerHandler() {return new NettyServerHandler(getUrl(), this);}protected void initServerBootstrap(NettyServerHandler nettyServerHandler) {boolean keepalive = getUrl().getParameter(KEEP_ALIVE_KEY, Boolean.FALSE);bootstrap.group(bossGroup, workerGroup).channel(NettyEventLoopFactory.serverSocketChannelClass()).option(ChannelOption.SO_REUSEADDR, Boolean.TRUE).childOption(ChannelOption.TCP_NODELAY, Boolean.TRUE).childOption(ChannelOption.SO_KEEPALIVE, keepalive).childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT).childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {//连接空闲超时时间int idleTimeout = UrlUtils.getIdleTimeout(getUrl());//NettyCodecAdapter中会创建Decoder和EncoderNettyCodecAdapter adapter = new NettyCodecAdapter(getCodec(), getUrl(), NettyServer.this);if (getUrl().getParameter(SSL_ENABLED_KEY, false)) {ch.pipeline().addLast("negotiation", new SslServerTlsHandler(getUrl()));}ch.pipeline()//注册Decoder和Encoder.addLast("decoder", adapter.getDecoder()).addLast("encoder", adapter.getEncoder())//注册IdleStateHandler.addLast("server-idle-handler", new IdleStateHandler(0, 0, idleTimeout, MILLISECONDS))//注册NettyServerHandler.addLast("handler", nettyServerHandler);}});}...
}
12.服务发布过程中RegistryProtocol的服务注册
(1)首先注册service-discovery-registry的URL
(2)然后注册registry的URL
服务发布过程中需要进行注册的URL有两个：
service-discovery-registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103
registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103(1)首先注册service-discovery-registry的URL
此时，在RegistryProtocol.export()方法中，进行服务注册时使用的Registry其实是一个ListenerRegistryWrapper装饰器，装饰着使用了ZookeeperServiceDiscovery的ServiceDiscoveryRegistry。
ZookeeperServiceDiscovery.doRegister()处理的URL注册其实就是在本地进行注册。
//-> RegistryProtocol.export()
//-> RegistryProtocol.getRegistry()
//-> RegistryFactory$Adaptive.getRegistry()
//-> RegistryFactoryWrapper.getRegistry()
//-> ServiceDiscoveryRegistryFactory.getRegistry()
//-> ServiceDiscoveryRegistryFactory.createRegistry()
//-> new ServiceDiscoveryRegistry()
//-> ServiceDiscoveryRegistry.createServiceDiscovery()
//=> ListenerRegistryWrapper、ServiceDiscoveryRegistry、ZookeeperServiceDiscovery//-> RegistryProtocol.register()
//-> ListenerRegistryWrapper.register()
//-> ServiceDiscoveryRegistry.register()
//-> AbstractServiceDiscovery.register()
//-> ZookeeperServiceDiscovery.doRegister()public class RegistryProtocol implements Protocol, ScopeModelAware {...@Overridepublic <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {//将"registry://"协议(Remote URL)转换成"zookeeper://"协议(Registry URL)URL registryUrl = getRegistryUrl(originInvoker);//url to export locally//获取export参数，其中存储了一个"dubbo://"协议的Provider URLURL providerUrl = getProviderUrl(originInvoker);//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(providerUrl);final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);Map<URL, NotifyListener> overrideListeners = getProviderConfigurationListener(providerUrl).getOverrideListeners();overrideListeners.put(registryUrl, overrideSubscribeListener);providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);//1.export invoker//下面进行导出服务，底层会通过会执行DubboProtocol.export()方法，启动对应的Server//也就是会涉及到对另外一个Protocol组件的调用，远程发布服务时其实就是执行DubboProtocol的export方法final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);//2.url to registry 完成服务注册的事情//下面会根据RegistryURL获取对应的注册中心Registry对象，其中会依赖RegistryFactory//远程发布时，下面的registry其实是一个ListenerRegistryWrapper装饰器，装饰着使用了ZookeeperServiceDiscovery的ServiceDiscoveryRegistry//在基于注册中心的url地址去构建对应的注册中心组件时，默认是基于zk的//而构建一个基于zk的注册中心组件，同时跟zk完成连接的建立，则由curator5框架来实现final Registry registry = getRegistry(registryUrl);//获取将要发布到注册中心上的Provider URL，其中会删除一些多余的参数信息final URL registeredProviderUrl = getUrlToRegistry(providerUrl, registryUrl);//decide if we need to delay publish (provider itself and registry should both need to register)//根据register参数值决定是否注册服务boolean register = providerUrl.getParameter(REGISTER_KEY, true) && registryUrl.getParameter(REGISTER_KEY, true);if (register) {//调用Registry.register()方法将registeredProviderUrl发布到注册中心register(registry, registeredProviderUrl);}//register stated url on provider model//将Provider相关信息记录到的ProviderModel中registerStatedUrl(registryUrl, registeredProviderUrl, register);exporter.setRegisterUrl(registeredProviderUrl);exporter.setSubscribeUrl(overrideSubscribeUrl);if (!registry.isServiceDiscovery()) {//Deprecated! Subscribe to override rules in 2.6.x or before.//向注册中心进行订阅override数据，主要是监听该服务的configurators节点registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);}//触发RegistryProtocolListener监听器notifyExport(exporter);//Ensure that a new exporter instance is returned every time exportreturn new DestroyableExporter<>(exporter);}protected Registry getRegistry(final URL registryUrl) {//通过SPI自适应机制，去拿到对应的extension实例//这里的registryFactory为RegistryFactory$AdaptiveRegistryFactory registryFactory = ScopeModelUtil.getExtensionLoader(RegistryFactory.class, registryUrl.getScopeModel()).getAdaptiveExtension();//调用RegistryFactory$Adaptive的getRegistry()方法return registryFactory.getRegistry(registryUrl);}private void register(Registry registry, URL registeredProviderUrl) {//下面会调用ListenerRegistryWrapper.register()方法registry.register(registeredProviderUrl);}private void registerStatedUrl(URL registryUrl, URL registeredProviderUrl, boolean registered) {ProviderModel model = (ProviderModel) registeredProviderUrl.getServiceModel();model.addStatedUrl(new ProviderModel.RegisterStatedURL(registeredProviderUrl,registryUrl,registered));}...
}public class RegistryFactory$Adaptive implements org.apache.dubbo.registry.RegistryFactory {public org.apache.dubbo.registry.Registry getRegistry(org.apache.dubbo.common.URL arg0) {if (arg0 == null) throw new IllegalArgumentException("url == null");org.apache.dubbo.common.URL url = arg0;String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() );//注册service-discovery-registry的URL时，extName=service-discovery-registryif (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.registry.RegistryFactory) name from url (" + url.toString() + ") use keys([protocol])");ScopeModel scopeModel = ScopeModelUtil.getOrDefault(url.getScopeModel(), org.apache.dubbo.registry.RegistryFactory.class);//此时获取到的extension为RegistryFactoryWrapper//RegistryFactoryWrapper的registryFactory为ServiceDiscoveryRegistryFactoryorg.apache.dubbo.registry.RegistryFactory extension = (org.apache.dubbo.registry.RegistryFactory)scopeModel.getExtensionLoader(org.apache.dubbo.registry.RegistryFactory.class).getExtension(extName);//调用RegistryFactoryWrapper的getRegistry()方法return extension.getRegistry(arg0);}
}public class RegistryFactoryWrapper implements RegistryFactory {//此时的registryFactory为ServiceDiscoveryRegistryFactoryprivate RegistryFactory registryFactory;public RegistryFactoryWrapper(RegistryFactory registryFactory) {this.registryFactory = registryFactory;}@Overridepublic Registry getRegistry(URL url) {//调用ServiceDiscoveryRegistryFactory的getRegistry()方法获取一个ServiceDiscoveryRegistry//所以这里会返回一个封装了ServiceDiscoveryRegistry的ListenerRegistryWrapperreturn new ListenerRegistryWrapper(registryFactory.getRegistry(url),Collections.unmodifiableList(url.getOrDefaultApplicationModel().getExtensionLoader(RegistryServiceListener.class).getActivateExtension(url, "registry.listeners")));}
}public abstract class AbstractRegistryFactory implements RegistryFactory, ScopeModelAware {...@Overridepublic Registry getRegistry(URL url) {...registry = createRegistry(url);...return registry;}...
}public class ServiceDiscoveryRegistryFactory extends AbstractRegistryFactory {@Overrideprotected Registry createRegistry(URL url) {if (UrlUtils.hasServiceDiscoveryRegistryProtocol(url)) {//将"service-discovery-registry://"协议替换为"zookeeper://"String protocol = url.getParameter(REGISTRY_KEY, DEFAULT_REGISTRY);url = url.setProtocol(protocol).removeParameter(REGISTRY_KEY);}return new ServiceDiscoveryRegistry(url, applicationModel);}
}public class ServiceDiscoveryRegistry extends FailbackRegistry {private final ServiceDiscovery serviceDiscovery;...public ServiceDiscoveryRegistry(URL registryURL, ApplicationModel applicationModel) {super(registryURL);this.serviceDiscovery = createServiceDiscovery(registryURL);this.serviceNameMapping = (AbstractServiceNameMapping) ServiceNameMapping.getDefaultExtension(registryURL.getScopeModel());super.applicationModel = applicationModel;}protected ServiceDiscovery createServiceDiscovery(URL registryURL) {//根据registryURL获取对应的ServiceDiscovery实现//此时由于url的协议已经由"service-discovery-registry://"变为"zookeeper://"//所以会获取一个ZookeeperServiceDiscovery进行返回return getServiceDiscovery(registryURL.addParameter(INTERFACE_KEY, ServiceDiscovery.class.getName()).removeParameter(REGISTRY_TYPE_KEY));}...
}public class ListenerRegistryWrapper implements Registry {private final Registry registry;...public void register(URL url) {...//此时下面会调用ServiceDiscoveryRegistry.register()方法registry.register(url);}
}public class ServiceDiscoveryRegistry extends FailbackRegistry {//RegistryProtocol.export()方法中获取Registry时，这里会是一个ZookeeperServiceDiscoveryprivate final ServiceDiscovery serviceDiscovery;...public final void register(URL url) {//检测URL中的side参数是否为providerif (!shouldRegister(url)) {return;}doRegister(url);}public void doRegister(URL url) {//将元数据发布到MetadataServiceurl = addRegistryClusterKey(url);//下面会调用ZookeeperServiceDiscovery.register()方法//此时只是将url添加到对象的属性中而已serviceDiscovery.register(url);}
}public abstract class AbstractServiceDiscovery implements ServiceDiscovery {protected volatile ServiceInstance serviceInstance;protected volatile MetadataInfo metadataInfo;...@Overridepublic void register(URL url) {//将要注册的url添加到metadataInfo属性metadataInfo.addService(url);}...
}public class ZookeeperServiceDiscovery extends AbstractServiceDiscovery {......
}public class MetadataInfo implements Serializable {//key format is '{group}/{interface name}:{version}:{protocol}'//map里存放了多个服务实例的ServiceInfoprivate final Map<String, ServiceInfo> services;...public synchronized void addService(URL url) {if (this.loader == null) {this.loader = url.getOrDefaultApplicationModel().getExtensionLoader(MetadataParamsFilter.class);}List<MetadataParamsFilter> filters = loader.getActivateExtension(url, "params-filter");//generate service level metadataServiceInfo serviceInfo = new ServiceInfo(url, filters);this.services.put(serviceInfo.getMatchKey(), serviceInfo);//extract common instance level paramsextractInstanceParams(url, filters);if (exportedServiceURLs == null) {exportedServiceURLs = new ConcurrentSkipListMap<>();}addURL(exportedServiceURLs, url);updated = true;}...
}(2)然后注册registry的URL
此时，在RegistryProtocol.export()方法中，进行服务注册时使用的Registry其实是一个ListenerRegistryWrapper装饰器，装饰着一个ZooKeeperRegistry。
ZooKeeperRegistry.doRegister()处理的URL注册其实就是往注册中心注册。
//-> RegistryProtocol.export()
//-> RegistryProtocol.getRegistry()
//-> RegistryFactory$Adaptive.getRegistry()
//-> RegistryFactoryWrapper.getRegistry()
//-> ZookeeperRegistryFactory.getRegistry()
//-> ZookeeperRegistryFactory.createRegistry()
//-> new ZookeeperRegistry()
//=> ListenerRegistryWrapper、ZookeeperRegistry//-> RegistryProtocol.register()
//-> ListenerRegistryWrapper.register()
//-> FailbackRegistry.register()
//-> ZookeeperRegistry.doRegister()public class RegistryProtocol implements Protocol, ScopeModelAware {...@Overridepublic <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {//将"registry://"协议(Remote URL)转换成"zookeeper://"协议(Registry URL)URL registryUrl = getRegistryUrl(originInvoker);//url to export locally//获取export参数，其中存储了一个"dubbo://"协议的Provider URLURL providerUrl = getProviderUrl(originInvoker);//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(providerUrl);final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);Map<URL, NotifyListener> overrideListeners = getProviderConfigurationListener(providerUrl).getOverrideListeners();overrideListeners.put(registryUrl, overrideSubscribeListener);providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);//1.export invoker//下面进行导出服务，底层会通过会执行DubboProtocol.export()方法，启动对应的Server//也就是会涉及到对另外一个Protocol组件的调用，远程发布服务时其实就是执行DubboProtocol的export方法final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);//2.url to registry 完成服务注册的事情//下面会根据RegistryURL获取对应的注册中心Registry对象，其中会依赖RegistryFactory//远程发布时，下面的registry其实是一个ListenerRegistryWrapper装饰器，装饰着使用了ZookeeperServiceDiscovery的ServiceDiscoveryRegistry//在基于注册中心的url地址去构建对应的注册中心组件时，默认是基于zk的//而构建一个基于zk的注册中心组件，同时跟zk完成连接的建立，则由curator5框架来实现final Registry registry = getRegistry(registryUrl);//获取将要发布到注册中心上的Provider URL，其中会删除一些多余的参数信息final URL registeredProviderUrl = getUrlToRegistry(providerUrl, registryUrl);//decide if we need to delay publish (provider itself and registry should both need to register)//根据register参数值决定是否注册服务boolean register = providerUrl.getParameter(REGISTER_KEY, true) && registryUrl.getParameter(REGISTER_KEY, true);if (register) {//调用Registry.register()方法将registeredProviderUrl发布到注册中心register(registry, registeredProviderUrl);}//register stated url on provider model//将Provider相关信息记录到的ProviderModel中registerStatedUrl(registryUrl, registeredProviderUrl, register);exporter.setRegisterUrl(registeredProviderUrl);exporter.setSubscribeUrl(overrideSubscribeUrl);if (!registry.isServiceDiscovery()) {//Deprecated! Subscribe to override rules in 2.6.x or before.//向注册中心进行订阅override数据，主要是监听该服务的configurators节点registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);}//触发RegistryProtocolListener监听器notifyExport(exporter);//Ensure that a new exporter instance is returned every time exportreturn new DestroyableExporter<>(exporter);}protected Registry getRegistry(final URL registryUrl) {//通过SPI自适应机制，去拿到对应的extension实例//这里的registryFactory为RegistryFactory$AdaptiveRegistryFactory registryFactory = ScopeModelUtil.getExtensionLoader(RegistryFactory.class, registryUrl.getScopeModel()).getAdaptiveExtension();//调用RegistryFactory$Adaptive的getRegistry()方法return registryFactory.getRegistry(registryUrl);}private void register(Registry registry, URL registeredProviderUrl) {//下面会调用ListenerRegistryWrapper.register()方法registry.register(registeredProviderUrl);}private void registerStatedUrl(URL registryUrl, URL registeredProviderUrl, boolean registered) {ProviderModel model = (ProviderModel) registeredProviderUrl.getServiceModel();model.addStatedUrl(new ProviderModel.RegisterStatedURL(registeredProviderUrl,registryUrl,registered));}...
}public class RegistryFactory$Adaptive implements org.apache.dubbo.registry.RegistryFactory {public org.apache.dubbo.registry.Registry getRegistry(org.apache.dubbo.common.URL arg0) {if (arg0 == null) throw new IllegalArgumentException("url == null");org.apache.dubbo.common.URL url = arg0;String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() );//注册registry的URL时，由于RegistryProtocol.export()方法会将"registry://"协议替换为"zookeeper://"协议//所以此时extName=zookeeperif (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.registry.RegistryFactory) name from url (" + url.toString() + ") use keys([protocol])");ScopeModel scopeModel = ScopeModelUtil.getOrDefault(url.getScopeModel(), org.apache.dubbo.registry.RegistryFactory.class);//此时获取到的extension为RegistryFactoryWrapper//RegistryFactoryWrapper的registryFactory为ZookeeperRegistryFactoryorg.apache.dubbo.registry.RegistryFactory extension = (org.apache.dubbo.registry.RegistryFactory)scopeModel.getExtensionLoader(org.apache.dubbo.registry.RegistryFactory.class).getExtension(extName);//调用RegistryFactoryWrapper的getRegistry()方法return extension.getRegistry(arg0);}
}public class RegistryFactoryWrapper implements RegistryFactory {//此时的registryFactory为ZookeeperRegistryFactoryprivate RegistryFactory registryFactory;public RegistryFactoryWrapper(RegistryFactory registryFactory) {this.registryFactory = registryFactory;}@Overridepublic Registry getRegistry(URL url) {//调用ZookeeperRegistryFactory的getRegistry()方法获取一个ZookeeperRegistry//所以这里会返回一个封装了ZookeeperRegistry的ListenerRegistryWrapperreturn new ListenerRegistryWrapper(registryFactory.getRegistry(url),Collections.unmodifiableList(url.getOrDefaultApplicationModel().getExtensionLoader(RegistryServiceListener.class).getActivateExtension(url, "registry.listeners")));}
}public abstract class AbstractRegistryFactory implements RegistryFactory, ScopeModelAware {...@Overridepublic Registry getRegistry(URL url) {...registry = createRegistry(url);...return registry;}...
}public class ZookeeperRegistryFactory extends AbstractRegistryFactory {private ZookeeperTransporter zookeeperTransporter;public ZookeeperRegistryFactory() {this(ApplicationModel.defaultModel());}public ZookeeperRegistryFactory(ApplicationModel applicationModel) {this.applicationModel = applicationModel;this.zookeeperTransporter = ZookeeperTransporter.getExtension(applicationModel);}@Overridepublic Registry createRegistry(URL url) {return new ZookeeperRegistry(url, zookeeperTransporter);}...
}public class ListenerRegistryWrapper implements Registry {private final Registry registry;...public void register(URL url) {...//此时下面会调用ZookeeperRegistry.register()方法//由于ZookeeperRegistry继承自FailbackRegistry//所以会调用FailbackRegistry.register()方法registry.register(url);}
}public abstract class FailbackRegistry extends AbstractRegistry {...@Overridepublic void register(URL url) {super.register(url);removeFailedRegistered(url);removeFailedUnregistered(url);doRegister(url);}public abstract void doRegister(URL url);...
}public class ZookeeperRegistry extends CacheableFailbackRegistry {//跟zk建立网络连接的客户端private ZookeeperClient zkClient;//刚开始构建这个zookeeper registry，核心的就是去连接zk，与zk建立连接public ZookeeperRegistry(URL url, ZookeeperTransporter zookeeperTransporter) {//首先根据传入的url执行父类的构造函数//该url就是zk的连接地址，比如zookeeper://localhost:2181/super(url);...//基于zk的API去构建与zk之间的连接this.zkClient = zookeeperTransporter.connect(url);...}@Overridepublic void doRegister(URL url) {//一个url代表了一个Provider服务实例的所有信息、配置和属性//或者说一个url就代表了一个Provider服务实例//服务注册中的核心注册，即Dubbo往zk进行服务实例注册的方法就在此处try {checkDestroyed();//对于一个应用而言，它的注册其实就是往zk中创建的一个znode节点zkClient.create(toUrlPath(url), url.getParameter(DYNAMIC_KEY, true));} catch (Throwable e) {throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);}}...
}
13.Dubbo服务发布的完整流程总结