Dubbo-06 20190320

感谢尚硅谷免费视频与资料 http://www.atguigu.com/

一、Dubbo RPC原理

一次完整的RPC调用流程（同步调用，异步另说）如下：
1）服务消费方（client）调用以本地调用方式调用服务；
2）client stub接收到调用后负责将方法、参数等组装成能够进行网络传输的消息体；
3）client stub找到服务地址，并将消息发送到服务端；
4）server stub收到消息后进行解码；
5）server stub根据解码结果调用本地的服务；
6）本地服务执行并将结果返回给server stub；
7）server stub将返回结果打包成消息并发送至消费方；
8）client stub接收到消息，并进行解码；
9）服务消费方得到最终结果。
RPC框架（Dubbo等）的目标就是要2~8这些步骤都封装起来，这些细节对用户来说是透明的，不可见的。

二、Netty 通信原理

Netty是一个异步事件驱动的网络应用程序框架（NIO），用于快速开发可维护的高性能协议服务器和客户端。它极大地简化并简化了TCP和UDP套接字服务器等网络编程。
BIO：(Blocking IO)：阻塞IO

NIO (Non-Blocking IO):非阻塞IO

Selector 一般称为选择器，也可以翻译为多路复用器，
Connect（连接就绪）、Accept（接受就绪）、Read（读就绪）、Write（写就绪）

Netty基本原理：
Netty是基于NIO的多路复用

Dubbo原理架构设计

http://dubbo.apache.org/zh-cn/docs/dev/design.html

Business 这是我们的业务自己写代码

RPC层完成远程调用：
config 配置层：对外配置接口，以 ServiceConfig, ReferenceConfig 为中心，可以直接初始化配置类，也可以通过 spring 解析配置生成配置类这个就是收集配置的数据！！
proxy 服务代理层：服务接口透明代理，生成服务的客户端 Stub 和服务器端 Skeleton, 以 ServiceProxy 为中心，扩展接口为 ProxyFactory
registry 注册中心层：封装服务地址的注册与发现，以服务 URL 为中心，扩展接口为 RegistryFactory, Registry, RegistryService 服务的发现和服务的注册
cluster 路由层：封装多个提供者的路由及负载均衡，并桥接注册中心，以 Invoker 为中心，扩展接口为 Cluster, Directory, Router, LoadBalance
monitor 监控层：RPC 调用次数和调用时间监控，以 Statistics 为中心，扩展接口为 MonitorFactory, Monitor, MonitorService
protocol 远程调用层：封装 RPC 调用，以 Invocation, Result 为中心，扩展接口为 Protocol, Invoker, Exporter

Remoting解决远程通讯：
exchange 信息交换层：封装请求响应模式，同步转异步，以 Request, Response 为中心，扩展接口为 Exchanger, ExchangeChannel, ExchangeClient, ExchangeServer
transport 网络传输层：抽象 mina 和 netty 为统一接口，以 Message 为中心，扩展接口为 Channel, Transporter, Client, Server, Codec
serialize 数据序列化层：可复用的一些工具，扩展接口为 Serialization, ObjectInput, ObjectOutput, ThreadPool

Dubbo标签解析

Spring解析标签都有一个类叫BeanDefinitionParser
而解析Dubbo的类是DubboBeanDefinitionParser
解析配置类的目的就是把配置文件的信息封装成一个一个的xxxxConfig
当然 service 和 reference 是封装成xxBean

public class DubboNamespaceHandler extends NamespaceHandlerSupport {static {Version.checkDuplicate(DubboNamespaceHandler.class);}@Overridepublic void init() {registerBeanDefinitionParser("application", new DubboBeanDefinitionParser(ApplicationConfig.class, true));registerBeanDefinitionParser("module", new DubboBeanDefinitionParser(ModuleConfig.class, true));registerBeanDefinitionParser("registry", new DubboBeanDefinitionParser(RegistryConfig.class, true));registerBeanDefinitionParser("config-center", new DubboBeanDefinitionParser(ConfigCenterBean.class, true));registerBeanDefinitionParser("metadata-report", new DubboBeanDefinitionParser(MetadataReportConfig.class, true));registerBeanDefinitionParser("monitor", new DubboBeanDefinitionParser(MonitorConfig.class, true));registerBeanDefinitionParser("provider", new DubboBeanDefinitionParser(ProviderConfig.class, true));registerBeanDefinitionParser("consumer", new DubboBeanDefinitionParser(ConsumerConfig.class, true));registerBeanDefinitionParser("protocol", new DubboBeanDefinitionParser(ProtocolConfig.class, true));registerBeanDefinitionParser("service", new DubboBeanDefinitionParser(ServiceBean.class, true));registerBeanDefinitionParser("reference", new DubboBeanDefinitionParser(ReferenceBean.class, false));registerBeanDefinitionParser("annotation", new AnnotationBeanDefinitionParser());}}

@SuppressWarnings("unchecked")private static BeanDefinition parse(Element element, ParserContext parserContext, Class<?> beanClass, boolean required) {RootBeanDefinition beanDefinition = new RootBeanDefinition();beanDefinition.setBeanClass(beanClass);beanDefinition.setLazyInit(false);String id = element.getAttribute("id");if ((id == null || id.length() == 0) && required) {String generatedBeanName = element.getAttribute("name");if (generatedBeanName == null || generatedBeanName.length() == 0) {if (ProtocolConfig.class.equals(beanClass)) {generatedBeanName = "dubbo";} else {generatedBeanName = element.getAttribute("interface");}}if (generatedBeanName == null || generatedBeanName.length() == 0) {generatedBeanName = beanClass.getName();}id = generatedBeanName;int counter = 2;while (parserContext.getRegistry().containsBeanDefinition(id)) {id = generatedBeanName + (counter++);}}if (id != null && id.length() > 0) {if (parserContext.getRegistry().containsBeanDefinition(id)) {throw new IllegalStateException("Duplicate spring bean id " + id);}parserContext.getRegistry().registerBeanDefinition(id, beanDefinition);beanDefinition.getPropertyValues().addPropertyValue("id", id);}if (ProtocolConfig.class.equals(beanClass)) {for (String name : parserContext.getRegistry().getBeanDefinitionNames()) {BeanDefinition definition = parserContext.getRegistry().getBeanDefinition(name);PropertyValue property = definition.getPropertyValues().getPropertyValue("protocol");if (property != null) {Object value = property.getValue();if (value instanceof ProtocolConfig && id.equals(((ProtocolConfig) value).getName())) {definition.getPropertyValues().addPropertyValue("protocol", new RuntimeBeanReference(id));}}}} else if (ServiceBean.class.equals(beanClass)) {String className = element.getAttribute("class");if (className != null && className.length() > 0) {RootBeanDefinition classDefinition = new RootBeanDefinition();classDefinition.setBeanClass(ReflectUtils.forName(className));classDefinition.setLazyInit(false);parseProperties(element.getChildNodes(), classDefinition);beanDefinition.getPropertyValues().addPropertyValue("ref", new BeanDefinitionHolder(classDefinition, id + "Impl"));}} else if (ProviderConfig.class.equals(beanClass)) {parseNested(element, parserContext, ServiceBean.class, true, "service", "provider", id, beanDefinition);} else if (ConsumerConfig.class.equals(beanClass)) {parseNested(element, parserContext, ReferenceBean.class, false, "reference", "consumer", id, beanDefinition);}Set<String> props = new HashSet<String>();ManagedMap parameters = null;for (Method setter : beanClass.getMethods()) {String name = setter.getName();if (name.length() > 3 && name.startsWith("set")&& Modifier.isPublic(setter.getModifiers())&& setter.getParameterTypes().length == 1) {Class<?> type = setter.getParameterTypes()[0];String beanProperty = name.substring(3, 4).toLowerCase() + name.substring(4);String property = StringUtils.camelToSplitName(beanProperty, "-");props.add(property);Method getter = null;try {getter = beanClass.getMethod("get" + name.substring(3), new Class<?>[0]);} catch (NoSuchMethodException e) {try {getter = beanClass.getMethod("is" + name.substring(3), new Class<?>[0]);} catch (NoSuchMethodException e2) {}}if (getter == null|| !Modifier.isPublic(getter.getModifiers())|| !type.equals(getter.getReturnType())) {continue;}if ("parameters".equals(property)) {parameters = parseParameters(element.getChildNodes(), beanDefinition);} else if ("methods".equals(property)) {parseMethods(id, element.getChildNodes(), beanDefinition, parserContext);} else if ("arguments".equals(property)) {parseArguments(id, element.getChildNodes(), beanDefinition, parserContext);} else {String value = element.getAttribute(property);if (value != null) {value = value.trim();if (value.length() > 0) {if ("registry".equals(property) && RegistryConfig.NO_AVAILABLE.equalsIgnoreCase(value)) {RegistryConfig registryConfig = new RegistryConfig();registryConfig.setAddress(RegistryConfig.NO_AVAILABLE);beanDefinition.getPropertyValues().addPropertyValue(beanProperty, registryConfig);} else if ("provider".equals(property) || "registry".equals(property) || ("protocol".equals(property) && ServiceBean.class.equals(beanClass))) {/*** For 'provider' 'protocol' 'registry', keep literal value (should be id/name) and set the value to 'registryIds' 'providerIds' protocolIds'* The following process should make sure each id refers to the corresponding instance, here's how to find the instance for different use cases:* 1. Spring, check existing bean by id, see{@link ServiceBean#afterPropertiesSet()}; then try to use id to find configs defined in remote Config Center* 2. API, directly use id to find configs defined in remote Config Center; if all config instances are defined locally, please use {@link org.apache.dubbo.config.ServiceConfig#setRegistries(List)}*/beanDefinition.getPropertyValues().addPropertyValue(beanProperty + "Ids", value);} else {Object reference;if (isPrimitive(type)) {if ("async".equals(property) && "false".equals(value)|| "timeout".equals(property) && "0".equals(value)|| "delay".equals(property) && "0".equals(value)|| "version".equals(property) && "0.0.0".equals(value)|| "stat".equals(property) && "-1".equals(value)|| "reliable".equals(property) && "false".equals(value)) {// backward compatibility for the default value in old version's xsdvalue = null;}reference = value;} else if ("onreturn".equals(property)) {int index = value.lastIndexOf(".");String returnRef = value.substring(0, index);String returnMethod = value.substring(index + 1);reference = new RuntimeBeanReference(returnRef);beanDefinition.getPropertyValues().addPropertyValue("onreturnMethod", returnMethod);} else if ("onthrow".equals(property)) {int index = value.lastIndexOf(".");String throwRef = value.substring(0, index);String throwMethod = value.substring(index + 1);reference = new RuntimeBeanReference(throwRef);beanDefinition.getPropertyValues().addPropertyValue("onthrowMethod", throwMethod);} else if ("oninvoke".equals(property)) {int index = value.lastIndexOf(".");String invokeRef = value.substring(0, index);String invokeRefMethod = value.substring(index + 1);reference = new RuntimeBeanReference(invokeRef);beanDefinition.getPropertyValues().addPropertyValue("oninvokeMethod", invokeRefMethod);} else {if ("ref".equals(property) && parserContext.getRegistry().containsBeanDefinition(value)) {BeanDefinition refBean = parserContext.getRegistry().getBeanDefinition(value);if (!refBean.isSingleton()) {throw new IllegalStateException("The exported service ref " + value + " must be singleton! Please set the " + value + " bean scope to singleton, eg: <bean id=\"" + value + "\" scope=\"singleton\" ...>");}}reference = new RuntimeBeanReference(value);}beanDefinition.getPropertyValues().addPropertyValue(beanProperty, reference);}}}}}}NamedNodeMap attributes = element.getAttributes();int len = attributes.getLength();for (int i = 0; i < len; i++) {Node node = attributes.item(i);String name = node.getLocalName();if (!props.contains(name)) {if (parameters == null) {parameters = new ManagedMap();}String value = node.getNodeValue();parameters.put(name, new TypedStringValue(value, String.class));}}if (parameters != null) {beanDefinition.getPropertyValues().addPropertyValue("parameters", parameters);}return beanDefinition;}

Dubbo 服务暴露流程和服务引用流程

http://dubbo.apache.org/zh-cn/docs/dev/design.html
我看了人家的视频服务暴露的流程我懂了的就是2点
第一点： dubbo 拿上一些东西然后去开启netty 服务
第二点：register 把地址和执行器存储起来<url,<Set<执行器>>>

第三点：refrence 去服务中心订阅服务
第四点：拿着服务中心的订阅地址去获取netty客户端获取消费者的invoker（执行器代理对象）
第五点：register 把消费者存储<url,set<执行器>>

第五点：代理对象执行方法，根据负载均衡策略找见合适的invoker 然后各种filter
最后DubboInvoker 拿到客户端（refrence 的时候拿过）远程调用底层就是netty mina调用了
返回结果

暴露服务：

引用服务：

调用链

说实话很难看了也只是简单了解