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Register Center Source Code Analysis of Http Register

· 29 min read
midnight2104
Apache ShenYu Committer

Apache ShenYu is an asynchronous, high-performance, cross-language, responsive API gateway.

In ShenYu gateway, the registration center is used to register the client information to shenyu-admin, admin then synchronizes this information to the gateway through data synchronization, and the gateway completes traffic filtering through these data. The client information mainly includes interface information and URI information.

This article is based on shenyu-2.5.0 version for source code analysis, please refer to Client Access Principles for the introduction of the official website.

1. Registration Center Principle​

When the client starts, it reads the interface information and uri information, and sends the data to shenyu-admin by the specified registration type.

The registration center in the figure requires the user to specify which registration type to use. ShenYu currently supports Http, Zookeeper, Etcd, Consul and Nacos for registration. Please refer to Client Access Configuration for details on how to configure them.

ShenYu introduces Disruptor in the principle design of the registration center, in which the Disruptor queue plays a role in decoupling data and operations, which is conducive to expansion. If too many registration requests lead to registration exceptions, it also has a data buffering role.

As shown in the figure, the registration center is divided into two parts, one is the registration center client register-client, the load processing client data reading. The other is the registration center server register-server, which is loaded to handle the server side (that is shenyu-admin) data writing. Data is sent and received by specifying the registration type.

  • Client: Usually it is a microservice, which can be springmvc, spring-cloud, dubbo, grpc, etc.
  • register-client: register the central client, read the client interface and uri information.
  • Disruptor: decoupling data from operations, data buffering role.
  • register-server: registry server, here is shenyu-admin, receive data, write to database, send data synchronization events.
  • registration-type: specify the registration type, complete data registration, currently supports Http, Zookeeper, Etcd, Consul and Nacos.

This article analyzes the use of Http for registration, so the specific processing flow is as follows.

On the client side, after the data is out of the queue, the data is transferred via http and on the server side, the corresponding interface is provided to receive the data and then write it to the queue.

2. Client Registration Process​

When the client starts, it reads the attribute information according to the relevant configuration, and then writes it to the queue. Let's take the official shenyu-examples-http as an example and start the source code analysis . The official example is a microservice built by springboot. For the configuration of the registration center, please refer to the official website client access configuration .

2.1 Load configuration, read properties​

Let's start with a diagram that ties together the initialization process of the registry client.

We are analyzing registration by means of http, so the following configuration is required.

shenyu:
  register:
    registerType: http
    serverLists: http://localhost:9095
  props:
    username: admin
    password: 123456
  client:
    http:
        props:
          contextPath: /http
          appName: http
          port: 8189  
          isFull: false

Each attribute indicates the following meaning.

  • registerType: the service registration type, fill in http.
  • serverList: The address of the Shenyu-Admin project to fill in for the http registration type, note the addition of http:// and separate multiple addresses with English commas.
  • username: The username of the Shenyu-Admin
  • password: The password of the Shenyu-Admin
  • port: the start port of your project, currently springmvc/tars/grpc needs to be filled in.
  • contextPath: the routing prefix for your mvc project in shenyu gateway, such as /order, /product, etc. The gateway will route according to your prefix.
  • appName: the name of your application, if not configured, it will take the value of spring.application.name by default.
  • isFull: set true to proxy your entire service, false to proxy one of your controllers; currently applies to springmvc/springcloud.

After the project starts, it will first load the configuration file, read the property information and generate the corresponding Bean.

The first configuration file read is ShenyuSpringMvcClientConfiguration, which is the http registration configuration class for the shenyu client, indicated by @Configuration which is a configuration class, and by @ImportAutoConfiguration which is a configuration class. to introduce other configuration classes. Create SpringMvcClientEventListener, which mainly handles metadata and URI information.

/**
 * Shenyu SpringMvc Client Configuration
 */
@Configuration
@ImportAutoConfiguration(ShenyuClientCommonBeanConfiguration.class)
@ConditionalOnProperty(value = "shenyu.register.enabled", matchIfMissing = true, havingValue = "true")
public class ShenyuSpringMvcClientConfiguration {

    // create SpringMvcClientEventListener to handle metadata and URI
    @Bean
    public SpringMvcClientEventListener springHttpClientEventListener(final ShenyuClientConfig clientConfig,
                                                                      final ShenyuClientRegisterRepository shenyuClientRegisterRepository) {
        return new SpringMvcClientEventListener(clientConfig.getClient().get(RpcTypeEnum.HTTP.getName()), shenyuClientRegisterRepository);
    }
}

ShenyuClientCommonBeanConfiguration is a shenyu client common configuration class that will create the bean common to the registry client.

  • Create ShenyuClientRegisterRepository, which is created by factory class.
  • Create ShenyuRegisterCenterConfig, which reads the shenyu.register property configuration.
  • Create ShenyuClientConfig, read the shenyu.client property configuration.

/**
 * Shenyu Client Common Bean Configuration
 */
@Configuration
public class ShenyuClientCommonBeanConfiguration {
    
   // create ShenyuClientRegisterRepository by factory 
    @Bean
    public ShenyuClientRegisterRepository shenyuClientRegisterRepository(final ShenyuRegisterCenterConfig config) {
        return ShenyuClientRegisterRepositoryFactory.newInstance(config);
    }
    
	// create ShenyuRegisterCenterConfig to read shenyu.register properties
    @Bean
    @ConfigurationProperties(prefix = "shenyu.register")
    public ShenyuRegisterCenterConfig shenyuRegisterCenterConfig() {
        return new ShenyuRegisterCenterConfig();
    }
    
  // create ShenyuClientConfig to read shenyu.client properties
    @Bean
    @ConfigurationProperties(prefix = "shenyu")
    public ShenyuClientConfig shenyuClientConfig() {
        return new ShenyuClientConfig();
    }
}

2.2 HttpClientRegisterRepository​

The ShenyuClientRegisterRepository generated in the configuration file above is a concrete implementation of the client registration, which is an interface with the following implementation class.

  • HttpClientRegisterRepository: registration via http.
  • ConsulClientRegisterRepository: registration via Consul.
  • EtcdClientRegisterRepository: registration via Etcd; EtcdClientRegisterRepository: registration via Etcd.
  • NacosClientRegisterRepository: registration via nacos; NacosClientRegisterRepository: registration via nacos.
  • ZookeeperClientRegisterRepository: registration through Zookeeper.

The specific way which is achieved by loading through SPI, the implementation logic is as follows.


/**
 * load ShenyuClientRegisterRepository
 */
public final class ShenyuClientRegisterRepositoryFactory {
    
    private static final Map<String, ShenyuClientRegisterRepository> REPOSITORY_MAP = new ConcurrentHashMap<>();
    
    /**
     * create ShenyuClientRegisterRepository
     */
    public static ShenyuClientRegisterRepository newInstance(final ShenyuRegisterCenterConfig shenyuRegisterCenterConfig) {
        if (!REPOSITORY_MAP.containsKey(shenyuRegisterCenterConfig.getRegisterType())) {
            // Loading by means of SPI, type determined by registerType
            ShenyuClientRegisterRepository result = ExtensionLoader.getExtensionLoader(ShenyuClientRegisterRepository.class).getJoin(shenyuRegisterCenterConfig.getRegisterType());
            //init ShenyuClientRegisterRepository
            result.init(shenyuRegisterCenterConfig);
            ShenyuClientShutdownHook.set(result, shenyuRegisterCenterConfig.getProps());
            REPOSITORY_MAP.put(shenyuRegisterCenterConfig.getRegisterType(), result);
            return result;
        }
        return REPOSITORY_MAP.get(shenyuRegisterCenterConfig.getRegisterType());
    }
}

The load type is specified by registerType, which is the type we specify in the configuration file at

shenyu:
  register:
    registerType: http
    serverLists: http://localhost:9095

We specified http, so it will go to load HttpClientRegisterRepository. After the object is successfully created, the initialization method init() is executed as follows.

@Join
public class HttpClientRegisterRepository implements ShenyuClientRegisterRepository {

    @Override
    public void init(final ShenyuRegisterCenterConfig config) {
        this.username = config.getProps().getProperty(Constants.USER_NAME);
        this.password = config.getProps().getProperty(Constants.PASS_WORD);
        this.serverList = Lists.newArrayList(Splitter.on(",").split(config.getServerLists()));
        this.setAccessToken();
    }
  
  // ......
}

Read username, password and serverLists from the configuration file, the username, password and address of sheenyu-admin, in preparation for subsequent data sending. The class annotation @Join is used for SPI loading.

SPI, known as Service Provider Interface, is a service provider discovery feature built into the JDK, a mechanism for dynamic replacement discovery.

shenyu-spi is a custom SPI extension implementation for the Apache ShenYu gateway, designed and implemented with reference to Dubbo SPI extension implementation.

2.3 SpringMvcClientEventListener​

Create SpringMvcClientEventListener, which is responsible for the construction and registration of client-side metadata and URI data, and its creation is done in the configuration file.

@Configuration
@ImportAutoConfiguration(ShenyuClientCommonBeanConfiguration.class)
public class ShenyuSpringMvcClientConfiguration {
     // ......
    
    // create SpringMvcClientEventListener
    @Bean
    public SpringMvcClientEventListener springHttpClientEventListener(final ShenyuClientConfig clientConfig,
                                                                      final ShenyuClientRegisterRepository shenyuClientRegisterRepository) {
        return new SpringMvcClientEventListener(clientConfig.getClient().get(RpcTypeEnum.HTTP.getName()), shenyuClientRegisterRepository);
    }
}

SpringMvcClientEventListener implements the AbstractContextRefreshedEventListener

The AbstractContextRefreshedEventListener is an abstract class. it implements the ApplicationListener interface and overrides the onApplicationEvent() method, which is executed when a Spring event occurs. It has several implementation classes, which support different kind of RPC styles.

  • AlibabaDubboServiceBeanListener：handles Alibaba Dubbo protocol.
  • ApacheDubboServiceBeanListener：handles Apache Dubbo protocol.
  • GrpcClientEventListener：handles grpc protocol.
  • MotanServiceEventListener：handles Motan protocol.
  • SofaServiceEventListener：handles Sofa protocol.
  • SpringMvcClientEventListener：handles http protocol.
  • SpringWebSocketClientEventListener：handles Websocket protocol.
  • TarsServiceBeanEventListener：handles Tars protocol.
public abstract class AbstractContextRefreshedEventListener<T, A extends Annotation> implements ApplicationListener<ContextRefreshedEvent> {

    //......

    // Instantiation is done through the constructor
    public AbstractContextRefreshedEventListener(final PropertiesConfig clientConfig,
                                                 final ShenyuClientRegisterRepository shenyuClientRegisterRepository) {
        // read shenyu.client.http properties
        Properties props = clientConfig.getProps();
        // appName 
        this.appName = props.getProperty(ShenyuClientConstants.APP_NAME);
        // contextPath
        this.contextPath = Optional.ofNullable(props.getProperty(ShenyuClientConstants.CONTEXT_PATH)).map(UriUtils::repairData).orElse("");
        if (StringUtils.isBlank(appName) && StringUtils.isBlank(contextPath)) {
            String errorMsg = "client register param must config the appName or contextPath";
            LOG.error(errorMsg);
            throw new ShenyuClientIllegalArgumentException(errorMsg);
        }
        this.ipAndPort = props.getProperty(ShenyuClientConstants.IP_PORT);
        // host
        this.host = props.getProperty(ShenyuClientConstants.HOST);
        // port
        this.port = props.getProperty(ShenyuClientConstants.PORT);
        // publish event
        publisher.start(shenyuClientRegisterRepository);
    }

    // This method is executed when a context refresh event(ContextRefreshedEvent), occurs
    @Override
    public void onApplicationEvent(@NonNull final ContextRefreshedEvent event) {
        // The contents of the method are guaranteed to be executed only once
        if (!registered.compareAndSet(false, true)) {
            return;
        }
        final ApplicationContext context = event.getApplicationContext();
        // get the specific beans 
        Map<String, T> beans = getBeans(context);
        if (MapUtils.isEmpty(beans)) {
            return;
        }
        // build URI data and register it
        publisher.publishEvent(buildURIRegisterDTO(context, beans));
        // build metadata and register it
        beans.forEach(this::handle);
    }
    
    @SuppressWarnings("all")
    protected abstract URIRegisterDTO buildURIRegisterDTO(ApplicationContext context,
                                                          Map<String, T> beans);


    protected void handle(final String beanName, final T bean) {
        Class<?> clazz = getCorrectedClass(bean);
        final A beanShenyuClient = AnnotatedElementUtils.findMergedAnnotation(clazz, getAnnotationType());
        final String superPath = buildApiSuperPath(clazz, beanShenyuClient);
        if (Objects.nonNull(beanShenyuClient) && superPath.contains("*")) {
            handleClass(clazz, bean, beanShenyuClient, superPath);
            return;
        }
        final Method[] methods = ReflectionUtils.getUniqueDeclaredMethods(clazz);
        for (Method method : methods) {
            handleMethod(bean, clazz, beanShenyuClient, method, superPath);
        }
    }

    // default implementation. build URI data and register it
    protected void handleClass(final Class<?> clazz,
                               final T bean,
                               @NonNull final A beanShenyuClient,
                               final String superPath) {
        publisher.publishEvent(buildMetaDataDTO(bean, beanShenyuClient, pathJoin(contextPath, superPath), clazz, null));
    }

    // default implementation. build metadata and register it
    protected void handleMethod(final T bean,
                                final Class<?> clazz,
                                @Nullable final A beanShenyuClient,
                                final Method method,
                                final String superPath) {
        // get the annotation
        A methodShenyuClient = AnnotatedElementUtils.findMergedAnnotation(method, getAnnotationType());
        if (Objects.nonNull(methodShenyuClient)) {
            // 构建元数据，发送注册事件
            publisher.publishEvent(buildMetaDataDTO(bean, methodShenyuClient, buildApiPath(method, superPath, methodShenyuClient), clazz, method));
        }
    }
    
    protected abstract MetaDataRegisterDTO buildMetaDataDTO(T bean,
                                                            @NonNull A shenyuClient,
                                                            String path,
                                                            Class<?> clazz,
                                                            Method method);
}

In the constructor, the main purpose is to read the property information and then perform the checksum.

shenyu:
  client:
    http:
      props:
        contextPath: /http
        appName: http
        port: 8189
        isFull: false

Finally, publisher.start() is executed to start event publishing and prepare for registration.

ShenyuClientRegisterEventPublisher is implemented via singleton pattern, mainly generating metadata and URI subscribers (subsequently used for data publishing), and then starting the Disruptor queue. A common method publishEvent() is provided to publish events and send data to the Disruptor queue.


public class ShenyuClientRegisterEventPublisher {
    
    private static final ShenyuClientRegisterEventPublisher INSTANCE = new ShenyuClientRegisterEventPublisher();

    private DisruptorProviderManage<DataTypeParent> providerManage;
    
    public static ShenyuClientRegisterEventPublisher getInstance() {
        return INSTANCE;
    }
    
    public void start(final ShenyuClientRegisterRepository shenyuClientRegisterRepository) {
        RegisterClientExecutorFactory factory = new RegisterClientExecutorFactory();
        factory.addSubscribers(new ShenyuClientMetadataExecutorSubscriber(shenyuClientRegisterRepository));
        factory.addSubscribers(new ShenyuClientURIExecutorSubscriber(shenyuClientRegisterRepository));
        providerManage = new DisruptorProviderManage(factory);
        providerManage.startup();
    }
    
    public <T> void publishEvent(final DataTypeParent data) {
        DisruptorProvider<DataTypeParent> provider = providerManage.getProvider();
        provider.onData(data);
    }
}

The logic of the constructor of AbstractContextRefreshedEventListener is analyzed, it mainly reads the property configuration, creates metadata and URI subscribers, and starts the Disruptor queue.

The onApplicationEvent() method is executed when a Spring event occurs, the parameter here is ContextRefreshedEvent, which means the context refresh event.

ContextRefreshedEvent is a Spring built-in event. It is fired when the ApplicationContext is initialized or refreshed. This can also happen in the ConfigurableApplicationContext interface using the refresh() method. Initialization here means that all Beans have been successfully loaded, post-processing Beans have been detected and activated, all Singleton Beans have been pre-instantiated, and the ApplicationContext container is ready to be used.

  • SpringMvcClientEventListener: the http implementation of AbstractContextRefreshedEventListener:
public class SpringMvcClientEventListener extends AbstractContextRefreshedEventListener<Object, ShenyuSpringMvcClient> {
    
    private final List<Class<? extends Annotation>> mappingAnnotation = new ArrayList<>(3);
    
    private final Boolean isFull;
    
    private final String protocol;
    
    // 构造函数
    public SpringMvcClientEventListener(final PropertiesConfig clientConfig,
                                        final ShenyuClientRegisterRepository shenyuClientRegisterRepository) {
        super(clientConfig, shenyuClientRegisterRepository);
        Properties props = clientConfig.getProps();
        // get isFull
        this.isFull = Boolean.parseBoolean(props.getProperty(ShenyuClientConstants.IS_FULL, Boolean.FALSE.toString()));
        // http protocol
        this.protocol = props.getProperty(ShenyuClientConstants.PROTOCOL, ShenyuClientConstants.HTTP);
        mappingAnnotation.add(ShenyuSpringMvcClient.class);
        mappingAnnotation.add(RequestMapping.class);
    }
    
    @Override
    protected Map<String, Object> getBeans(final ApplicationContext context) {
        // Configuration attribute, if isFull=true, means register the whole microservice
        if (Boolean.TRUE.equals(isFull)) {
            getPublisher().publishEvent(MetaDataRegisterDTO.builder()
                    .contextPath(getContextPath())
                    .appName(getAppName())
                    .path(PathUtils.decoratorPathWithSlash(getContextPath()))
                    .rpcType(RpcTypeEnum.HTTP.getName())
                    .enabled(true)
                    .ruleName(getContextPath())
                    .build());
            return null;
        }
        // get bean with Controller annotation
        return context.getBeansWithAnnotation(Controller.class);
    }
    
    @Override
    protected URIRegisterDTO buildURIRegisterDTO(final ApplicationContext context,
                                                 final Map<String, Object> beans) {
        // ...
    }
    
    @Override
    protected String buildApiSuperPath(final Class<?> clazz, @Nullable final ShenyuSpringMvcClient beanShenyuClient) {
        if (Objects.nonNull(beanShenyuClient) && StringUtils.isNotBlank(beanShenyuClient.path())) {
            return beanShenyuClient.path();
        }
        RequestMapping requestMapping = AnnotationUtils.findAnnotation(clazz, RequestMapping.class);
        // Only the first path is supported temporarily
        if (Objects.nonNull(requestMapping) && ArrayUtils.isNotEmpty(requestMapping.path()) && StringUtils.isNotBlank(requestMapping.path()[0])) {
            return requestMapping.path()[0];
        }
        return "";
    }
    
    @Override
    protected Class<ShenyuSpringMvcClient> getAnnotationType() {
        return ShenyuSpringMvcClient.class;
    }
    
    @Override
    protected void handleMethod(final Object bean, final Class<?> clazz,
                                @Nullable final ShenyuSpringMvcClient beanShenyuClient,
                                final Method method, final String superPath) {
        // get RequestMapping annotation
        final RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(method, RequestMapping.class);
        // get ShenyuSpringMvcClient annotation
        ShenyuSpringMvcClient methodShenyuClient = AnnotatedElementUtils.findMergedAnnotation(method, ShenyuSpringMvcClient.class);
        methodShenyuClient = Objects.isNull(methodShenyuClient) ? beanShenyuClient : methodShenyuClient;
        // the result of ReflectionUtils#getUniqueDeclaredMethods contains method such as hashCode, wait, toSting
        // add Objects.nonNull(requestMapping) to make sure not register wrong method
        if (Objects.nonNull(methodShenyuClient) && Objects.nonNull(requestMapping)) {
            getPublisher().publishEvent(buildMetaDataDTO(bean, methodShenyuClient, buildApiPath(method, superPath, methodShenyuClient), clazz, method));
        }
    }
    
    //...
    
    // 构造元数据
    @Override
    protected MetaDataRegisterDTO buildMetaDataDTO(final Object bean,
                                                   @NonNull final ShenyuSpringMvcClient shenyuClient,
                                                   final String path, final Class<?> clazz,
                                                   final Method method) {
        //...
    }
}

The registration logic is done through publisher.publishEvent().

The Controller annotation and the RequestMapping annotation are provided by Spring, which you should be familiar with, so I won't go into details. The ShenyuSpringMvcClient annotation is provided by Apache ShenYu to register the SpringMvc client, which is defined as follows.


/**
 * ShenyuSpringMvcClient
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface ShenyuSpringMvcClient {

    // path
    @AliasFor(attribute = "path")
    String value() default "";
    
    // path
    @AliasFor(attribute = "value")
    String path();
    
    // ruleName
    String ruleName() default "";
    
    // desc info
    String desc() default "";

    // enabled
    boolean enabled() default true;
    
    // register MetaData 
    boolean  registerMetaData() default false;
}

It is used as follows.

  • register the entire interface
@RestController
@RequestMapping("/test")
@ShenyuSpringMvcClient(path = "/test/**")  // register the entire interface
public class HttpTestController {
    //......
}
  • register current method
@RestController
@RequestMapping("/order")
@ShenyuSpringMvcClient(path = "/order")
public class OrderController {

    /**
     * Save order dto.
     *
     * @param orderDTO the order dto
     * @return the order dto
     */
    @PostMapping("/save")
    @ShenyuSpringMvcClient(path = "/save", desc = "Save order") // register current method
    public OrderDTO save(@RequestBody final OrderDTO orderDTO) {
        orderDTO.setName("hello world save order");
        return orderDTO;
    }
  • publisher.publishEvent()

This method sends the data to the Disruptor queue. More details about the Disruptor queue are not described here, which does not affect the flow of analyzing the registration.

When the data is sent, the consumers of the Disruptor queue will process the data for consumption.

This method sends the data to the Disruptor queue. More details about the Disruptor queue are not described here, which does not affect the flow of analyzing the registration.

  • QueueConsumer

QueueConsumer is a consumer that implements the WorkHandler interface, which is created in the providerManage.startup() logic. The WorkHandler interface is the data consumption interface for Disruptor, and the only method is onEvent().

package com.lmax.disruptor;

public interface WorkHandler<T> {
    void onEvent(T event) throws Exception;
}

The QueueConsumer overrides the onEvent() method, and the main logic is to generate the consumption task and then go to the thread pool to execute it.


/**
 * 
 * QueueConsumer
 */
public class QueueConsumer<T> implements WorkHandler<DataEvent<T>> {
    
	// ......

    @Override
    public void onEvent(final DataEvent<T> t) {
        if (t != null) {
            // Use different thread pools based on DataEvent type
            ThreadPoolExecutor executor = orderly(t);
            // create queue consumption tasks via factory
            QueueConsumerExecutor<T> queueConsumerExecutor = factory.create();
            // set data
            queueConsumerExecutor.setData(t.getData());
            // help gc
            t.setData(null);
            // put in the thread pool to execute the consumption task
            executor.execute(queueConsumerExecutor);
        }
    }
}

QueueConsumerExecutor is the task that is executed in the thread pool, it implements the Runnable interface, and there are two specific implementation classes.

  • RegisterClientConsumerExecutor：the client-side consumer executor.
  • RegisterServerConsumerExecutor：server-side consumer executor.

As the name implies, one is responsible for handling client-side tasks, and one is responsible for handling server-side tasks (the server side is admin, which is analyzed below).

  • RegisterClientConsumerExecutor

The logic of the rewritten run() is as follows.


public final class RegisterClientConsumerExecutor<T extends DataTypeParent> extends QueueConsumerExecutor<T> {
    
	//...... 

    @Override
    public void run() {
        // get data
        final T data = getData();
        // call the appropriate processor for processing according to the data type
        subscribers.get(data.getType()).executor(Lists.newArrayList(data));
    }
    
}

Different processors are called to perform the corresponding tasks based on different data types. There are two types of data, one is metadata, which records the client registration information. One is the URI data, which records the client service information.

public enum DataType {
   
    META_DATA,
    
    URI,
}
  • ExecutorSubscriber#executor()

The actuator subscribers are divided into two categories, one that handles metadata and one that handles URIs. There are two on the client side and two on the server side, so there are four in total.

Here is the registration metadata information, so the execution class is ShenyuClientMetadataExecutorSubscriber.

  • ShenyuClientMetadataExecutorSubscriber#executor()

The metadata processing logic on the client side is: iterate through the metadata information and call the interface method persistInterface() to finish publishing the data.

public class ShenyuClientMetadataExecutorSubscriber implements ExecutorTypeSubscriber<MetaDataRegisterDTO> {
   
    //......
    
    @Override
    public DataType getType() {
        return DataType.META_DATA;
    }
    
    @Override
    public void executor(final Collection<MetaDataRegisterDTO> metaDataRegisterDTOList) {
        for (MetaDataRegisterDTO metaDataRegisterDTO : metaDataRegisterDTOList) {
            // call the interface method persistInterface() to finish publishing the data
            shenyuClientRegisterRepository.persistInterface(metaDataRegisterDTO);
        }
    }
}

The two registration interfaces get the data well and call the publish() method to publish the data to the Disruptor queue.

  • ShenyuServerRegisterRepository

The ShenyuServerRegisterRepository interface is a service registration interface, which has five implementation classes, indicating five types of registration.

  • ConsulServerRegisterRepository: registration is achieved through Consul;
  • EtcdServerRegisterRepository: registration through Etcd.
  • NacosServerRegisterRepository: registration through Nacos.
  • ShenyuHttpRegistryController: registration via Http; ShenyuHttpRegistryController: registration via Http.
  • ZookeeperServerRegisterRepository: registration through Zookeeper.

As you can see from the diagram, the loading of the registry is done by means of SPI. This was mentioned earlier, and the specific class loading is done in the client-side generic configuration file by specifying the properties in the configuration file.


/**
 * load ShenyuClientRegisterRepository
 */
public final class ShenyuClientRegisterRepositoryFactory {
    
    private static final Map<String, ShenyuClientRegisterRepository> REPOSITORY_MAP = new ConcurrentHashMap<>();
    
    /**
     * create ShenyuClientRegisterRepository
     */
    public static ShenyuClientRegisterRepository newInstance(final ShenyuRegisterCenterConfig shenyuRegisterCenterConfig) {
        if (!REPOSITORY_MAP.containsKey(shenyuRegisterCenterConfig.getRegisterType())) {
            // loading by means of SPI, type determined by registerType
            ShenyuClientRegisterRepository result = ExtensionLoader.getExtensionLoader(ShenyuClientRegisterRepository.class).getJoin(shenyuRegisterCenterConfig.getRegisterType());
            // perform initialization operations
            result.init(shenyuRegisterCenterConfig);
            ShenyuClientShutdownHook.set(result, shenyuRegisterCenterConfig.getProps());
            REPOSITORY_MAP.put(shenyuRegisterCenterConfig.getRegisterType(), result);
            return result;
        }
        return REPOSITORY_MAP.get(shenyuRegisterCenterConfig.getRegisterType());
    }
}

The source code analysis in this article is based on the Http way of registration, so we first analyze the HttpClientRegisterRepository, and the other registration methods will be analyzed afterwards.

Registration by way of http is very simple, it is to call the tool class to send http requests. The registration metadata and URI are both called by the same method doRegister(), specifying the interface and type.

  • Constants.URI_PATH = /shenyu-client/register-metadata: the interface provided by the server for registering metadata.
  • Constants.META_PATH = /shenyu-client/register-uri: Server-side interface for registering URIs.
@Join
public class HttpClientRegisterRepository extends FailbackRegistryRepository {

    private static final Logger LOGGER = LoggerFactory.getLogger(HttpClientRegisterRepository.class);

    private static URIRegisterDTO uriRegisterDTO;

    private String username;

    private String password;

    private List<String> serverList;

    private String accessToken;
    
    public HttpClientRegisterRepository() {
    }
    
    public HttpClientRegisterRepository(final ShenyuRegisterCenterConfig config) {
        init(config);
    }

    @Override
    public void init(final ShenyuRegisterCenterConfig config) {
        // admin username
        this.username = config.getProps().getProperty(Constants.USER_NAME);
        // admin paaword
        this.password = config.getProps().getProperty(Constants.PASS_WORD);
        // admin server address
        this.serverList = Lists.newArrayList(Splitter.on(",").split(config.getServerLists()));
        // set access token
        this.setAccessToken();
    }

    /**
     * Persist uri.
     *
     * @param registerDTO the register dto
     */
    @Override
    public void doPersistURI(final URIRegisterDTO registerDTO) {
        if (RuntimeUtils.listenByOther(registerDTO.getPort())) {
            return;
        }
        doRegister(registerDTO, Constants.URI_PATH, Constants.URI);
        uriRegisterDTO = registerDTO;
    }

    @Override
    public void doPersistInterface(final MetaDataRegisterDTO metadata) {
        doRegister(metadata, Constants.META_PATH, Constants.META_TYPE);
    }

    @Override
    public void close() {
        if (uriRegisterDTO != null) {
            uriRegisterDTO.setEventType(EventType.DELETED);
            doRegister(uriRegisterDTO, Constants.URI_PATH, Constants.URI);
        }
    }

    private void setAccessToken() {
        for (String server : serverList) {
            try {
                Optional<?> login = RegisterUtils.doLogin(username, password, server.concat(Constants.LOGIN_PATH));
                login.ifPresent(v -> this.accessToken = String.valueOf(v));
            } catch (Exception e) {
                LOGGER.error("Login admin url :{} is fail, will retry. cause: {} ", server, e.getMessage());
            }
        }
    }

    private <T> void doRegister(final T t, final String path, final String type) {
        int i = 0;
        // iterate through the list of admin services (admin may be clustered)
        for (String server : serverList) {
            i++;
            String concat = server.concat(path);
            try {
                // 设置访问token
                if (StringUtils.isBlank(accessToken)) {
                    this.setAccessToken();
                    if (StringUtils.isBlank(accessToken)) {
                        throw new NullPointerException("accessToken is null");
                    }
                }
                // calling the tool class to send http requests
                RegisterUtils.doRegister(GsonUtils.getInstance().toJson(t), concat, type, accessToken);
                return;
            } catch (Exception e) {
                LOGGER.error("Register admin url :{} is fail, will retry. cause:{}", server, e.getMessage());
                if (i == serverList.size()) {
                    throw new RuntimeException(e);
                }
            }
        }
    }
}

Serialize the data and send it via OkHttp.


public final class RegisterUtils {
   
   //...... 

    // Sending data via OkHttp
    public static void doRegister(final String json, final String url, final String type) throws IOException {
        if (!StringUtils.hasLength(accessToken)) {
            LOGGER.error("{} client register error accessToken is null, please check the config : {} ", type, json);
            return;
        }
        Headers headers = new Headers.Builder().add(Constants.X_ACCESS_TOKEN, accessToken).build();
        String result = OkHttpTools.getInstance().post(url, json, headers);
        if (Objects.equals(SUCCESS, result)) {
            LOGGER.info("{} client register success: {} ", type, json);
        } else {
            LOGGER.error("{} client register error: {} ", type, json);
        }
    }
}

At this point, the logic of the client registering metadata by means of http is finished. To summarize: construct metadata by reading custom annotation information, send the data to the Disruptor queue, then consume the data from the queue, put the consumer into the thread pool to execute, and finally send an http request to the admin.

Similarly, ShenyuClientURIExecutorSubscriber is the execution class of registering URI information.

  • ShenyuClientURIExecutorSubscriber#executor()

The main logic is to iterate through the URI data collection and implement data registration through the persistURI() method.


public class ShenyuClientURIExecutorSubscriber implements ExecutorTypeSubscriber<URIRegisterDTO> {
    
    //......
    
    @Override
    public DataType getType() {
        return DataType.URI; 
    }
    
    // register URI
    @Override
    public void executor(final Collection<URIRegisterDTO> dataList) {
        for (URIRegisterDTO uriRegisterDTO : dataList) {
            Stopwatch stopwatch = Stopwatch.createStarted();
            while (true) {
                try (Socket ignored = new Socket(uriRegisterDTO.getHost(), uriRegisterDTO.getPort())) {
                    break;
                } catch (IOException e) {
                    long sleepTime = 1000;
                    // maybe the port is delay exposed
                    if (stopwatch.elapsed(TimeUnit.SECONDS) > 5) {
                        LOG.error("host:{}, port:{} connection failed, will retry",
                                uriRegisterDTO.getHost(), uriRegisterDTO.getPort());
                        // If the connection fails for a long time, Increase sleep time
                        if (stopwatch.elapsed(TimeUnit.SECONDS) > 180) {
                            sleepTime = 10000;
                        }
                    }
                    try {
                        TimeUnit.MILLISECONDS.sleep(sleepTime);
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
                    }
                }
            }
            ShenyuClientShutdownHook.delayOtherHooks();
            
            shenyuClientRegisterRepository.persistURI(uriRegisterDTO);
        }
    }
}

The while(true) loop in the code is to ensure that the client has been successfully started and can connect via host and port.

The logic behind it is: add the hook function for gracefully stopping the client .

Data registration is achieved through the persistURI() method. The whole logic is also analyzed in the previous section, and ultimately it is the OkHttp client that initiates http to shenyu-admin and registers the URI by way of http.

The analysis of the registration logic of the client is finished here, and the metadata and URI data constructed are sent to the Disruptor queue, from which they are then consumed, read, and sent to admin via http.

The source code analysis of the client-side metadata and URI registration process is complete, with the following flow chart.

3. Server-side registration process​

3.1 ShenyuHttpRegistryController​

From the previous analysis, we know that the server side provides two interfaces for registration.

  • /shenyu-client/register-metadata: The interface provided by the server side is used to register metadata.
  • /shenyu-client/register-uri: The server-side interface is provided for registering URIs.

These two interfaces are located in ShenyuHttpRegistryController, which implements the ShenyuServerRegisterRepository interface and is the implementation class for server-side registration. It is marked with @Join to indicate loading via SPI.

@RequestMapping("/shenyu-client")
@Join
public class ShenyuHttpRegistryController implements ShenyuServerRegisterRepository {

    private ShenyuServerRegisterPublisher publisher;

    @Override
    public void init(final ShenyuServerRegisterPublisher publisher, final ShenyuRegisterCenterConfig config) {
        this.publisher = publisher;
    }
    
    // register Metadata
    @PostMapping("/register-metadata")
    @ResponseBody
    public String registerMetadata(@RequestBody final MetaDataRegisterDTO metaDataRegisterDTO) {
        publisher.publish(metaDataRegisterDTO);
        return ShenyuResultMessage.SUCCESS;
    }
        
   // register URI
    @PostMapping("/register-uri")
    @ResponseBody
    public String registerURI(@RequestBody final URIRegisterDTO uriRegisterDTO) {
        publisher.publish(uriRegisterDTO);
        return ShenyuResultMessage.SUCCESS;
    }
}

The exact method used is specified by the configuration file and then loaded via SPI.

In the application.yml file in shenyu-admin configure the registration method, registerType specify the registration type, when registering with http, serverLists do not need to be filled in, for more configuration instructions you can refer to the official website Client Access Configuration.

shenyu:
  register:
    registerType: http 
    serverLists:
  • RegisterCenterConfiguration

After introducing the relevant dependencies and properties configuration, when starting shenyu-admin, the configuration file will be loaded first, and the configuration file class related to the registration center is RegisterCenterConfiguration.

@Configuration
public class RegisterCenterConfiguration {
    @Bean
    @ConfigurationProperties(prefix = "shenyu.register")
    public ShenyuRegisterCenterConfig shenyuRegisterCenterConfig() {
        return new ShenyuRegisterCenterConfig();
    }
    
    //create ShenyuServerRegisterRepository to register in admin
    @Bean(destroyMethod = "close")
    public ShenyuServerRegisterRepository shenyuServerRegisterRepository(final ShenyuRegisterCenterConfig shenyuRegisterCenterConfig, final List<ShenyuClientRegisterService> shenyuClientRegisterService) {
        // 1. get the registration type from the configuration property
        String registerType = shenyuRegisterCenterConfig.getRegisterType();
        // 2. load the implementation class by registering the type with the SPI method
        ShenyuServerRegisterRepository registerRepository = ExtensionLoader.getExtensionLoader(ShenyuServerRegisterRepository.class).getJoin(registerType);
        // 3. get the publisher and write data to the Disruptor queue
        RegisterServerDisruptorPublisher publisher = RegisterServerDisruptorPublisher.getInstance();
        // 4. ShenyuClientRegisterService, rpcType -> registerService
        Map<String, ShenyuClientRegisterService> registerServiceMap = shenyuClientRegisterService.stream().collect(Collectors.toMap(ShenyuClientRegisterService::rpcType, e -> e));
        // 5. start publisher
        publisher.start(registerServiceMap);
        // 6. init registerRepository
        registerRepository.init(publisher, shenyuRegisterCenterConfig);
        return registerRepository;
    }
}

Two beans are generated in the configuration class.

  • shenyuRegisterCenterConfig: to read the attribute configuration.

  • shenyuServerRegisterRepository: for server-side registration.

In the process of creating shenyuServerRegisterRepository, a series of preparations are also performed.

    1. get the registration type from the configuration property.
    1. Load the implementation class by the registration type with the SPI method: for example, if the specified type is http, ShenyuHttpRegistryController will be loaded.
    1. Get publisher and write data to the Disruptor queue.
    1. Register Service, rpcType -> registerService: get the registered Service, each rpc has a corresponding Service. The client for this article is built through springboot, which belongs to the http type, and other client types: dubbo, Spring Cloud, gRPC, etc.
    1. Preparation for event publishing: add server-side metadata and URI subscribers, process the data. And start the Disruptor queue.
    1. Initialization operation for registration: http type registration initialization operation is to save publisher.

  • RegisterClientServerDisruptorPublisher#publish()

The server-side publisher that writes data to the Disruptor queue , built via the singleton pattern.


public class RegisterClientServerDisruptorPublisher implements ShenyuServerRegisterPublisher {
    private static final RegisterClientServerDisruptorPublisher INSTANCE = new     private static final RegisterClientServerDisruptorPublisher INSTANCE = new RegisterServerDisruptorPublisher();
();

    public static RegisterClientServerDisruptorPublisher getInstance() {
        return INSTANCE;
    }
    
   //prepare for event publishing, add server-side metadata and URI subscribers, process data. And start the Disruptor queue.
    public void start(final Map<String, ShenyuClientRegisterService> shenyuClientRegisterService) {
        RegisterServerExecutorFactory factory = new RegisterServerExecutorFactory();
        // add URI data subscriber
        factory.addSubscribers(new URIRegisterExecutorSubscriber(shenyuClientRegisterService));
        // add Metadata subscriber
        factory.addSubscribers(new MetadataExecutorSubscriber(shenyuClientRegisterService));
        //start Disruptor
        providerManage = new DisruptorProviderManage(factory);
        providerManage.startup();
    }
    
    // write data to queue
    @Override
    public <T> void publish(final DataTypeParent data) {
        DisruptorProvider<Object> provider = providerManage.getProvider();
        provider.onData(Collections.singleton(data));
    }

    // write data to queue on batch
    @Override
    public void publish(final Collection<? extends DataTypeParent> dataList) {
        DisruptorProvider<Collection<DataTypeParent>> provider = providerManage.getProvider();
        provider.onData(dataList.stream().map(DataTypeParent.class::cast).collect(Collectors.toList()));
    }
    
    @Override
    public void close() {
        providerManage.getProvider().shutdown();
    }
}

The loading of the configuration file, which can be seen as the initialization process of the registry server, is described in the following diagram.

3.2 QueueConsumer​

In the previous analysis of the client-side disruptor queue consumption of data over. The server side has the same logic, except that the executor performing the task changes.

The QueueConsumer is a consumer that implements the WorkHandler interface, which is created in the providerManage.startup() logic. The WorkHandler interface is the data consumption interface for disruptor, and the only method is onEvent().

package com.lmax.disruptor;

public interface WorkHandler<T> {
    void onEvent(T var1) throws Exception;
}

The QueueConsumer overrides the onEvent() method, and the main logic is to generate the consumption task and then go to the thread pool to execute it.

/**
 * 
 * QueueConsumer
 */
public class QueueConsumer<T> implements WorkHandler<DataEvent<T>> {
    
	// ......

    @Override
    public void onEvent(final DataEvent<T> t) {
        if (t != null) {
            // Use different thread pools based on DataEvent type
            ThreadPoolExecutor executor = orderly(t);
            // create queue consumption tasks via factory
            QueueConsumerExecutor<T> queueConsumerExecutor = factory.create();
            // set data
            queueConsumerExecutor.setData(t.getData());
            // help gc
            t.setData(null);
            // put in the thread pool to execute the consumption task
            executor.execute(queueConsumerExecutor);
        }
    }
}

QueueConsumerExecutor is the task that is executed in the thread pool, it implements the Runnable interface, and there are two specific implementation classes.

  • RegisterClientConsumerExecutor: the client-side consumer executor.
  • RegisterServerConsumerExecutor: server-side consumer executor.

As the name implies, one is responsible for handling client-side tasks and one is responsible for handling server-side tasks.

  • RegisterServerConsumerExecutor#run()

RegisterServerConsumerExecutor is a server-side consumer executor that indirectly implements the Runnable interface via QueueConsumerExecutor and overrides the run() method.


public final class RegisterServerConsumerExecutor extends QueueConsumerExecutor<List<DataTypeParent>> {
   // ...

    @Override
    public void run() {
        //get the data from the disruptor queue and check data
        Collection<DataTypeParent> results = getData()
                .stream()
                .filter(this::isValidData)
                .collect(Collectors.toList());
        if (CollectionUtils.isEmpty(results)) {
            return;
        }
        //execute operations according to type
        getType(results).executor(results);
    }
    
    // get subscribers by type
    private ExecutorSubscriber<DataTypeParent> selectExecutor(final Collection<DataTypeParent> list) {
        final Optional<DataTypeParent> first = list.stream().findFirst();
        return subscribers.get(first.orElseThrow(() -> new RuntimeException("the data type is not found")).getType());
    }
}

  • ExecutorSubscriber#executor()

The actuator subscribers are divided into two categories, one that handles metadata and one that handles URIs. There are two on the client side and two on the server side, so there are four in total.

  • MetadataExecutorSubscriber#executor()

In case of registering metadata, this is achieved by MetadataExecutorSubscriber#executor(): get the registered Service according to the type and call register().

public class MetadataExecutorSubscriber implements ExecutorTypeSubscriber<MetaDataRegisterDTO> {
 
    //......

    @Override
    public DataType getType() {
        return DataType.META_DATA; 
    }

    @Override
    public void executor(final Collection<MetaDataRegisterDTO> metaDataRegisterDTOList) {
        // Traversing the metadata list
        metaDataRegisterDTOList.forEach(meta -> {
            Optional.ofNullable(this.shenyuClientRegisterService.get(meta.getRpcType())) // Get registered Service by type
                    .ifPresent(shenyuClientRegisterService -> {
                        // Registration of metadata, locking to ensure sequential execution and prevent concurrent errors
                        synchronized (shenyuClientRegisterService) {
                            shenyuClientRegisterService.register(meta);
                        }
                    });
        });
    }
}
  • URIRegisterExecutorSubscriber#executor()

In case of registration metadata, this is achieved by URIRegisterExecutorSubscriber#executor(): construct URI data, find Service according to the registration type, and achieve registration by the registerURI method.


public class URIRegisterExecutorSubscriber implements ExecutorTypeSubscriber<URIRegisterDTO> {
    //......
    
    @Override
    public DataType getType() {
        return DataType.URI; 
    }
    
    @Override
    public void executor(final Collection<URIRegisterDTO> dataList) {
        if (CollectionUtils.isEmpty(dataList)) {
            return;
        }
        
        findService(dataList).ifPresent(service -> {
            Map<String, List<URIRegisterDTO>> listMap = buildData(dataList);
            listMap.forEach(service::registerURI);
        });
        final Map<String, List<URIRegisterDTO>> groupByRpcType = dataList.stream()
                .filter(data -> StringUtils.isNotBlank(data.getRpcType()))
                .collect(Collectors.groupingBy(URIRegisterDTO::getRpcType));
        for (Map.Entry<String, List<URIRegisterDTO>> entry : groupByRpcType.entrySet()) {
            final String rpcType = entry.getKey();
            // Get registered Service by type
            Optional.ofNullable(shenyuClientRegisterService.get(rpcType))
                    .ifPresent(service -> {
                        final List<URIRegisterDTO> list = entry.getValue();
                        // Build URI data types and register them with the registerURI method
                        Map<String, List<URIRegisterDTO>> listMap = buildData(list);
                        listMap.forEach(service::registerURI);
                    });
        }
    }
    
    // Find Service by type
    private Optional<ShenyuClientRegisterService> findService(final Collection<URIRegisterDTO> dataList) {
        return dataList.stream().map(dto -> shenyuClientRegisterService.get(dto.getRpcType())).findFirst();
    }
}

  • ShenyuClientRegisterService#register()

ShenyuClientRegisterService is the registration method interface, which has several implementation classes.

  • AbstractContextPathRegisterService: abstract class, handling part of the public logic.
  • AbstractShenyuClientRegisterServiceImpl: : abstract class, handles part of the public logic.
  • ShenyuClientRegisterDivideServiceImpl: divide class, handles http registration types.
  • ShenyuClientRegisterDubboServiceImpl: dubbo class, handles dubbo registration types.
  • ShenyuClientRegisterGrpcServiceImpl: gRPC class, handles gRPC registration types.
  • ShenyuClientRegisterMotanServiceImpl: Motan class, handles Motan registration types.
  • ShenyuClientRegisterSofaServiceImpl: Sofa class, handles Sofa registration types.
  • ShenyuClientRegisterSpringCloudServiceImpl: SpringCloud class, handles SpringCloud registration types.
  • ShenyuClientRegisterTarsServiceImpl: Tars class, handles Tars registration types.
  • ShenyuClientRegisterWebSocketServiceImpl： Websocket class，handles Websocket registration types.

From the above, we can see that each microservice has a corresponding registration implementation class. The source code analysis in this article is based on the official shenyu-examples-http as an example, it is of http registration type, so the registration implementation class for metadata and URI data is ShenyuClientRegisterDivideServiceImpl: ShenyuClientRegisterDivideServiceImpl.

  • register():
public abstract class AbstractShenyuClientRegisterServiceImpl extends FallbackShenyuClientRegisterService implements ShenyuClientRegisterService {

    //......

    public String register(final MetaDataRegisterDTO dto) {
        // 1.register selector information
        String selectorHandler = selectorHandler(dto);
        String selectorId = selectorService.registerDefault(dto, PluginNameAdapter.rpcTypeAdapter(rpcType()), selectorHandler);
        // 2.register rule information
        String ruleHandler = ruleHandler();
        RuleDTO ruleDTO = buildRpcDefaultRuleDTO(selectorId, dto, ruleHandler);
        ruleService.registerDefault(ruleDTO);
        // 3.register metadata information
        registerMetadata(dto);
        // 4.register contextPath
        String contextPath = dto.getContextPath();
        if (StringUtils.isNotEmpty(contextPath)) {
            registerContextPath(dto);
        }
        return ShenyuResultMessage.SUCCESS;
    }
}

The whole registration logic can be divided into 4 steps.

    1. Register selector information
    1. Register rule information
    1. Register metadata information
    1. Register `contextPath

This side of admin requires the construction of selectors, rules, metadata and ContextPath through the metadata information of the client. The specific registration process and details of processing are related to the rpc type. We will not continue to track down the logical analysis of the registration center, tracking to this point is enough.

The source code of the server-side metadata registration process is analyzed and the flow chart is described as follows.

  • registerURI()
public abstract class AbstractShenyuClientRegisterServiceImpl extends FallbackShenyuClientRegisterService implements ShenyuClientRegisterService {

    //......

    public String registerURI(final String selectorName, final List<URIRegisterDTO> uriList) {
        if (CollectionUtils.isEmpty(uriList)) {
            return "";
        }
        // Does the corresponding selector exist
        SelectorDO selectorDO = selectorService.findByNameAndPluginName(selectorName, PluginNameAdapter.rpcTypeAdapter(rpcType()));
        if (Objects.isNull(selectorDO)) {
            return "";
        }
        // Handle handler information in the selector
        String handler = buildHandle(uriList, selectorDO);
        selectorDO.setHandle(handler);
        SelectorData selectorData = selectorService.buildByName(selectorName, PluginNameAdapter.rpcTypeAdapter(rpcType()));
        selectorData.setHandle(handler);

        // Update records in the database
        selectorService.updateSelective(selectorDO);
        // publish Event to gateway
        eventPublisher.publishEvent(new DataChangedEvent(ConfigGroupEnum.SELECTOR, DataEventTypeEnum.UPDATE, Collections.singletonList(selectorData)));
        return ShenyuResultMessage.SUCCESS;
    }
}

After admin gets the URI data, it mainly updates the handler information in the selector, then writes it to the database, and finally publishes the event notification gateway. The logic of notifying the gateway is done by the data synchronization operation, which has been analyzed in the previous article, so we will not repeat it.

The source code analysis of the server-side URI registration process is complete and is described in the following diagram.

At this point, the server-side registration process is also analyzed, mainly through the interface provided externally, accept the registration information from the client, and then write to the Disruptor queue, and then consume data from it, and update the admin selector, rules, metadata and selector handler according to the received metadata and URI data.

4. Summary​

This article focuses on the http registration module of the Apache ShenYu gateway for source code analysis. The main knowledge points involved are summarized as follows.

  • The register center is for registering client information to admin to facilitate traffic filtering.
  • http registration is to register client metadata information and URI information to admin.
  • http service access is identified by the annotation @ShenyuSpringMvcClient.
  • construction of the registration information mainly through the application listener ApplicationListener.
  • loading of the registration type is done through SPI.
  • The Disruptor queue was introduced to decouple data from operations, and data buffering.
  • The implementation of the registry uses interface-oriented programming, using design patterns such as template methods, singleton, and observer.