com.alibaba.cloud.dubbo.autoconfigure

Class DubboServiceDiscoveryAutoConfiguration

java.lang.Object

com.alibaba.cloud.dubbo.autoconfigure.DubboServiceDiscoveryAutoConfiguration

@Configuration(proxyBeanMethods=false)
 @ConditionalOnClass(name="org.springframework.cloud.client.discovery.DiscoveryClient")
 @ConditionalOnProperty(name="spring.cloud.discovery.enabled",
                       matchIfMissing=true)
 @AutoConfigureAfter(name={"org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration","org.springframework.cloud.zookeeper.discovery.ZookeeperDiscoveryAutoConfiguration","org.springframework.cloud.consul.discovery.ConsulDiscoveryClientConfiguration","com.alibaba.cloud.nacos.discovery.NacosDiscoveryAutoConfiguration"},
                    value=DubboServiceRegistrationAutoConfiguration.class)
public class DubboServiceDiscoveryAutoConfiguration
extends Object

Dubbo Service Discovery Auto Configuration (after DubboServiceRegistrationAutoConfiguration).

Author:

Mercy

See Also:

DubboServiceRegistrationAutoConfiguration, Configuration, DiscoveryClient

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	DubboServiceDiscoveryAutoConfiguration.EurekaConfiguration Eureka Customized Configuration.
class	DubboServiceDiscoveryAutoConfiguration.ZookeeperConfiguration Zookeeper Customized Configuration.

Field Summary

Fields

Modifier and Type	Field and Description
static String	CONSUL_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME ConsulDiscoveryClientConfiguration.
static String	NACOS_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME NacosDiscoveryAutoConfiguration.
static String	ZOOKEEPER_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME ZookeeperDiscoveryAutoConfiguration.

Constructor Summary

Constructors

Constructor and Description

DubboServiceDiscoveryAutoConfiguration(DubboServiceMetadataRepository dubboServiceMetadataRepository, org.springframework.context.ApplicationEventPublisher applicationEventPublisher, org.springframework.cloud.client.discovery.DiscoveryClient discoveryClient, org.springframework.beans.factory.ObjectProvider<Predicate<org.springframework.cloud.client.discovery.event.HeartbeatEvent>> heartbeatEventChangedPredicate)

Method Summary

Modifier and Type	Method and Description
Predicate<org.springframework.cloud.client.discovery.event.HeartbeatEvent>	defaultHeartbeatEventChangePredicate() The default Predicate implementation of HeartbeatEvent based on the comparison between previous and current state value, the DiscoveryClient implementation may override current.
void	onHeartbeatEvent(org.springframework.cloud.client.discovery.event.HeartbeatEvent event) Dispatch a ServiceInstancesChangedEvent when the HeartbeatEvent raised, use for these scenarios: Eureka : CloudEurekaClient.onCacheRefreshed() publishes a HeartbeatEvent instead of CacheRefreshedEvent Zookeeper : ZookeeperServiceWatch.childEvent(CuratorFramework, TreeCacheEvent) publishes a HeartbeatEvent when the services' root path has been changed Consul : ConsulCatalogWatch.catalogServicesWatch() publishes a HeartbeatEvent when Consul's Blocking Queries response Nacos : NacosWatch.nacosServicesWatch() publishes a HeartbeatEvent under a TaskScheduler every NacosDiscoveryProperties.getWatchDelay() milliseconds

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ZOOKEEPER_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME

public static final String ZOOKEEPER_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME

ZookeeperDiscoveryAutoConfiguration.

See Also:

Constant Field Values

CONSUL_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME

public static final String CONSUL_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME

ConsulDiscoveryClientConfiguration.

See Also:

Constant Field Values

NACOS_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME

public static final String NACOS_DISCOVERY_AUTO_CONFIGURATION_CLASS_NAME

NacosDiscoveryAutoConfiguration.

See Also:

Constant Field Values

Constructor Detail

DubboServiceDiscoveryAutoConfiguration

public DubboServiceDiscoveryAutoConfiguration(DubboServiceMetadataRepository dubboServiceMetadataRepository,
                                              org.springframework.context.ApplicationEventPublisher applicationEventPublisher,
                                              org.springframework.cloud.client.discovery.DiscoveryClient discoveryClient,
                                              org.springframework.beans.factory.ObjectProvider<Predicate<org.springframework.cloud.client.discovery.event.HeartbeatEvent>> heartbeatEventChangedPredicate)

Method Detail

onHeartbeatEvent

@EventListener(value=org.springframework.cloud.client.discovery.event.HeartbeatEvent.class)
public void onHeartbeatEvent(org.springframework.cloud.client.discovery.event.HeartbeatEvent event)

Dispatch a ServiceInstancesChangedEvent when the HeartbeatEvent raised, use for these scenarios:

• Eureka : CloudEurekaClient.onCacheRefreshed() publishes a HeartbeatEvent instead of CacheRefreshedEvent
• Zookeeper : ZookeeperServiceWatch.childEvent(CuratorFramework, TreeCacheEvent) publishes a HeartbeatEvent when the services' root path has been changed
• Consul : ConsulCatalogWatch.catalogServicesWatch() publishes a HeartbeatEvent when Consul's Blocking Queries response
• Nacos : NacosWatch.nacosServicesWatch() publishes a HeartbeatEvent under a TaskScheduler every NacosDiscoveryProperties.getWatchDelay() milliseconds

In order to reduce the duplicated handling for ServiceInstancesChangedEvent, defaultHeartbeatEventChangePredicate() method providers the default implementation to detect whether the state is changed or not. If and only if changed, the #dispatchServiceInstancesChangedEvent(String, Collection) will be executed.

Note : Spring Cloud HeartbeatEvent has a critical flaw that can't figure out which service was changed precisely, it's just used for a notification that the subscribed services used to notify the Dubbo consumer cached URLs. Because of some DiscoveryClient implementations have the better and fine-grained the event mechanism for service instances change, thus HeartbeatEvent handle will be ignored in these scenarios:

• Zookeeper : Watcher, see DubboServiceDiscoveryAutoConfiguration.ZookeeperConfiguration.heartbeatEventChangedPredicate()
• Nacos : EventListener , see NacosConfiguration#heartbeatEventChangedPredicate()

If the customized DiscoveryClient also providers the similar mechanism, the implementation could declare a Spring Bean of Predicate of HeartbeatEvent to override default one.

Parameters:

event - the instance of HeartbeatEvent

See Also:

HeartbeatEvent

defaultHeartbeatEventChangePredicate

@Bean
 @ConditionalOnMissingBean
public Predicate<org.springframework.cloud.client.discovery.event.HeartbeatEvent> defaultHeartbeatEventChangePredicate()

The default Predicate implementation of HeartbeatEvent based on the comparison between previous and current state value, the DiscoveryClient implementation may override current.

Returns:

Predicate HeartbeatEvent

See Also:

DubboServiceDiscoveryAutoConfiguration.EurekaConfiguration.heartbeatEventChangedPredicate()