Service Provider会向Eureka Server做

/**
 *
 * com.netflix.discovery.DiscoveryClient.java
 *
 *
 * 
     * Initializes all scheduled tasks.
     */
    private void initScheduledTasks() {
        //从Eureka Server获取所有服务列表，并在本地缓存
        if (clientConfig.shouldFetchRegistry()) {
            // registry cache refresh timer
            int registryFetchIntervalSeconds = clientConfig.getRegistryFetchIntervalSeconds();
            int expBackOffBound = clientConfig.getCacheRefreshExecutorExponentialBackOffBound();
            scheduler.schedule(
                    new TimedSupervisorTask(
                            "cacheRefresh",
                            scheduler,
                            cacheRefreshExecutor,
                            registryFetchIntervalSeconds,
                            TimeUnit.SECONDS,
                            expBackOffBound,
                            new CacheRefreshThread()
                    ),
                    registryFetchIntervalSeconds, TimeUnit.SECONDS);
        }
        //本地环境注册到开发环境
        if (clientConfig.shouldRegisterWithEureka()) {
            int renewalIntervalInSecs = instanceInfo.getLeaseInfo().getRenewalIntervalInSecs();
            int expBackOffBound = clientConfig.getHeartbeatExecutorExponentialBackOffBound();
            logger.info("Starting heartbeat executor: " + "renew interval is: " + renewalIntervalInSecs);
            // Heartbeat timer
            scheduler.schedule(
                    new TimedSupervisorTask(
                            "heartbeat",
                            scheduler,
                            heartbeatExecutor,
                            renewalIntervalInSecs,
                            TimeUnit.SECONDS,
                            expBackOffBound,
                            new HeartbeatThread()
                    ),
                    renewalIntervalInSecs, TimeUnit.SECONDS);
            // InstanceInfo replicator
            /**************************封装了定时任务**********************************/
            instanceInfoReplicator = new InstanceInfoReplicator(
                    this,
                    instanceInfo,
                    clientConfig.getInstanceInfoReplicationIntervalSeconds(),
                    2); // burstSize
            statusChangeListener = new ApplicationInfoManager.StatusChangeListener() {
                @Override
                public String getId() {
                    return "statusChangeListener";
                }
                @Override
                public void notify(StatusChangeEvent statusChangeEvent) {
                    if (InstanceStatus.DOWN == statusChangeEvent.getStatus() ||
                            InstanceStatus.DOWN == statusChangeEvent.getPreviousStatus()) {
                        // log at warn level if DOWN was involved
                        logger.warn("Saw local status change event {}", statusChangeEvent);
                    } else {
                        logger.info("Saw local status change event {}", statusChangeEvent);
                    }
                    instanceInfoReplicator.onDemandUpdate();
                }
            };

            if (clientConfig.shouldOnDemandUpdateStatusChange()) {
                applicationInfoManager.registerStatusChangeListener(statusChangeListener);
            }

            //点击可以查看start方法
            instanceInfoReplicator.start(clientConfig.getInitialInstanceInfoReplicationIntervalSeconds());
        } 

        else 
        {
            logger.info("Not registering with Eureka server per configuration");
        }
    }



//以initialDelayMs为间隔调用。

    public void start(int initialDelayMs) {
       if (started.compareAndSet(false, true)) {
           instanceInfo.setIsDirty();  // for initial register
           Future next = scheduler.schedule(this, initialDelayMs, TimeUnit.SECONDS);
           scheduledPeriodicRef.set(next);
       }
}
//ScheduledExecutorService的task的具体业务:com.netflix.discovery.InstanceInfoReplicator.run()
//看到调用了了client的register方法。
 public void run() {
       try {
           discoveryClient.refreshInstanceInfo();
           Long dirtyTimestamp = instanceInfo.isDirtyWithTime();
           if (dirtyTimestamp != null) {
               //客户端发送hhtp注册请求的真正入口
               discoveryClient.register();
               instanceInfo.unsetIsDirty(dirtyTimestamp);
           }
       } catch (Throwable t) {
           logger.warn("There was a problem with the instance info replicator", t);
       } finally {
           Future next = scheduler.schedule(this, replicationIntervalSeconds, TimeUnit.SECONDS);
           scheduledPeriodicRef.set(next);
       }
}





//client的register方法

 public void run() {
       try {
           discoveryClient.refreshInstanceInfo();
           Long dirtyTimestamp = instanceInfo.isDirtyWithTime();
           if (dirtyTimestamp != null) {
               //客户端发送hhtp注册请求的真正入口
               discoveryClient.register();
               instanceInfo.unsetIsDirty(dirtyTimestamp);
           }
       } catch (Throwable t) {
           logger.warn("There was a problem with the instance info replicator", t);
       } finally {
           Future next = scheduler.schedule(this, replicationIntervalSeconds, TimeUnit.SECONDS);
           scheduledPeriodicRef.set(next);
       }
}


/**
 * Register with the eureka service by making the appropriate REST call.
 */
boolean register() throws Throwable {
    logger.info(PREFIX + appPathIdentifier + ": registering service...");
    EurekaHttpResponse<Void> httpResponse;
    try {
        //Eureka Client客户端，调用Eureka服务端的入口
        httpResponse = eurekaTransport.registrationClient.register(instanceInfo);
    } catch (Exception e) {
        logger.warn("{} - registration failed {}", PREFIX + appPathIdentifier, e.getMessage(), e);
        throw e;
    }
    if (logger.isInfoEnabled()) {
        logger.info("{} - registration status: {}", PREFIX + appPathIdentifier, httpResponse.getStatusCode());
    }
    return httpResponse.getStatusCode() == 204;
}