Eureka重要对象简介

在进行分析EurekaClient和EurekaServer之间通信的源码之前，我们首先需要熟悉一下几个实体类

`InstanceInfo`

这个类代表着EurekaClient实例，客户端向服务端请求注册时就会携带着这个实例，这个实例中包含了当前客户端的一些基本信息：

    private volatile String instanceId;

    private volatile String appName;

    @Auto

    private volatile String appGroupName;

    private volatile String ipAddr;

    private static final String SID_DEFAULT = "na";

    @Deprecated

    private volatile String sid = SID_DEFAULT;

    private volatile int port = DEFAULT_PORT;

    private volatile int securePort = DEFAULT_SECURE_PORT;

    @Auto

    private volatile String homePageUrl;

    @Auto

    private volatile String statusPageUrl;

    @Auto

    private volatile String healthCheckUrl;

    @Auto

    private volatile String secureHealthCheckUrl;

    @Auto

    private volatile String vipAddress;

    @Auto

    private volatile String secureVipAddress;

    @XStreamOmitField

    private String statusPageRelativeUrl;

    @XStreamOmitField

    private String statusPageExplicitUrl;

    @XStreamOmitField

    private String healthCheckRelativeUrl;

    @XStreamOmitField

    private String healthCheckSecureExplicitUrl;

    @XStreamOmitField

    private String vipAddressUnresolved;

    @XStreamOmitField

    private String secureVipAddressUnresolved;

    @XStreamOmitField

    private String healthCheckExplicitUrl;

    @Deprecated

    private volatile int countryId = DEFAULT_COUNTRY_ID; // Defaults to US

    private volatile boolean isSecurePortEnabled = false;

    private volatile boolean isUnsecurePortEnabled = true;

    private volatile DataCenterInfo dataCenterInfo;

    private volatile String hostName;

    private volatile InstanceStatus status = InstanceStatus.UP;

    private volatile InstanceStatus overriddenStatus = InstanceStatus.UNKNOWN;

    @XStreamOmitField

    private volatile boolean isInstanceInfoDirty = false;

    private volatile LeaseInfo leaseInfo;

    @Auto

    private volatile Boolean isCoordinatingDiscoveryServer = Boolean.FALSE;

    @XStreamAlias("metadata")

    private volatile Map<String, String> metadata;

    @Auto

    private volatile Long lastUpdatedTimestamp;

    @Auto

    private volatile Long lastDirtyTimestamp;

    @Auto

    private volatile ActionType actionType;

    @Auto

    private volatile String asgName;

    private String version = VERSION_UNKNOWN;

`InstanceStatus`

这个枚举中包含了客户端可能存在的状态

        UP,

        DOWN,

        STARTING,

        OUT_OF_SERVICE,

        UNKNOWN;

`Lease`

这个类是服务端用来保存客户端的租约信息的，其中holder中持有的就是InstanceInfo对象

// 租约过期时间

 public static final int DEFAULT_DURATION_IN_SECS = 90;

//客户端实例

private T holder;

//服务下线时间

private long evictionTimestamp;

//注册起始时间

private long registrationTimestamp;

//取消注册时间

private long serviceUpTimestamp;

// 最后更新时间

private volatile long lastUpdateTimestamp;

//租约持续时间

private long duration;

`PeerEurekaNode`

这个对象代表着集群节点信息

 /**

     * 服务地址

     */

    private final String serviceUrl;

    /**

     * Eureka-Server 配置

     */

    private final EurekaServerConfig config;

    /**

     * 批任务同步最大延迟

     */

    private final long maxProcessingDelayMs;

    /**

     * 应用实例注册表

     */

    private final PeerAwareInstanceRegistry registry;

    /**

     * 目标 host

     */

    private final String targetHost;

    /**

     * 集群  EurekaHttpClient

     */

    private final HttpReplicationClient replicationClient;

    /**

     * 批量任务分发器

     */

    private final TaskDispatcher<String, ReplicationTask> batchingDispatcher;

    /**

     * 单任务分发器

     */

    private final TaskDispatcher<String, ReplicationTask> nonBatchingDispatcher;

`EurekaHttpClient`

这个是Eureka客户端与服务端通信的接口

public interface EurekaHttpClient {

    EurekaHttpResponse<Void> register(InstanceInfo info);

    EurekaHttpResponse<Void> cancel(String appName, String id);

    EurekaHttpResponse<InstanceInfo> sendHeartBeat(String appName, String id, InstanceInfo info, InstanceStatus overriddenStatus);

    EurekaHttpResponse<Void> statusUpdate(String appName, String id, InstanceStatus newStatus, InstanceInfo info);

    EurekaHttpResponse<Void> deleteStatusOverride(String appName, String id, InstanceInfo info);

    EurekaHttpResponse<Applications> getApplications(String... regions);

    EurekaHttpResponse<Applications> getDelta(String... regions);

    EurekaHttpResponse<Applications> getVip(String vipAddress, String... regions);

    EurekaHttpResponse<Applications> getSecureVip(String secureVipAddress, String... regions);

    EurekaHttpResponse<Application> getApplication(String appName);

    EurekaHttpResponse<InstanceInfo> getInstance(String appName, String id);

    EurekaHttpResponse<InstanceInfo> getInstance(String id);

    void shutdown();

}

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