| Package | Description | 
|---|---|
| org.apache.hadoop.hdfs.server.federation.router | The router package includes the core services for a HDFS federation router. | 
| org.apache.hadoop.hdfs.server.federation.store | The federation state store tracks persistent values that are shared between
 multiple routers. | 
| Modifier and Type | Class and Description | 
|---|---|
| class  | NamenodeHeartbeatServiceThe  Routerperiodically checks the state of a Namenode (usually on
 the same server) and reports their high availability (HA) state and
 load/space status to theStateStoreService. | 
| class  | RouterHeartbeatServiceService to periodically update the Router current state in the State Store. | 
| class  | RouterQuotaUpdateServiceService to periodically update the  RouterQuotaUsagecached information in theRouter. | 
| class  | RouterSafemodeServiceService to periodically check if the  StateStoreServicecached information in theRouteris up to date. | 
| Modifier and Type | Class and Description | 
|---|---|
| class  | StateStoreCacheUpdateServiceService to periodically update the  StateStoreServicecached information in theRouter. | 
| class  | StateStoreConnectionMonitorServiceService to periodically monitor the connection of the StateStore
  StateStoreServicedata store and to re-open the connection
 to the data store if required. | 
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