Heartbeat

The Heartbeat service enables a Java Dynamic Management Kit manager to detect when the connection to a Java Dynamic Management Kit agent has been lost or terminated, and vice-versa. This is done through the specific connector part of either the manager or the agent. It is assumed that a manager has a connector client and an agent has a connector server.

The Heartbeat service is manager-driven in that all heartbeat operations are configured on the manager side. The connector client implements the HeartBeatClientHandler interface. At predefined intervals, the manager, through it's connector client, sends out a request to the agent, through the agent's connector server. The connector server listens for these requests and responds to this request. You can specify the request time intervals yourself.

Connection loss of an agent

If the connector client receives no response to the request from the connector server at the time the next request is due to be sent, the connector client may try re-sending the request. The number of times the request is resent depends on the value you set. By default, the connector client will try to resend the request six times. The time lapse (known as the HeartBeatPeriod) between retries is ten seconds. Therefore, the connector client will wait for a response for sixty seconds (HeartBeatPeriod x HeartBeatRetries). You may change the values of both the HeartBeatPeriod and HeartBeatRetries. If no response is received after the allotted time, the connector client will register the agent as being no longer alive and the connector client will clean up all its resources and specific agent information by:

• sending connection lost notifications to all registered heartbeat notification listeners.

• stopping the pull mechanism, if this is the method used for notifications.

• disconnecting the connector client.

However, if one of the retries is successful the connection to the connector server will be reestablished and a connection reestablished notification will be sent to all registered heartbeat notification listeners.

Connection loss of a manager

The connector server waits for a request to be sent from the connector client. It waits for the allocated time (HeartBeatPeriod x HeartBeatRetries). If the connector server receives no request from the connector client after this allotted time , sixty seconds by default, the particular connector client will be registered as being no longer alive and all information specific to that connector client will be cleaned up on the connector server side.