2.3.1.3 Monitoring Standard Connectors Using the Heartbeat Mechanism

All connectors provided in the Java DMK implement a heartbeat mechanism. This is true for both legacy connectors and the new standard connectors. This section outlines the heartbeat mechanism used for standard connectors. For information on the heartbeat mechanism used for legacy connectors, see 4.1.2 Monitoring Legacy Connectors Using the Heartbeat Mechanism.

The heartbeat mechanism monitors the connection between a manager and an agent, and automates the cleanup procedure when the connection is lost. This allows both the manager and the agent to free resources that were allocated for maintaining the connection.

The mechanism is entirely contained in the connector client and connector server components. No additional objects are involved. In addition, connector clients and servers send notifications that the manager application can receive to be aware of changes in the status of a connection.

The connector client generates a periodic heartbeat, by performing an innocuous operation on the server. If any beat fails because of a communication failure, the connection is considered to be dead. The server does not need to know that the heartbeat exists. The innocuous beat operations look like any other client operation.

Furthermore, client death is not detected by heartbeat. Instead, connectors are defined in such a way that there is no permanent client state on the server. Thus, the server can close client connections after a specified idle time. If the client is still alive, it will establish another connection. This is essentially an implicit lease mechanism.