X Agent detects that a predetermined event has occurred, traps are generated by the agent and sent to one or more trap destinations, the Object Managers. An Object Manager can determine what kind of event caused the agent to gener- ate the trap by examining the data stored in the variable bindings ("varbinds") of OSS for Telecom Networks each trap message. 49 The varbinds contain the identity and values of MIB variables that provide information on the specific event. To identify the trap destinations, AdventNet's SNMP API has implemented a pro- prietary table called the Trap Forwarding Table that contains all necessary informa- tion regarding the trap destination. A TL1 autonomous message is sent from an agent to the appropriate Manager without an explicit input message associated with it. These are unsolicited messages from the agent to report alarmed and non-alarmed events to the manager. The TL1 autonomous messages are sent to the Managers which have established a connec- tion with the JMX Agent using the TL1 protocol. 12.10.4.1.1 Retrieving Lost Notifications The notification can be either persistent or non-persistent. The SNMP traps and the TL1 autonomous messages received by the Managers are stored in the database and can be retrieved later. The notification log table and the varbind log table track the notifications sent and the varbind contents, respectively. This persistence feature allows lost notifications to be retrieved. All notifications sent to the Managers are stored in the database. If the Manager fails to receive a notification, then it can be retrieved from the database. To this end, the Manager has been equipped to access readily the notification log and varbind log tables. Through the notification log index, it is possible to recover notifications selectively. The notification log table summarises all notifications. The details of the notifications are available in the varbind log table. The number of notifications that can be stored in the database can be specified via the maxRows attribute 