Understanding how the gateway handles incremental resynchronization

Use this information to understand how the gateway handles incremental resynchronization.

On startup, the gateway performs an incremental resynchronization with EIF when the Gate.TIVOLI_EIF.Resync and Gate.TIVOLI_EIF.FullResync properties defined in the NCO_GATE.props properties file are set to the values TRUE and FALSE, respectively.

Incremental resynchronization makes use of the alerts.eif_gw_resync table in Tivoli Netcool/OMNIbus and an associated trigger called eif_gw_resync trigger. The tivoli_eifgw_setup.sql script installs both the alerts.eif_gw_resync table and the eif_gw_resync trigger. The tivoli_eifgw_setup.sql script delivers with the gateway and needs to be loaded into the ObjectServer using the nco_sql utility.

During incremental resynchronization, the gateway performs the following operations:

  • First, the gateway informs the EIF receiver of all of the Identifier values that exist in the alerts.status table in the ObjectServer. This gives the EIF target the opportunity to compare this list with Identifiers that it knows about. Any that it knows about that are missing from the ObjectServer can be inferred as having been deleted from the ObjectServer before the gateway started. See Understanding resync event formats for details about the resync event formats. of the resync start, identifier list(s) and resync end messages that are sent.
  • Secondly, with the aid of the eif_gw_resync trigger, the gateway causes alerts that have been inserted or updated since the gateway's last run to be updated. To accomplish this, the gateway reads the last statechange value written to the last statechange file on startup to determine the latest statechange of any event the gateway has seen coupled with the writing of data to the alerts.eif_gw_resync table. Recent unseen versions of alerts are then updated by the eif_gw_resync trigger to cause them to be forwarded to the gateway through the normal IDUC notification process.

    In previous versions of the gateway, the file containing the last statechange value (if any) is $NCHOME/var/tivoli_eif/last_statechange.txt and is not configurable. Thus, if more than one gateway runs within a Tivoli Netcool/OMNIbus installation, a conflict occurs.

    The current version of the gateway defines a property called Gate.TIVOLI_EIF.LastStatechangeFile in the NCO_GATE.props properties file. With this property, you can specify the name (not the location) of the last state change file.

    See Understanding how the gateway makes use of the latest state change file for information about the last state change file and the Gate.TIVOLI_EIF.LastStatechangeFile property.