Implementable Functions

Each JavaScript filter must defined one or more functions that are used to operate the filter process. The filter() function must be defined, as it contains the primary operation sequence for the defined filter. The function is supplied the event from the THL as the events are processed by the replicator.

In addition, two other JavaScript functions can optionally be defined that are executed before and after the filter process. Additional, user-specific, functions can be defined within the filter context to support the filter operations.

  • prepare()

    The prepare() function is called when the replicator is first started, and initializes the configured filter with any values that may be required during the filter process. These can include loading and identifying configuration values, creating lookup, exception or other reference tables and other internal JavaScript tables based on the configuration information, and reporting the generated configuration or operation for debugging.

  • filter(event)

    The filter() function is the main function that is called each time an event is loaded from the THL. The event is parsed as the only parameter to the function and is an object containing all the statement or row data for a given event.

  • release()

    The release() function is called when the filter is deallocated and removed, typically during shutdown of the replicator, although it may also occur when a processing thread is restarted.