Rolling Barrel Module
The DELFT-FEWS databases (central database and local data store) are not meant to store forecast related data indefinitely. To make sure that the database system does not fill up, a rolling barrel of configurable length is applied to all data. All dynamic data is kept in the system for a configurable length of time. This is identified by setting an expiry time to each item of dynamic data saved in the database. DELFT-FEWS can run a module to remove data for which the expiry date has passed from the database. This module should be scheduled to run on a daily basis on the live system (usually at times when the system is not used extensively- e.g. around midnight). On operator clients the rolling barrel is run when the system identifies that enough data is expired to make the run worthwhile.
As all functional tasks are run by DELFT-FEWS through a workflow, a moduleInstance is created to allow the rolling barrel to be run. The module instance must be correctly registered in the moduleInstanceDescriptors (see Regional Configuration), and point to the relevant class in the moduleDesriptors configuration (see System Configuration). The module does not require any configuration. There is therefore not an XML file available, nor need one be configured to run this module.
