Before the update can be started on the update subsystem, all users must be disconnected from the original production system and transferred to the bridge subsystem.

The transfer from the production system to the bridge subsystem runs smoothly at database connection level. This process runs unnoticed by the users.

The bridge subsystem is a separate subsystem in the context of the production system. Once all users are transferred to the bridge subsystem after the MAIN_BRITRANS/REQ_USER_ROLLOVER_FINAL phase, the repository tables as well as other tables that need to be accessed by the update are renamed. The bridge subsystem retains access to the renamed tables.

After the update has finished, all activities that were started on the bridge subsystem must be completed. All users are logged off the bridge subsystem and all activities are shut down. The users are then logged on to the production system again.