...
At a high level, the updater:
Verifies the updater package.
Unzips the package.
Deactivates the various Wise Owl Legal components.
Installs the various Wise Owl Legal components.
Performs any other Appliance updates or configuration.
Restarts all Wise Owl Legal components.
Notifies that the update was successfully installed.
Low Level Initialisation
The updater first makes a "shadow copy" of itself. This allows the updater to update itself.
...
It can then decide what package to install based on what the user selected on the About page. A A Wise Owl Technician can instruct you to run the updater from a command prompt; if no update was selected from the About page you will be presented with a list of packages to install.
The updater now has all the information it needs to install the package.
Update Initialisation
At this point the updater double checks everything it needs: database access, the package file, that the new version is greater than or equal to the current one and that there is sufficient disk space available for the update.
...
Several housekeeping tasks are run first:
The job to upload logs after the updater completes is scheduled.
An update pending file is created.
The updater checks if this version has already failed and is retrying: if it has failed too many times (more than 5), it fails and gives up. Manual intervention is required to repair the Appliance.
The Appliance web server is deactivated.
The full system backup is started. This can take several minutes to run. However, backups are incremental, so only data changed since the last backup is copied. If the backup fails or runs for too long, the update is aborted.
...