Top Level View is a hierarchy based status view for Icinga Web 2.
You can define a hierarchical structure containing hosts, services and hostgroups.
And the view presents you an overview of the overall status of the sub-hierarchies.
With a caching layer, this view can aggregate thousands of status objects and
make them easily available for overview and drill down.
This view extends the status logic and behavior of Icinga Web 2 a bit,
please see the documentation on details.