About the Hierarchy Service

The Hierarchy Service provides an efficient method of creating a logical navigation tree for the Niagara system. Rather than defining each element of the tree in a Nav file, the Hierarchy Service allows you to define the navigation tree based on a set of level definition rules referred to as “LevelDefs”.

The hierarchy module is required in order to use hierarchies.

The HierarchyService, installed by default in the station’s Services directory, is the parent container for all hierarchy definitions. The default view for the Hierarchy Service is the Property Sheet view, as shown.

Hierarchy Service properties

Type	Value	Description
`Status`	text	Read-only field. Indicates the condition of the component at last polling. {ok} indicates that the component is licensed and polling successfully. {down} indicates that polling is unsuccessful, perhaps because of an incorrect property. {fault} indicates another problem.
Fault Cause	read-only	Indicates the reason why a system object (network, device, component, extension, etc.) is in fault. This property is empty unless a fault exists.
Enabled	`true` or `false`	Activates and deactivates use of the component.
`Hierarchy Timeout`	`00000h 00m 00s` (hours, minutes, seconds), 45 seconds (default)	In Niagara 4.3 and later, this property allows you to configure the wait time for hierarchy query processing. When navigating a hierarchy, if the time it takes to process a hierarchy query exceeds the hierarchy timeout value, an error message displays in Workbench You may increase the timeout value to allow a longer wait time for results, or decrease the timeout value to abandon hierarchy query processing earlier.

Hierarchy palette

The hierarchy palette provides the HierarchyService component, the Hierarchy component which you use to create a new hierarchy definition, as well as default level definition components (LevelDefs) which you must add to a hierarchy definition to define the node levels within a hierarchy.