This topic describes item classes and subclasses and their importance within Location Awareness Services for WebSphere® Premises Server.
Item classes define items through a set of properties and attributes for them. For example, you might have the following classes: Person and Asset. Within these classes, you can also have subclasses with extended properties and attributes. For example, the Person class might have the subclass Administrators.
Items must belong to a class. Once an item is created and assigned to a class, you cannot move the item to another class. Because classes are in the form of a tree-structured hierarchy, an item cannot belong to more than one class directly. However, an item is automatically considered to be an instance of any superclasses of the given class. Items have the attributes defined for the class that they belong to. Class attributes are either defined directly for the class, or are inherited from its superclasses (if any).
Using the example of the Person class and the Administrator subclass, if a tag is assigned to class Administrator, it is also considered to be an instance of the superclass Person. Therefore the rule, "let me know when a Person enters the HAZARD zone," triggers an alert for Administrators as well as any other subclasses of "Person."
All classes have some common attributes, such as an icon label and tag ID. You can define required, or key, properties such as social security number or first name and last name, as well as optional properties such as telephone number. You can also define properties that are specific to your organization.
One specific property for all classes is the container attribute. If this is set, all items of the class are potential containers and can contain other items.