Figure PR.18 - PhysicalDeviceRole and HardwareRole

We’ve talked about the different roles that a given device can have, and graphically represented this in the following Figure.Most of the attributes (and all of the methods) defined for a PhysicalDevice are not appropriate for the business view – it is enough simply to be able to refer to a PhysicalDevice, such as a router, as a complete, atomic unit. Please refer to the Physical Resource System View Addendum for more information on non-business characteristics and behavior of this entity.<br/>Physical roles, however, are appropriate for discussion in this Addendum. There are two types of physical roles that are called PhysicalDeviceRole and HardwareRole.<br/>There is a profound difference between the SpecifiesPhysicalResourceRoles aggregation and the RolesDescribePhysicalResource aggregation. The former defines the set of PhysicalResourceRoles that a particular PhysicalResource must have (since it is defined by the specification for that PhysicalResource). This enables functionality to be specified for a particular physical component. The latter aggregation defines the set of physical roles that are used to describe an instance of a particular PhysicalResource.<br/>In other words, the difference between the SpecifiesPhysicalResourceRoles aggregation and the PhysicalResourceRoleDescribes aggregation is that the former defines functionality of a PhysicalResource using PhysicalResourceRoles. In contrast, the PhysicalResourceRoleDescribes describes functionality using PhysicalResourceRoles.<br/>