System-wide properties are attributes of a device that have system-wide significance. It allows components to be aware of the state of the device. They are defined by system-wide property policies within a SSM plug-in that can be customised by licensees. These policies determine the set of properties, their permissible values and transitions, and the tasks that are performed when each value changes.
A component with appropriate platform security capabilities can request a change to a system-wide property value. The SSM distributes notifications of the changing of system-wide property values to components that have requested notifications. A reference plug-in implements policies for the system-wide properties defined by Symbian.
The system-wide property is indicated to interested parties using the P&S mechanism. When a new value for a system-wide property is indicated to SysStateMgr, depending on the policy associated with that transition, a commandList is run (by SysCLE.exe).
System-wide property transitions are queued, accepted or rejected. If accepted, then they are put in a First In First Out (FIFO) queue. If a system-wide property transition is requested when an existing transition is in progress, the SSM calls TransitionAllowed() as if there was no existing transition in progress.
The differences between system state and system-wide properties are listed in the following table:
| System state | System-wide property |
|---|---|
A device can only be in one state. |
A device can have multiple system-wide properties. |
The state and different properties can be combined with the policy to generate new status indications and actions. |
The value of any system-wide properties is normally independent of the system state. |
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