Desktop interactive applications will require the monitor to be turned on when the application/user is active. For example Powerpoint user on a laptop - while doing a presentation the monitor should not be turned off even if the user is not active on the keyboard. The disk can be turned off (not to worry, when ever the system needs to read or write data it will automatically turn the disk on). If the user is away from the desktop and PowerPoint is not running - the monitor can be turned off. Here is the example for PowerPoint. Imagine the situation if you didn't have application sensors, if you enable power savings on Windows with the default power policies, while you are doing a presentation the monitor turns off if you are away from the keyboard for a while and interrupts your presentation and irritates your audience.
Applications sensor enable fine-grain power management. For each application the administrator can specify which components of a system can be selectively turned off or not and finally whether the entire system can be moved to standby/shutdown or not. Multiple applications can be selected and the fine-grain power control can be specified for each of the applications. The policy can be enabled or disabled for each of the applications. The following example show the application sensor definition for running virtual machines using VmWare Player.
Now let us look at another scenario of a server which is used most of the time in the day and at night it can be moved to a standby mode when the batch job is completed. In the application sensor policy define the name of the batch job and specify that the system cannot be in standby/hibernate/shutdown state when the batch job process is running. After the batch job completes the power policies will move the system to the low power state.
Multiple application sensors can be defined simultaneously, each application sensor policy can be associated with one or more power policies. However at a given time - which ever power policy is enforced will select the corresponding application sensor policy. In the following diagram you can see that the Power Scheme is referring to the default Application Senor Policy. You can edit the existing Application Sensor Policies or Create New ones.
To summarize Application Sensors provide a mechanism to enable fine-grain power savings while allowing the respective applications to function and enable the user to work uninterrupted.