System Resources and Status

System resources refer to the hardware and software components of the Windows Powered server appliance that provide crucial functionality to the overall system, and for which the user will need to know the real-time status on a regular basis. Examples of system resources include the hard disk and network card, as well as some device-specific tasks, such as system backup.

The status of system resources is always displayed on the status page, either in text or icon form. The local UI framework provides machine, hard disk, network, and IP address status information.

The following illustration shows Microsoft's suggested architecture to control display of the status icons, given the need to display real-time status information.

As illustrated here, the monitor DLL calls the status DLL when the monitor DLL has status information to report. Depending upon the nature of the available resources, status information may be obtained one of two ways: using either a passive filter or an active checker. If a passive filter is used to obtain status information, the filter simply checks to determine whether the event is of interest when it occurs, whereas the active checker option polls the resource at regular intervals. The polling frequency will depend on the nature of the resource being checked. In general, the passive filter method is preferable, because it requires less processing time.

When the status DLL receives the report from the monitor DLL, the status DLL checks for a change in the system resource status by comparing the incoming status data to the status data that is currently displayed. If there is no change in the status data, the report is ignored. However, if there is a status change, the status DLL should use the resource identifier and status identifier to send the corresponding status text or icon to the HTML rendering engine. The bitmap that is generated can then be sent to the video manager of the local display to render the LCD.

The status DLL must ensure that no more than one frame of bitmap is sent to the local display video manager per 0.5 second interval. In the event that the video manager does receive more than one status change per resource from the monitor DLL within a 0.5 second interval, the video manager must maintain the more recent status data.

To avoid overuse of processor time in the LCD, it is important that when the video manager processes the status report from a resource after the 0.5 second interval has expired, the video manager compares the new status data to the status data that is currently displayed. If there is no change in status, the video manager must ignore the status report.