Architecture Client Server Power Aware Software: Client-side software designs that just a few years ago were straightforward now require rethinking in the context of two new user expectations: intermittent connectivity and power conservation.

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by Andrew Binstock, principal analyst, Pacific Data-Works LLC. Intel Corp.

The recent surge in the popularity of wireless solutions brings new challenges to the software developer. Client-side software designs that just a few years ago were straightforward now require rethinking in the context of two new user expectations: intermittent connectivity and power conservation. These two concerns are addressed by Intel in its Occasionally Connected Computing (OCC) initiative. Other articles on this site discuss the implications of occasional connectivity (see Resources section); this article discusses the importance of power management at the level of application design.

Historically, power management has been viewed as a function handled by the operating system. Through user-selectable settings, various versions of Windows determine when to put the system into a sleep state. With the exception of limited options (Wake on LAN, for example), exiting the sleep state requires user interaction. Most client applications have not concerned themselves with power awareness, because these could only be put to sleep after fairly long periods of user inactivity. In such cases, the applications were not likely to be working actively so a transition-to-sleep state was not likely to cause untoward effects.

This disregard for active power management will soon become an impossible view to adopt. As users invest in notebooks, such as Intel® Centrino® mobile technology, whose distinguishing components are geared to extending battery life, applications that do not conserve power will be increasingly unwelcome.

Power conservation
The Intel Pentium® M processor in the Intel Centrino mobile technology platform uses an architecture that is substantially different from previous Intel processors. Ground-breaking technology on the chip can actually power down sections of the processor's cache and even its data input buffers for periods as short as a few clock cycles. The cumulative effect of these small power savings is to greatly extend the life of a single battery charge. In view of this substantial user benefit, developers should design client-side applications so that the Pentium M processor can turn off selected parts often by not being forced to perform needless computations. Or more accurately, conserve power by reducing activities that keep the processor working but which are not central to the application.