More on Xperia and AlarmManager

After Friday’s blog post about the Xperia Z and AlarmManager, I was notified that Sony had blogged about this previously… with respect to other Xperia models with a similar feature.

Their post, from October, is for the “Extended Standby Mode” of the Xperia P, Xperia U, Xperia sola, and Xperia go. It has the same impact on AlarmManager:

With Extended Standby Mode enabled, most scheduled background activities will be prevented. Fifteen minutes after the screen has been locked, the data is automatically turned off and the background activities will be prevented from waking up since there is no data coming in… Unlike most power save apps available for Android that just turn off data traffic, Extended Standby Mode also prevents your apps from trying to synch data. This is handled in the Android™ AlarmManager, which will not allow apps to schedule wake up alarms during Extended Standby Mode. This method saves more energy than simply turning off data traffic, since it actually pauses all activity in the apps.

One difference that I can see in the screenshots is that it does not appear that “Extended Standby Mode” has the whitelist feature that the Xperia Z’s STAMINA Mode does. One hopes that either I am misinterpreting the screenshot or that the whitelist feature is added to these devices in the future.

One common question that I have received on this topic has been “why did these devices pass the CTS?” The Compatibility Test Suite (CTS) is a JUnit-based test battery, designed to exercise a device’s implementation of the Android SDK. Only devices that pass the CTS are able to legitimately have the Play Store on them.

I surmised that the CTS cannot readily test, in an automated fashion, how alarms behave during a standby mode. As it turns out, I happened to bump into Karim Yaghmour, Android internals wizard, yesterday (in Newark Airport, of all places). He did a quick check of CTS that seemed to confirm my suspicions. Whether the CTS might be augmented to cover this AlarmManager behavior is anyone’s guess. And, particularly if the CTS does not cover this scenario, I cannot fault Sony for implementing this feature.

I look forwared to any further information that Sony provides regarding these battery-saving modes and what developers should expect.

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