iPhone Pushing?

iPhone developers will have to wait a bit longer for the handset's "push" functionality, as Apple has missed a self-imposed deadline for introducing the service. Push notification was promised at the Apple Worldwide Developer Conference (WWDC) in June as a workaround for a limitation that has been built into the iPhone software development kit (SDK) since the beginning - a ban on running applications in the background.

Instead, developers will be able to use a server-based system to alert users when remote content has changed. This could allow an instant-messaging badge to display the number of unread messages, even if the process itself isn't running, much as the App Store badge displays an updated figure of available applications without the need to run the App Store process. The notification system is also to enable custom alert sounds and pop-up messages, Apple has said.

In June, Apple senior vice president of iPhone software Scott Forstall said push notification wouldn't appear in version 2.0 of the iPhone SDK, but promised the feature for September. Apple did indeed ship a significant iPhone OS update in September – version 2.1 – but the update did not include push notification. Indeed according to rumours circulating on some websites, Apple removed push notification from the beta version of iPhone Firmware 2.1 in August. Apple began supporting developer support for the feature with Firmware 2.1 Beta 1, but removed it as of Beta 4, according to reports from the MacRumors website and others.

Apple's non-disclosure agreement (NDA) for iPhone developers restricts them from discussing features in test versions of iPhone software, so such unreleased features can't be confirmed openly. Developers were, in fact, only recently allowed to discuss features that have been released, after a modification to the NDA.

Apple does not appear to have introduced this restriction out of hard-heartedness. As Craig Hockenberry, developer of the popular Twitterific Twitter desktop solution, wrote in a March blog post, background calls, which may also access the internet, consume enormous amounts of power. A prototype version of Twitterific running on a "jailbroken" iPhone proved to be a "huge design failure". "After doing XML queries every 5 minutes, the phone’s battery was almost dead after 4 hours," Hockenberry wrote.

Apple has recently been forced to delay some of its iPhone plans due to significant problems with major features, such as MobileMe and UMTS support. However, developers have noted that push notification seems in fact to already be supported on built-in iPhone applications, with features such as Calendar event reminders, SMS notifications and Clock timers and alarms functioning despite the lack of a backgroud process for those applications.

"These apps… don’t run in the background. They post and set notifications through other means, system-level OS services that aren't available (to my knowledge) through the iPhone SDK," wrote John Gruber on the Daring Fireball blog. Apple's own Phone, Mail, Safari and iPod applications are the only officially sanctioned applications that run in the background, according to Gruber.

(Matthew Broersma)

(djwm)