Mac App Store - Back to the Mac: OS X 10.7 Lion Review

Apple introduced the Mac App Store (MAS) in its Back To The Mac event last October. It was released to public on January 6th and was automatically included in the 10.6.6 update. It’s obvious that the MAS is a spinoff of Apple’s extremely popular iOS App Store. While the MAS has been available for over six months now, Lion will bring some healthy improvements.

First, there will be support for in-app purchases. Since Apple does not allow trials, this is mainly useful for applications that can have additional commercial features or are subscription based.

Second, developers can now send push notifications to alert users. As in iOS, the usefulness of this feature varies from app to app, but the presence of third-party plugins like Growl speaks to the demand for this sort of thing.

Third, app updates are now just patches instead of full copies of the app. Apple refers to these as "delta updates," which is the traditional development term for an update delivered by replacing only the changed files/bytes in a application. In Snow Leopard and in iOS, you had to re-download the whole application to update it. That was very inefficient, especially if you were updating a bigger app. After iOS 5 comes out this fall, both it and OS X will feature app updates via patches, just like most other programs have been doing forever.

On a technical note, the structure of OS X application bundles makes them fairly well suited to these kinds of updates. But it's not clear at this time whether Apple is replacing whole files or doing binary patching to minimize the update size. Valve’s Steam service recently transitioned from doing file replacement to binary patching for this very reason, as games typically use a handful of large archives to store their content. For regular applications the difference is subtle, but the difference will have an impact on games distributed through the MAS.

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