Inside iCloud: Apple's new Documents & Data cloud serviceStrength in numbers
Apple is working to make it appealing for developers to feature iCloud integration in their apps. The company similarly encouraged developers to add support for .Mac/MobileMe sync, something that many developers did add, despite the relatively limited number of subscribers that service had (believed to be around 3 million). In contrast, the entire installed base of Mac OS X Lion and all mobile users who upgrade to iOS 5 will have free access to iCloud, a number that will quickly boost iCloud users into the tens of millions.
Activating iCloud in iOS 5 is integrated right into the new operating system's self-contained setup system. Once configured in the iOS iCloud menu within the Settings app, turning on Documents & Data is simply a matter of sliding a switch. A sub option unique to Documents & Data allows users the option of transferring updates over cellular. Because Documents & Data delivers incremental changes (similar to an undo stack) of a document as it is edited, rather than pushing around entire document files, this option won't be a huge tax on cellular connections. Conversely, backups, over the air OS updates, and features like Photo Stream are confined to WiFi connections.
In Mac OS X Lion, iCloud is configured in the new Mail Contacts & Calendar Preference Pane unlike (and replacing) MobileMe's separate configuration pane. While existing builds of iOS 5 can connect to MobileMe and iCloud simultaneously, the latest build of Lion can reportedly only connect to iCloud if MobileMe is turned off. Additionally, the new iCloud interface incorporates Back to My Mac (formerly a tab within MobileMe) and the new Find my Mac feature within the same simple settings panel.
Third party apps that tap into the features of iCloud Document & Data will "just work" once users activate the service on their system. Again, this is somewhat similar to Time Machine, where simply turning it on creates a system wide benefit that specific apps can be optimized to take special advantage of with some work by their developer. There's nothing to configure within an app that has been enhanced to use iCloud, as all the configuration is done on the operating system level in both iOS and Mac OS X Lion.
Apple's beta iCloud web client, as has been profiled by some developers and media sources already, enables users to see and download copies of the files they are using from the browser, and currently supports translation of their Pages, Numbers and Keynote documents into PDF or Microsoft Office compatible formats. It's not clear if Apple will extend its iCloud web offerings to also add access to the files of third party apps with iCloud Documents & Data support.
However, iCloud's Documents & Data will also be useful to more than just those app that work with documents. The "& Data" portion of the feature alludes to apps that make use of data, but don't actually generate files. An example of this might be an app that records events, such as a run tracker or an instrument monitor. These apps will similarly be able to push their raw data into iCloud and keep every other instance of the app current with the same information. This could conceivably work to allow an iOS app to remotely gather data that a desktop Mac app then presents "automagically" in real time without any manual syncing by the user.
As noted by API Evangelist, iCloud can store both apps' documents and "key-value data," which could include application state (allowing apps on various devices to sync their behaviors, such as resuming the same playback point in a video player app on another device), settings and "other important information that delivers a better user experience. Although not as apparent to the end-user, key-value storage will be just as important as document storage," the site notes.
"The iCloud service handles storage searches, change notifications, version control, conflicts, and security for applications that integrate with a users iCloud storage account," that site reports, concluding "neither document storage or key-value storage in the cloud are anything new. But when it is implemented as part of the IOS platform, it becomes much bigger. Apple is solving everyday problems users face when using their smart phones, by storing data centrally in the cloud."
Inside iCloud: Apple's new web services for iOS and Mac OS X Lion
Inside iCloud: Apple's new Documents & Data cloud service