Inside OS X 10.8 Mountain Lion: a Preview of how Apple is enhancing the file system with iCloudPreview, Apple's simple, utilitarian image and PDF viewer, offers insight into how the company plans to deeply integrate iCloud into apps and simplify and improve file management in general in this summer's release of OS X Mountain Lion.
iCloud was a top billed feature of OS X 10.7 Lion, replacing MobileMe and adding Photo Stream, Find My Mac and early support for Documents & Data.
In Mountain Lion, iCloud adds new support for configured Accounts sync between systems, and enhances Back to My Mac with automated troubleshooting fixes. As pictured below, iCloud's System Preferences pane now offers to automatically enable NAT Port Mapping Protocol on your AirPort base station to make sure BTMM will work as intended.
The evolution of iCloud
Prerelease builds of Mountain Lion indicate Apple has been experimenting with how to add iCloud features to its own apps, including the simple Text Edit. Initially, iCloud was simply added as the default location for new files (if a user was signed into the service). When you save a Text Edit document, iCloud appears as an alternative location, despite being nowhere on the real local file system.
This behavior is similar to how iDisk worked, and also similar to using a remote file server. Among other Mountain Lion apps however, support for iCloud is far more sophisticated and simplified, with a strong resemblance to iOS. A key example of how it works is visible in Preview.
Preview not only shows off how Apple is rethinking the toolbar, it also demonstrates how the company wants apps to access documents saved to iCloud. In the open file dialog below, Preview presents two options: the default, graphical iCloud window showing files in Preview's App Library of documents saved on iCloud (below top), and the standard file system available by clicking On My Mac (below bottom).
You can add files to Preview's iCloud App Library by dragging them into the iCloud open file window from the Finder or desktop. You can also organize documents into iOS style Folders, which work the same way, as shown below.
ICloud is more than remote storage
While often compared to Dropbox, Microsoft SkyDrive or other cloud storage services, iCloud is a package of unique offerings that goes far beyond offering just web-based file storage. Apple introduced iDisk for Mac users back in 2000, allowing simple remote internet storage of files. There's nothing new about that.
One major new difference with iCloud it that ties documents with their application. This is similar to how iOS stores apps' files within the apps' own sandbox. When iOS or Mac apps save files to iCloud, they're similarly protected within that app's private library of documents.
This prevents rogue apps from accessing, erasing or modifying your data. While viruses aren't a problem for Macs today, there is malware users can inadvertently install on their own or be tricked to open. Without the kind of app-level security iCloud provides, these could damage or spy on your data.
In that sense, iCloud offers apps' documents a new level of security from other, potentially dangerous apps similar to the way file permissions work on a user level to protect all of a user's files from other, potentially dangerous users who might access the system (including a remote attacks).
On page 2 of 2: The opposite of OpenDoc, Saved in the cloud incrementally
On Topic: Mac OS X