One of my favorite things about OS X is how Apple and the developer community have found a way to do application packaging and distribution that encourages good organization. Application “bundles” and disk images solve (or at least improve on) a bunch of problems we had on OS 9 in a way most of us don’t even notice.
In your typical OS 9 applications folder, double-clickable executables were scattered among many folders at various depths of the file system. Sometimes apps were packaged in their own folders even when they didn’t have a bunch of support files going with them — all you’d find in an app’s folder is the stuff it was distributed with (readme’s, release notes, an URL-file or two) which you probably looked at once when you downloaded the app and will never touch again.
Because of this mess of folders, we couldn’t easily use the Finder as a quick-and-easy application launcher the way it was intended, so we created all kinds of tools to fill that role by becoming intermediaries between the user and the file system: folders or popup folders or an Apple menu full of aliases, launchers, task bars, et cetera. Because of issues such as version numbers in folder names, upgrading applications usually required rebuilding whatever aliases or links these launchers used. All this setup and maintenance was difficult for inexperienced users and an annoying waste of time for advanced users.
Thanks to “bundled” applications on OS X, we get a marked improvement on an out-of-the-box system. Before, your average “Mom & Pop” or university computer-lab user only knew how to launch apps that the local computer expert had given them easy access to (and required assistance in digging for anything else). Now an Applications folder full of double-clickable app icons is quickly and easily accessible without needing expert setup — and the Dock provides an option for even-quicker access that even a novice can learn how to customize for themselves.
Of course, this nice organization is just the initial state; the tricky part is maintaining it as new software is added. If we followed the OS 9 pattern but for the addition of bundled apps, new software would come as (after automatic processing) a folder on the desktop, containing not just the app but also a readme and some URLs and other junk you’re probably only ever going to look at once. Instinctively, most users would drag that whole folder to their Applications folder. (Except for the truly novice users who leave the whole mess, plus the .sit and .bin files it came from on their desktops forever.) And after a few iterations of this process we’d end up with file system as disorganized as OS 9′s.
This is where disk images play an ingeniously subtle role. The root directory of your typical disk-image software distribution contains the same stuff yesterday’s folder did (readme’s you’re apt to ignore after reading once and whatnot). But the first point of interaction is the user looking at what’s inside the container, not the user looking at the outside of container — so they’re more likely to, of their own volition, pick and pull our the stuff they want to keep instead of dumping the whole thing on their hard drive and needing to clean it up later. (And thanks to custom window backgrounds, we can provide a prompt so the truly novice users know there’s more to do before the software is fully “installed”.)
So why the long rant about this — after all, OS 9 is dead and gone, and thanks to these changes, the world of OS X is a better place, right? Not quite. For one thing, here’s still a number of products out there using old-style distribution methods… hopefully their developers will notice the trend towards simpler distribution/installations schemes and follow along, but they could probably use some encouragement. For another, even the disk image scheme in its current design isn’t perfect — Apple doesn’t make it all that easy for developers to put together well-built installation images (auto-open, license agreement, etc). And the “disk image file” concept is still difficult for the novice user to wrap their head around (an issue complicated by the fact that so many disk images are distributed as .dmg.sit, .dmg.bin, or even .dmg.tar.gz archives because developers haven’t figured out how to set up their web servers to transmit the proper MIME type for disk image files). There are signs of improvement on the horizon, though (image mounting via HTTP looks like a good step towards working around the concept problem). But we’ve got a way to go…
