Migrating from disk images to ZIP archives

For many years, I've been releasing my Mac OS X software on disk images. For a long time, they seemed the most elegant way to provide software to people: they provide a single downloadable container that can be saved in a compressed state, and they can include a pretty background image that explains how to install the app.

A more recent innovation was to include an alias (actually a symbolic link) of the Applications folder, with an arrow in the background indicating to drag the application to that folder to install:

Simon disk image

But all that complicates the release process for me, and for my customers.

For me, when I do a release build I need to copy the build to a standard location then run FileStorm, an application that builds the disk image, then upload the resulting disk image. Doesn't sound too hard, except that FileStorm tended to misbehave for me all too often, resulting in incorrectly laid-out disk images and other problems, requiring several attempts to get it right. It also had compatibility issues with Leopard, forcing me to run it on a Tiger machine, which had other complications.

For my customers, disk images have more hassles. After downloading, they are usually mounted automatically by the OS, though sometimes that didn't work for some people. The images are "internet enabled", so people downloading via Safari get only the contents of the disk images, while people using other browsers get the disk image window as above. Then they need to find it and drag the application to install it... but some people run it directly off the disk image, then wonder where it went after they've dismounted the disk image (or restarted their computer). Plus the disk image has to be dismounted, another hassle.

There's got to be a better way... and there is. The humble ZIP archive.

A ZIP archive is a simple compressed file. They can be created and expanded using built-in commands in the Finder. So for me, creating one is a trivial operation; no more messing around with FileStorm. And they are more convenient for my customers too. After downloading, the archive is automatically expanded, with the application appearing in the download folder. They can then easily install it by dragging to the Applications folder, or try it directly from the downloads folder if preferred — without it mysteriously vanishing after a restart.

So, as I release new versions of my apps, I have been switching to the ZIP archive format. Downloads work exactly the same from my site, but the result is much more convenient for everyone.

As always, I welcome feedback on this. So far, I haven't had any complaints, though one potential problem has come up: one person with an incorrectly installed copy of StuffIt had difficulty expanding the archive by double-clicking on it. The solution was simply to tell the Finder to use the built-in archive expander instead (which is called "BOMArchiveHelper" on Tiger or "Archive Utility" on Leopard).

justG's picture

But they're so pretty

I understand the rationale behind switching to .zip distribution and certainly can't fault the logic, but I will miss the DMGs. As a recent (late '06) switcher, DMGs have not yet lost their appeal from a purely aesthetic perspective; in fact I've got a set of them up on Flickr. I find their design quite inspiring, and always look forward to seeing how a new one will look.

That said, it's not a huge loss. =)

David Sinclair's picture

Re: But they're so pretty

Yes, they do certainly have aesthetic value... but the hassles for everyone seems to outweigh that, unfortunately.

I think most developers liked them for the same reason, but I'm seeing a trend away from them now. In part, perhaps, because ZIP archiving didn't used to be included in the OS, and people wanted to avoid the old StuffIt format, so disk images were a good solution. But that's no longer an issue.