This one is getting to be fairly common, and the logic behind it is dumbfounding. Apparently, it is possible to save a few bytes of download bandwidth by taking a DMG file and compressing it with bzip2. Therefore, over a long time the developer will save a bit of money. Sounds great, right? Wrong.
- I download your application.
- I get a warning from Safari that the download might contain an application. I choose to continue.
- Where is the application? Nowhere. On my Desktop is an XXXX.dmg.bz2 (or other) file.
- I double-click it. Now I have an XXX.dmg.bz2 and an XXX.dmg file.
- I click on the DMG file and finally get close to your application.
- As a final step, I have to drag your application to somewhere else because it is on a read-only disk.
Something like this sends a very clear message to the user that the developer likes to make things complicated. That the developer is willing to make things harder on the customer just to save a few pennies a year. This is a developer I would rather not do business with. This is a developer who has no interest in making my life easier.
Do not be difficult. Pick one format (preferably ZIP, as discussed below) and stick with it. Keep things as simple as possible for your users.
In some instances, multiple formats are used to get around Web servers that do not handle the inner format properly. Certainly this is an issue, but multiple formats is not the answer. Better to use a format that the Web server can handle than to complicate the user's experience.
Our friends over at Object Development employ this annoying type of bundling. Though I absolutely love their application LaunchBar, because of its packaging I cringe every time I have to update the application.