Howard Chu (hyc@symas.com) on 1/31/09 wrote:
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>At my previous company I worked on an Appleshare server that ran on Unix. We just
>used a hidden directory (.afp) and parallel files for the resource forks. No visible
>mess, but perfectly functional from both Macs and the Unix command line.

We used a directory/folder for each original data file in another case, where we wanted to associate many files with the original file.

Competitors embedded the same information in the original file instead. The problem is that if the file was then opened in an application that wasn't aware of this additional information, then resaved, it would be lost.

It also locked the users in to using a particular file format for the original data (one that allowed extra data to be embedded) whereas our software placed no such restrictions. Even worse, the file format they use because of this is extremely inefficient for the type of data being stored, causing an order of magnitude file-size bloat.

We didn't make the folders hidden, though, because making them user-visible gave benefits (less likely to mess things up by moving/renaming the original file and forgetting or not knowing about the associated data; the ability to simply delete the associated data to save space knowing that it can be recreated again in the future at the cost of some processing power) at the expense of some clutter (an extra folder for each file).

>(You had
>to use our afp_rename/afp_copy commandline tools if you wanted to preserve this
>stuff while manipulating from the Unix side. Again, user-level formats require user-level tools...)

Since this is not an uncommon problem, it would be really nice for this idea to be built into the OS, allowing the application to say "If you see a file/folder with the same name but this extension, perform any operations like copying, moving, deleting, and renaming that the user requests on the original file on this associated file as well". You could also "Hide associated files for known associated file types" (analogous to "Hide extensions") if you didn't want to see them.

In effect it would be similar to streams (which could well be implemented as hidden directories) but portable and as transparent as the user wanted it to be. Previously there were floppy discs and now USB thumb drives that used FAT and would make relying on streams dangerous.

>The hidden folder takes care of the aesthetics...

Yes, although if there's only one file to be associated with the original file then a hidden file will be less overhead. Unfortunately you then need to introduce new tools for manipulating the files and most of our users are going to just use drag and drop/rename in Explorer. If they "forget" to use the magic tools just once then they'll lose all of the associated data and it won't be obvious when or why.

In your case only technical people who knew how the system worked would have been accessing the Unix server and in a position to break things. In our case we're dealing with the end users (the Macintosh users in your scenario) and while they are generally very smart individuals, their background is not in computing. They can understand the idea of another file (or even another folder) but would quickly get concerned if we told them they weren't allowed to do things in Explorer.

>This is probably one of the reasons it took so long for Apple to switch to a Unix-based
>OS. Structuring this database for good performance was one of the harder problems
>I had to solve in our code, there's no natural analogue in Unix. [inode numbers
>are neither unique nor permanent...] (And yes, my code was the fastest AppleShare
>server in the world, far outclassing Apple's own stuff and any other 3rd parties.)

Why didn't they simply implement the same idea on the Unix-based OS? It would have made it less "Unixy", but I don't think they are trying to make the Macintosh look Unixy, they are trying to build a Macintosh on top of Unix.