Zwabel’s Weblog

March 29, 2009

Portable Meta-Information

Filed under: KDE — zwabel @ 9:55 am
Tags: , , , ,

KDE4 is all about new technologies, and standardizing. Now we have a central mechanism to store metadata, called Nepomuk. However it basically still follows the somewhat problematic approach that all the metadata is stored in one central place.

I think there is nothing more valuable than the data of the user, and meta-information like for example ratings of a song, tags, or comments attached to a file, are user-generated data, that needs to be treated as carefully as the files themselves.

I have already used many different applications in my lifetime, different email-applications, different music-players, image-management software, etc., and all kept the user-generated meta-information closed within the application, which means that when the lifetime of the application is over, the information is lost, or with luck, can be exported with some effort into some re-usable format.

Due to those experiences, application-specific meta-information has only a low value to me. I think, for the future, we need to find a way to keep the users data together, so it is as persistent and approachable as the files themselves:
– When the user copies his photo archive or backs it up to a CD, no matter what application he uses, meta-information like ratings, comments, or tags, have to move together with the photos
– When the user has a fresh install, and copies his photo archive from a CD to the disk, the meta-information for the photos should be just there
– User-generated meta-data should _never_ be lost just because a file/directory was renamed, a mount-point changed, or whatever
– User-generated meta-data should not be lost when a file completely unrelated to the item is damaged or deleted(Database)
– In 20 years, when KDE4 is history for a long time, and I find an old photo backup CD, the meta-data should still be readable

When these conditions are met, then metadata would finally be worthy. But how can it be reached?

I think with Nepomuk and Strigi we have most of the needed infrastructure available, there is just a few missing pieces:
1. Store user-generated file-related meta-data directly where the file is stored, in a standard format, example:
User-generated meta-information:
[/media/archiv/pictures/.picture1.jpg.meta] or in shared directories: [/media/archiv/pictures/.picture1.jpg.meta.nolden]
Could contain something like:

2. Change file-managers to move/copy meta-information together with the files when handling them individually(I think this already is the case in dolphin), and delete the meta-information when the file is deleted
3. When finding orphaned meta-information, ask the user what to do withit(Don’t forget: It’s valuable information)

Strigi could collect the information from those meta-data files, and nepomuk would manipulate them. Nepomuks database would be a kind of cache for the metadata.

The whole behavior should be standardized among desktop-environments at some point, so the meta-information would not only be persistent, but also accessible from within every application.

With this reached, I could finally start doing using image- or music-rating, tagging, etc. without having the feeling of wasting my time in my stomach.

What do you think?

Actually probably the best way would be this:
With the meta-information not hidden at all, so you will be aware of it when using the command-line. Aware file-managers like dolphin should hide the meta-information automatically, and all other file-managers that are not aware would show it. I think as long this would only be used for user-generated meta-information like ratings, it would be worth it.

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