Common spec/interface for file metadata

[Jody Goldberg]

On Mon, Sep 05, 2005 at 01:37:15PM +0100, Jamie McCracken wrote:
> 
> GetMetaDataForFile
>   input DBUS_TYPE_STRING s (the file uri)
>   input DBUS_TYPE_STRING s (the metadata type name)
>   output DBUS_TYPE_STRING s (the metadata value)

We'd need some agreement on the types and structure of metadata.  It
is by no means standard across MS Office and OOo.  Calling
everything a string is not sufficient for preview images, file
creation times, or organiztion specific extensions.

- MS OLE2 (MS Office and most win32 apps)
    : multiple streams of metadata per file (for embedded document)
    : each stream is a dictionary of key/value pairs with the
      ability to mark a value as 'linked' to a named item in the
      document.
- OOo
    : There is a nested heirarchy of metadata
    : The keys are an amalgam of dublin core and OOo app specific
      items
    : No facility for 'linked' items yet.
 
> I should also define a set of common metadata type names like:
> 
> Artist
> Author
> Album
> Bitrate
> Samplerate
> Genre
> Encoding
> Title
> Subject
> Comments
> Emblems
> KeyWords
> MimeType
> ThumbnailPath
> WordCount

Dublin core already defines these.  In libgsf we have a parser for
MS OLE2 files and will be moving a parser for OOo there.