Common spec/interface for file metadata

[Jamie McCracken]

Jody Goldberg wrote:
> 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.

The spec was intended primarily (although by no means exclusively) for 
use by file managers for displaying metadata for files hence the 
strings. Its not a spec for creating a semantic desktop as we are only 
dealing with simple key/value pairs here. I can use DBUS_TYPE_VARIANT 
for the metadata value if it will help.

> 
> - 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

We need to match the user visible metadata in these apps or perhaps try 
to persuade these apps to adopt our spec for displaying metadata if its 
different.

>     : 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.  

Well I cant define Album, Bitrate, Samplerate, Emblems and ThumbnailPath 
cleanly in Dublin Core. Im no expert here so if you could define those 
it would help.

As soon as I have a wiki page for this, we can extend and refine things 
further.

-- 
Mr Jamie McCracken
http://www.advogato.org/person/jamiemcc/