[Tracker] Metadata exchange format for removable devices

[Philip Van Hoof <spam pvanhoof be>]

Hi all,

We'd like to have a data format for exchanging previously collected
metadata on removable devices, and storing it on the removable device.

This is a first proposal that I have written down. 

   http://live.gnome.org/MetadataOnRemoveableDevices

The proposal uses the Terse RDF Triple Language (Turtle) which is a
widely known format for storing RDF triples and designed as the
successor of N-Triples and Notation 3.

The proposed format restricts the shape of the records. I added a
predicate for removed records too.

The specification clarifies conflict resolution. It makes it possible to
have a duplicate/new triple for a URI at the end of the file.

Why (at the end of the file)? Because then you can append newest data
without having to rewrite the entire file. Which is useful for appending
latest changes just-in-time before the unmount event.

You can compare it with a progressive JPEG. As you go over the file, you
fix up older material with newest material.

I have added an advisory for periodically cleaning up the metadata file
(compressing it) in a correct way. For example if you are certain the
user will keep the removable device in the machine for a few seconds,
you can do a periodical compressed rewrite of the .ttl file.

I plan to throw this proposal to for example the Xesam initiative too.
But let's get something implemented in Tracker first, as a proof of
concept.

Suggestions are welcome.


-- 
Philip Van Hoof, freelance software developer
home: me at pvanhoof dot be 
gnome: pvanhoof at gnome dot org 
http://pvanhoof.be/blog
http://codeminded.be