OK, so a post about annotating files and desktop search. KDE guys might be interested because libferris uses soprano, the base of RDF on that desktop, maemo guys might be interested because all this works on that platform too, and I have a specialized index structure for n810 power level devices in libferris.
Tagging and Annotations are closely related. Tags (or emblems in libferris terms) are great for assigning one or more concepts to a file.
Annotations are great for adding some free text to something. While a short annotation might seem like one, two, or three tags, as in the example below, annotations also carry linguistic weight. Normally with tags you don't care about the order the tags are added to the file. With an annotation and a full text index you should be able to do proximity matching and ordered searching "seed collection" matches but "collection seed" doesn't. There are also issues of human language stemming which many tag systems silently ignore but full text indexes tend to have to address.
Below is the ego file manager 0.30.0 with the Annotation side panel. This panel auto saves the annotation if you select a new file or if you stop changing it for a few seconds. Hotkeys make this all quite handy. I'm using Control-t to start interactive tagging and Control-6 to switch to the annotation sidepanel with focus in the text block there. Hitting tab in the annotation sidepanel moves focus to the file list, so you can skip to and from annotating each file without the rodent.
You can of course add, view, and edit these same annotations from the command line. The fedit command runs vi on the annotation, allowing you to freely change it.
I have just fixed a slight inconsistency in the fedit command so it now accepts the "-a attribute" option too. The fcat views the annotation "-a attribute" from the file.
$ >| tfile
$ fedit -a annotation tfile
$ fcat -a annotation tfile
hi, the new annotation
$ feaindexquery '(annotation=~new)'
Found 1 matches at the following locations:
Another nifty trick is to see the annotation right inside an fls output. Use mtime-display if you want the time to be more human readable than an epoch time_t.
$ fls --show-ea name,size,mtime,annotation tfile
tfile 0 1265954823 hi, the new annotation
Remember also that fls --xml gives you XML output, so with an XSLT stylesheet you can serve a directory of files and their annotation through your web server.
If this is of interest, see apps/phpsearchinterface/xml-results-to-xhtml.xsl for an initial stylesheet with row colour striping. It should be easy to extend the stylesheet to present other attributes. Bonus marks for anyone who makes it handle arbitrary XML attributes and orders them according to a predefined POSET. Patches always welcome...
When libferris saves an annotation, if DBus is enabled a signal is emitted on the session bus: "org.libferris.desktop", "AnnotationSaved"
which carries the URL and Path for the file you changed. This allows not only reindexing to happen, but you are free to hook up some Perl or whatnot to monitor this signal, then you can actually run some logic to work out what to do. If an annotation is saved, you might like to update an RSS feed for example.
And so ends the libferris tip of the day... happy annotating!
This post has been fueled by 99% cocoa, thanks to Jan-Piet Mens ;-)