[Tracker] Writing custom extractors docs?

["Spivak, Max" <spivak lab126 com>]

Hi there,

I've been looking at tracker and I like it a lot. Great job.  

I'm looking to write custom extractors for the 0.7.x version. I'm wondering what docs exist.

I found http://library.gnome.org/devel/libtracker-extract/unstable/libtracker-extract-tracker-extract.html  
and http://library.gnome.org/devel/libtracker-common/unstable/ -- is this valid and current? Any other docs?

How is the custom extractor registered with tracker-extract? Is it just that the libextract-<abc>.so is 
present in the lib/tracker-extract/tracker-0.7/extract-modules directory or is something else necessary? 

Is there a registry that maps a document's file extension to its mimetype? Say I have a <filename>.abc -- 
what maps it to libextract-abc.so. This is especially interesting if I have custom documents for which I 
invented an extension and a mime type.

I've run across some posts that tracker will/may use LibStreamAnalysers from Strigi. Should I use LSA for my 
extractors or not?

Thx,
Max