Lately there's been quite a bit of attention being paid to 
making sure that the data that describes the things that we like,  
our attention data, is portable.  With portable attention data, we 
could go to any music store and be directed to the music that we are 
most likely to want to listen to.  We won't have to spend any time 
rating tracks or artists, we'll just show the music store our taste 
data.  Of course, this taste data needs to be in some standard 
format so that everyone can understand it. One effort at standardizing 
our taste data is APML.  APML is an 
XML based language that allows users to share their own personal taste 
data in much the same way that OPML allows the exchange of 
				reading lists between blog readers.   APML is new and not 
finished yet, but even in its infant state, it is garnering lots of 
support.   
I am particularly interested in how APML 
could be used to represent an individual's music taste.   One 
possibility is to have the APML file for the individual list the artists
 that a person likes (or vehemently dislikes).  Another approach is
 to have the preferences be more abstract - to list weighted affinities 
toward music genres or styles.   The latter approach seemed 
much more interesting to me - it offers some bit of privacy (instead of 
seeing Paris Hilton in my APML file, you would just see  Female Pop
 Singer).  
As an experiment, I've created a little APML 
generator web service for last.fm users.  If you give the web 
service your last.fm user name, the service goes to last.fm, retrieves 
data about your listening habits and generates an APML representation of
 your taste.  For example, to retrieve the APML for my listening 
tastes visit the following URL:
http://research.sun.com:8080/AttentionProfile/apml/music/lamere
This yields:
<APML version="0.6">
<Head>
  <Title>music taste for lamere</Title>
  <Generator>Created by TasteBroker.org in 2777 ms </Generator>
  <DateCreated>2007-11-21T16:15:24</DateCreated> 
</Head>
<Body defaultprofile="music">
  <Profile name="music">
  <ImplicitData>
   <Concepts>
       <Concept key="rock" value="1.0" from="tastebroker.org" updated="2007-11-21T16:15:24"/>
       <Concept key="alternative" value="0.74616855" from="tastebroker.org" updated="2007-11-21T16:15:24"/>
       <Concept key="indie" value="0.63257456" from="tastebroker.org" updated="2007-11-21T16:15:24"/>
       <Concept key="alternative rock" value="0.38583755" from="tastebroker.org" updated="2007-11-21T16:15:24"/>
     <!-- many lines omitted -->
   </Concepts>
  </ImplicitData>
 </Profile>
</Body>
</APML>
To
 generate the implicit concepts, I gather the top 50 artists for the 
user, and for each of these artists I gather the top 50 tags that have 
been applied to each of those artists.  I adjust the weight of the 
tags based on the user's affinity for the associated artist. I then take
 top scores to generate the APML. Of course, all this chattering with 
last.fm can make the web service quite slow.  I do try to cache as 
much data as I can to try to speed things up, but if you have eclectic 
tastes, it can take up to a minute or so to generate your APML file.
The
 resulting APML seems to be a good representation of my taste.  I'm
 interested in hearing from others that might be last.fm users whether 
or not the generated APML file is a good map of their taste.  Feel 
free to try out the web service.  The URL is:
http://research.sun.com:8080/AttentionProfile/apml/music/YOUR_LAST_FM_USER_NAME
 The next step is to see how well we can generate recommendations based upon these APML files.