RE: Composition as planning

I would point out that the mapping of web services to compositions 
has largely been done in the past, even in the best work in this 
area, with some simplifications that generally "twist" web services 
into a planning framework -- there's huge parts of the web service 
world that need to be explored before we can really say AI planning 
has shown a success in web services other than as an evocative idea 
--  the reason is that a real web services engine will need to deal 
with (at least):
   - scaling issues way beyond anything we've seen in planning to date 
(there may be thousands of services each with multiple ports, 
optional arguments, etc.)
   - the issues Dana mentioned (side effects, change in the world, 
etc.) that make Strips-operators planning an approximation at best 
(the assumption that change occurs only through the operators under 
the control of this planner is clearly wrong)
   - issues of interaction with users - web service planning better be 
mre mixed-initiative
   - issues of preferences v. constraints
   - issues of interaction between planning agents out there (you buy 
the book I'm in the process of planning to buy)
    - knowledge engineering issues (when planners take ebXML and WSDL 
as inputs, instead of requiring specialized planning-like langauges 
like Owl-S, then we'll see a lot more excitement on the outside - 
OWL-S is an interesting starting place,  but we fool ourselves if we 
think it really is going to be widely used for process specification 
in its current form)
   In fact, I'll wager that it will be absolutely trivial to prove 
that web services planning, even w/simplifications, is inherently 
undecidable, so we'll need to explore a lot of the issues from the 
old "dynamic planning" world as well
   All this, by the way,  I see as good news - it means this is a 
fertile and exciting research area for those of us in planning, with 
good heuristic solutions being transitionable.

That said, in the past I have tried to get AI planning people to 
think outside the box and failed miserably, and I'll be surprised if 
the web services planning stuff doesn't become an "applied" area 
being ignored by the bulk of the research community (who, if you'll 
apologize my saying so, still have their heads up their 
you-know-whats worrying about scaling simple problems in all the 
wrong ways)
   Forgive my pessimism, but the planning community has spent many 
years resisting change - I don't see why just because we have a new 
and potentially revolutionary problem that could expand the field 
greatly, the leopards will change their spots...
  -Jim Hendler
p.s. Of course, I also think the Sem Web will be largely ignored by 
traditional AI types until it kicks them in the head, so maybe this 
is just more of the same :->
-- 
Professor James Hendler			  http://www.cs.umd.edu/users/hendler
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  240-277-3388 (Cell)

Received on Sunday, 1 February 2004 16:15:39 UTC