OWL-S Grounding and WSDL

Dear all,
 
I have a question which I get confused these days. If I have a process model
defined in OWL-S which should be an abstraction of my service and some
services in my repository. When I want to find the service that match with
the IOPE that I have described in the service profile and process model, I
think it should be possible that we locate the services directly from this
repository (if my assumption here is correct, please let me know).
Then my main question is that, if the above assumption is true:
1)       I might find more than one services that satisfy my needs at a time
in the registry repository. In this case, I might want to do some evaluation
which one fits my needs best and then do I need to create the grounding part
to bind the service model to a concrete implementation?
2)       If I need to, then can I create it on the fly? Because it would be
really beneficial to do so otherwise I think there is on meaning for doing
service discovery. Please correct me if I'm wrong.
 
Please let me know. Thank you very much in advance.
 
Sakda