session detect and terminate

Hi,

Does postgresql has a way to detect a lock, like Oracle:
update ...... nowait????
Does postgres(or dba) has a privalege to kill a user session inside
the database, like Oracle: kill session.

I believe they are very useful, I have a web based java application
communicate with postgresql via jdbc.
sometime the application will be unexpectly crashed, but the connection
with database is still exist even I close all IE windows. With dead
application open another window often cause trouble.
using unix command 'kill' is not a good solution, so I 'd like find a way
to detect user's session when loading application, and kill the residual
dead session.

thanks.

Jie LIANG

St. Bernard Software

10350 Science Center Drive
Suite 100, San Diego, CA 92121
Office:(858)320-4873

jliang(at)ipinc(dot)com
www.stbernard.com
www.ipinc.com