I am working with SICStus Prolog.
SICStus Prolog offers the possibility to call Prolog from Java and visa
versa using the so-call Jasper library.
The Jasper library is based on the native interface. A saved program file is
accessed for the call of Prolog from Java.
My question are following:

+ I cannot assert a clause, when I call Prolog from Java. I use an
"open_query"-statement, which I close with "query_cut" or
  "query_close", alteratively
                for example "assert(a)" is always accepted, but "listing(a)"
cannot find a fact "a"
                However, I can use the assert inside of a clause or use the
query "assert(a), listing(a)" without any errors.
  What can I do in order to be able to assert and retract clauses and facts?
  How can I save (make persistent) my changes of the database?

+ I want to use always the last version of my saved prolog file.
   How can I make shure that I open (restore) always the last version?
   Is there a chance to check this in Java?

+ I am using services written in Java. Serveral running services are sharing
the same (Java Virtual Machine) JVM.
   A service calls Prolog.
   Does anybody knows a problem if I call Java again from Prolog, which has
to use the same JVM, then?

Many thanks for your help!

Reinhold Kloos