NX: lock and unlock

my assignment is :
"public void lock(int record)
public void unlock(int record)
The unlock method simply removes the lock from the specified record. If an attempt is made to unlock a record that has not been locked by this connection, then no action is be taken."

so my question: how can iimplement the unlock without modified its definition?
i have two choice :
one is :
call lock(i)-modify(Data)-unlock(i) from client site, but client will call server three time in this way. i think how can modified a record does need known by client too.
second :
call lock(i)-modify(Data)-unlock(i) from server site,and server implements rmi interface, but i can't make sure it correspond with sun's requeriment.
which one should i chose , and is there any other good idea to implment it?
what your advice? thanks!

lock requirement description:
The lock method should block until the requested lock can be applied. The integer argument indicates the record to be locked. If the method is called with an argument of -1, the entire database should be locked

why no person replay, it is very urgent!

closed， i have resolved it.
thanks.

Hi JQ,
Welcome to JavaRanch.
Sorry I didnt get to your post until now. I hope you will still stick around and give us more chances to help.
I am glad you solved your problem. Davidd was tackling the same problem in this thread - you may be interested in the solution we were discussing there.
Regards, Andrew

thank you very much! i have gone to the Topic: NX: About data consistent.
it is very good.
i will not level here.