boolean isExclusive = Boolean.valueOf(exclusive).booleanValue();
boolean isInherit = Boolean.valueOf(inherit).booleanValue();
// expires after one minute
Date expire = new Date(System.currentTimeMillis() + 1000*60);
SlideToken slideToken = new SlideTokenImpl(new CredentialsToken(caller));
Lock lock = nat.getLockHelper();
try {
nat.begin();
lock.lock(slideToken,new NodeLock(uri,subject,type,expire,isExclusive,isInherit));