2·If so, what is the nature of the interface (for instance, synchronous, asynchronous, uni-directional, bi-directional)?
如果是，该连接的性质是什么(例如，同步、异步、单向、双向)？
3·I was forced to do it this way because the association is uni-directional — employee rows know about their position rows but not the other way around.
因为关联是单向的——employee那些行知道它们的位置行，但反过来就不行——所以我必须这么做。