object serialization limitations OOBINLINE socket option OP_ACCEPT OP_WRITE Open Directory interface Open Source Rhino JavaScript interpreter open( ) methods DatagramChannel class Folder class Selector class ServerSocketChannel class SocketChannel class 2nd openConnection( ) methods opening jar URLs (URLConnection class) URL class URLStreamHandler class openStream( ) method (URL class) organization-wide multicast addresses output streams 2nd flushing failure to OutputStreamWriter class 2nd 3rd