移动节点模型

代码说明：

应用背景 * Redistribution and use in source and binary forms, with or without  * modification, are permitted provided that the following conditions  * are met:  * 1. Redistributions of source code must retain the above copyright  *    notice, this list of conditions and the following disclaimer.  * 2. Redistributions in binary form must reproduce the above copyright  *    notice, this list of conditions and the following disclaimer in the  *    documentation and/or other materials provided with the distribution.  * 3. All advertising materials mentioning features or use of this software  *    must display the following acknowledgement:  * This product includes software developed by the Computer Systems  * Engineering Group at Lawrence Berkeley Laboratory.  * 4. Neither the name of th