网络白板：在线用户、图形绘制、图形共享、可扩展增加：【图形移动、变更、白板操作迸发控制】，客户端之间互发消息，服务器转发 -Network whiteboard: Online users, graphics rendering, graphic shared, scalable increase: [Graphic move, change, whiteboard operating burst control], each message between the client, the