useful link

http://blog.sina.com.cn/WealthSky

http://www.cnblogs.com/engine1984/default.html?OnlyTitle=1

http://bbs.lesport.cn/index.asp?boardid=65

http://www.uml.org.cn/oobject/OObject.asp#3

http://www.cnblogs.com/zhenyulu/articles/36058.html

http://community.csdn.net/Expert/topic/5391/5391604.xml?temp=.1258814