参考：
http://www.silverlightchina.net/html/developer/2010/0505/1093.html
http://www.silverlightchina.net/html/developer/2010/0504/1081.html
http://www.silverlightchina.net/html/developer/2010/0125/623.html
http://www.silverlightchina.net/html/developer/2009/1117/239.html