转载：http://wuaner.iteye.com/blog/1843799
http://www.javaworld.com/article/2077780/java-web-development/acegi-security-in-one-hour.html
Scale-up(纵向扩展) vs Scale-out(横向扩展)
原文：http://www.cnblogs.com/diyunpeng/p/3556243.html
