http://jamie-wang.iteye.com/blog/1849193
event -- onmessage, onopen, onerror
不是方法，而是事件
http://school.youth.cn/px/lamp/2012/1130/38537.shtml
http://www.ibm.com/developerworks/cn/web/1307_chengfu_serversentevent/index.html?ca=drs
http://bbs.lampbrother.net/read-htm-tid-149631.html