1. Introduction
With the development and popularization of web technologies, web-based learning is becoming more and
more acceptable by people. As the education pioneers, many colleges began to establish their web-based
learning system to support distance higher education in the late 90’s. Large project such as CALAT; CALsurf;
WebCAI; The University of the Air; California Virtual University; WIDE University were established during
this time [1-2]. These systems are usually used for course resource display, homework assignment and class