Design and implement of COD system

Abstrcat Learning by COD is one of the most basic and central way in modern distance education. According to the requirements of COD, this system supplies functions of query and COD based on B/S mode. This paper gives an elaboration on the critical parts in developing the COD system. In term of designing and implementing, the paper introduces the construction of software platform, the designment of database and solutions of two critical technologies.