Design And Implementation Of Net Classroom Based On Campus Network

Remote Education is a kind of education approach that can break through the limit of space. It can greatly improve the efficiency of education resource spreading,and maximize the resource sharing. Remote Education has been well-developed in recent years,and there are many modes of remote education,such as transfer CAI courseware in the LAN,remote education based on artificial satellite TV system,net education based on WEB or E-mail through the Internet and so on. In these modes,net classroom has become the most effective method because of its real time capability,vitality,and interactive capability.This project implemented a net classroom that can cross different LANs. The environment of this project is Windows98/NT OS and campus network. In the data transfer part of the project,we advanced the dynamic configuring VLAN method to implement multicast data transfer,which solved the router bottleneck problem of IP-Multicast in the campus network,and improved the data transfer capability. In the transfer control part,we designed and implemented application layer transfer control protocol above the connectionless lower network protocol. Through departing and recombining the screen,recognizing each frame's sequence and synchronization,this protocol can make sure that screen to be displayed correctly at the remote computer,it can also make the client have more anti-disturb capability and stability. In the education function implementing part,through Windows API function we have completed the screen and audio information's capture,transfer and representation. In order to improve its efficiency,we made use of multithread program Tech. to operate image and audio separately. In the interactive part,we defined Net-classroom Teaching Control Protocol (NTCP),and implemented e-attendence checking,hand raising and questioning,text and audio communication control,etc. This system can transfer data in different modes according to the network's condition,so it has a good adapting ability to the environment.