Today, today's highway is rapidly developed, the application of network technology is increasingly wide, how to use Internet and campus network to conduct distance education is being received by people. Distance education is a modern education model. In the case of time and space separation, he has to use modern education technology to maintain teaching, and complete the process of studying and learning activities. It is a means of developing prospects using Internet education, which can be implemented, interactive, graphic and online education. Anyone can learn and exam through the network, and is not subject to time-to-domain restrictions. In my country, universities have already established a campus network to make full use of this resource for online teaching, with broad application prospects.
1. Development status of network test system
Based on the Internet-based remote education model can be divided into three levels, which are content layers, interface layers, and facility-based layers. Content layers provide resources related to teaching, such as textbooks, exercises, testing waists. The interface layer provides teachers to teach, student learning interfaces, such as e-mail, ftp, bbs and other tools, and applications that complete exercises, tests. The infrastructure layer includes a computer, network, network connection, and the like.
Based on the above analysis, the network test system is an integral part of distance education, and you can divide these three levels. If only the software portion of the network test system is considered, it is generally constructed of two or three layers. The two-layer structure is the C / S structure, and the three-layer structure is based on the two-layer structure to increase an intermediate layer, typically a B / M / S structure. At present, there are many network test systems that have developed successfully at home and abroad, and they can basically be divided into C / S structures or B / S structures. Two typicals are analyzed.
1.1 Network Examination System Based on BMD Structure
The BROWSER / Web Server / DB Server, which is a typical three-layer network distributed application framework. It is developed by the B / S two-layer structure, which is advantageous for the maintenance of the system compared to the B / S two-layer structure. The network test system under this structure typically builds a user interface in an HTML language in the Browser end, then connects the Browser-end user input data through an interactive mechanism (such as CGI, ISAPI, JSP, PHP, ASP), with WebServer. Submit to the Web Server side and processes, the processing ends to DB Server Save.
A key point is the choice of the Browser end interactive mechanism. Implement the interaction of the browser and the server, which is generally available in CGI, ISAPI, and ASP.
CGI, CommON Gate Interface, which is a standard interface for WWW server host external service, which is to deliver information between hypertext files and server host applications. As a standard interface of a web server, CGI has a good cross-platform characteristic, which can be implemented on any operating system, such as DOS, Windows, UNIX, OS / 2, Macintosh, etc. CGI applications are generally a separate executable, and the WWW server has different processes, and generally one CGI program can only process one user request. In this way, every user request will activate a CGI process, and when the number of requests is very advanced, the resource resources such as memory, CPU time, etc. will cause low efficiency.
