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Recently Web-Based Instruction (WBI) has been adopted for many educational systems in order to support distance education. WBI has become popular in that it overcomes time and space limitation in traditional educational systems. But due to lack of face-to-face communication, it is crucial that WBI provide interactivity and motivation for students. This(More)
In this paper, we present a locking-based concurrency control scheme for object-oriented databases (OODBs). Our scheme deals with class hierarchy which is an important property in OODBs. The existing concurrency controls for a class hierarchy perform well only for specific environments. Our scheme is based on so called special classes and can be used for(More)
The use of the Web (World Wide Web) has had many positive effects on education. It overcomes time and space limitations in traditional schools. Teachers and students are now using the Web to access vast amounts of information and resources in the cyberspace. Also, learning via the Web enables both synchronous and asynchronous communication. Despite of many(More)