ED-MEDIA 1999 Proceedings Book - Association for the ...

Java can significantly increase the minimum system requirements for their sites. In most cases, the use of Java
will increase the minimum system requirements for acceptable performance even if the theoretical minimum
system requirements remain the same.
The Problem of Data Processing - Internet content providers of all types are quickly realizing that a major
hurdle to overcome is the selection of methods for organizing, storing and retrieving large amounts of data.
Relational databases such as Oracle, Sybase, MySQL, and Microsoft SQL have become the rage among
content providers due to their flexibility and speed in dealing with arbitrarily large and diversely organized
data sets. The choice of a database engine, however, results in additional constraints and choices to be made.
Specifically, content providers must create mechanisms for client communication with the database. Many
sites choose a CGI-based approach, but this is often insufficient. The major drawback of CGI programs is that
each client request involving a CGI causes a new program to be launched and run on the server. Even if the
CGI programs themselves are small and fast, the overhead involved in launching them is quite high.
The Problem of Bandwidth - Bandwidth is a measure of how much data can be transferred over the path that
exists between a server and a client. The problem of bandwidth is related to both data processing and
graphical content. However, whereas control of data and graphics resides primarily with the content provider,
control of bandwidth does not. Unfortunately, the nature of the Web is such that insufficient client-side
connectivity can reflect poorly on the content provider, even if no server-side bottlenecks exist.
The Problem of Scalability - A scalable system is one that can handle higher traffic by straightforward
means such as purchasing new or additional hardware rather than more complicated means such as major
software redesign. This is one of the foremost concerns of all Internet content providers, especially since the
number of users approaching the Internet is increasing at a phenomenal rate.
These issues have been at the forefront of many technological decisions we have made in the design of our
Web-based Integrated Science Environment. Our experiences have shown that if classroom bandwidth is
sufficient, the end users' experiences can be positive even on classroom machines that are five years old or
older. Our presentation will discuss how this has been achieved in the WISE Project, focusing on the five
problem areas mentioned above. The presentation will also show that with proper server-side preparation, it is
possible to balance desired functionality against technological limitations for a very wide range of client
machines. Finally, it will touch upon the necessary trade-offs between server-side performance and cost. The
purpose of this presentation is not only to share our experiences in implementing a high-tech learning
environment, but also to invite discourse among others who have had similar experiences.
References
Bell, P., Davis, E. A., & Linn, M. C. (1995). The knowledge integration environment: Theory and design.
Proceedings of the Computer Supported Collaborative Learning Conference (CSCL '95: Bloomington, IN),
(pp. 14-21). Hillsdale, NJ: Lawrence Erlbaum Associates.
Linn, M. C. (1992). The Computer as Learning Partner: Can Computer Tools Teach Science In K.
Sheingold, L. G. Roberts, and S. M. Malcolm (Eds.),Technology for and Learning. Washington, DC:
American Association for the Advancement of Science.
Slotta, J. D. & Linn, M. C. (in press). How do students make sense of Internet resources in the science
classroom In Jacobson, M. J. & Kozma, R. (Ed.), Learning the Sciences of the 21st Century. Hilldale, NJ:
Lawrence Erlbaum & Associates.
Acknowledgements
The WISE Project is funded through NSF Grant #REC 98-05420.