Multiple Dynamic View Support for Cooperative Work Yusuke Yokota Tatsuya Nakamura Hiroyuki Tarumi Yahiko Kambayashi Graduate School of Informatics Kyoto University Sakyo Kyoto 606-8501, Japan yy@kuis.kyoto-u.ac.jp Abstract VIEW Media is a cooperative hypermedia system, which supports cooperative work utilizing hypermedia documents. It provides fundamental functions for cooperative work sup- port system and enables developers to construct various groupware such as distributed presentation systems, educa- tion systems, conference systems, and so forth. This sys- tem provides a powerful and flexible mechanism of cus- tomization. The mechanism can alter presentation, struc- ture, behavior and authority of hypermedia documents and workspace, which supports dynamic change of roles of users. This paper describes the purpose of VIEW Media, its basic model and implementation, and a user interface which supports conferences among users who have differ- ent access rights to shared documents. 1. Introduction Recent development of network and computer technol- ogy enables us to support our daily work using distributed systems. Principally, various kinds of researches have been put emphasis on realizing cooperative work in distributed environment as well as real world. Furthermore, our re- search intends to realize what we can’t do in real world by using these systems. One of the functions for such purpose is customization. This function needs a mechanism which enables multiple views including methods, which changes under constraints on mutual relationships. The mechanism is formalized as environment model. We have developed a cooperative hypermedia system VIEW (Virtual Interactive Environment for Workgroups) Media, which is a fundamen- tal system to develop various application systems easily and realizes the functions, mechanisms and notions mentioned above. Currently at IMAGICA Corporation. Characteristics of VIEW Media are summarized as fol- lows. Data sharing among users and different applica- tions: Many groupware realize sharing applications among users and put emphasis on providing facilities for converting existing stand-alone applications into distributed ones. This approach combines applications and data tightly, hence it is difficult to sharing data among different applications. Cooperative work in VIEW Media is based on the no- tion of sharing data, not applications. It enables to use same data in different applications and different pur- poses. Persistence and reuse of data: VIEW Media supports synchronous and asynchronous collaboration. To sup- port asynchronous collaboration, persistence of data is indispensable. Furthermore, persistence of data links synchronous work and asynchronous work through the notions of action history and action history view[9]. These notions realize powerful functions of reusing data. Customization of data: By achieving data sharing, users in collaborative work can see the identical data in the same representation. This is called WYSIWIS (What You See Is What I See) principle, a common concept for groupware. However, this principle is too restrictive to support a variety of cooperative work. VIEW Media realizes customization of data which relaxes restriction of the WYSIWIS principle. Cus- tomization of data has two aspects: Customization of representation: Representation of data is able to be changed according to users’ prefer- ence or configuration of their computer (display reso- lution, network bandwidth, etc.). For example, users can change window size, font type and size, back- ground and foreground color, etc. or view different