Philippe Merle

This paper deals with system support for the design of CSCW environments. Our model introduces objects spaces shared by cooperating participants and cooperation spaces which group participants involved in a particular cooperation together. Objects spaces are only accessed via cooperation spaces. This makes our model strongly cooperation oriented. The Group notion structures our system, called OSACA. A group includes both cooperation spaces and objects spaces and represents a domain suitable for a cooperative activity. We investigate CORBA-compliant architectures to support this system level structuring tool. 1 The OSACA Model The growth of distributed systems supporting features such as le sharing, communications between thousands of internet users or distributed applications opens a door to a new class of applications: these related to Computer Supported Cooperative Work (CSCW). This new generation of applications deals with groups of users cooperating in a common task Ellis 91]. Cooperating editing, teleconferencing, collaborative learning are such applications. In return, these applications raise new needs, as far as computer systems are concerned, that are still not well supported. These needs are mainly characterized by two points which are common to most of cooperative applications: Users may not always be active at the same time, may be connected to a wide-area network and may use diierent cooperation tools. The notion of distributed applications is here replaced by the notion of distributed sets of cooperative applications. The system has to support this evolution. Users have to be aware of other users' presence, in order to be able to establish conversation with them. However, traditional systems (centralized or distributed) appear to their users as monouser systems, even when several users work at the same time. On the contrary, systems which will support cooperative applications have to fully integrate the notion of cooperating users.