Resource Management for a Virtual Planning Room

In the last few years we have been prototyping a multiperson virtual environment using low-cost workstations interconnected with relatively high-speed networks. This domain makes use of interactive and on-demand continuous media in addition to a number of other tasks that fall on a spectrum between hard real-time and best-e ort response. A brute force implementation of applications in this type of domain demands excessive system resources, even though the actual requirements by di erent parts of the application vary according to the way the virtual environment is being used at the moment. A more sophisticated approach would be to provide both the user and the applications with the ability to dynamically adjust resource requirements according to their current needs and the availability of system resources. This position paper summarizes the nature of the support required from the operating system, then describes our approaches to resource management based on these requirements. Permanent address is School of Computer Science, Florida International University, Miami, FL Department of Computer Science and Engineering, University of Colorado at Denver, Denver, CO 1 The Application Domain To support collaboration among human users, computers need to provide an e ective set of domain-speci c tools embedded in a free-form communication environment [18]. The virtual planning room (VPR) [19] is a multiperson virtual environment (VE) supporting free-form communication in a manner similar to electronic meeting rooms [7, 23] and other virtual environments [1, 3, 5]. It di ers from most other virtual environments in that it is designed to be extended with \domain-speci c tools." For example, in [17] we describe how a formal work ow/process modeling system can be embedded in the VPR to focus on group coordination. We are also currently building agent-based software to extend the VPR so that a group can navigate and control a blimp with its own onboard computer, navigation equipment, and videocamera (\FLOATERS") [21]. 1.1 The Virtual Planning Room AVPRworld is de ned by a collection of objects, with visual representations and behaviors of varying complexity. Domain-speci c tools are added to the VPR by incorporating additional objects having \complex" behavior. The fundamental role of the VPR is to to provide realtime audio and video support across the network, to render objects on each user's screen, and to provide an environment in which to add domain-speci c extensions. The VPR is a client-server system where each person uses a client workstation to implement the human-computer interface. Hence, the client must render each visible artifact from a (VRML) representation in the corresponding object, and cause behaviors (such as modi cations to objects) to be re ected in all other appropriate clients. For our prototype, we have used widely-available system software and interfaces: CORBA for the object interface, UNIX for the system call interface, and various network interfaces to support streams. This has allowed us to explore the VPR design, implementation, and functionality, even though the performance of the prototypes is severely limited by the hardware resources. Despite the number of papers focusing on VE/VR functionality, design, and user interfaces, (e.g., see [2, 11, 12]) there is surprisingly little on the e ect the operating system has on the VE's performance. Now that we have a rudimentary VPR, our goal is to explore system software design and organization are well-suited for this rapidly-evovling application domain.