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Collaborative Environments

Commercially available groupware products (such as Lotus Notes or DEC LinkWorks) provide a standard suite of services for group interaction in corporate, medium-sized, enterprise domains (conferencing, electronic mail, multimedia document management, scheduling, workflow). They do not deal with the problems that arise when CSCW (Computer Supported Cooperative Work) is extended to widely distributed and dynamically changing environments. The following classification lists approaches for various application domains that try to address exactly such issues.

Distributed Virtual Reality

Distributed Virtual Reality (DVR) systems aim at real-time simulations of 3D worlds in which multiple users can interact with each other [Roe95a] [Loe95]. The central problem of such systems is how to minimize communication between sites while presenting each participant a consistent view of the virtual environment. Because of the bandwidth constraints of wide-area-network connections [BMZ95], most systems rely on multicasting schemes where each host sends the state changes it caused to the affected group of other hosts. Locking schemes are used to guarantee a minimum amount of consistency.

NPSNET

of the American Naval Postgraduate School is a test-bed for research and development on distributed VR systems with focus on military battlefield simulation [MZP+94] [NPS95]. It is based on the DIS (Distributed Interactive Simulation) protocol which extrapolates the position ofs objects from its last known position and state. The current version of the software is freely available but utilizes proprietary SGI hardware and software features and is therefore not portable to other systems.

DIVE

(Distributed Interactive Virtual Environment) is a toolkit developed by the Swedish Institute for Computer Science (SICS) for building distributed VR applications [CH95] [DIV95a]. Every host of the simulation network has a complete copy of the world database; updates are broadcasted to all other hosts. Binaries for various platforms (but not the source code) are freely available.

AVIARY

is a generic world model for distributed VR systems [WHH+93] [Sno95]. AVIARY uses an object-oriented framework where a virtual world is represented as a collection of communicating and concurrently executing autonomous objects. A distributed Environment Database (EDB) manages the spatial extents of objects and notifies them when collisions are detected; it is up to the objects to resolve the collision. A prototype implementation of the AVIARY model has been produced on a local-area network; issues of scalability and non-local distribution are not addressed.

MASSIVE

(Model, Architecture and System for Spatial Interaction in Virtual Environments) is a VR tele-conferencing system [GB95] [Gre95]. It integrates real-time video and audio into a virtual 3D environment consisting of multiple worlds with portals to move between worlds. The system works with up to about 10 users and is not a general-purpose VR application development environment.

CVE

(CRG Virtual Environment) is a joint effort by the developers of AVIARY and MASSIVE on the development of a new VR platform to support Collaborative Virtual Environments (CVEs) [BGL77] [CVE97]. Multiple users can communicate via a combination of 3D graphics, real-time packet audio and text; the system provides an extensible object-oriented developers API. A first developers version is expected for spring 1997.

PARADISE

(Performance Architecture for Advanced Distributed Interactive Simulation Environments) of the Stanford Distributed Systems Group aims to build a large-scale networked simulation environment over a wide-area network [Gro95b]. The current Version 0.1 of the PARADISE software incorporates an Area of Interest directory service for distributing information about entities to the participating hosts. Ongoing work pursues real-time distributed agreement protocols (for distributed collision detection and resolution).

Concurrent Engineering

There exist various approaches to supporting distributed design and manufacturing tasks:

MADE

(Manufacturing Automation and Design Engineering) [MAD96] is an ARPA program supporting research in the development and demonstration of next-generation design environments, specifically for electromechanical systems.

PACT

(Palo Alto Collaborative Testbed) [CEF+93] was designed as a testbed for cooperative research and knowledge sharing in concurrent engineering [CEF+93]. PACT was based on a set of agents sharing and exchanging knowledge using a Knowledge Query and Manipulation Language and a standard Knowledge Interchange Format.

SHADE

(Shared Dependency Engineering) [KMW+94] is an extension of PACT providing a medium in the context of the Internet that allows designers to accumulate and share engineering knowledge in a distributed environment.

dVISE

is a virtual reality environment developed by the British company Division for manufacturing simulation [Ghe95] [Div95b]. It comes with a collaborative design feature that allows multiple users in remote locations to connect to the simulation and to review and interact with complex assemblies. Each user in the collaborative session is represented by a user-definable object. Individuals can pick up parts, move them around, and hand them to one another in real time.

Virtual Classrooms

Most work on CSCL (Computer Supported Cooperative Learning) concentrates more on the pedagogical and interaction issues rather than on the basic technical environments required for building wide-area distributed virtual classrooms [CSC95] [OM95]. The essential constituents of such classrooms are typically video-conferencing systems and electronic whiteboards as employed in the MUNIN project [MUN96] that applys MBONE multimedia conferencing tools piloted in the MICE project [MIC97].

The ARPA program CAETI (Computer Assisted Education and Training Initiative) [CAE96] is concerned with the provision of intelligent tutoring capabilities in an Internet infrastructure. It supports individualized learning regardless of the availability of local resources, as well as enhancing group training and education through multiuser environments and simulation. One of its initiatives, Collaborative Applications for Project-based Education Resources (CAPER) includes multimedia environments supporting involvement, experimentation, exploration, and collaboration in cross-disciplinary projects.

The ALN Web (Web of Asynchronous Learning Networks) [ALN97] documents various activities in this area.