Interactive On-Line Conferences

A real-time conference allows a group of users, each at his or her own workstation, to conduct a problem-solving meeting by collectively viewing and manipulating a shared space of on-line application information while using a voice communication channel for discussion and negotiation. A real-time conference thus supplements asynchronous communication services, such as electronic mail, by permitting simultaneous manipulation of shared information. Techniques are presented in this thesis for designing and implementing real-time conferences on distributed computer systems. Useful functions for real-time conferences are proposed: control over who may join a conference, and over concurrent participant commands within a conference; "private" spaces and transfer of information between shared and private spaces; display of "status" information describing who is present in a conference and who is entering commands; eliciting and collecting responses to be used in decisionmaking; planning a conference and making it known to potential participants; and maintaining and reviewing records of a conference. The tradeoffs involved in selecting a comprehensible set of commands for these functions are illustrated by the detailed design of a real-time conferencing system for joint editing of documents. Different implementation techniques for real-time conferences are evaluated, with particular emphasis on minimizing the response time of the system to participants' commands. Criteria for choosing among alternative techniques are provided to guide a system designer in tailoring a real-time conferencing system for his particular application, user community, and implementation environment. An architecture is presented that permits dynamic selection of the implementation method based on run-time performance parameters. The feasibility of implementing real-time conferences using the given techniques is demonstrated by two prototype systems. Thesis supervisor: Dr. Irene Greif Title: Principal Research Associate