Although individual use of computers is fairly widespread, in meetings we tend to leave them behind. At Xerox PARC, an experimental meeting room called the Colab has been created to study computer support of collaborative problem solving in face-to-face meetings. The long-term goal is to understand how to build computer tools to make meetings more effective.
WYSIWIS (What You See Is What I See) is a foundational abstraction for multiuser interfaces that expresses many of the characteristics of a chalkboard in face-to-face meetings. In its strictest interpretation, it means that everyone can also see the same written information and also see where anyone else is pointing. In our attempts to build software support for collaboration in meetings, we have discovered that WYSIWIS is crucial, yet too inflexible when strictly enforced. This paper is about the design issues and choices that arose in our first generation of meeting tools based on WYSIWIS. Several examples of multiuser interfaces that start from this abstraction are presented. These tools illustrate that there are inherent conflicts between the needs of a group and the needs of individuals, since user interfaces compete for the same display space and meeting time. To help minimize the effect of these conflicts, constraints were relaxed along four key dimensions of WYSIWIS: display space, time of display, subgroup population, and congruence of view. Meeting tools must be designed to support the changing needs of information sharing during process transitions, as subgroups are formed and dissolved, as individuals shift their focus of activity, and as the group shifts from multiple parallel activities to a single focused activity and back again.
Based on a review of some actual expert-system projects, guidelines are proposed for choosing appropriate applications and managing the development process.
CommonLoops blends object-oriented programming smoothly and tightly with the procedure-oriented design of Lisp. Functions and methods are combined in a more general abstraction. Message passing is invoked via normal Lisp function call. Methods are viewed as partial descriptions of procedures. Lisp data types are integrated with object classes. With these integrations, it is easy to incrementally move a program between the procedure and object-oriented styles.
One of the most important properties of CommonLoops is its extensive use of meta-objects. We discuss three kinds of meta-objects: objects for classes, objects for methods, and objects for discriminators. We argue that these meta-objects make practical both efficient implementation and experimentation with new ideas for object-oriented programming.
CommonLoops' small kernel is powerful enough to implement the major object-oriented systems in use today.
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