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Sec 9.1
Sec 9.2
Sec 9.3

Chapter 9


The Hermes substrate includes a mechanism for organizing knowledge in a design environment into a network of perspectives. These perspectives provide support for design as a process of interpretation and deliberation. They allow designers to interpret the design situation according to their individual and group interests. Perspectives provide a mechanism for creating, managing, and selectively activating different sets of design knowledge, such as critics, spatial relations, domain distinctions, palette items, and argumentation, so that alternative ideas can be deliberated and either adopted, rejected, or modified.

The perspectives mechanism organizes all the design information in the knowledge base. A designer always works within a particular perspective. At any time, the designer can select a different perspective by name. When a given perspective is selected (“active”) then only information indexed for that perspective (or for a perspective inherited by that perspective) can be accessed, traversed, or displayed.

A new perspective can be created by assigning a name to it and selecting existing perspectives for it to inherit. Perspectives are connected in an inheritance network; a perspective can modify knowledge inherited from its parents or it can add new knowledge. Designers switch perspectives to examine a design from different viewpoints. Switching perspectives changes the currently effective definitions of critics, the terms used in these definitions, and other domain knowledge. For example, imagine that Archie was collaborating with Desi using the Hermes computer system. Then he could create archie’s habitat perspective and select desi’s habitat perspective to inherit from. This would allow him to build upon and critique Desi’s work, without altering what is viewed by Desi in his perspective.

The organization of information by perspectives encourages users to view knowledge in terms of structured, meaningful categories that they can create and modify. It provides an extensible structure of knowledge contexts that can correspond to categories meaningful in the design domain. This eases the cognitive burden of manipulating potentially large numbers of alternative versions of critics, rationale, graphics, language expression definitions, and other design knowledge.

The perspectives mechanism allows items of knowledge to be bundled in various ways, which can overlap orthogonally or inter-connect. Common types of perspectives are:

*    personal and group viewpoints of individual designers and teams

*    topical groupings by content traditions (e.g., kitchen design)

*    technical aspects by specialties (e.g., plumbing)

*    historical versions (e.g., Archie’s Monday morning habitat design)

For instance, archie’s habitat perspective might include considerations specific to Archie’s design, as well as incorporating many ideas from Desi’s. If Desi and Archie are part of a larger team, then the team’s perspective could display concepts and rationale from all its members, or it could select from and modify the knowledge inherited from multiple sources. Archie would also want to inherit knowledge from lunar habitat design traditions and related technical specialties. Then, as his design evolved, Archie could define perspectives for archiving versions of his work.

Lunar habitat design takes advantage of information from many technical disciplines and domain traditions: kitchen and bathroom design, low-gravity and vacuum considerations, electrical and lighting expertise, submarine and Antarctic isolation experiences. It can borrow selectively from both space station and Mars habitat prior designs. Each of these bodies of knowledge can be defined within a network of domains and subdomains that inherit, share, and modify knowledge from each other. Perspectives can also be used to save networks of historical versions of developing designs. The Hermes perspectives mechanism is a general—but hypermedia specific—implementation of contexts[1] that can be used to supply a variety of functionality to a design environment.

This chapter will present the Hermes perspectives mechanism in three sections. First, Section 9.1 offers a scenario to show how a design team using Hermes might approach the task documented in the protocol analysis of Section 3.2, “Perspectives on Privacy.” Second, Section 9.2 describes the techniques used to implement the perspectives mechanism in Hermes. This will detail the hypermedia character of the implementation. Third, Section 9.3 discusses how the perspectives mechanism can provide computer support for cooperative work. This will include examples of interface features for displaying, browsing, and sharing knowledge in multiple perspectives representing different people, interests, or domains.

[1] The terms perspective and context will be used interchangeably in this Chapter. Technically, the functionality of perspectives is implemented by defining contexts. As M. Gross suggested, perspectives are similar to the notion of “binding contexts” in programming languages: a definition is bound within the perspective in which it was created.

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This page last modified on January 05, 2004