Raymond McCall

Rationale Management in Software Engineering

This is a detailed summary of research on design rationale providing researchers in software engineering with an excellent overview of the subject. Professional software engineers will find many examples, resources and incentives to enhance their ability to make decisions during all phases of the software lifecycle. Software engineering is still primarily a human-based activity and rationale management is concerned with making design and development decisions explicit to all stakeholders involved.

JANUS: integrating hypertext with a knowledge-based design environment

Hypertext systems and other complex information stores offer little or no guidance in helping users find information useful for activities they are currently engaged in. Most users are not interested in exploring hypertext information spaces per se but rather in obtaining information to solve problems or accomplish tasks. As a step towards this we have developed the JANUS design environment. JANUS allows designers to construct artifacts in the domain of architectural design and at the same time to be informed about principles of design and the reasoning underlying them. This process integrates two design activities: construction and argumentation. Construction is supported by a knowledge-based graphical design environment and argumentation is supported by a hypertext system. Our empirical evaluations of JANUS and its predecessors has shown that integrated support for construction and argumentation is necessary for full support of design.

Supporting knowledge-base evolution with incremental formalization

A number of systems have been built which integrate the knowledge representations of hypermedia and knowledge-based systems. Experiences with such have shown users are willing to use the semi-formal mechanisms of such systems systems leaving much structure implicit rather than use the formal mechanisms provided. The problem remains that it is hard (1) to encode knowledge in the formal languages required by knowledge-based systems and (2) to provide support with the semi-formal knowledge found in hypermedia systems. Incremental formalization enables users to enter information into the system in an informal or semi-formal representation and to have computer support for the formalization of this information. The domain independent Hyper-Object Substrate (HOS) differs from other systems that integrate hypermedia and knowledge-based system styles of representations in that it enables the incremental addition of formalism to any piece of information in the system. HOS actively supports incremental formalization with a set of tools which suggest new formalizations to be added to the information space. These suggestions are based on patterns in the informally and semi-formally represented information and the existing formalized knowledge in the information space. An important assumption is that suggestions need not be completely accurate to be of general benefit to users. These suggestions provide a starting point which can be edited, thus changing part of of formalization from creation to modification. XNetwork, an environment the process supporting the design of computer networks, is one of several applications that have been created with HOS. Experiences with HOS show that its flexibility for incrementally adding and formalizing information is useful for the rapid prototyping and modification of semi-formal information spaces.

Seeding, evolutionary growth and reseeding: supporting the incremental development of design environments

We describe an approach to acquiring information during the creation and use of domain-oriented design environments. Our model consists of three phases: seeding, evolutionary growth, and reseeding. A seed for a domainoriented design environment is created through a participatory design process between environment developers and domain designers by incorporating domain-specific knowledge into a domain-independent architecture for design environments. Evolutionary growth takes place as domain designers use the seeded environment to undertake specific projects. Reseeding is a process that reinvolves the environment developers to help domain designers better organize, formalize, and generalize knowledge added during the use phases,

Design environments for constructive and argumentative design

Design Environments are computer systems which support design by enabling cooperative problem solving between designer and computer. There are two complementary problem solving activities in design: constructive design and argumentative design. We have created two computer-supported environments, CRACK and VIEWPOINTS, to support these two activities. CRACK is a knowledge-based critic which has knowledge about how kitchen appliances can be assembled into functional kitchens. VIEWPOINTS is a hypertext system based on the IBIS design methodology and contains useful information about the principles of kitchen design. The integration of these two types of systems will eliminate shortcomings of the individual systems.

Supporting indirect collaborative design with integrated knowledge-based design environments

We are developing a conceptual framework and a demonstration system for collaboration among members of design teams when direct communication among these members is impossible or impractical. Our research focuses on the long-term, indirect communication needs of project teams rather than the short-term needs of face-to-face communication or electronic mail. We address these needs with integrated, domain-oriented design environments. Our conceptual framework and our system-building efforts address two major issues: (a) How does individual work blend into project work (especially in large projects that span great distances and time)? and (b) What role do the work objects play in this coordination? We use a specific domain-oriented design environment (NETWORK-HYDRA-for the design of computer networks) to illustrate our approach, and we discuss HYDRA as the underlying domain-independent, multifaceted architecture for design environments.

Integrating different perspectives on design rationale: Supporting the emergence of design rationale from design communication

Design rationale is a topic that implies different things to different people. To some it implies argumentation and frameworks for argumentation. To others it implies the documentation of design, like that required for many types of industrial or government work. Still others describe design rationale as the capture and potential reuse of normal communication about design. These perspectives of design rationale use different representations, which influence their ability to capture and to retrieve and use information. We propose an integrated approach to design rationale where design communication is captured and, over time, incrementally structured into argumentation and other formalisms to enable improved retrieval and use of this information. Two systems, PHIDIAS and the Hyper-Object Substrate, are used to demonstrate: (1) how to capture and integrate a variety of design information, (2) how to support the structuring of unstructured information, and (3) how to use design information to actively support design.

PHI: a conceptual foundation for design hypermedia

PHI (Procedural Hierarchy of Issues) extends the IBIS ( Issue-Based Information System) method developed by Rittel to support an argumentative approach to design. PHI extend that approach, because it uses an additional argumentative process and deals with a greater range of design issues. PHI has recently gained recognition as the conceptual foundation for a number of design hypermedia systems

Rationale-Based Software Engineering

Many decisions are required throughout the software development process. These decisions, and to some extent the decision-making process itself, can best be documented as the rationale for the system, which will reveal not only what was done during development but the reasons behind the choices made and alternatives considered and rejected. This information becomes increasingly critical as software development becomes more distributed and encompasses the corporate knowledge both used and refined during the development process. The capture of rationale helps to ensure that decisions are well thought out and justified and the use of rationale can help avoid the mistakes of the past during both the development of the current system and when software products (architecture and design, as well as code) are reused in future systems. Burge, Carroll, McCall, and Mistrk describe in detail the capture and use of design rationale in software engineering to improve the quality of software. Their book is the firs t comprehensive and unified treatment of rationale usage in software engineering. It provides a consistent conceptual framework and a unified terminology for comparing, contrasting and combining the myriad approaches to rationale in software engineering. It is both an excellent introductory text for those new to the field and a uniquely valuable reference for experienced rationale researchers. The book covers the use of rationale for decision making throughout the software lifecycle, starting from the first decisions in a project and continuing through requirements definition, design, implementation, testing, maintenance, redesign and reuse.

Making large-scale information resources serve communities of practice

Community memory can provide the crucial bridge between large-scale information bases like digital libraries and the day-to-day activities of a communitys members. Just as a digital library is based on a general structure and conventional means of access to diverse collections of materials, a community memory will help cull and shape the structure and contents of this collection to meet more particular needs. But it is by no means straightforward for people to collect, maintain, share, and apply the materials that are part of a community memory. Useful and usable community memories require support for: (1) the acquisition and evolution of content and structure; (2) the identification of materials and community members relevant to a particular task; and (3) the maintenance of organizations that are mutually intelligible across the community. In this paper, we explore issues related to these three requirements based on a meta-analysis of our collective experiences with the development and use of shared hypermedia information resources.