A design rationale (DR) is a representation of the reasoning behind the design of an artifact. In recent years, the use of semiformal notations for structuring arguments about design decisions has attracted much interest within the human-computer interaction and software engineering communities, leading to a number of DR notations and support environments. This paper examines two foundational claims made by argumentation-based DR approaches: that expressing DR as argumentation is useful, and that designers can use such notations. The conceptual and empirical basis for these claims is examined, firstly by surveying relevant literature on the use of argumentation in non-design contexts (from which current DR efforts draw much inspiration), and secondly, by surveying DR work. Evidence is classified according to the research contribution it makes, the kind of data on which claims are based (anecdotal or experimental), the extent to which the claims made are substantiated, and whether or not the users of the approach were also the researchers. In the survey, a trend towards tightly integrating DR with other design representations is noted, but it is argued that taken too far, this may result in the loss of the original vision of argumentative

Readers annotate paper books as a routine part of their engagement with the materials; it is a useful practice, manifested through a wide variety of markings made in service of very different purposes. This paper examines the practice of annotation in a particular situation: the markings students make in university-level textbooks. The study focuses on the form and function of these annotations, and their status within a community of fellow textbook readers. Using this study as a basis, I discuss issues and implications for the design of annotation tools for a digital library setting.

Collaborative systems provide a rich but potentially chaotic environment for their users. This paper presents a system that allows users to control collaboration by enacting policies that serve as general guidelines to restrict and define the behavior of the system in reaction to the state of the world. Policies are described in terms of access control rights on data objects, and are assigned to groups of users called roles. Roles represent not only statically-defined collections of users, but also dynamic descriptions of users that are evaluated as applications are run. This run-time aspect of roles allows them to react flexibly to the dynamism inherent in collaboration. We present a specification language for describing roles and policies, as well as a number of common "real-world" policies that can be applied to collaborative settings.

The ability to share synchronized views of interactions with an application is critical to supporting synchronous collaboration. This paper suggests a simple synchronous collaboration paradigm in which the sharing of the views of user/application interactions occurs at the window level within a multi-user, multi-window application. The paradigm is incorporated in a toolkit, DistView, that allows some of the application windows to be shared at a fine-level of granularity, while still allowing other application windows to be private. The toolkit is intended for supporting synchronous collaboration over wide-area networks. To keep bandwidth requirements and interactive response time low in such networks, DistView uses an object-level replication scheme, in which the application and interface objects that need to be shared among users are replicated. We discuss the design of DistVlew and present our preliminary experience with a prototype version of the system.

Abstract. The role of models in the design of computer systems to support interpersonal and cooperative work is examined. It is argued that the current generation of models over-emphasise determinism at the expense of interpretation in the work process. It is further argued that there are many cases in which designs pass between many different professional groups (office workers, managers, analysts, designers, programmers). Each of these groups has its own worldview and specialised language, and hence they are termed "semantic communities". When designs pass between semantic communities, something is lost and something is gained-- but the objects on which each community works are not commensurable. The distinct objects of work (office problems, analyses, designs, programs) do not map onto each other, and cannot be mutually tested using simple truelfalse criteria. This is termed a problem of "ontological drift", and arises whenever several distinct semantic communities work on the "same " system. It is suggested that the disparity so often observed between design expectations and the ways systems are actually used is therefore quite normal. Current efforts are directed at eliminating the disparity. We suggest that a more fruitful approach might be to accept that the final determination of a system rests with the users. In the long run this might give rise to different types of design principles than those used at the moment. In the short run, even the consciousness of this perspective could make significant differences to design dialogues and attitudes to "users".

This essay considers the problem of defining the context that context aware systems should pay attention to from a human perspective. In particular, we argue that there are human aspects of context that cannot be sensed or even inferred by technological means, so context aware systems cannot be designed simply to act on our behalf. Rather they will have to be able to defer to users in an efficient and non-obtrusive fashion. Our point is particularly relevant for systems that are constructed such that applications are architecturally isolated from the sensing and inferencing that governs their behavior. We propose a design framework that is intended to guide thinking about accommodating human aspects of context. This framework presents four design principles that support intelligibility of system behavior and accountability of human users and a number of human-salient details of context that must be accounted for in context aware system design.

This paper discusses a conceptual model of groupware consisting of three complementary components or models: a description of the objects and operations on these objects available in the system; a description of the activities (and their orderings) that the users of the system can perform; and a description of the interface of users with the system, and with other users. KEYWORDS: Groupware, CSCW, collaboration technology, system modelling, ontological model, coordination model, user interface model. INTRODUCTION This paper is concerned with technology mediated workgroup systems, also sometimes called CSCW systems or groupware. We take the broad definition of these terms, as presented by Schmidt and Bannon [16]. We present a conceptual model which is applicable to a wide range of groupware---from electronic meeting rooms, through video conferencing, to workflow systems. The issues raised by the model are sometimes similar to, but frequently distinct from single user systems issues. T...

Digital web-accessible annotations are a compelling medium for personal comments and shared discussions around documents. Only recently supported by widely used products, "in-context" digital annotation is a relatively unexamined phenomenon. This paper presents a case study of annotations created by members of a large development team using Microsoft Office 2000---approximately 450 people created 9,000 shared annotations on about 1250 documents over 10 months. We present quantitative data on use, supported by interviews with users, identifying strengths and weaknesses of the existing capabilities and possibilities for improvement. Keywords Annotation, asynchronous collaboration, distributed work, computer mediated communication, World Wide Web 1 INTRODUCTION Highlighting and writing comments in the margins as we read is a natural activity. These annotations are often personal notes for subsequent reference. When shared among co-workers they also support communication and collaborat...

objects define underlying data while view objects define how these data are viewed and manipulated by users. An abstract object is shared among a group of users by creating a view object for each of these users and defining constraints that keep the abstract object consistent with its view objects. Views of an abstract object are shared by making the associated view objects copies of a special sharing object. The access rights to the views of a sharing object are shared by making guards that authorize actions independent of the identity of the user that invokes the action. There are three main similarities between Rendezvous and Suite: First, like Suite it supports semantics, presentation, and access couplings 5 . Second, like Suite, Rendezvous supports a fine-grained coupling model that allows different view objects displayed to a user to be coupled differently with their counterparts displayed to other users. Third, the constraint mechanism supported by Rendezvous corresponds to th...

Asynchronous collaboration is characterized by the degree of independence collaborators have from one another. In particular, collaborators working asynchronously typically have little need for frequent and fine-grained coordination with one another, and typically do not need to be notified immediately of changes made by others to any shared artifacts they are working with. We present an infrastructure, called Bayou, designed to support the construction of asynchronous collaborative applications. Bayou provides a replicated, weakly-consistent, data storage engine to application writers. The system supports a number of mechanisms for leveraging application semantics; using these mechanisms, applications can implement complex conflict detection and resolution policies, and choose the level of consistency and stability they will see in their databases. We present a number of applications we have built or are building using the Bayou system, and examine how these take advantage of the Bayo...