In this paper, a formal basis for multimedia collaborations is proposed. The formal basis establishes a precise mathematical framework for supporting a wide spectrum of structured collaborative tasks, ranging from simple meetings and conferences to classrooms and examinations, and from corporate negotiations, work flow tasks, and team design endeavors to courtroom hearings. We mechanize three levels of abstraction: streams at the lowest level, for media communication, sessions at the next level, which represent collections of semantically related media streams, and conferences, which represent temporally related sequences of sessions. The mathematical framework has been mechanized in Prototype Verification System (PVS) from SRI International. The mechanization allows us to experiment with different formal models, and reason about properties of multimedia collaborations efficiently. The mechanized framework supports unification of both interactive and non-interactive collaborations, so...

this paper, we will present some novel ideas on workflow modularity and reusability in different contexts, and how transactional features can still be incorporated into workflow techniques in such a way that they better serve as integrating technology on top of legacy systems. For the purpose of this paper, we assume that the environment consists of a global and a local level. The global level supports the process modeling and execution through workflows and the local level supports existing legacy applications and databases. In the sequel, we focus on the global level workflows only. We perceive a workflow as a collection of tasks organized to accomplish a complex activity. Work-

. Workflow management techniques have become an intensive area of research in information systems. In large scale workflow systems modularity and reusability of existing task structures with context dependent (parametrized) task execution are essential components of a successful application. In this paper we study the issues related to management of overlapping transactional workflows, i.e., workflows that share component tasks and thus avoid redundancy in design. The notion of parametrized transactional properties of workflow tasks is introduced and analyzed, and the underlying implementation mechanism based on Event/Condition/Action (ECA) rules is discussed. 1 Introduction Workflow management techniques have become one of the most exciting areas of research in information systems. The underlying concepts have been around in various forms for a long time, however, only recently the know how to implement commercial systems has been available. Modern business applications are usually c...

Floor control in synchronous groupware is the problem of how, when, and why participants interact in a shared computing environment while working simultaneously on common tasks. This thesis contends that floor control is a broader problem in synchronous groupware than has been seen by previous approaches, which have relied on narrow interpretations of the problem, and advocates a view of floor control that takes into account the role of floor control not only in managing conflicts but also in structuring a group and its communications. This view is supported by a descriptive model of floor control, referred to as G/TS/PAC (Group/Turn System/Perceive--Act--Cycle), which represents floor control as a process of communicating detailed floor control intent among participants. It is derived from a social--psychological model of turn--taking in conversation and a model of human--machine interaction, and generalizes those models in the context of synchronous groupware. G/TS/PAC represents fl...

Many organizational problems can be decomposed into nearly independent subproblems the solution of which is the responsibility of independent agents. In this kind of work, which we call distributed work, the problems are only nearly independent since dependencies exist between the comlllitinents required from each agent. As a consequence of these dependencies, the coordination problelll becoines one of maintaining a consistent global solution in the face of the possibly conflicting activities of each agent. We define a normative model for coordination pr~t~ocols that indicates the formal requirements for maintaining a globally consistent solution. The model identifies several properties that the protocol must enforce, namely serializability, atomiczty, conzplete~iess, and soundness. We show that these properties are desirable in coordination protocols for distributed work problems. 1