The ability to rapidly locate useful on-line services (e.g. software applications, software components, process models, or service organizations), as opposed to simply useful documents, is becoming increasingly critical in many domains. Current service retrieval technology is, however, notoriously prone to low precision. This paper describes a novel service retrieval approached based on the sophisticated use of process ontologies. Our preliminary evaluations suggest that this approach offers qualitatively higher retrieval precision than existing (keyword and tablebased) approaches without sacrificing recall and computational tractability/scalability.

At first glance it seems absurd that busy people doing important jobs should want their computers to interrupt them. Interruptions are disruptive and people need to concentrate to make good decisions. However, successful job performance also frequently depends on people's abilities to (a) constantly monitor their dynamically changing information environments, (b) collaborate and communicate with other people in the system, and (c) supervise background autonomous services. These critical abilities can require people to simultaneously query a large set of information sources, continuously monitor for important events, and respond to and communicate with other human operators. Automated monitoring

People working collaboratively must establish and maintain awareness of one another's intentions, actions and results. Notification systems typically support awareness of the presence, tasks and actions of collaborators, but they do not adequately support awareness of persistent and complex activities. We analysed awareness breakdowns in use of our Virtual School system---stemming from problems related to the collaborative situation, group, task and tool support---to motivate the concept of activity awareness. Activity a areness builds on prior conceptions of social and action a areness, but emphasizes the importance of activity context factors like planning and coordination. This ork suggests design strategies for notification systems to better support collaborative activity.

Multi-agent systems... In this paper we introduce three additional organisational concepts - organisational rules, organisational structures, and organisational patterns - and discuss why we believe they are necessary for the complete specification of computational organisations. In particular, we focus on the concept of organisational rules and introduce a formalism, based on temporal logic, to specify them. This formalism is then used to drive the definition of the organisational structure and the identification of the organisational patterns. Finally, the paper sketches some guidelines for a methodology for agent-oriented systems based on our expanded set of organisational abstractions.

. Floor control allows users of networked multimedia applications to utilize and share resources such as remote devices, distributed data sets, telepointers, or continuous media such as video and audio without access conflicts. Floors are temporary permissions granted dynamically to collaborating users in order to mitigate race conditions and guarantee mutually exclusive resource usage. A general framework for floor control is presented. Collaborative environments are characterized and the requirements for realization of floor control will be identified. The differences to session control, as well as concurrency control and access control are elicited. Based upon a brief taxonomy of collaboration-relevant parameters, system design issues for floor control are discussed. Floor control mechanisms are discerned from service policies and principal architectures of collaborative systems are compared. The structure of control packets and an application programmer's interface are proposed and...

The term distributed computing conjures the image of a fixed network structure whose nodes support the execution of processes that communicate with each other via messages traveling along links. Peer-to-peer communication is feasible but client-server relationships dominate. More recently, servers have been augmented with brokerage capabilities to facilitate discovery of available services. Stability is the ideal mode of operation; changes are relatively slow; even in the case of failure, nodes and links are expected eventually to come back up. By contrast, mobility represents a total meltdown of all the stability assumptions (explicit or implicit) associated with distributed computing. The network structure is no longer fixed, nodes may come and go, processes may move among nodes, and even programs (the code executed by processes) may evolve and change structure. The challenges and opportunities associated with this computational melee form the main subject of this paper. We seek to sort out this chaotic form of computing by focusing our attention on the formulation of a simple framework for viewing mobility, on precise definition of terms, and on research issues mobility poses for the software engineering community. 1

. The notion of "time" plays an important role when coordinating

A critical challenge to creating effective agent-based systems is allowing them to operate effectively when the operating environment is complex, dynamic, and error-prone. In this paper we will review the limitations of current "agent-local" approaches to exception handling in agent systems, and propose an alternative approach based on a shared exception handling service that is "plugged", with little or no customization, into existing agent systems. This service can be viewed as a kind of "coordination doctor; it knows about the different ways multi-agent systems can get "sick", actively looks system-wide for symptoms of such illnesses, and prescribes specific interventions instantiated for this particular context from a body of general treatment procedures. Agents need only implement their normative behavior plus a minimal set of interfaces. We claim that this approach offers simplified agent development as well as more effective and easier to modify exception handling behavior.

The metaphors of autonomous agents and agent societies havethepotential to make a signi cant impact on the processes of analysis, design, and development of complex software systems on the Internet. In this chapter, we concentrate predominantly on agent societies, and show howwork on coordination models and technologies provides apowerful framework for the engineering of Internet-based, multi-agent systems. First, we introduce the concepts of agent, multi-agent system, and agent-oriented software engineering, and highlight the speci c issues that arise when we take the Internet as the environment thatagents inhabit. We thenprovide a brief survey of the state of the art in the area of agent-oriented methodologies, paying particular attention to the Gaia methodology for agent-oriented analysis and design. Gaia was originally conceived for benevolent agents inhabiting closed systems. However, to broaden its scope, we show how insights from the area of coordination models can be incorporated in order to make it more suitable for developing Internet-based applications.

In this article we consider the ways in which visual information is used as a conversational resource in the accomplishment of collaborative physical tasks. We focus on the role of visual information in maintaining task awareness and in achieving mutual understanding in conversation. We first describe the theoretical framework we use to analyze the role of visual information in physical collaboration. Then, we present two experiments that vary the amount and quality of the visual information available to participants during a collaborative bicycle repair task. We examine the effects of this visual information on performance and on conversational strategies. We conclude with a general discussion of how situational awareness and conversational grounding are achieved in collaborative repair and with some design considerations for systems to support remote collaborative repair.