Event-Oriented Dynamic Adaptation of Workflows: Model, Architecture and Implementation

Workflow management is widely accepted as a core technology to support long-term business processes in heterogeneous and distributed environments. However, conventional workflow management systems do not provide sufficient flexibility support to cope with the broad range of failure situations that may occur during workflow execution. In particular, most systems do not allow to dynamically adapt a workflow due to a failure situation, e.g., to dynamically drop or insert execution steps. As a contribution to overcome these limitations, this dissertation introduces the agent-based workflow management system AgentWork. AgentWork supports the definition, the execution and, as its main contribution, the event-oriented and semi-automated dynamic adaptation of workflows. Two strategies for automatic workflow adaptation are provided. Predictive adaptation adapts workflow parts affected by a failure in advance (predictively), typically as soon as the failure is detected. This is advantageous in many situations and gives enough time to meet organizational constraints for adapted workflow parts. Reactive adaptation is typically performed when predictive adaptation is not possible. In this case, adaptation is performed when the affected workflow part is to be executed, e.g., before an activity is executed it is checked whether it is subject to a workflow adaptation such as dropping, postponement or replacement. In particular, the following contributions are provided by AgentWork: A Formal Model for Workflow Definition, Execution, and Estimation: In this context, AgentWork first provides an object-oriented workflow definition language. This language allows for the definition of a workflow\u92s control and data flow. Furthermore, a workflow\u92s cooperation with other workflows or workflow systems can be specified. Second, AgentWork provides a precise workflow execution model. This is necessary, as a running workflow usually is a complex collection of concurrent activities and data flow processes, and as failure situations and dynamic adaptations affect running workflows. Furthermore, mechanisms for the estimation of a workflow\u92s future execution behavior are provided. These mechanisms are of particular importance for predictive adaptation. Mechanisms for Determining and Processing Failure Events and Failure Actions: AgentWork provides mechanisms to decide whether an event constitutes a failure situation and what has to be done to cope with this failure. This is formally achieved by evaluating event-condition-action rules where the event-condition part describes under which condition an event has to be viewed as a failure event. The action part represents the necessary actions needed to cope with the failure. To support the temporal dimension of events and actions, this dissertation provides a novel event-condition-action model based on a temporal object-oriented logic. Mechanisms for the Adaptation of Affected Workflows: In case of failure situations it has to be decided how an affected workflow has to be dynamically adapted on the node and edge level. AgentWork provides a novel approach that combines the two principal strategies reactive adaptation and predictive adaptation. Depending on the context of the failure, the appropriate strategy is selected. Furthermore, control flow adaptation operators are provided which translate failure actions into structural control flow adaptations. Data flow operators adapt the data flow after a control flow adaptation, if necessary. Mechanisms for the Handling of Inter-Workflow Implications of Failure Situations: AgentWork provides novel mechanisms to decide whether a failure situation occurring to a workflow affects other workflows that communicate and cooperate with this workflow. In particular, AgentWork derives the temporal implications of a dynamic adaptation by estimating the duration that will be needed to process the changed workflow definition (in comparison with the original definition). Furthermore, qualitative implications of the dynamic change are determined. For this purpose, so-called quality measuring objects are introduced. All mechanisms provided by AgentWork include that users may interact during the failure handling process. In particular, the user has the possibility to reject or modify suggested workflow adaptations. A Prototypical Implementation: Finally, a prototypical Corba-based implementation of AgentWork is described. This implementation supports the integration of AgentWork into the distributed and heterogeneous environments of real-world organizations such as hospitals or insurance business enterprises

Recent advances in petri nets and concurrency

CEUR Workshop Proceeding

Continuation-Passing Enactment of Distributed Recoverable Workflows

Abstract. Scalability, reliability and adaptability are among the key requirements for the enactment of distributed workflows. In addition, system resources should be efficiently utilized. Central workflow engines and static analysis of workflow specifications are some of the important obstacles to meeting these requirements. We propose a fully decentralized approach to workflow enactment that is not subject to these obstacles. In addition, it supports automatic recovery. The approach is of continuation-passing style, where continuations, or the reminder of the executions, are passed along with asynchronous messages for workflow enactment. Two continuations are associated to an execution: a success continuation and a failure continuation. Recovery plans for workflows are automatically generated at runtime and included in failure continuations. A prototype is implemented.

What is 'digital literacy'? A Pragmatic investigation.

Digital literacy has been an increasingly-debated and discussed topic since the publication of Paul Gilster’s seminal Digital Literacy in 1997. It is, however, a complex term predicated on previous work in new literacies such as information literacy and computer literacy. To make sense of this complexity and uncertainty I come up with a ‘continuum of ambiguity’ and employ a Pragmatic methodology. This thesis makes three main contributions to the research area. First, I argue that considering a plurality of digital literacies helps avoid some of the problems of endlessly-redefining ‘digital literacy’. Second, I abstract eight essential elements of digital literacies from the research literature which can lead to positive action. Finally, I argue that co-constructing a definition of digital literacies (using the eight essential elements as a guide) is at least as important as the outcome

Deep Time Iterations: Familiarity, Horizons, and Pattern Among Finland's Nuclear Waste Safety Experts

This ethnography reconsiders nuclear waste risk’s deep time horizons’ often-sensationalized aesthetics of horror, sublimity, and awe. It does so by tracking how Finland’s nuclear energy and waste experts made visions of distant future Finlands appear more intelligible through mundane corporate, regulatory, financial, and technoscientific practices. Each chapter unpacks how informants iterated and reiterated traces of the very familiar to establish shared grounds of continuity for moving forward in time. Chapter 1 explores how Finland’s energy sector’s “mankala” cooperative corporate form was iterated and reiterated to give shape to political and financial time horizons. Chapter 2 explores how workplace role distinctions between recruit/retiree and junior/senior were iterated and reiterated to reckon nuclear personnel successions’ intergenerational horizons. Chapter 3 explores how input/output and part/whole distinctions were iterated and reiterated to help model distant future worlds in a portfolio of “Safety Case” evidence made to demonstrate the Olkiluoto repository’s safety to Finnish nuclear regulator STUK. Chapter 4 explores how Safety Case experts iterated and reiterated memories of a deceased predecessor figure in everyday engagements with deep time. What emerges are three insights about how futures attain discernible features – insights about the “continuity,” “thinkability,” and “extensibility” of expert thought – that, I argue, can help twenty-first century experts better navigate not only deep time, but also unknown futures of nuclear technologies, planetary environment, and expertise itself

Video Vortex reader : responses to Youtube

The Video Vortex Reader is the first collection of critical texts to deal with the rapidly emerging world of online video – from its explosive rise in 2005 with YouTube, to its future as a significant form of personal media. After years of talk about digital convergence and crossmedia platforms we now witness the merger of the Internet and television at a pace no-one predicted. These contributions from scholars, artists and curators evolved from the first two Video Vortex conferences in Brussels and Amsterdam in 2007 which focused on responses to YouTube, and address key issues around independent production and distribution of online video content. What does this new distribution platform mean for artists and activists? What are the alternatives

Technē/Technology:Researching Cinema and Media Technologies - Their Development, Use, and Impact

Technē/Technology is the up-to-date critical volume on the theories, philosophies, and debates on technology and their productivity for the fields of film and media studies. Comprehensive as well as innovative, it is not organised around a single thesis - except the assertion that technique is a major concern for film and media scholars, whether this is approached in terms of philosophy, techno-aesthetics, semiotics, apparatus theory, (new) film history, media archaeology, the industry or the sensory / cognitive experiences. Technē/Technology deliberately includes contributions by film and media experts working in very different ways on a wide range of technology-related issues. A major questions to be addressed in this book is how the new philosophies (of technology) created in relation to major technological transformations - such as the new philosophies of (media) technology formulated by Benjamin, Heidegger, McLuhan, Kittler, or Stiegler - could or did contribute in turn to the modification of film theory and some of its key concepts