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

Un método computacional para la detección y caracterización de conflictos en redes de Petri

En este artículo se presenta un método que permite detectar la presencia deconflictos en modelos construidos con base en el formalismo matemático de lasRedes de Petri. Se muestra cómo mediante la aplicación de un algoritmo que tomacomo datos de entrada la representación matricial de una red, es posible detectar laexistencia de conflictos y caracterizar su tipo, identificando, además, el conjunto deelementos que los presentan. La utilización del método propuesto se ilustra usandouna Red de Petri Ordinaria

Recent advances in petri nets and concurrency

CEUR Workshop Proceeding

Construction Workflow and Document Diagnostics

This research aims to determine if there is sufficient information encoded within construction workflow histories and document meta-data that may be exploited for the development of knowledge constructs such as diagnosis, thereby contributing to the body of knowledge of automation in construction, with a focus on advanced construction information systems. Electronic Product and Process Management [EPPM] systems provide the capability to establish and map information flow between different parties in a construction project as well as to model project processes. The wealth of information contained in an EPPM system can be exploited to extract knowledge that can provide significant benefits to construction companies. Much of the information relating to processes and their structure, the actors (people and machines) that operate them, and the data associated with each instance of a process is encapsulated within workflows. Workflows, therefore, provide an ideal medium for the capture of knowledge over the course of a project lifecycle. Project managers have recognized that workflows provide greater visibility and help enforce stricter compliance standards for project processes. While workflows do facilitate process compliance by ensuring constituent tasks are executed as per ordered definitions, the compliance of these individual tasks and their impact on the compliance of the workflow has not been explored. A framework has been developed to address stricter quality control by capturing knowledge of the execution times of work-items, which was then used as a basis for filtering workflows that may violate compliance norms. This significantly reduces the number of workflow instances that would need to be analyzed in detail during an audit. The framework was applied to a case study of a construction project located in British Columbia and validated. In an ideal EPPM system, the workflow engine would operate silently and seamlessly in the background, automating structured information exchange from the start to the end of a project. In reality, most workflows used in construction projects are of a semi-automated nature requiring manual involvement for tasks ranging from selection of participants to delegation of actors. An adaptive algorithm that is able to recognize and incorporate emergent patterns from prior executed workflow instances and also determine the relative availability of resources can greatly improve the performance of a workflow implementation by reducing its semi-automated nature. An algorithm was developed to demonstrate how a self-adapting workflow methodology could be applied to construction workflows, and two specific cases based on data from a construction project were analyzed showing promising results in terms of time savings. During a construction project, it is important to ensure that accurate and pertinent knowledge is delivered on time to appropriate personnel. Determining the criticality of documents at different stages of the project can aid companies with managing the flow of information in an organized manner, while providing for the detection of potentially disruptive, erroneous material that could result in delays and costs. An algorithm was designed based upon the meta-data and access interaction logs associated with documents in an EPPM system to identify critical documents. A scenario based on a real event and real data was developed on an EPPM system implementation and a simulation was conducted to determine the applicability of the algorithm and demonstrate its effectiveness. It is concluded that there is sufficient information encoded within construction workflow histories and document meta-data that may be exploited for the development of knowledge constructs such as diagnosis. Diagnosis based knowledge was used to discriminate between executed behavior and planned behavior to aid compliance checking. Analysis of workflow histories resulted in the development of patterns in workflows which demonstrated time savings if implemented as self-adapting workflows