Qingtian Zeng

Conflict detection and resolution for workflows constrained by resources and non-determined durations

The correctness of a workflow specification is critical for the automation of business processes. Therefore, errors in the specification should be detected and corrected at build-time. In this paper, we present a conflict verification and resolution approach for a kind of workflow constrained by resources and non-determined duration based on Petri net. In this kind of workflow, there are two timing functions for each activity to present the minimum and maximum duration of each activity, and the implementations of some activities require resources. Based on the Petri net model obtained, the earliest time to start each activity can be calculated and the key activities influencing the implementation of the workflow can be determined, with which the resource consistency between activities can be verified. Key-activity and waiting-short priority strategies are adopted to remove the resource conflicts between activities, which can ensure that most of the subsequent activities start as early as possible and that the whole workflow be finished in a shorter time. Through experiments, it is proved that the proposed removal strategy for resource conflicts is better than other strategies.

Process-Mining-Based Workflow Model Fragmentation for Distributed Execution

A complex workflow is often executed by geographically dispersed partners or different organizations. As a solution for dealing with the decentralized nature of workflow applications, a workflow can be fragmented into small pieces and scheduled to different servers for its execution. An important challenge in distributed workflows is to optimize the fragmentation and distribution to achieve efficiency with respect to time and server resources. To tackle this challenge, we propose the application of process mining to the fragmentation of a workflow for distributed execution. The workflow model discovered through process mining records the actual execution of a workflow and allows in-depth analysis of its temporal behavior. Based on examination of the model resulting from process mining, we demonstrate how to determine the minimum time to finish a workflow and how to partition the workflow in order to achieve efficient server usage.

Cross-organizational collaborative workflow mining from a multi-source log

Todays enterprise business processes become increasingly complex given that they are often executed by geographically dispersed partners or different organizations. Designing and modeling such a cross-organizational workflow is a complicated, time-consuming process and requires that a designer has extensive experience. Workflow logs captured by different cross-organizational systems provide a very valuable source of information on how business processes are executed in reality and thus can be used to derive workflow models through process mining. In this paper, we investigate the application of process mining for workflow integration based on the concept of RM_WF_Net, a type of Petri net extended with resource and message factors. Four coordination patterns are defined for workflow integration. A process mining approach is presented to discover the coordination patterns between different organizations and the workflow models in different organizations from the running logs containing the information about resource allocation. A process integration approach is then presented to obtain the model for a cross-organizational workflow based on the model mined for each organization and the coordination patterns between different organizations.

Modeling and Verification for Cross-Department Collaborative Business Processes Using Extended Petri Nets

Recently, cross-department business processes are becoming more and more complex. Different kinds of coordination patterns exist among different departments, which make modeling and analysis work more difficult. To our best knowledge, there is no formal method to give systematic modeling and verification for the cross-department processes when considering different kinds of coordination patterns among different departments. This paper proposes such a method based on Petri nets. The WF-net model extended with resource and message factors, RM_WF_Net for short, is first introduced. Then, the formal model of tasks is proposed and its coordination relations are given. Next, RM_WF_Net modeling for intradepartment processes is investigated and cross-department coordination patterns, including message interaction pattern, resource interaction pattern, task collaboration pattern, procedure abstract, service outsourcing pattern, and process activation pattern, are formally defined. The soundness of the RM_WF_Net is verified based on the reachability graph. A running case of the cross-department medical diagnosis business process is given to validate our proposed method.

Classification and evaluation of timed running schemas for workflow based on process mining

The system running logs of a workflow contain much information about the behavior and logical structure between activities. In this paper, a mining approach is proposed to discover the structural and temporal model for a workflow from its timed running logs. The mining results are represented in the formalized form of Petri nets extended with two timing factors that allows validation or verification the actual behaviors, especially the temporal constraints between activities. According to the reachability graph of the extended Petri net model mined, all running schemas of a workflow can be generated, which defines the temporal constraints between running activities. By calculating the earliest and latest start time of each activity, the earliest starting and latest existing time of each state in the running schema can be determined. Based on the temporal relations between the timing factors of each running state, the running schemas can be classified into six classes. The effects of the six classes of running schemas on the implementation of the whole workflow are evaluated so as to obtain the best one that can ensure the workflow is finished in the shortest time. The standards for the ideal, reliable and favorable running schemas and their existence conditions are discussed, which can be used to evaluate the running logs and control the future running of a workflow.

Hierarchy Modeling and Formal Verification of Emergency Treatment Processes

Petri nets are suitable for modeling and analysis of business processes. However, the lack of data concepts often makes Petri-net-based models excessively large and difficult to analyze especially when process logic is sensitive to changes of process attribute values. Emergency treatment processes are a typical example of this situation. To solve the aforementioned problems, this paper proposes a new hierarchical Petri net model for modeling and verification of emergency treatment processes. The hierarchical Petri net model includes three separate but closely related models, i.e., a business process logic net, a business process semantic net, and a set of case models. Business process logic nets are used to model the task dependencies disregarding semantic information. Business process semantic nets introduce data concepts to business process logic nets to model semantic information such as process attributes or conditions of sequence flows. Case models are used to model the practical routes of specific business instances. Based on the three models, a formal verification algorithm of an emergency treatment process is presented. Finally, the hierarchical modeling and verification methods are validated by an emergency treatment process of highways under snow/ice weather conditions.

Synchronization-Core-Based Discovery of Processes with Decomposable Cyclic Dependencies

Traditional process discovery techniques mine process models based upon event traces giving little consideration to workflow relevant data recorded in event logs. The neglect of such information usually leads to incorrect discovered models, especially when activities have decomposable cyclic dependencies. To address this problem, the recorded workflow relevant data and decision tree learning technique are utilized to classify cases into case clusters. Each case cluster contains causality and concurrency activity dependencies only. Then, a set of activity ordering relations are derived based on case clusters. And a synchronization-core-based process model is discovered from the ordering relations and composite cases. Finally, the discovered model is transformed to a BPMN model. The proposed approach is validated with a medical treatment process and an open event log. Meanwhile, a prototype system is presented.

Resource conflict detection and removal strategy for nondeterministic emergency response processes using Petri nets

Correctness of an emergency response process specification is critical to emergency mission success. Therefore, errors in the specification should be detected and corrected at build-time. In this paper, we propose a resource conflict detection approach and removal strategy for emergency response processes constrained by resources and time. In this kind of emergency response process, there are two timing functions representing the minimum and maximum execution time for each activity, respectively, and many activities require resources to be executed. Based on the RT_ERP_Net, the earliest time to start each activity and the ideal execution time of the process can be obtained. To detect and remove the resource conflicts in the process, the conflict detection algorithms and a priority-activity-first resolution strategy are given. In this way, real execution time for each activity is obtained and a conflict-free RT_ERP_Net is constructed by adding virtual activities. By experiments, it is proved that the resolution strategy proposed can shorten the execution time of the whole process to a great degree.

Petri Net Based Behavior Description of Cross-Organization Workflow with Synchronous Interaction Pattern

Today’s workflow systems are crossing organizational boundaries and usually involve multiple organizations or partners, and the cross-organization workflow has received much public attention from both the academia and the industry. This way the property analysis as well as system control for a cross-organization workflow is very important. In this paper, we focus on a kind of loosely coupled workflow architecture with synchronous interaction pattern, i.e. each organization owns its private workflow process and can operate independently, and they need to synchronize through certain tasks. Its behavior description approach is obtained using the synchronized shuffle operation of Petri net language. It is proved that our approach benefits the behavior characterization of cross-organizational workflow with synchronous interaction pattern and can be further used to decide and control the fairness, liveness, deadlock and trap for the cross-organization workflow. A running case of cross-organizational medical diagnosis workflow is given to validate our approaches throughout the whole paper.

LogRank: An Approach to Sample Business Process Event Log for Efficient Discovery.

Considerable amounts of business process event logs can be collected by modern information systems. Process discovery aims to uncover a process model from an event log. Many process discovery approaches have been proposed, however, most of them have difficulties in handling large-scale event logs. Motivated by PageRank, in this paper we propose LogRank, a graph-based ranking model, for event log sampling. Using LogRank, a large-scale event log can be sampled to a smaller size that can be efficiently handled by existing discovery approaches. Moreover, we introduce an approach to measure the quality of a sample log with respect to the original one from a discovery perspective. The proposed sampling approach has been implemented in the open-source process mining toolkit ProM. The experimental analyses with both synthetic and real-life event logs demonstrate that the proposed sampling approach provides an effective solution to improve process discovery efficiency as well as ensuring high quality of the discovered model.