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Workflow Evolution
- Data and Knowledge Engineering
, 1996
"... A basic step towards flexibility in workflow systems is the consistent and effective management of workflow evolution, i.e., of changing existing workflows while they are operational. In this area, the most challenging issue is the handling of running instances when their schema is modified: simple ..."
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Cited by 207 (3 self)
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A basic step towards flexibility in workflow systems is the consistent and effective management of workflow evolution, i.e., of changing existing workflows while they are operational. In this area, the most challenging issue is the handling of running instances when their schema is modified: simple solutions can be devised, but these often imply loosing all the work done or failing in capturing the advantages offered by workflow modifications; this is unacceptable for many applications. In this paper we address the problem of workflow evolution, from both a static and a dynamic point of view. We define a complete, minimal, and consistent set of modification primitives that allow modifications of workflow schemata and we introduce a taxonomy of policies to manage evolution of running instances when the corresponding workflow schema is modified. Formal criteria are introduced, based on a simple workflow conceptual model, in order to determine which running instances can be transparently...
Analyzing process models using graph reduction techniques
- INFORMATION SYSTEMS
, 2000
"... The foundation of a process model lies in its structural specifications. Using a generic process modeling language for workflows, we show how a structural specification may contain deadlock and lack of synchronization conflicts that could compromise the correct execution of workflows. In general, i ..."
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Cited by 127 (4 self)
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The foundation of a process model lies in its structural specifications. Using a generic process modeling language for workflows, we show how a structural specification may contain deadlock and lack of synchronization conflicts that could compromise the correct execution of workflows. In general, identification of such conflicts is a computationally complex problem and requires development of effective algorithms specific for the target modeling language. We present a visual verification approach and algorithm that employs a set of graph reduction rules to identify structural conflicts in process models for the given workflow modeling language. We also provide insights into the correctness and complexity of the reduction process. Finally, we show how the reduction algorithm may be used to count possible instance subgraphs of a correct process model. The main contribution of the paper is a new technique for satisfying well-defined correctness criteria in process models.
Actor-Oriented Design of Scientific Workflows
- In 24st Intl. Conference on Conceptual Modeling
, 2005
"... Scientific workflows are becoming increasingly important as a unifying mechanism for interlinking scientific data management, analysis, simulation, and visualization tasks. Scientific workflow systems are problem-solving environments, supporting scientists in the creation and execution of scienti ..."
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Cited by 67 (21 self)
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Scientific workflows are becoming increasingly important as a unifying mechanism for interlinking scientific data management, analysis, simulation, and visualization tasks. Scientific workflow systems are problem-solving environments, supporting scientists in the creation and execution of scientific workflows.
Tolerating Deviations in Process Support Systems Via Flexible Enactment of Process Models
"... Process Support Systems (PSSs) support business organizations in modeling, improving, and automating their business process. Thanks to their ability in enacting process models, they can be used to guide people in performing their daily work and to automate the repetitive tasks that do not require hu ..."
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Cited by 57 (5 self)
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Process Support Systems (PSSs) support business organizations in modeling, improving, and automating their business process. Thanks to their ability in enacting process models, they can be used to guide people in performing their daily work and to automate the repetitive tasks that do not require human intervention. Given these potential benefits, it is surprising to observe that PSSs are not widely adopted. This is especially true in case of highly flexible and human-intensive processes such as design processes in general and software processes in particular. This fact can be explained by observing that currently available PSSs do not fulfill some crucial needs of modern business organizations. One of their major drawbacks is that they do not offer adequate mechanisms to cope with unforeseen situations. They are good at supporting business processes if all proceeds as expected, but if an unexpected situation is met, which would require to deviate from the process model, they often bec...
Verification Problems in Conceptual Workflow Specifications
- Data and Knowledge Engineering
, 1996
"... Most of today's business requirements can only be accomplished through integration of various autonomous systems which were initially designed to serve the needs of particular applications. In the literature workflows are proposed to design these kinds of applications. The key tool for designin ..."
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Cited by 48 (9 self)
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Most of today's business requirements can only be accomplished through integration of various autonomous systems which were initially designed to serve the needs of particular applications. In the literature workflows are proposed to design these kinds of applications. The key tool for designing such applications is a powerful conceptual specification language. Such a language should be capable of capturing interactions and cooperation between component tasks of workflows among others. These include sequential execution, iteration, choice, parallelism and synchronisation. The central focus of this paper is the verification of such process control aspects in conceptual workflow specifications. As it is generally agreed upon that the later in the software development process an error is detected, the more it will cost to correct it, it is of vital importance to detect errors as early as possible in the systems development process. In this paper some typical verification problems in work...
An Alternative Way to Analyze Workflow Graphs
- Proceedings of the 14th International Conference on Advanced Information Systems Engineering (CAiSE’02), volume 2348 of Lecture Notes in Computer Science
, 2002
"... At the CAiSE conference in Heidelberg in 1999, Wasim Sadiq and Maria Orlowska presented an algorithm to verify workflow graphs [19]. The algorithm uses a set of reduction rules to detect structural conflicts. This paper shows that the set of reduction rules presented in [19]isnot complete and propos ..."
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Cited by 41 (7 self)
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At the CAiSE conference in Heidelberg in 1999, Wasim Sadiq and Maria Orlowska presented an algorithm to verify workflow graphs [19]. The algorithm uses a set of reduction rules to detect structural conflicts. This paper shows that the set of reduction rules presented in [19]isnot complete and proposes an alternative algorithm. The algorithm translates workflow graphs into so-called WF-nets. WF-nets are a class of Petri nets tailored towards workflow analysis. As a result, Petri-net theory and tools can be used to verify workflow graphs. In particular, our workflow verification tool Woflan [21] can be used to detect design errors. It is shown that the absence of structural conflicts, i.e., deadlocks and lack of synchronization, conforms to soundness of the corresponding WF-net [2]. In contrast to the algorithm presented in [19], the algorithm presented in this paper is complete. Moreover, the complexity of this alternative algorithm is given. 1
Beyond the Black Box: Event-based Inter-Process Communication in Process Support Systems
- In Proc. of the 19th Intl. Conference on Distributed Computing Systems
, 1999
"... Existing workflow management systems encapsulate the data and behavior of a process within its execution scope, preventing other processes from accessing this information until the process terminates. There are, however, many situations in which allowing running processes to exchange information wou ..."
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Cited by 34 (8 self)
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Existing workflow management systems encapsulate the data and behavior of a process within its execution scope, preventing other processes from accessing this information until the process terminates. There are, however, many situations in which allowing running processes to exchange information would be a great help to speed up processing time, improve service quality, and increase customer satisfaction. This paper describes the concept and implementation of an inter-process-communication facility based on the exchange of events between concurrently running processes. In contrast to previous approaches based on shared data stored in a common database, our approach has the advantage of being platform independent and providing straightforward support for distribution. In addition, we also explore the problem of process atomicity and consistency when events are revoked due to the abort of processes. The paper presents a family of recovery protocols that allow to control the effects of ab...
Comparing Petri Net and Activity Diagram Variants for Workflow Modelling - A Quest for Reactive Petri Nets
- In Weber et al
, 2002
"... Petri net variants are widely used as a workflow modelling technique. Recently, UML activity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets ..."
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Cited by 32 (4 self)
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Petri net variants are widely used as a workflow modelling technique. Recently, UML activity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets and on the surface, one may think that they are variants of each other. To substantiate or deny this claim, we need to formalise the intended semantics of activity diagrams and then compare this with various Petri net semantics. In previous papers we have defined two formal semantics for UML activity diagrams that are intended for workflow modelling. In this paper, we discuss the design choices that underlie these two semantics and investigate whether these design choices can be met in low-level and high-level Petri net semantics. We argue that the main di#erence between the Petri net semantics and our semantics of UML activity diagrams is that the Petri net semantics models resource usage of closed, active systems that are non-reactive, whereas our semantics of UML activity diagrams models open, reactive systems.
UML Activity Diagrams as a Workflow Specification Language
, 2001
"... . If UML activity diagrams are to succeed as a standard in the area of organisational process modeling, they need to compare well to alternative languages such as those provided by commercial Workflow Management Systems. This paper examines the expressiveness and the adequacy of activity diagram ..."
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Cited by 29 (1 self)
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. If UML activity diagrams are to succeed as a standard in the area of organisational process modeling, they need to compare well to alternative languages such as those provided by commercial Workflow Management Systems. This paper examines the expressiveness and the adequacy of activity diagrams for workflow specification, by systematically evaluating their ability to capture a collection of workflow patterns. This analysis provides insights into the relative strengths and weaknesses of activity diagrams. In particular, it is shown that, given an appropriate clarification of their semantics, activity diagrams are able to capture situations arising in practice, which cannot be captured by most commercial Workflow Management Systems. On the other hand, the study shows that activity diagrams fail to capture some useful situations, thereby suggesting directions for improvement. 1
