Design of a Petri Net-Based Workflow Engine

European journal of operational research, 2001

Despite their wide range of applications, work¯ow systems still suer from lack of an agreed and standard modelling technique. It is a motivating research area and some researchers have proposed dierent modelling techniques. Petri nets, among the other techniques, are one of the mainly used modelling techniques for both qualitative and quantitative analysis of work¯ow and work¯ow systems. We have brie¯y presented a way of mapping work¯ow into Petri nets, which can be used as a basis for such systems. A lot of available papers on Petri net-based modelling of work¯ow have been reviewed and classi®ed. Ó

Lecture Notes in Computer Science, 2003

Petri nets are widely used for modeling and analyzing workflows. Using the token-game semantics, Petri net-based workflow models can be analyzed before the model is actually used at run time. At run time, a workflow model prescribes behavior of a reactive system (the workflow engine). But the token-game semantics models behavior of closed, active systems. Thus, the token-game semantics behavior of a Petri net-based workflow model will differ considerably from its behavior at run time. In this paper we define a reactive semantics for Petri nets. This semantics can model behavior of a reactive system and its environment. We compare this semantics with the token-game semantics and prove that under some conditions the reactive semantics and the token-game semantics induce similar behavior. Next, we apply the reactive semantics to workflow modeling and show how a workflow net can be transformed into a reactive workflow net. We prove that under some conditions the soundness property of a workflow net is preserved when the workflow net is transformed into a reactive workflow net. This result shows that to analyze soundness, the token-game semantics can safely be used, even though that semantics is not reactive.

Proceedings of the Fourth Workshop on the Practical Use of Coloured Petri Nets and CPN Tools (CPN 2002), 2002

Contemporary workflow management systems are driven by explicit process models, i.e., a completely specified workflow design is required in order to enact a given workflow process. Creating a workflow design is a complicated time-consuming process which is often hampered by the limitations of the workflow language being used. To identify the differences between the various languages, we have collected a fairly complete set of workflow patterns. Based on these patterns we have evaluated 15 workflow products and detected considerable differences in expressive power. Languages based on Petri nets perform better when it comes to state-based workflow patterns. However, some patterns (e.g. involving multiple instances, complex synchronizations or non-local withdrawals) are not easy to map onto (high-level) Petri nets. These patterns pose interesting modeling problems and are used for developing the Petri-net-based language YAWL (Yet Another Workflow Language).

Grid and Services Evolution, 2009

Scientific workflows are becoming increasingly important as a vehicle for enabling science at a large scale. Lately, many Workflow Management Systems (WfMSs) have been introduced in order to support the needs of several scientific fields, such as bioinformatics and cheminformatics. However, no platform is practically capable to address the computational power and storage capacity provided by production Grids needed by complex scientific processes. In this paper, we introduce a novel design for a WfMS which has been proposed inside the CoreGRID project. Based on the micro-kernel design pattern, we have developed a lightweight Petri Net engine where complex functionalities -such as the interaction towards Grid middlewares -are provided at higher-level and described by means of Petri Net-based workflows. As the interaction with resources is described by workflows, it is possible to extend our platform by programming it using the Grid Workflow Description Language (GWorkflowDL).

IEEE Transactions on Systems, Man, and Cybernetics: Systems, 2015

In this paper, a robust and as simple as possible concept of a Petri net (PN) computer is proposed. It has a similar structure and behavior to weak sound priority workflow nets. It is shown that all recursive functions are PN computable and, vice-versa, PN computable functions are recursive. This shows that the PN computers we have proposed have exactly the power of Turing machines. Complexity classes of PN computable functions are defined, and the relationship between them and similar complexity classes defined by counter machines is investigated. Finally, the close relationship between PN computers and weak sound (priority) workflow nets is investigated.

Grid computing refers to the deployment of a widely distributed architecture for the execution of computationally challenging tasks. The grid provides a set of distributed resources which can be used for "computing on demand" or for constructing a "virtual supercomputer". Recently, several researchers started to look at the relation between workflow management and grid computing. The flow of work through a grid can be seen as a classical "workflow". However, as opposed to the classical workflows, the resources are not humans and are not managed by some centralized client-server architecture. Instead, the grid is highly distributed and the resources are computing power, memory, etc. Currently, there is no conceptual framework for grid computing and the role of workflows in grids is unclear. This paper provides initial steps towards a conceptual framework expressed in terms of Colored Petri Nets. CPN Tools is used to model grids while focusing on the workflow aspects. The resulting model can be analyzed to detect deadlocks, etc. The framework is illustrated using process mining as an application.

2003

A top-down approach for workflow design is proposed in the framework of Petri net theory. Simple but powerful refinement rules are proposed that guarantee soundness of the resulting workflow nets. The refinement process supports the definition of regions, which are parts of the workflow that correspond to logistically related items. Exception handlers can be associated to regions. Defining regions helps determining the impact areas of the unexpected events during workflow execution.

Computing Research Repository, 2009

Workflow management systems allow the users to develop complex applications at a higher level, by orchestrating functional components without handling the implementation details. Although a wide range of workflow engines are developed in enterprise environments, the open source engines available for scientific applications lack some functionalities or are too difficult to use for non-specialists. Our purpose is to develop a workflow management platform for distributed systems, that will provide features like an intuitive way to describe workflows, efficient data handling mechanisms and flexible fault tolerance support. We introduce here an architectural model for the workflow platform, based on the ActiveBPEL workflow engine, which we propose to augment with an additional set of components.

Arxiv preprint arXiv: …, 2011

With recent increasing computational and data requirements of scientific applications, the use of large clustered systems as well as distributed resources is inevitable. Although executing large applications in these environments brings increased performance, the automation of the process becomes more and more challenging. While the use of complex workow management systems has been a viable solution for this automation process in business oriented environments, the open source engines available for scientific applications lack some functionalities or are too difficult to use for non-specialists. In this work we propose an architectural model for a grid based workflow management platform providing features like an intuitive way to describe workflows, efficient data handling mechanisms and flexible fault tolerance support. Our integrated solution introduces a workflow engine component based on ActiveBPEL extended with additional functionalities and a scheduling component providing efficient mapping between tasks and available resources.

Information Systems, 2005