BPMN: An introduction to the standard

We may not be able to make you love reading, but production workflow concepts and techniques will lead you to love reading starting from now. Book is the window to open the new world. The world that you want is in the better stage and level. World will always guide you to even the prestige stage of the life. You know, this is some of how reading will give you the kindness. In this case, more books you read more knowledge you know, but it can mean also the bore is full.

Production workflow: concepts and techniques

Any developer of discrete event systems knows that the most impor tant quality of the final system is that it be functionally correct by exhibiting certain functional, or qualitative properties decided upon as being important. Once assured that the system behaves correctly, it is also important that it is efficient in that its running cost is min imal or that it executes in optimum time or whatever performance measure is chosen. While functional correctness is taken for granted, the latter quantitative properties will often decide the success, or oth erwise, of the system. Ideally the developer must be able to specify, design and implement his system and test it for both functional correctness and performance using only one formalism. No such formalism exists as yet. In recent years the graphical version of the Specification and Description Lan guage (SDL) has become very popular for the specification, design and partial implementation of discrete systems. The ability to test for functional correctness of systems specified in SDL is, however, lim ited to time consuming simulative executions of the specification and performance analysis is not possible. Petri nets, although graphical in format are somewhat tedious for specifying large complex systems but, on the other hand were developed exactly to test discrete, dis tributed systems for functional correctness. With a Petri net specifi cation one can test, e. g., for deadlock, liveness and boundedness of the specified system."

Stochastic Petri Nets: An Introduction to the Theory

Up to now there is neither data available on how many errors can be expected in process model collections, nor is it understood why errors are introduced. In this article, we provide empirical evidence for these questions based on the SAP reference model. This model collection contains about 600 process models expressed as Event-driven Process Chains (EPCs). We translated these EPCs into YAWL models, and analyzed them using the verification tool WofYAWL. We discovered that at least 34 of these EPCs contain errors. Moreover, we used logistic regression to show that complexity of EPCs has a significant impact on error probability.

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Detection and prediction of errors in EPCs of the SAP reference model

Business process modeling plays an important role in the management of business processes. As valuable design artifacts, business process models are subject to quality considerations. In this context, the absence of formal errors, such as deadlocks, is of paramount importance for the subsequent implementation of the process. This talk presents the results of my doctoral thesis that provides a fourfold contribution to the understanding of such errors in business process models with a particular focus on Event-driven Process Chains (EPCs), a business process modeling language that is frequently used in practice. Firstly, I formalize the operational semantics of EPCs in a novel way so that matching OR-splits and OR-joins never deadlock. Secondly, and based on these semantics, we introduce a soundness criterion for EPCs that offers a precise identification of those models which have errors. For the verification of this soundness notion in practice, I present two analysis tools, a ProM plug-in for a verification based on the reachability graph, and a batch program called xoEPC for a verification based on reduction rules. Thirdly, I define a set of business process model metrics that are supposed to serve as predictors for error probability of an individual EPC. Fourthly, I use statistical methods and a sample of about 2000 EPCs from practice to derive a regression function for the prediction of error probability. This function is validated against a holdout set of 113 EPCs from textbooks showing that 90% of the EPCs could be classified correctly as having errors or not. These results emphasize the importance of quality issues in business process modeling, and provides the foundations for innovations in tool support.

On the Detection and Prediction of Errors in EPC Business Process Models.

This paper presents TimeNET, a software tool for the modelling and performability evaluation using stochastic Petri nets. The tool has been designed especially for models with non-exponentially distributed firing delays. A general overview of the software package and its new features is given. The graphical user interface is completely rewritten. It integrates different model classes in a user-friendly and consistent way. One of the recent enhancements is an environment for the modelling and performance evaluation of manufacturing systems based on coloured stochastic Petri nets. A manufacturing system is modelled and analysed as an application example.

Petri Net Modelling and Performability Evaluation with TimeNET 3.0

Support for the efficient design and operation of complex manufacturing systems requires an integrated modelling, analysis, and control methodology as well as its implementation in a software tool. In this paper the Petri net based design engine TimeNET is presented for this task. Petri nets are able to capture the characteristic features of manufacturing systems in a concise form. A subclass of coloured Petri nets is used, which has been developed especially for the application area of manufacturing. Structure and work plans are modelled separately. Stochastic as well as deterministic and more general distributions are adopted for the firing times of transitions. Fundamental questions about system properties can be answered using qualitative analysis. For an efficient performance and dependability prediction, different evaluation techniques are proposed: direct numerical analysis, approximate analysis, and simulation. Finally, the model can be used to evaluate different control strategies and to control ...

A Petri net based design engine for manufacturing systems

One of the main features of Event driven Process Chains (EPCs) is the non-local semantics of the OR-join and the XOR-join connectors. Simulating this non-local semantics faithfully and efficiently is still a challenging problem. A year ago, we have shown that the semantics of moderately sized EPCs can be calculated in reasonable time by using techniques from symbolic model checking. For larger EPCs, however, this method still takes too long for practical use. In this paper, we introduce and discuss a new technique for calculating the semantics of EPCs: We combine an explicitly forward construction of the transition system with a backward marking algorithm for checking the non-local constraints. Though this method does not always provide a result, it works for most practical examples and, in most cases, it is much faster than the symbolic algorithm. Basically, the computation time is linear in the size of the resulting transition system. The algorithm works for large EPCs as long as the resulting transition systems are small (where transition systems with millions of states and transitions are still considered to be small), which is true for many practical EPCs.

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On the semantics of EPCs: Faster calculation for EPCs with small state spaces

The design of real-time systems requires modeling and analysis techniques, to ensure their correct and timely operation. In many cases a realistic model should be able to cover both fixed and stochastic times. Stochastic Petri nets are a promising description technique in this field, but mixing deterministic and randomly distributed times in one model makes the analysis often impossible. This paper shows that Petri net models with an underlying discrete time can be advantageous for the modeling and analysis of real-time systems. For a demonstration a simple application example is modeled and its behavior computed using the software tool TimeNET.

Discrete time stochastic petri nets for modeling and evaluation of real-time systems

Not only since the upcoming of Service-oriented Architectures the modelling of cross-organizational business processes is a heavily investigated field comprising dozens of standards based on different concepts. New techniques on the implementation site, e.g. Web Service orchestration and choreography, further extended the possibilities and requirements on such standards. To systematically order and present a comprehensive state of the art of relevant methods and standards this paper first describes requirements that occur in cross-organizational business processes both for concepts and modelling languages. Then the most important state of the art concepts for modelling cross-organizational processes are described. Based on the requirements defined before and the presented concepts, selected modelling languages are analysed.

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Jörn Freiheit

Papers

Petri Net Modelling and Performability Evaluation with TimeNET 3.0

A Petri net based design engine for manufacturing systems

On the semantics of EPCs: Faster calculation for EPCs with small state spaces

Discrete time stochastic petri nets for modeling and evaluation of real-time systems

Modelling of Cross-Organizational Business Processes - Current Methods and Standards