This paper deals with a form of workflow flexibility called case handling as applied to healthcare systems, called careflow systems. We consider a case study of cutaneous melanoma to illustrate flexibility of careflow systems. We first present algorithmic version of medical guidelines for cutaneous melanoma and then model these medical guidelines using YAWL workflow design tool that is based on Petri nets model of computation. We consider both rigid and flexible models of related careflow systems. The YAWL flexible model uses case handling as a form of careflow flexibility. We compare both models from a perspective of functionality and usability.
<p class="MsoNormal" style="text-align: left; margin: 0cm 0cm 0pt; layout-grid-mode: char;" align="left"><span class="text"><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;">Inter-Organizational Workflows (IOWF) become important as they provide solution for data sharing, heterogeneity in resources and work coordination at global level. However, a secured computing infrastructure like Multilevel Security (MLS) is needed to support today’s vast businesses.</span></span><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;"> <span class="text">In this paper Message Sequence Charts (MSC) are used to specify the positive and negative interactions between cooperating organizations. Petri nets are used to model the workflows in each organization. IOWF is obtained by combining Message Sequence Charts (MSC) and workflows of local organizations.</span> <span class="text">We present an algorithm to incorporate MLS features into IOWFs using Bell-LaPadula security model. In this model security labels of subject and object are verified before the subject can access the object. The algorithm reduces the workflows of participating organizations using the reduction rules while preserving the communication patterns between organizations. We also present an algorithm to identify implicit places in the IOWF with MLS features. Our method and algorithms are illustrated by a running example.</span></span></p>
Abstract. Development of complex concurrent systems is very often performed in a top-down or bottom-up approach depending on design circumstances. Such design reflects vertical conceptual modeling of concurrent systems with certain number of abstraction/ refinement layers. Petri net morphisms have been proven to be useful in this process as long as certain desired structural and behavioral properties of such systems are preserved. We use example of a renting agency to illustrate applicability of morphisms in systematic development of distributed systems. Preservation of structural and behavioral properties of Petri net morphisms is also discussed.
Motivation and IntroductionPetri nets are formal, graphical, and executable mathematical models that are appropriate for the development of concurrent, discrete-event dynamic systems. It has been under development since the beginning of the 1960's. After forty years of research and development, Petri nets have been proven to be applicable to a variety of areas. It can be used in design and analysis of concurrent and distributed systems, workflow management systems, requirement specifications in software engineering, specifications of communication protocols, and so on.Usually there are two different approaches in Petri net system modeling. One is the top-down approach and the other is the bottom-up approach. In top-down approach, one can start modeling a system from the highest conceptual level of abstraction, then refine the system using techniques such as rule-based refinement [11], general refinement [4], and hierarchical modeling [5] until reaching a satisfying level of detail of the system. In bottom-up approach, one starts the modeling of a system at the lowest level of abstraction, then abstracts the system model step by step until reaching the highest level of abstraction.In practice, the top-down approach is relatively easy to achieve. Yet modeling a system using the bottom-up approach is very difficult, because there are very few techniques about 'how to shrink' a system model to a higher level of abstraction without losing the structural and behavioral properties of the system. However, this approach is practically very important in system modeling.
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