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Figurę 5.2 is a conccptual Petri net model of the Online Computer shopping system. The Online Computer shopping system concems the concurrent modeling of an online Computer shopping process secn from ftve different pcrspectives: the customcr perspectivc, Dell perspective, UPS pcrspective, factory perspcctive and customer’s credit bank pcrspective. Customcr pcrspcctive, Dell perspcctivc, UPS perspective will be discussed next for illustration purpose. The customer perspectivc emphasizes the different possiblc States of the customcr, with the online Computer shopping process viewed as some form of transition with which customer interaets. The emphasis oh Dell perspective is to be able to track down the order handling process. The UPS pcrspective emphasizes the product shipping procedurę. To save space and make the conceptual Petri net model easy to understand, in Figurę 5.2, we did not model the exccption condition such as “ If there are some problems with customeUs credit chccking”, “If the delivery of the Computer failed”. (Plcase check appcndix for practical meaning of all places and transitions appeared in this seclion.)

5.3.3 Application of Petri net morphisms to online Computer shopping system

Nexl Petri net morphisms will be applied to abstract the Petri net model of online Computer shopping system in Figurę 5.2 to gain different level of abstractions and different perspectives of the model.

During these abstraction processes, Petri net subnels that are combined into a single place or transition arc denoted by a surrounding larger oval (for places) or larger rectangle (for transitions). In this manner it is straightforward to tracę consecutive transformat i on steps.