W.M.P. van der Aalst. Workflow verification: finding control-flow errors using Petri-net-based techniques. In: W.M.P. van der Aalst et al., editors. Business process management: models, techniques, and empirical studies. Lecture Notes in Computer Science 1806. Berlin, Springer-Verlag, pp.161-183, 2000.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....events. This Petri net models the same workflow as the activity diagram in Fig. 3. The envelope and the clock denote external and temporal trigger events respectively. Unfortunately, although the importance of input events is recognised, hardly ever a semantics is given for them. Van der Aalst [2] gives an interesting motivation for abstracting from events, that we will discuss below. But first we study two approaches to model events in ordinary Petri nets that map events to transitions and places, respectively. We will compare both approaches with our semantics of input events. Event ....

....of tokens for e is not known beforehand, since the number of transitions to be fired depends upon the current WFS state. We therefore would have to introduce a lot of spare tokens. This makes existing verification techniques for Petri nets inapplicable, e.g. the ones introduced by Van der Aalst [2]. Another drawback is that dependency between value change events cannot be modelled faithfully, just like in the event as transition approach (or coloured tokens must be used) A final drawback of the event as token approach is that the resulting Petri net looks like ravioli, since the place ....

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W.M.P. van der Aalst. Workflow verification: Finding control-flow errors using Petri-net-based techniques. In W. van der Aalst, J. Desel, and A. Oberweis, editors, Business Process Management. Springer, 2000.

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W.M.P. van der Aalst. Workflow verification: finding control-flow errors using Petri-net-based techniques. In: W.M.P. van der Aalst et al., editors. Business process management: models, techniques, and empirical studies. Lecture Notes in Computer Science 1806. Berlin, Springer-Verlag, pp.161-183, 2000.

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van der Aalst, W. M. P. (2000) Workflow verification: finding control-flow errors using Petri-net-based techniques. In van der Aalst, W. M. P., Desel, J. and Oberweis, A. (eds), Business Process Management: Models, Techniques, and Empirical Studies. Lecture Notes in Computer Science, 1806, 161--183. Springer, Berlin.

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W.M.P. van der Aalst. Workflow Verification: Finding Control-Flow Errors using Petri-netbased Techniques. In W.M.P. van der Aalst, J. Desel, and A. Oberweis, editors, Business Process Management: Models, Techniques, and Empirical Studies, volume 1806 of Lecture Notes in Computer Science, pages 161--183. Springer-Verlag, Berlin, 2000.

....( # # # ) 4. method use: # # ###### # , 5. visible start: for any # #. #### 6. visible end : for any # #.#: # # . Note that the connectedness requirement implies that there is one unique source and one unique sink place. For the readers familiar with the work presented in [1, 4]: the WF nets defined in this paper are extended with the latter three requirements, i.e. all methods are actually used in the network, and the start transitions #. and stop transitions have non # labels. The P T nets shown in figures 2 and 10 are WF nets. The structure of a WF net al..lows us ....

W.M.P. van der Aalst. Workflow Verification: Finding Control-Flow Errors using Petri-netbased Techniques. In W.M.P. van der Aalst, J. Desel, and A. Oberweis, editors, Business Process Management: Models, Techniques, and Empirical Studies, volume 1806 of Lecture Notes in Computer Science, pages 161--183. Springer-Verlag, Berlin, 2000.

....behaviour in di#erent Petri net variants. In the sequel, we presuppose some basic knowledge of Petri nets and high level Petri nets (see e.g. 105, 129, 136, 141, 142] We have looked at Petri net variants that are traditionally used to specify and analyse workflows, namely Workflow Nets [2, 3], Information Control Nets [55] INCOME WF [132] FunSoft nets [49, 58] Milano WFMS [10] Next, we have looked at Petri net variants that are not specifically tailored towards workflow modelling but nevertheless can be useful: Open Nets [16] Petri nets with synchronous communication [37] ....

....events in a Petri net. The activity diagram in Figure 8.2 models the same workflow. The envelope and the clock denote external and temporal trigger events respectively. Unfortunately, although the importance of input events is recognised, hardly ever a semantics is given for them. Van der Aalst [3] gives an interesting motivation for abstracting from events for analysis purposes, that we will discuss below. But first we study two approaches to specify events in ordinary Petri nets and compare both approaches with our semantics of input events. Event as token. For each input event a place ....

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W.M.P. van der Aalst. Workflow verification: Finding control-flow errors using Petri-net-based techniques. In Aalst et al. [1], pages 161--183.

....by constructing and inspecting the reachability graph. It is also shown that soundness coincides with liveness and boundedness of the short circuited net [1] For subclasses such as free choice workflow nets and workflow nets without PT and TP handles soundness can be analyzed in polynomial time [5]. However, for arbitrary workflow nets, the best known algorithm is non primitive recursive space [43] An open question is whether the structure of a workflow net can be exploited to improve this algorithm. 2. How to calculate differences commonalities of processes Inheritance is well defined ....

W.M.P. van der Aalst. Workflow Verification: Finding Control-Flow Errors using Petri-netbased Techniques. In W.M.P. van der Aalst, J. Desel, and A. Oberweis, editors, Business Process Management: Models, Techniques, and Empirical Studies, volume 1806 of Lecture Notes in Computer Science, pages 161--183. Springer-Verlag, Berlin, 2000.

....generating meaningful diagnostic information. Since the release of version 1.0 of the tool in 1997, we have been continuously improving Woflan. Both new theoretical results and practical experiences stimulated several enhancements. Pivotal to Woflan is the notion of soundness of a workflow process [1, 2, 4]. This notion expresses the minimal requirements any workflow should satisfy. Informally, a workflow process is sound if it satisfies the following conditions. option to complete) It should always be possible to complete a case (workflow instance) that is handled according to the process. This ....

....A WF net N is well structured iff N is well handled, i.e. the short circuited net has no PT handles and TP handles (see Definition 2.7) THEOREM 4.3. Sound and well structured vs. S coverable) Let N be a sound, well structured WF net. The shortcircuited WF net N is S coverable. Proof. See [4]. Theorem 4.3 can be used in the analysis of WF nets in a similar way as Theorem 4.2 can be used. Theorem 4.3 does not provide useful information for our running example, because short circuited WF net N of Figure 3 is not well structured. As a side remark, note that for a given well structured ....

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W.M.P. van der Aalst. Workflow Verification: Finding Control-Flow Errors using Petri-net-based Techniques. In Van der Aalst et al. [7], pages 161--183.

....generating meaningful diagnostic information. Since the release of version 1.0 of the tool in 1997, we have been continuously improving Woflan. Both new theoretical results and practical experiences stimulated several enhancements. Pivotal to Woflan is the notion of soundness of a workflow process [1, 3, 5]. This notion expresses the minimal requirements any workflow should satisfy. Informally, some given workflow process is sound if it satisfies the following conditions. option to complete) It should always be possible to complete a case that is handled according to the process. This condition ....

....II can be used. Theorem III does not provide useful information for our running example, because short circuited WF net N of Figure 3 is not well structured. As a side remark, note that for a given well structured WF net, it can be decided in polynomial time whether or not it is sound. See [5]; the proof uses Theorem I and the fact that short circuited WF nets without PT handles and TP handles are elementary extended non self controlling [13] Also note that the classes of free choice WF nets and well structured WF nets are incomparable. That is, there are free choice nets that are ....

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W.M.P. van der Aalst. Workflow Verification: Finding Control-Flow Errors using Petri-netbased Techniques. In W.M.P. van der Aalst et al.

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W.M.P. van der Aalst. Workflow Verification: Finding Control-Flow Errors using Petri-net-based Techniques. In W.M.P. van der Aalst, J. Desel, and A. Oberweis, editors, Business Pro cess Management:Mo dels, Techniques, and Empirical Studies, volume LectureNoVfl in Co89K.x Science, pages 161--183. SpringerVerlag, Berlin, 2000.

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Wil M. P. van der Aalst. Workflow verification: Finding control-flow errors using petri-netbased techniques. Lecture Notes in Computer Science, 1806, 2000.

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W. M. P. van der Aalst. Workflow verification: Finding control-flow errors using petri-net-based techniques. Lecture Notes in Computer Science, 1806, 2000.

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W.M.P. van der Aalst. Workflow verification: Finding control-flow errors using Petri-net-based techniques. In Aalst et al. [1], pages 161--183.

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van der Aalst, W.: Workflow Verification: Finding Control-Flow Errors Using PetriNet -Based Techniques. In: van der Aalst, W., Desel, J., and Oberweis, A. (eds.), Business Process Management (Models, Techniques, and Empirical Studies). Number 1806 in Lecture Notes in Computer Science. Berlin. 2000. Springer.

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