Dierencegraph - A ProM Plugin for Calculating and Visualizing Dierences between Processes

Abstract

The analysis of dierences and commonalities between process models or between instances which progressed through the model (henceforth referred to as instance trac) plays an important role in companies. For example, companies are often confronted with dierent versions or variants of a process model and hence need methods to identify redundancies or inconsistencies between them. Dierencegraph is a plugin for ProM which supports the identication of dierences and commonalities between process models as well as between their instance trac. For this purpose a so-called dierence graph between two process models and their instance trac is calculated and visualized. This generated dierence graph supports decision making in various business cases such as nding deviations between processes.

Keywords

• Dierences between Processes
• Visualization
• Process Model
• Process Visualization
• Process Mining
• Instance Trac

-

Since companies frequently need to analyze and manage dierent process model versions and variants (e.g., to adapt to new requirements or to optimize business processes) [ 7 ], it is necessary to support analysts in nding dierences and commonalities between process models. In today’s business many processes are orchestrated by information systems. Since such systems often store performed activities within log les, process mining techniques have become increasingly important. In its simplest form such a log le contains information about tasks and traces. Each task represents an activity. A trace represents one process instance and consists of several tasks. All tasks within one trace are stored according to their execution order. These log les can then be used by business Copyright c 2015 for this paper by its authors. Copying permitted for private and academic purposes. analysts for process model generation. Therefore, not only the analysis of differences and commonalities between process models itself but also between the instances which progressed through the model (i.e., instance trac [ 6 ]) is of interest. For example, the analysis of instance trac allows analysts to detect more or less executed paths.

In this paper we introduce the plugin Dierencegraph which has been implemented for ProM [ 2 ] an open-source framework that includes most of the existing process mining techniques as plugins. The plugin allows analysts to compare two process models together with their instance trac. In contrast to other approaches which focus on comparing process models generated from real world behavior with hand crafted process models, the focus of our plugin is to compare two real world process models with each other. The plugin oers the following main features:

Comparison of process models represented as Heuristic net or Petri net.

These process models can either be generated directly within our plugin by using the heuristics [ 9 ] or alpha miner [ 1 ] oered by ProM or can be generated by other mining/transformation plugins and then passed as input to our plugin. The process models itself can either be based on two distinct process logs or can be derived from a single process log by splitting it into two parts (determined by user-specied dates).

Visualization of dierences with color coding and/or symbols. The visualization also includes two model types which can be visualized: Heuristic net (see Figure 1) or Petri net (see Figure 2).

Interactions like zooming, panning, and brushing and linking allow for an easy navigation and orientation within our visualization.

In the following we sketch two use cases to give an impression about possible tasks for which the plugin can be of interest: Use Case 1: As a result of reorganization two departments were merged under a joint management. Prior to that both departments developed and applied their own process variants. After both departments were merged, dierent process variants for the description of the same process existed. To reduce the number of process variants it is necessary to identify redundant ones or nd ways to properly merge them. Analysts can use the plugin to compare the dierent process variants in order to identify their commonalities and dierences. Use Case 2: A company has a process log which spans two years and is interested in how the process execution has changed from the rst to the second year. In this case the comparison of instance trac enables the analysts to see how the process has changed, e.g., which tasks or paths were executed more or less often. This also allows to see trends which, in turn, can help to optimize and coordinate processes in order to avoid bottlenecks.

Dierencegraph

Plugin

The plugin written in Java is based on the dierence graph and instance trac concept introduced by Kriglstein et al. [ 6 ]. For the calculation of the dierence graph, two process models are necessary as input. These models can be generated based on dierent process logs or by splitting one process log into two parts (as mentioned in the second use case). The resulting dierence graph uses ve dierent markings to represent the dierences and commonalities: New, Unchanged, Deleted, and if instance trac is of interest Decreased as well as Increased. A description of the calculation itself can be found in [ 6 ]. For the visual representation of these markings color-coding and/or symbols can be used. Installation. To install the plugin the ProM nightly build [ 8 ] is required. After extracting ProM, run the PackageManager and download the Dierencegraph plugin under the category not installed. All required dependencies are automatically downloaded by ProM.

Usage. After starting the plugin the user can either select two log les or a single log le and split it into two parts. Afterwards some initial conguration can be made using a wizard. This includes, choosing which mining algorithm (heuristic or alpha miner) should generate the process models for dierence calculation. Furthermore, the visual properties for visualizing the dierence graph can be selected (these properties can also be changed later within the visualization). Since traces may not be stored in order of processing, the plugin oers the possibility to order the entries of the log les in ascending order using the Sort Log option. This can be of interest when one log should be split into two parts or only specic time spans of two distinct log les should be compared. In the latter case date pickers can be used to select the dates which should be considered for dierence calculation.

After the conguration is completed the plugin passes the log les to the chosen mining algorithm to generate the two process models. These process models are then used for the dierence calculation (more information about the calculation can be found in [ 6 ]) and the resulting dierence graph is visualized. Interface. Figure 1 shows the interface of the plugin and the visualization of the two input models and the dierence graph with selected options Weights on Nodes 4, Color Coding, and Symbols. Each node represents a task while each edge represents the control ow from one task to the next. To ease orientation for the users the plugin tries to preserve the mental map [ 3 ] as much as possible by trying to arrange the nodes in such a way that their locations do not change signicantly between the dierent views. A legend at the bottom right shows which color/symbol represents which marking. For example, in Figure 1 node D (labeled 1 in the image) is represented as Decreased and therefore drawn in orange along with a symbol. Decreased means that the weight associated with 4 Weights reect the amount of instances executing a task, i.e., the instance trac.

B was reduced from Input 1 to Input 2 (specically by -4.0). Each visualization allows zooming and panning. Brushing and linking is also supported, that is, if one or multiple nodes are selected within a graph then the respective nodes are also selected within the other graphs. For example, node E was selected in Input 1 and thus E is also selected in the other two views.

A more detailed introduction about the plugin, survey data, screencasts, and an installation guide can be found at the website of the plugin [ 4 ]. 3

Maturity and Signicance to the BPM eld

For the visual representation of the dierences we conducted a user study [ 5 ] to nd out which representations are suited to highlight dierences in a graph. We investigated nine dierent types of representations based on dierent visual properties (e.g., color, symbol, and size). Among these representations, colorcoding and symbols were ranked highest by the participants and achieved the highest average rating in terms of expressiveness (see 2 in Figure 1 for an example of these properties). As shown in Figure 1- 3 our plugin also allows to use both properties simultaneously to highlight the dierences.

During development the plugin was tested with log les with up to 25.000 traces and 250 tasks. Figure 2 shows an example of a dierence graph visualized as Petri net with 23 tasks generated from 2000 traces. However, a higher number of traces and tasks aects response time of the graphical interface and leads to longer computation times for process model generation done by the alpha or heuristics miner.

Currently we are not aware of any other tool that allows comparison and visualization of instance trac dierences. Conformance checking is closely related to the purpose of our plugin but does not focus on comparing real world processes for insight generation. Due to its focus on real world execution semantics of business processes stored within log les we believe that our Dierencegraph plugin can contribute to the analysis of process models in various ways, some of which we have shortly outlined above.

Acknowledgments. Simone Kriglstein was supported by CVAST (funded by the Austrian Federal Ministry of Science, Research, and Economy in the exceptional Laura Bassi Centres of Excellence initiative, project nr: 822746).

References

1. van der Aalst , W.: Process mining: discovery, conformance and enhancement of business processes . Springer Science & Business Media ( 2011 )

2. van Dongen, B. , de Medeiros , A. , Verbeek , H. , Weijters , A., van der Aalst , W.: The ProM framework: A new era in process mining tool support . In: Applications and Theory of Petri Nets 2005 , LNCS, vol. 3536 , pp. 444454 . Springer ( 2005 )

3. Eades , P. , Lai , W. , Misue , K. , Sugiyama , K. : Preserving the mental map of a diagram . In: Proceedings of COMPUGRAPHICS . vol. 91 , pp. 2433 ( 1991 )

4. Gall , M. , Rinderle-Ma , S.: Dierencegraph ( 2015 ), http://gruppe.wst.univie.ac. at/projects/diffgraph/

5. Gall , M. , Wallner , G. , Kriglstein , S. , Rinderle-Ma, S.: A study of dierent visualizations for visualizing dierences in process models . In: Proceedings of Workshop on Event Modeling and Processing in Business Process Management (EMoV2015) in conjunction with 34th International Conference on Conceptual Modeling (ER 2015 ). Springer ( 2015 )

6. Kriglstein , S. , Wallner , G. , Rinderle-Ma, S.: A visualization approach for dierence analysis of process models and instance trac . In: Business Process Management, LNCS , vol. 8094 , pp. 219226 . Springer ( 2013 )

7. Rinderle , S. , Reichert , M. , Dadam , P. : Correctness criteria for dynamic changes in workow systems: A survey . Data Knowl. Eng . 50 ( 1 ), 934 ( 2004 )

8. Verbeek , E. , Gnter , C. : Prom nightly build ( 2010 ), http://www.promtools.org/ prom6/nightly/

9. Weijters , A., van der Aalst , W., Alves de Medeiros, A.K. : Process mining with the heuristics miner-algorithm . Technische Universiteit Eindhoven, Tech. Rep. WP 166 , 134 ( 2006 )