# Monitoring Constraints in Business Processes Using Object-Centric Constraint Graphs

- Type: Conference paper
- URL: https://www.gyunam.com/publication/2022-pqmi/
- Date: 2023-03-01
- Authors: Gyunam Park, Wil M. P. van der Aalst
- Venue: Process Mining Workshops - ICPM 2022 International Workshops, Bozen-Bolzano, Italy, October 23-28, 2022, Revised Selected Papers
- DOI: https://doi.org/10.1007/978-3-031-27815-0_35
- PDF: https://www.gyunam.com/publication/2022-pqmi/paper.pdf
- Link (URL): https://doi.org/10.1007/978-3-031-27815-0_35
- Research lines: [Object-centric process mining](https://www.gyunam.com/research-line/object-centric-process-mining/index.md)

## Abstract

Constraint monitoring aims to monitor the violation of constraints in business processes, e.g., an invoice should be cleared within 48 h after the corresponding goods receipt, by analyzing event data. Existing techniques for constraint monitoring assume that a single case notion exists in a business process, e.g., a patient in a healthcare process, and each event is associated with the case notion. However, in reality, business processes are object-centric , i.e., multiple case notions (objects) exist, and an event may be associated with multiple objects. For instance, an Order-To-Cash (O2C) process involves order , item , delivery , etc., and they interact when executing an event, e.g., packing multiple items together for a delivery. The existing techniques produce misleading insights when applied to such object-centric business processes. In this work, we propose an approach to monitoring constraints in object-centric business processes. To this end, we introduce Object-Centric Constraint Graphs (OCCGs) to represent constraints that consider the interaction of objects. Next, we evaluate the constraints represented by OCCGs by analyzing Object-Centric Event Logs (OCELs) that store the interaction of different objects in events. We have implemented a web application to support the proposed approach and conducted two case studies using a real-life SAP ERP system.

## Practical problem

Compliance officers and process owners define rules such as 'an invoice must be cleared within 48 hours of the goods receipt' or 'clearing an invoice must involve exactly one invoice' and want to be told from event data when the rules are broken. Existing constraint monitoring techniques assume every event belongs to a single case, for example one patient or one order, but in real purchase-to-pay or order-to-cash processes one event touches a purchase order, several materials, a goods receipt and an invoice at once. Squeezing such data into a single case notion produces false violations, for instance reporting that an item was picked after the invoice was sent when the two belong to different object lifecycles. Rules about which and how many objects an activity may involve cannot be expressed at all.

## Research questions

1. How can constraints that account for the interaction of multiple object types be represented formally and graphically?
2. How can violations of such constraints be evaluated directly on object-centric event logs, including constraints on object involvement and cardinality?
3. Is the approach feasible on event data from a real SAP ERP system?

## Contributions

- Object-centric behavioral metrics over Object-Centric Event Logs (OCELs): causal, concurrent and choice ordering relations per object type, object involvement metrics (absent, singular, multiple) and underspecified performance metrics.
- Object-Centric Constraint Graphs (OCCGs), a directed graph notation with activity, object type and formula nodes and control-flow, object involvement and performance edges with thresholds, plus formal violation semantics.
- A monitoring engine that computes the metrics from an OCEL, reusing the OPerA object-centric performance analysis for sojourn, waiting, synchronization, pooling and lagging times, and evaluates OCCG violations.
- A web application (`ProPPa`) for importing OCELs in JSON, XML and CSV, designing OCCGs graphically and visualizing monitoring results, with demo video, manual and event logs on GitHub.
- Two case studies on a production process and a purchase-to-pay process of an SAP ERP (enterprise resource planning) system.

## Key findings

- In the motivating order-to-cash example, flattening on orders makes three control-flow constraints appear violated, whereas the item-aware version of the first constraint is satisfied because each item is picked directly before packing.
- In the production process (four object types, monthly logs Jan. to Mar. 2022), 'no reservation for purchase requisition approval' and 'excessive reservations per production order' are violated in all three months, 'skipping approval' only in Feb. and Mar., and 'delayed purchase order release' only in Feb.
- In the purchase-to-pay process (five object types, three windows from Aug. 2021 to May 2022), concurrency between verify material and plan goods issue and clearance of multiple invoices are violated only in the first two windows, while excessive materials per order and delayed order creation appear only in the last.
- The case studies demonstrate feasibility on a fictitious company's SAP system rather than measuring accuracy against a baseline; OCCGs cover only the constraints introduced, cannot separate direct from eventual causality and lack timed constraints.