The document proposes a concept for modeling exceptional situations and triggering corrective actions in business processes. Constraints are defined and attached to activities or scopes in a process. Metrics provide input data for constraint parameters, which are evaluated at defined points to detect violations. If violated, a constraint handler executes additional logic, either concurrently or by terminating the normal flow. The concept was implemented by mapping constraint handlers to existing BPEL constructs like fault and event handlers to integrate it with BPEL engines without extending the language. Future work includes implementing the capabilities in a BPEL engine and exploring dynamic constraint binding.

1. Enforcement from the Inside – Improving Quality of Business in ProcessManagement

2. Outline ALLOW Project 1 Introduction and Motivation 2 Concept 3 Implementation 4 Outlook and Conclusion 5

4. What is a flow? (Beyond classical workflows) 4

5. Outline ALLOW Project 1 Introduction and Motivation 2 Concept 3 Implementation 4 Outlook and Conclusion 5

6. Motivation Often the successful completion of a business process depends on the time for detection of exceptional situations and the time for performing corrective actions E.g. in cold chains In pervasive scenarios exceptional situation can be sensed (detected) Exceptional cases should be modeled separately Goal: Providing a concept enabling the detection of exceptional situations and the triggering of corrective actions 6

7. Scenario – Peas Cold Chain Harvesting Processing Quick- freezing Packaging Delivery Temperature must not go above -18°C for longer than 2 min, if this cannot be assured, peas need to be checked to ensure quality Must be done within 2 days, if this cannot be ensured peas have to be thrown away

8. Idea Exceptional cases can be modeled or defined using constraints Constraints can be evaluated e.g. using sensor data Violation of constraint is detected and may trigger corrective actions Constraints may be based on laws, like Hazard Analysis and Critical Control Points (US) Principles and requirements of food law, establishing the European food safety authority (EU) 8

9. Contributions Concept of Constraint Modeling in Workflows Identify required modeling elements Definition semantics of modeling elements Implementation using BPEL Using BPEL as workflow language, we define the semantic integration of constraint approach in BPEL navigation

10. Outline ALLOW Project 1 Introduction and Motivation 2 Concept 3 Implementation in BPEL 4 Outlook and Conclusion 5

11. Concept Overview

12. Scenario – Peas Cold Chain Harvesting Processing Quick- freezing Packaging Delivery Must be done within 2 days, if this cannot be ensured peas have to be thrown away Temperature must not go above -18°C for longer than 2 min, if this cannot be assured, peas need to be checked to ensure quality Time Time Temperature T < 2 days Handler Time < 2 min Temp > -18 Handler harvesting Transportation tofabric Processing Quick Freezing Packaging Delivery

13. Overview of Constraint Modeling Elements Metrics define what is to be measured and the measurement unit provide values which serve as input to the constraints parameters Constraints define conditions to be fulfilled Constraint Handler Semantics - execute some additional process logic either: concurrently to the running normal business logic or as an alternative execution path and terminate running normal business logic

14. Attachment of Constraints Constraints, Constraint Handlers and Metrics are attached to scopes or activities Reminder A scope is a set of activities sharing the same common properties E.g. transactional behavior In BPEL scopes must be properly nested 14

15. Evaluation Time of Constraints Constraint evaluation time is modeled relative to events of the grouped activities, like Entering the group of activities Leaving the group of activities Both entering and leaving of the group of activities Constraint must be evaluated over and over again during the execution of the group of activities. 15 Time T < 2 days Handler harvesting Transportation tofabric Processing

16. Outline ALLOW Project 1 Introduction and Motivation 2 Concept 3 Implementation 4 Outlook and Conclusion 5

18. Extending BPEL causes an extension of the BPEL Engine

19. A Mapping to Standard BPEL allows to implement the concept based on several engines, even commercial ones.

20. E.g. Apache ODE, WebSphere Process Server17

21. Constraints & Scope Life Cycle Constraints and Metrics do not influence execution semantics The evaluation of constraints is started by the affected scopes (CET) State changes relevant to metric measurement and constraint evaluation time

22. Constraint State Space Constraint lifecycle Constraint is activated, when scope is started Constraint is evaluated according to modeled constraint evaluation time Constraint is deactivated, when scope completes or FCT-handling is executed

25. Outline ALLOW Project 1 Introduction and Motivation 2 Concept 3 Implementation 4 Outlook and Conclusion 5

26. Future Work XML Rendering Constraints, Metrics and Constraint Handlers Attachment mechanism based on WS-Policy Implementation of constraint handling capabilities into a BPEL engine (ODE) Dynamic binding of constraints Increases flexibility and configurability as processes and constraints can be modeled separately E.g. binding of constraint annotations depending on country of execution

27. Conclusion Description of a new concept for constraint modeling and execution for workflows, which allows to Separate normal business logic from exceptional cases Facilitates enforcement of e.g. laws In configurable and flexible manner Implementation based on BPEL in a non-intrusive manner Architecture for extending a BPEL engine

29. XML – Example (Rendering) <scopeisolated="yes|no"? exitOnStandardFault="yes|no"? standard-attributes> standard-elements Scope-elements Activity <constraints> <constraintcet=„continous“> -constraintdescriptionlanguage--> <throwconstraintViolationName="QName" faultVariable="BPELVariableName"? standard-attributes> standard-elements </throw> </constraint> </constraints> <metrics> metricsdescriptionlanguage </metrics> <faultHandlers> <catch constraintViolationName=„OutOfTemperature" faultVariable="BookOutOfStockVariable"> ... </catch> <catchAll>...</catchAll> </faultHandlers> </scope>