Enforcement from the Inside: Improving Quality of Business in Process Management

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In this paper we introduce a new modeling tool for constraint handling in the area of workflow technology. The constraint handlers can be used to improve the quality of business processes but without changing already existing business logic. Todays workflow languages provide no possibility to model constraints and the actions in case the constraints get violated explicitly. Fault and event handling mechanisms to react to events not expected in normal executions are only provided by the BPEL language. Using BPEL as workflow language we integrate the constraint handling extension without changing any existing semantics in a smart way. In our approach we use this fault and event handling mechanisms to extend the BPEL language with a constraint handling mechanism. By integrating this constraint handling tool into the BPEL language we provide an approach for quality driven process modeling with the BPEL language.

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Enforcement from the Inside: Improving Quality of Business in Process Management

  1. 1. Enforcement from the Inside – Improving Quality of Business in ProcessManagement<br />
  2. 2. Outline<br />ALLOW Project<br />1<br />Introduction and Motivation<br />2<br />Concept<br />3<br />Implementation<br />4<br />Outlook and Conclusion<br />5<br />
  3. 3. Project Objectives<br />New programming paradigm for flow-based pervasive applications<br />Our vision is that everything can be modeled. <br />Design of suitable models<br />Execution infrastructure for the models<br />Away from programming towards modeling<br /><ul><li>Bringing together BPM and pervasive systems</li></ul>3<br />http://www.allow-project.eu<br />
  4. 4. What is a flow? (Beyond classical workflows)<br />4<br />
  5. 5. Outline<br />ALLOW Project<br />1<br />Introduction and Motivation<br />2<br />Concept<br />3<br />Implementation<br />4<br />Outlook and Conclusion<br />5<br />
  6. 6. Motivation<br />Often the successful completion of a business process depends on the time for detection of exceptional situations and the time for performing corrective actions<br />E.g. in cold chains<br />In pervasive scenarios exceptional situation can be sensed (detected) <br />Exceptional cases should be modeled separately<br />Goal: Providing a concept enabling the detection of exceptional situations and the triggering of corrective actions<br />6<br />
  7. 7. Scenario – Peas Cold Chain<br />Harvesting<br />Processing <br />Quick-<br />freezing <br />Packaging<br />Delivery<br />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<br />Must be done within 2 days, <br />if this cannot be ensured peas have to be thrown away<br />
  8. 8. Idea<br />Exceptional cases can be modeled or defined using constraints<br />Constraints can be evaluated e.g. using sensor data<br />Violation of constraint is detected and may trigger corrective actions<br />Constraints may be based on laws, like<br />Hazard Analysis and Critical Control Points (US)<br />Principles and requirements of food law, establishing the European food safety authority (EU)<br />8<br />
  9. 9. Contributions<br />Concept of Constraint Modeling in Workflows<br />Identify required modeling elements<br />Definition semantics of modeling elements<br />Implementation using BPEL<br />Using BPEL as workflow language, we define the semantic integration of constraint approach in BPEL navigation<br />
  10. 10. Outline<br />ALLOW Project<br />1<br />Introduction and Motivation<br />2<br />Concept<br />3<br />Implementation in BPEL<br />4<br />Outlook and Conclusion<br />5<br />
  11. 11. Concept Overview<br />
  12. 12. Scenario – Peas Cold Chain<br />Harvesting<br />Processing <br />Quick-<br />freezing <br />Packaging<br />Delivery<br />Must be done within 2 days, <br />if this cannot be ensured peas have to be thrown away<br />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<br />Time<br />Time <br />Temperature<br />T &lt; 2 days<br />Handler<br />Time &lt; 2 min Temp &gt; -18<br />Handler<br />harvesting<br />Transportation tofabric<br />Processing<br />Quick Freezing<br />Packaging<br />Delivery<br />
  13. 13. Overview of Constraint Modeling Elements<br />Metrics<br />define what is to be measured and the measurement unit<br />provide values which serve as input to the constraints parameters<br />Constraints define conditions to be fulfilled<br />Constraint Handler<br />Semantics - execute some additional process logic either: <br />concurrently to the running normal business logic or<br />as an alternative execution path and terminate running normal business logic<br />
  14. 14. Attachment of Constraints<br />Constraints, Constraint Handlers and Metrics are attached to scopes or activities<br />Reminder<br />A scope is a set of activities sharing the same common properties<br />E.g. transactional behavior<br />In BPEL scopes must be properly nested<br />14<br />
  15. 15. Evaluation Time of Constraints<br />Constraint evaluation time is modeled relative to events of the grouped activities, like <br />Entering the group of activities<br />Leaving the group of activities<br />Both entering and leaving of the group of activities<br />Constraint must be evaluated over and over again during the execution of the group of activities.<br />15<br />Time<br />T &lt; 2 days<br />Handler<br />harvesting<br />Transportation tofabric<br />Processing<br />
  16. 16. Outline<br />ALLOW Project<br />1<br />Introduction and Motivation<br />2<br />Concept<br />3<br />Implementation<br />4<br />Outlook and Conclusion<br />5<br />
  17. 17. Implementation Overview<br />Two possible approaches<br />Extension of BPEL with a Constraint Handler<br />Mapping the Constraint Handlers to standard BPEL<br /><ul><li>We decided to map the Constraint Handler to BPEL
  18. 18. Extending BPEL causes an extension of the BPEL Engine
  19. 19. A Mapping to Standard BPEL allows to implement the concept based on several engines, even commercial ones.
  20. 20. E.g. Apache ODE, WebSphere Process Server</li></ul>17<br />
  21. 21. Constraints & Scope Life Cycle<br />Constraints and Metrics do not influence execution semantics<br />The evaluation of constraints is started by the affected scopes (CET)<br />State changes relevant to metric measurement and constraint evaluation time<br />
  22. 22. Constraint State Space<br />Constraint lifecycle<br />Constraint is activated, when scope is started<br />Constraint is evaluated according to modeled constraint evaluation time<br />Constraint is deactivated, when scope completes or FCT-handling is executed<br />
  23. 23. Constraint Handler – Mapping<br />Define the business logic as part of the new modeling element: constraint handler.<br />Reuse already defined BPEL semantics and forward the events received by the constraint handler to already existing modeling elements<br />fault handlers (-> terminate)<br />event handlers (-> concurrency)<br /><ul><li>Thisapproachavoids redundancy in semantics of modeling elements
  24. 24. Fault, compensation and termination handling of BPEL must not be adapted</li></li></ul><li>Runtime Architecture<br />Values<br />Scope Events <br />Values<br />Scope Events <br />Values<br />Time<br />Time <br />Temperature<br />T &lt; 2 days<br />Handler<br />Time &lt; 2 min Temp &gt; -18<br />Handler<br />Harvesting<br />Transportation tofabric<br />Processing<br />Quick Freezing<br />Packaging<br />Delivery<br />
  25. 25. Outline<br />ALLOW Project<br />1<br />Introduction and Motivation<br />2<br />Concept<br />3<br />Implementation<br />4<br />Outlook and Conclusion<br />5<br />
  26. 26. Future Work<br />XML Rendering<br />Constraints, Metrics and Constraint Handlers<br />Attachment mechanism based on WS-Policy<br />Implementation of constraint handling capabilities into a BPEL engine (ODE)<br />Dynamic binding of constraints<br />Increases flexibility and configurability as processes and constraints can be modeled separately <br />E.g. binding of constraint annotations depending on country of execution<br />
  27. 27. Conclusion<br />Description of a new concept for constraint modeling and execution for workflows, which allows to<br />Separate normal business logic from exceptional cases<br />Facilitates enforcement of e.g. laws<br />In configurable and flexible manner<br />Implementation based on BPEL in a non-intrusive manner<br />Architecture for extending a BPEL engine<br />
  28. 28.
  29. 29. XML – Example (Rendering)<br />&lt;scopeisolated=&quot;yes|no&quot;? exitOnStandardFault=&quot;yes|no&quot;? standard-attributes&gt;<br />standard-elements<br />Scope-elements<br />Activity<br />&lt;constraints&gt;<br />&lt;constraintcet=„continous“&gt;<br />-constraintdescriptionlanguage--&gt;<br /> &lt;throwconstraintViolationName=&quot;QName&quot; faultVariable=&quot;BPELVariableName&quot;?<br />standard-attributes&gt;<br />standard-elements<br /> &lt;/throw&gt;<br />&lt;/constraint&gt;<br />&lt;/constraints&gt;<br />&lt;metrics&gt;<br />metricsdescriptionlanguage<br />&lt;/metrics&gt;<br />&lt;faultHandlers&gt;<br />   &lt;catch constraintViolationName=„OutOfTemperature&quot;<br />      faultVariable=&quot;BookOutOfStockVariable&quot;&gt;<br />      ...<br />   &lt;/catch&gt;<br />   &lt;catchAll&gt;...&lt;/catchAll&gt;<br />&lt;/faultHandlers&gt;<br />&lt;/scope&gt;<br />

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