1. Interaction Patterns in Workflow Environments Research presentation by Martin Vasko

2. Presentation outline 1. Introduction to BPEL4WS 2. Overview of patterns 3. Interaction primitives in workflows 4. Introduction to the WS - * specifications 5. Putting it all together… 6. Challenges 7. Prototype Integration 8. References

3. 1. Introduction to BPEL4WS Positioning of my work:

4. 1. Introduction to BPEL4WS Currently standardized in version 1.1 by a consortium of Microsoft, IBM, SAP, Siebel et.al. Layered on XML standards as WSDL 1.1, XML Schema 1.0 and XPath 1.0 WSDL had most influence on the process model of BPEL (peer-to-peer interaction) Mutual visible message exchange (Businesses do not want to share their Business processes) Simple abstraction – mechanisms Orchestrates Web Service Interactions

5. 1. Introduction to BPEL4WS Activities are the actions that are being carried out within a business process. An important action in a business process is to simply wait for a message to be received from a partner More powerful mechanism is the usage of activity Specifies a whole set of messages that can be received 1 <receive partner="customer" 2 portType="itineraryPT" 3 operation="sendItinerary" 4 container="itinerary" 5 6

6. 1. Introduction to BPEL4WS Listing provides an in-out operation Input is consumed by, output is produced by activity 25 <receive partner="customer", 26 portType="itineraryPT", 27 operation="sendItinerary", 28 container="itinerary" 29 createInstance="yes"/> 30 31 <reply partner="customer", 32 portType="travelPT", 33 operation="sendTickets", 34 container="tickets"/>

7. 1. Introduction to BPEL4WS Partners are connected to a process in a bliateral manner called a service link type Specifies two collections of Web Services, referred to as roles. Example for a service link type definition: 1 2 3 4 5 6 7 8

8. 1. Introduction to BPEL4WS As BPEL processes interact with WSDL ports, these may send fault messages, or erroneous situations occur during execution Fault Handlers add an Exception mechanism to Business processes 35 36 37 <invoke partner="customer" 38 portType="travelPT" 39 operation="sendRejection" 40 inputContainer="rejection"/> 41 42

9. 2. Overview of patterns The motivation for the identification of patterns:  Independence of specific languages or techniques  Capture the essence of a problem  Offer valuable problem-solving insights

10. 2. Overview of patterns Related work:  Workflow Patterns Elaborated to formulate workflow requirements for workflow languages Abstract from specific workflow languages Summarized in the Workflow pattern initiative  http://www.workflowpatterns.com http://www.workflowpatterns.com

11. 2. Overview of patterns Service Interaction Patterns  Analyze the scope and capabilities of BPEL and related specifications such as WSDL and WS – Addressing Simple Patterns as Send, Receive, Send/Receive Complex Patterns  Racing Incoming Messages  Request with referral

12. 2. Overview of patterns Service Interaction Patterns  Service oriented analysis  WSDL, WS – Addressing, … Human – Service Interaction Patterns  Human oriented  BPEL4People, Human Task Specification Human – Human Interaction Patterns  Collaboration between Human workflow participants is central  Human Task Specification, Service Level Agreements

13. 2. Overview of patterns Current approaches lead to the integration of human participants into workflow modeling. Additional workflow participants lead to more precise modeling possibilities

14. 2. Overview of patterns BPEL Extension BPEL4People:  Designed to address the Human User Interaction requirements in workflows  Generic Human Roles  People Links  People Activities  Tasks  Properties

15. 3. Interaction primitives in workflows Human Service Interaction patterns  Service execution WS - * Specifications  Task execution Human Task Specification, Service Level Agreement

16. 3. Interaction primitives in workflows Task delegation: Workflow participants delegate work to other participants [service / human]

17. 3. Interaction primitives in workflows Pattern Participants:  Delegator  Delegates work  Delegation Partner/Service  Participant who accepts the delegation [Human / Service Hybrid]  Executing Participant/Service  Human participant or Service which performs the task

18. 3. Interaction primitives in workflows Other primitives:  Participant Proxy  Participant Notification  Task Broker Contribution Patterns  Complex Information  Simple Information

19. 4. Introduction to the WS - * specifications Web Service Addressing Web Service Policy Web Service Transactions  WS – Coordination  WS – AtomicTransaction  WS - BusinessActivity Web Service Reliable Messaging  WS – ReliableMessaging  WS – ReliableMessaging Policy Web Service Security

20. 4. Introduction to the WS - * specifications Web Service Addressing  provides transport-neutral mechanisms to address Web Services and messages. Web Service Policy Framework  defines a base set of constructs that can be used and extended by other Web Services specifications to describe a broad range of service requirements and capabilities.

21. 4. Introduction to the WS - * specifications WS – Coordination Describes an extensible framework for providing protocols that coordinate the actions of distributed applications WS – AtomicTransaction Folgt einem „All-or-nothing“ Ansatz. Von den teilnehmenden Services wird ein hohes Vertrauen gefordert -> Trust. WS – BusinessActivity BusinessAgreementWithParticipantCompletion: Ein Teilnehmer beauftragt einen Koordinator, der die Verwaltung übernimmt. BusinessAgreementWithCoordinatorCompletion: Sobald eine Aktion abgeschlossen ist, wird der Koordinator informiert.

22. 4. Introduction to the WS - * specifications Web Service Reliable Messaging  Describes a protocol that allows messages to be delivered reliably between distributed applications in the presence of software component, system or network failures. The protocol is described in a transport-independent manner. Web Service Security  Provides comprehensive solutions to secure Web Service communication. In general these issues are addressed: Authentication Authorization Secure Messaging Secure data access Denial of service

23. 5. Putting it all together… Pattern Identification Workflow Optimization through automated resolution of execution requirements „Pattern Pool“:  Domain-specific Logistics, Healthcare, …  Aspect-specifc Security, Reliability, Time, Cost, …

24. 6. Challenges Identification of Interaction Primitives Elaboration of impacts on supporting environment Automated integration of advanced requirements

25. 7. Prototype Integration Existing BPEL Runtimes:  ActiveBPEL [http://www.activebpel.org]  Eclipse BPEL [http://www.eclipse.org/bpel] Workflow Runtime:  Windows Workflow Foundation [http://msdn.microsoft.com/workflow] WS - * Frameworks:  WS Apache [http://ws.apache.org]  Microsoft WSE [http://msdn.microsoft.com/webservices/webservices/building/ws e/default.aspx]

26. 8. References Patterns:  W.M.P. van der Aalst et al. “Workflow Patterns”, Distributed and Parallel Databases, 14(3), pages 5-51. July 2003  A. Barros, M. Dumas and A.ter Hofstede: „Service Interaction Patterns: Towards a Reference Framework for Service-based Business Process Interconnection“. Technical Report. March 2005  U. Zdun and P. Avgeriou. „Modeling architectural patterns using architectural primitives“. Object-Oriented Programming, Systems, Languages and Applications (OOPSLA 2005), pages 133-146. October 2005 BPEL4WS :  ftp://www6.software.ibm.com/software/developer/library/ws-bpel.pdf ftp://www6.software.ibm.com/software/developer/library/ws-bpel.pdf  C. Ouyang, W.M.P. van der Aalst, M. Dumas and A. ter Hofstede: „Translating BPMN to BPEL“. BPM Center Report, BPMcenter.org, 2006.  W.M.P. van der Aalst, M. Dumas, A.H.M. ter Hofstede and P. Wohed: „Pattern-Based Analysis of BPEL4WS“. QUT Technical Report, 2002.  M. Kloppmann, D. König, F. Leymann, A. Rickayzen: „WS-BPEL Extension for People BPEL4People“. Joint white paper, IBM and SAP, July 2005 …

27. Questions? Solutions? Suggestions? Thank you very much for your attention!