1. The METOER-S Framework for Semantic Web Process Composition Kaarthik Sivashanmugam Large Scale Distributed Information Systems (LSDIS) Lab, Department of Computer Science, The University of Georgia

2. Acknowledgements Advisory Committee –Dr. John A. Miller (Major Advisor) –Dr. Amit P. Sheth (Co-advisor) –Dr. Hamid R. Arabnia LSDIS Student Members –Kunal Verma, Deepti Chafekar, Ivan Vasquez, Preeda Rajasekaran and others

3. Outline Introduction to Web services, Web services conceptual stack and Web processes Challenges in Web services adoption Semantics at different layers of Web services conceptual stack Semantics for Web service life-cycle METEOR-S project at LSDIS lab –Discovery Infrastructure (MWSDI) –Composition Framework (MWSCF)

4. Outline (contd) MWSDI –P2P network of Web service registries –Semantics based publication and discovery of Web services MWSCF –Need and advantages of Semantic Web process composition –Template based process generation –Tool for Template construction, Web service discovery and Process generation Conclusion and Future Work References

5. Web Services A Web service is a software application identified by a URI, whose interfaces and binding** are capable of being defined, described and discovered by XML artifacts and supports direct interactions with other software applications using XML based messages via Internet-based protocols. (W3C definition) **- An association between an Interface, a concrete protocol and a data format Software applications (conforming set of standards) that can communicate with other software applications independent of their operating systems, programming languages etc. to enable interoperability and to deliver complex value added services

6. Web Service Conceptual Stack 1 Description Messaging Network Description:Web Service Description Language (WSDL) –To describe Web Service interfaces and implementations –Details in WSDL files (data types, operations, binding details, access location) are used for service invocation Messaging:(SOAP) –XML based messaging protocol Network:(HTTP) –Network protocol 1 [Kreger]

7. Web Service Conceptual Stack 1 Publication:(UDDI) –To make service descriptions available for search Discovery:(UDDI) –To locate service descriptions Publication Discovery Description Messaging Network Flow Flow:(BPEL4WS, WSCI etc.) –To compose web services to form a composite web service / process 1 [Kreger]

8. Web Processes Web Processes are next generation workflow technology to facilitate the interaction of organizations with markets, competitors, suppliers, customers etc. supporting enterprise-level and core business activities –encompass the ideas of both intra and inter organizational workflow. –created from the composition of Web Services When all the tasks involved in a Web process are semantically described, we may call such process as Semantic Web Processes

9. Workflows GlobalEnterpriseInter-Enterprise Web Processes E-Services Globalization of Processes Distributed Workflows B2B

10. BIG Challenges Heterogeneity and Autonomy –Solution: Machine understandable descriptions Dynamic nature of business interactions –Demands: Efficient Discovery, Composition etc. Scalability (Enterprises  Web) –Needs: Automated service discovery/selection and composition Proposition: Semantics is the most important enabler to address these challenges

11. METEOR-SMETEOR-S Project @ LSDIS lab METEOR-S exploits Workflow, Semantic Web, Web Services, and Simulation technologies to meet these challenges in a practical and standards based approach. –Applying Semantics in Annotation, Quality of Service, Discovery, Composition, Execution of Web Services –Adding semantics to different layers of Web services conceptual stack –Use of ontologies to provide underpinning for information sharing and semantic interoperability

12. Semantics at Different Layers Publication Discovery Description Messaging Network Flow Description Layer: Why: Unambiguously understand the functionality of the services and the semantics of the operational data How: Using Ontologies to semantically annotate WSDL constructs (conforming to extensibility allowed in WSDL specification version 1.2) to sufficiently explicate the semantics of the –data types used in the service description and –functionality of the service Present scenario: WSDL descriptions are mainly syntactic (provides operational information and not functional information) Semantic matchmaking is not possible

13. Semantics at Different Layers (contd..) Publication Discovery Description Messaging Network Flow Publication and Discovery Layers: Why: Enable scalable, efficient and dynamic publication and discovery (machine processable / automation) How: Use of ontology to categorize registries based on domains and characterize them by maintaining the 1. properties of each registry 2. relationships between the registries Capturing the WSDL annotations in UDDI Present scenario: Suitable for simple searches ( like services offered by a provider, services that implement an interface, services that have a common technical fingerprint etc.) Categories are too broad Automated service discovery (based on functionality) and selecting the best suited service is not possible

14. Semantics at Different Layers (contd..) Publication Discovery Description Messaging Network Flow Flow Layer: Why: Design (composition), analysis (verification), validation (simulation) and execution (exception handling) of the process models To employ mediator architectures for automated composition, control flow and data flow based on requirements To employ user interface to capture template requirements and generate template based on that How: Using –Functionality/preconditions/effects of the participating services –Knowledge of conversation patterns supported by the service –Formal mathematical models like process algebra, concurrency formalisms like State Machines, Petri nets etc. –Simulation techniques Present Scenario: Composition of Web services is static. Dynamic service discovery, run-time binding, analysis and simulation are not supported directly

15. Semantics in WS stack and METEOR-S Publication Discovery Description Messaging Network Flow MWSDI: Scalable Infrastructure of Registries for Semantic publication and discovery of Web Services MWSDI: Semantic Annotation of WSDL (WSDL-S) MWSCF: Semantic Web Process Composition Framework

16. Semantics for Web Services Data/Information Semantics –What: Formal definition of data in input and output messages of a web service –Why: for discovery and interoperability –How: by annotating input/output data of web services using ontologies Functional/Operational Semantics –Formally representing capabilities of web service –for discovery and composition of Web Services –by annotating operations of Web Services as well as provide preconditions and effects; Annotating TPA/SLA Execution Semantics –Formally representing the execution or flow of a services in a process or operations in a service –for analysis (verification), validation (simulation) and execution (exception handling) of the process models –using State Machines, Petri nets, activity diagrams etc. QoS Semantics –Formally describing operational metrics of a web service/process –To select the most suitable service to carry out an activity in a process –using QoS model [Cardoso and Sheth, 2002] for web services

17. Data / Information Semantics Development / Description / Annotation WSDL, WSEL DAML-S Meteor-S (WSDL Annotation) Publication / Discovery UDDI WSIL, DAML-S METEOR-S (P2P model of registries) Composition BPEL, BPML, WSCI, WSCL, DAML-S, METEOR-S (SCET,SPTB) Execution BPWS4J, Commercial BPEL Execution Engines, Intalio n3, HP eFlow Semantics for Web Service Life-Cycle

18. Data / Information Semantics Publication / Discovery WSDL, WSEL DAML-S Meteor-S (WSDL Annotation) UDDI WSIL, DAML-S METEOR-S (P2P model of registries) BPWS4J, Commercial BPEL Execution Engines, Intalio n3, HP eFlow Development / Description / Annotation Composition Execution BPEL, BPML, WSCI, WSCL, DAML-S, METEOR-S (SCET,SPTB) Semantics for Web Service Life-Cycle

19. Functional / Operational Semantics Publication / Discovery WSDL, WSEL DAML-S Meteor-S (WSDL Annotation) UDDI WSIL, DAML-S METEOR-S (P2P model of registries) BPWS4J, Commercial BPEL Execution Engines, Intalio n3, HP eFlow Development / Description / Annotation Composition Execution BPEL, BPML, WSCI, WSCL, DAML-S, METEOR-S (SCET,SPTB) Semantics for Web Service Life-Cycle

20. QoS Semantics Publication / Discovery WSDL, WSEL DAML-S Meteor-S (WSDL Annotation) UDDI WSIL, DAML-S METEOR-S (P2P model of registries) BPWS4J, Commercial BPEL Execution Engines, Intalio n3, HP eFlow Development / Description / Annotation Composition Execution BPEL, BPML, WSCI, WSCL, DAML-S, METEOR-S (SCET,SPTB) Semantics for Web Service Life-Cycle

21. Execution Semantics Publication / Discovery WSDL, WSEL DAML-S Meteor-S (WSDL Annotation) UDDI WSIL, DAML-S METEOR-S (P2P model of registries) BPWS4J, Commercial BPEL Execution Engines, Intalio n3, HP eFlow Development / Description / Annotation Composition Execution BPEL, BPML, WSCI, WSCL, DAML-S, METEOR-S (SCET,SPTB) Semantics for Web Service Life-Cycle

22. Publication / Discovery WSDL, WSEL DAML-S Meteor-S (WSDL Annotation) UDDI WSIL, DAML-S METEOR-S (P2P model of registries) BPWS4J, Commercial BPEL Execution Engines, Intalio n3, HP eFlow Semantics Required for Web Processes Execution Semantics QoS Semantics Functional / Operational Semantics Data / Information Semantics Development / Description / Annotation Composition Execution BPEL, BPML, WSCI, WSCL, DAML-S, METEOR-S (SCET, SPTB) Semantics for Web Service Life-Cycle

23. METEOR-S components for Semantic Web Services Discovery Infrastructure (MWSDI) –Semantic Annotation and Discovery of Web Services 1 –Semantic Peer-to-Peer network of Web Services Registries 2 Composer –SCET: Service Composition and Execution Tool 3 –Semantics Process Template Builder and Process Generator 4 –QoS Management Specify, compute, monitor and control QoS (SWR algorithm) 5 Orchestrator (Under development) –Analysis and Simulation 6 –Execution –Monitoring 6 1 [Sivashanmugam et al.-1], 2 [Verma et al.], 3 [Chandrasekaran et al.], 4 [Sivashanmugam et al.-2], 5 [Cardoso et al.], 6 [Silver et al.]

24. Service Discovery METEOR-S Web Service Discovery Infrastructure (MWSDI) - uses Functional, Data and QoS semantics

25. Service Selection METEOR-S Web Service Discovery Infrastructure (MWSDI) - uses Functional, Data and QoS semantics

26. Search retrieves lot of services (irrelevant results included) Which service to select ? How to select? UBR Registry is universal and provides non-semantic search Keyword match, taxonomy The problem in discovery..

27. Registries are categorized Select relevant registries (semantic filtering) Select service(s) of interest Domain Registry Registry is domain specific and supports semantic search Ontology Scalable Solution..

28. Search for services to book an air ticket (using categories)* unspsc-org: unspsc:3-1 –Travel, Food, Lodging and Entertainment Services Travel facilitation –Travel agents »Travel agencies Services: 3 records found. –AirFares Returns air fares from netviagens.com travel agent –Hotel reservations Reservations for hotels in Asia, Australia and New Zealand –Your Vacation Specialists Web enabled vacation information Providers: 2 records found. * Search carried out in one of the Universal Business Registries

29. Search for services to book an air ticket (using keywords)* air ticket –1 record with name air tickets booking airticket, ticketbooking, airtravel, air travel, travel agent, airticketbooking, air ticket booking, travel agency, travelagency –0 records were returned travelagent –1 record with name travelagent test 4 services: BookFlight, cancelFlightBooking etc. Descriptions say that both these services are “XML based Web services” No URL for WSDL Travel –15 records. Purpose/functionality understood from descriptions 2 services : TravelBooks 4 services : TravelInformation 2 services : Reservation and cancallation of travel tickets 1 service : Emergency Services for travellers 1 service : Travel documentation and itinerary 5 services : Description is ambiguous/not present * Search carried out in one of the Universal Business Registries

30. Semantic Discovery: Overview Annotation and Publication –WSDL file is annotated using ontologies and the annotations are captured in UDDI Discovery –Requirements are captured as templates that are constructed using ontologies and semantic matching is done against UDDI entries Functionality of the template, its inputs, outputs, preconditions and effects are represented using ontologies Use of ontologies –brings service provider and service requestor to a common conceptual space –helps in semantic matching of requirements and specifications

31. Use of ontologies enables shared understanding between the service provider and service requestor Semantic Publication and Discovery For simplicity of depicting, the ontology is shown with classes for both operation and data

32. WSDL-S (WSDL with Semantic Annotation) Mapping Input and Output Message Parts to Ontology –XML Schema elements used in Input/Output messages do not reflect the semantics of the data involved in Web Service operation –Use of ontologies or standard vocabulary* provides well defined semantics for operational data Mapping Operations to Ontology –Service selection involves discovering appropriate WSDL description and locating an operation to invoke –Operations with same signature could have different functionalities –Ontology or vocabulary* depicting functionality is used for annotation Additional tags to represent pre-conditions and effects of each operation –Preconditions and effects are added for each operation –Can be optionally used for service discovery and selection * RosettaNet Business/Technical dictionary or ebXML Core Component catalog/dictionary * Current implementation uses vocabularies The focus of our work is not in developing ontologies for representing functionality/preconditions/effects but to use such ontologies for semantic annotation

33. Annotation Syntax* Each Operation in WSDL is annotated using an fully qualified attribute name-value pair in the operation element under portType element. The attribute name is operation-concept Each Message part is annotated using a fully qualified attribute name-value pair in the part element under message element. The attribute name is onto-concept Preconditions and effects are respectively represented using fully qualified additional tags with the names precondition and effect. These elements have two attributes name (optional) and precondition-concept (or effect- concept). Each operation can have multiple precondition and effect elements. * conforms to extensibility support in WSDL version 1.2

34. WSDL Annotation Example <wsdl:definitions xmlns:TravelOnto=lsdis.cs.uga.edu//METEORS/TravelServiceOntology.daml ….. >lsdis.cs.uga.edu//METEORS/TravelServiceOntology.daml

35. Semantics in UDDI tModels are used to categorize and characterize service entries in UDDI (limited form of semantics) Our approach categorizes* (using metadata constructs tModels and CategoryBags) the services in UDDI based on the semantic annotations * similar to [Paolucci et al.]

36. Semantic Categorization of Services in UDDI* Service KeyedReferenceGroup (SemanticGroupTModelKey) KeyedReferenceGroup (SemanticGroupTModelKey) CategoryBag TmodelKey:OperationalTModelKey, Value:TicketBooking, Name:buyTicket TmodelKey:InputTModelKey, Value:TicketInformation TmodelKey:OutputTModel, Value:ConfirmationMessage * conforming to UDDI Version 3 spec [UDDI-v3] TmodelKey:OperationalTModelKey, Value:TicketCancellation, Name:cancelTicket TmodelKey:InputTModelKey, Value:TicketInformation TmodelKey:OutputTModel, Value:ConfirmationMessage For the example discussed earlier: Travel Arrangement Service with two operations buyTicket and cancelTicket

37. Semantic Categorization of Services in UDDI* Service KeyedReferenceGroup (SemanticGroupTModelKey) KeyedReferenceGroup (SemanticGroupTModelKey) CategoryBag TmodelKey:OperationalTModelKey, Value:TravelOnto:TicketBooking, Name:buyTicket TmodelKey:InputTModelKey, Value:TravelOnto:TicketInformation TmodelKey:OutputTModelKey, Value:GeneralTradeOnto:ConfirmationMessage TmodelKey:OperationalTModelKey, Value: TravelOnto:TicketCancellation, Name:cancelTicket TmodelKey:InputTModelKey, Value: TravelOnto:TicketInformation TmodelKey:OutputTModelKey, Value: GeneralTradeOnto: ConfirmationMessage Functional/Operational Semantics: Operation-ontology mapping in WSDL for buyTicket operation * conforming to UDDI Version 3 spec [UDDI-v3]

38. Semantic Categorization of Services in UDDI* Service KeyedReferenceGroup (SemanticGroupTModelKey) KeyedReferenceGroup (SemanticGroupTModelKey) CategoryBag TmodelKey:OperationalTModelKey, Value:TicketBooking, Name:buyTicket TmodelKey:InputTModelKey, Value:TravelOnto:TicketInformation TmodelKey:OutputTModelKey, Value: GeneralTradeOnto:ConfirmationMessage TmodelKey:OperationalTModelKey, Value:TravelOnto:TicketCancellation, Name:cancelTicket TmodelKey:InputTModelKey, Value: GeneralTradeOnto:TicketInformation TmodelKey:OutputTModel, Value: GeneralTradeOnto:ConfirmationMessage Data/Information Semantics: Input Message part-ontology mapping in WSDL for buyTicket operation * conforming to UDDI Version 3 spec [UDDI-v3]

39. Semantic Categorization of Services in UDDI* Service KeyedReferenceGroup (SemanticGroupTModelKey) KeyedReferenceGroup (SemanticGroupTModelKey) CategoryBag TmodelKey:OperationalTModelKey, Value:TicketBooking, Name:buyTicket TmodelKey:InputTModelKey, Value:TravelOnto:TicketInformation TmodelKey:OutputTModelKey, Value: GeneralTradeOnto:ConfirmationMessage TmodelKey:OperationalTModelKey, Value:TravelOnto:TicketCancellation, Name:cancelTicket TmodelKey:InputTModelKey, Value: GeneralTradeOnto:TicketInformation TmodelKey:OutputTModel, Value: GeneralTradeOnto:ConfirmationMessage Data/Information Semantics: Output Message part-ontology mapping in WSDL for buyTicket operation * conforming to UDDI Version 3 spec [UDDI-v3]

40. Discovery using UDDI V1 API Our implementation used UDDI Version 1 API –KeyedReferenceGroups are not supported –Each operation is grouped with its operation-concept, input and output onto- concepts each as a keyedReference in the keyedReferenceVector as tModelKey = “OpTModel” KeyValue = “operation-concept” KeyName = “OpName” tModelKey = “InTModel” KeyValue = “onto-concept” KeyName = “OpName” tModelKey = “OutTModel” KeyValue = “onto-concept” KeyName = “OpName” OpTModel: Key for the tModel representing functional semantics of the operation named “OpName” in a WSDL file linked to the UDDI entry InTModel: Key for the tModel representing semantics of the inputs of the operation named “OpName” in the WSDL OutTModel: Key for the tModel representing semantics of the outputs of the operation named “OpName” in the WSDL operation-concept: Fully qualified Id of a class in a functional ontology represented by OpTModel onto-concept: Fully qualfied Id of a class in a ontology that is used to annotate inputs (or outputs) represented by InTModel (or OutTModel)

41. Summary of Steps in Discovery 1.Services selection based on the functional requirements Using operation-ontology mapping 2.Ranking based on semantic similarity based on input/output semantics of candidate services and requirement template Using message part-ontology mapping 3.Optional step includes semantic similarity based on semantics of preconditions/effects of the candidate services and requirement template Using precondition and effect tags

42. METEOR-S Web Service Composition Framework (MWSCF) - needed for the world where business processes never stop changing.

43. Activity Interfaces Process Templates Ontologies XML Repositories Repositories are used to store 1. Web Service Interfaces 2. Ontologies 3. Process Templates Template Builder Process Generator Process Designer 1. Template Construction - interfaces - services - semantic activity templates - other details 2. Process Generation - Service discovery and selection - Data flow MWSCF Architecture UDDI Execution Engine Discovery Infrastructure (MWSDI) Process Execution 1. Validation and deployment 2. Executing the process using a client

44. Web Process Life-Cycle Find Matches Rank Services Select a Service Discovery Add to Process Data Transformation Data Flow Composition Generate Process Validate Syntax Execute Execution Design Create Process WSDL Create Process Template and Add Activities Add Control Flow Find Ontologies & Annotate Activity Requirements

45. Template Construction Discovery not needed Process Template can be constructed with 3 types of activities –Concrete Web Service Implementation activity is bound to Web service by linking it to a WSDL file and an operation in it –Web Service Interface activity is bound to a Web service interface by linking it to a interface identifier (which is linked to a WSDL file ) and an operation in it –Semantic Activity Template activity is semantically enriched by linking it to semantic specifications of its inputs/outputs/functionality/precondition and effects

46. Template Construction QoS requirements are specified too Process Template can be constructed with 3 types of activities –Concrete Web Service Implementation activity is bound to Web service by linking it to a WSDL file and an operation in it –Web Service Interface activity is bound to a Web service interface by linking it to a interface identifier (which is linked to a WSDL file ) and an operation in it –Semantic Activity Template activity is semantically enriched by linking it to semantic specifications of its inputs/outputs/functionality/precondition and effects

47. Template Construction (contd) Activities are linked by a control flow constructs Template can have protocol variables that do not have any assignment –These protocol variables are assigned a value (output of a WS) during process generation –Process generator will handle replacing the protocol variable with a relevant container and message details –Example: will be converted into During process generation inventory-availability is manually assigned to output of activity whose output container name is inventoryResponse and the output message part name is avail

48. Input, output messages, portType (of reserveRoom operation) and targetNamespace details are extracted from the given WSDL <invoke-activity name=“RoomReservation” type=“ServiceImpl” wsdl-URL=“ http://lsdis.cs.uga.edu/proj/meteors/wsdl/Hotel.wsdl ” operation-name=“reserveRoom” /> Activity as Concrete Web Service Implementation

49. <invoke-activity name=“RoomReservation” type=“WSInterface” tModel-id=“uuid: f4a6574b-49f4-a657-f908-45fa62354d84 ” operation-name=“reserveRoom” qos-spec=“qos-2” ranking-weight=“ranking-2” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Activity as Web Service Interface

50. <invoke-activity name=“RoomReservation” type=“WSInterface” tModel-id=“uuid: f4a6574b-49f4-a657-f908-45fa62354d84 ” operation-name=“reserveRoom” qos-spec=“qos-2” ranking-weight=“ranking-2” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Activity as Web Service Interface All the services that implement the interface (a WSDL without service/binding/ port details identified by a tModel-id) are bound to the given tModel (using binding template construct in UDDI). Discovery is based on this binding.

51. An interface may have multiple operations. The input, output messages, portType details (of reserveRoom operation) and targetNamespace details are extracted from the WSDL of the selected service during process generation. <invoke-activity name=“RoomReservation” type=“WSInterface” tModel-id=“uuid: f4a6574b-49f4-a657-f908-45fa62354d84 ” operation-name=“reserveRoom” qos-spec=“qos-2” ranking-weight=“ranking-2” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Activity as Web Service Interface

52. Ranking of the discovered services are based on the QoS criteria expanded as under element in the process template <invoke-activity name=“RoomReservation” type=“WSInterface” tModel-id=“uuid: f4a6574b-49f4-a657-f908-45fa62354d84 ” operation-name=“reserveRoom” qos-spec=“qos-2” ranking-weight=“ranking-2” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Activity as Web Service Interface

53. Ranking-weight will be expanded as under in the template. It will have weights for different QoS critria. <invoke-activity name=“RoomResercation” type=“WSInterface” tModel-id=“uuid: f4a6574b-49f4-a657-f908-45fa62354d84 ” operation-name=“reserveRoom” qos-spec=“qos-2” ranking-weight=“ranking-2” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Activity as Web Service Interface

54. <invoke-activity name=“RoomReservation” type=“WSInterface” tModel-id=“uuid: f4a6574b-49f4-a657-f908-45fa62354d84 ” operation-name=“reserveRoom” qos-spec=“qos-2” ranking-weight=“ranking-2” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Activity as Web Service Interface Access URL of the UDDI registry may be given in the attribute discovery-URL. future work will aim to use a concept from Registries Ontology instead of discovery-URL

55. <invoke-activity name=“RoomReservation” type=“WSInterface” tModel-id=“uuid: f4a6574b-49f4-a657-f908-45fa62354d84 ” operation-name=“reserveRoom” qos-spec=“qos-2” ranking-weight=“ranking-2” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Activity as Web Service Interface qos-spec, ranking-weight and discovery-URL attributes are optional Discovery will be any of the UBRs by default Weight for qos will be considered 0 if the qos-spec attribute is missing Weight is distributed equally among different QoS criteria if ranking-weight is missing

56. Activity as Semantic Activity Template <invoke-activity name=“RoomReservation” type=“SemanticTemplate” semantic-spec=“RoomReservationServiceSemantics” qos-spec=“qos-1” ranking-weights=“ranking-1” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” />

57. Activity as Semantic Activity Template <invoke-activity name=“RoomReservation” type=“SemanticTemplate” semantic-spec=“RoomReservationServiceSemantics” qos-spec=“qos-1” ranking-weights=“ranking-1” discovery-URL=“http://westpoint.cs.uga.edu:8080/registry- server/RegistryServerServlet” /> Services that match the RoomReservationServiceSemantics are discovered and ranked based on the Semantic Matching and QoS Matching

58. Functional/Operational Semantics Semantic Specifications (Example)

59. Input Semantics: Data/Information Semantics Semantic Specifications (Example)

60. Output Semantics: Data/Information Semantics Semantic Specifications (Example)

61. Sample Ontology Air Travel Air Travel Ontology Airport Airport Class …………………. Tickets Tickets Ontology Travel type Travel type for the trip

62. Ranking Scheme Helps in Service selection Discovery mechanism is supplemented with a ranking model and scheme Activity types –WSInterface Uses QoS requirements for ranking –SemanticTemplate Uses Semantic and QoS requirements for ranking Overall ranking value is the Weighted arithmetic mean of Semantic and QoS Criteria Matching values

63. Semantic Matching i = 1  Functionality of the services i = 2  Inputs of the services i = 3  Outputs of the services i = 4  Preconditions of the services i = 5  Effects of the services Wi  Weights assigned for each of i Mi  Semantic Matching value of i th criterion between activity requirements and service description

64. QoS criteria matching i = 1  Task Delay Time of the services i = 2  Task Process Time of the services i = 3  Task Realization Cost of the services i = 4  Task Reliability of the services Wi  Weights assigned for each of i Mi  QoS criteria matching value of i th criterion between activity requirements and service description Reference: [Cardoso et. al]

65. Using the framework Template Repository Process Generator Template Customized Template Executable BPEL Process BPEL Execution Engine Manual service selection & data flow

66. Template Construction

67. Process Generation

69. Advantages of SPT in the framework Flexible and rapid approach to process composition –Configuration and re-use of templates –Process is not bound to any Web service interfaces or implementations. (partners/services can be dynamically changed) –Template/Process designer need not perform discovery of services. Discovery can be delegated to the tool Well defined semantics for each activity –Using ontologies –Richer description of semantics of activities Can be generated in executable process in any standard Process re-design is easier Can be advertised/published as reference/business models for reuse across vertical industry segments

70. Testing

71. Conclusions Present Problems in Process Composition –Static discovery of Web Services –Design/deployment-time binding of Web services –Process Composition is based on interfaces of participating services Proposition –Semantics is the enabler to address the problems of scalability, heterogeneity (syntactic and semantic), machine understandability faced by Web services Semantics for Web Services –Semantics can be applied to different layers of Web Services conceptual stack –Semantics for Web Services can be categorized into at least 4 different dimensions namely Data, Functional, Execution and Quality (QoS).

72. Conclusions (contd) Semantic Web Process Composition Framework –Utilizes Data, Functional, QoS Semantics during template construction and service discovery –Dynamic discovery and deployment-time binding –Template can be agnostic of the interfaces of participating services –Semi-automatic generation of executable processes based on selected services Results from preliminary testing –Semantic discovery is better in locating semantically appropriate services in comparison with keyword/taxonomy based present discovery mechanisms supported by UDDI –Semantic Process Template (SPT) is helpful to capture the semantics of activities in a process and can be generated into an executable process preserving the semantics specified in the template

73. Future Work Specifying collaboration/conversation needed for or expected from an activity in the SPT Mapping the template to concurrency formalisms (State Machines/Petri nets) to specify Execution Semantics in the template Using a SPT in conjunction with an activity in another SPT Incorporating e-business aspects like SLAs, negotiation and contracts in the process template and service discovery Specifying goal definition (using UML) as a part of the template and developing an user interface for this purpose

74. References [Kreger] http://www-3.ibm.com/software/solutions/webservices/pdf/WSCA.pdfhttp://www-3.ibm.com/software/solutions/webservices/pdf/WSCA.pdf [Sivashanmugam et al.-1] Adding Semantics to Web Services Standards [Sivashanmugam et al.-2] Framework for Semantic Web Process Composition [Verma et al.] MWSDI: A Scalable Infrastructure of Registries for Semantic Publication and Discovery of Web Services [Chandrasekaran et al.] Performance Analysis and Simulation of Composite Web Services [Cardoso et al.] Modeling Quality of Service for Workflows and Web Service Processes [Silver et al.] Modeling and Simulation of Quality of Service for Composition of Web Services [Paolucci et al.] Importing Semantic Web in UDDI [UDDI-v3] http://uddi.org/pubs/uddi-v3.00-published-20020719.htm

75. Questions and Comments

76. Thank You !