MFI-7: Metamodel for Service Registration

1. ISO/IEC JTC1/SC32/WG2 N1485 MFI-7: Metamodel for Service Registration Zaiwen Feng, Keqing He, Chong Wang, Jian Wang, Peng Liang SKLSE, Wuhan University, P.R. China 2010.11.09

2. Outline Motivation of this Work Definition of Service Scope of MFI-7 Metamodel for Service Registration Service Registration Example MFI-7 v.s. UDDI Summary

3. Outline • Motivation of this Work • Definition of Service • Scope of MFI-7 • Metamodel for Service Registration • Service Registration Example • MFI-7 v.s. UDDI • Summary

4. Motivation of this Work Solution: Providing a metamodel as the common registration mechanism for different kinds of services. • Heterogeneity in service • Different Description languages WSMO, OWL-S, WADL, WSDL, SAWSDL, SA-rest…

5. Outline Motivation of this Work Definition of Service Scope of MFI-7 Metamodel for Service Registration Service Registration Example MFI-7 v.s. UDDI Summary

6. Definitions of Service • Service (systems architecture): the provision of a discrete function within a systems environment • In the context of Enterprise architecture, Service-orientation, and Service-oriented architecture, the term service refers to a set of related software functionality, together with the policies that should control their usage. From: wikipedia (http://en.wikipedia.org/wiki/Service_(systems_architecture)) • Web service: a software system to support interaction over a network • OASIS : a mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface and is exercised consistent with constraints and policies as specified by the service description. • Web services are frequently just Internet Application Programming Interfaces (API) that can be accessed over a network, such as the Internet, and executed on a remote system hosting the requested services • From: Wikipedia – Web Service

7. Service Definition in MFI-7 • Service is defined as a modular functionality entity with provision of value that can be invoked by accessing its interface. • Currently, we focus on • SOAP Web service • Restful Web service • Web API

8. Outline Motivation of this Work Definition of Service Scope of MFI-7 Metamodel for Service Registration Service Registration Example MFI-7 v.s. UDDI Summary

9. Scope of MFI-7(1/2) Common Facilities in MFI • WSDL: Web Services Description Language (W3C) • OWL-S: Web Ontology Language for Services(W3C) • WSMO: Web Service Modeling Ontology(W3C) • WADL: Web Application Description Language(W3C) • SA-Rest: Semantic Annotation-representational state transfer(Wright State University, US) • SAWSDL: Semantic Annotation Web Services Description Language(W3C) • SWSO: Semantic Web Service Ontology (W3C) Service Registry based on MFI-7 Registration Interoperation Specification … SA-REST OWL-S WSMO WADL SAWSDL SWSO

10. Scope of MFI-7(2/2) • It is intended to • specify a metamodel for registering services that can enable users to discover appropriate services. • define the common functional and nonfunctional description of services. • promote semantic interoperation between various services. • It does not specify • the elements expressed in specific languages • details of service composition

11. Outline Motivation of this Work Definition of Service Scope of MFI-7 Metamodel for Service Registration Service Registration Example MFI-7 v.s. UDDI Summary

12. Overview of Service Semantics in MFI-7 Objective Semantic Functional Semantic Service Semantic Interaction Semantic Non Functional Semantic

13. Objective Semantics of Service • Objective Semantics • Objective that a client may have when consulting a Web Service • For example: • WSMO: It describe Objective semantic by post-condition and effect in service goal

14. Function Semantics of Services • Function Semantics describes service functionality, i.e. what a service can offer to its clients when it is invoked. It includes that: • Capability: the functionality defined using conditions which must hold before and after service invocation

15. Function Semantics of Services • For example: • Function Semantics • WSMO: It describes function semantics by preconditon, postcondition(constrained input/output), and assumption, effect (conditions for service usage) • SWSO: It describes function of service by input, output, precondition and effect • SAWSDL(WSDL): It describes function of service by interface_name, operation_name, input and output • OWL-S Profile: It describes feature of service by specifying the category of a given service, for example, the category of service within the UNSPSC classification system. Further, it shows function semantics through input, output, pre-condition and post-condition

16. Interaction Semantic of Service • Interaction semantic: It is the formal description which defines a service’s public behavior. • MFI-7 focuses on External behavior, which describes a protocol that can be used by the client to consume the service functionality • We call the public behavior of service is choreography in MFI-7

17. Interaction Semantic of Service • Interaction semantic • OWL-S: From orchestration perspective, it describes a process model inside service • WSMO: From choreography view, it specifies the behavior interface for service consumption; and from orchestration view, it specifies how the functionality of a web service is achieved by aggregating other web services • SWSO: From orchestration view, it defines how to construct a process model inside a service

18. Non-Function Semantic of Service • Non-Function Semantic: It describes attributes specifying quality of service • We describe quality of service based on WS-Policy framework in MFI-7 • WS-Policy contains an attachment specification, WS-PolicyAttachment, which defines mechanisms for associating policies with policy subjects

19. Non Function Semantic of Service • Non Functional Semantic of Service • For example: • WSDL-S 1.0: It investigates how to represent QoS assertions using ontologies and rules by extending the WS-Policy framework (future work) • OWL-S Profile: It provides information about quality rating of service • SWSO: It consists of various attributes in the part of Service Descriptors, e.g. Service Trust, Service Reliability and Service Cost in order to describe QoS • WSMO: It describes Web Service specific non-Functional properties in the part of Capability, e.g. Accuracy, Availability, Financial…

20. How MFI-7 is constructed • Harmonization of Service models for registration • WSDL (Web Services Description Language, W3C, 2007) • OWL-S (Web Ontology Language for Services, W3C, 2007) • WSMO (Web Service Modeling Ontology, W3C, 2005) • SAWSDL(Semantic Annotation for WSDL, W3C, 2007) • SWSO(Semantic Web Service Ontology, W3C, 2005) • WADL (Web Application Description Language, W3C, 2009) • SA-Rest: Semantic Annotation-representational state transfer (W3C, 2010) • …

21. How to select elements and relationships from current service-related specifications? • Function Semantics • Non-Function Semantics • Objective Semantics • Interaction Semantics

22. Service concepts in OWL-S

23. Service concepts in WSMO

24. Service concepts in SAWSDL

25. Service concepts in SWSO From: W3C, Semantic Web Services Ontology, http://www.w3.org/Submission/SWSF-SWSO/ access on: 2010-11-09

26. Service concepts in SA-REST From: W3C, SA-REST: Semantic Annotation of Web Resources, http://www.w3.org/Submission/SA-REST/ access on: 2010-11-09

27. Service Concept in WADL From: W3C, Web Application Description Language, http://www.w3.org/Submission/wadl/ access on: 2010-11-09

28. MFI-7: Metamodel for Service Registration

29. Comparison between MFI-7 and Other Specifications

30. Function-related Metaclasses(1) • Precondition • specifies the state that should be satisfied before a service is invoked • Postcondition • specifies the state that should be satisfied after a service is invoked successfully Their properties are Parameter and Predicate

31. Function-related Metaclasses(2) • Input, output • the link between service and outer space • Their type can be depicted as Message_Type • Message_Type • specifies the type of message that is used, as input variable, out variable. • It can be the domain concepts in Ontology

32. Non-Function Related Metaclass(1) Policy: It provides a grammar for representing the non-functional attributes of entities in a Web service based XML environment Quality_Property_Type: Current WS-Policy specification makes assertion in different domains, e.g. security, transaction, cost…

33. Non-Function Related Metaclass(2) A policy is defined as a finite set of alternatives. It can also be expressed as a disjunction of all its alternatives An alternative is defined as a finite set of assertions. It can also be expressed as a conjunction of all its assertions

34. Non-Function Related Metaclass(3) <semsecurity:TokenType assertionType="sempolicy:Requirement" valueType="owl:object" comparisonOperator="sempolicy:EQ"> semsecurity:Kerberosv5TGT </semsecurity:TokenType > • Assertion: A policy assertion represents an individual requirement, capability, or other property of a behavior. • valueType: It is used to specify whether an assertion is a numeric or a non-numeric assertion • comparisonOperator: It is used to represent the relationship between the assertion name and value • assertionName: It describes name of assertion

35. Interaction Related Metaclass • Choreography • The Choreography interface describes the behaviour of the service from the client's point of view (W3C Glossary, 2004) • Users may be other Web Services, applications or human beings • Transitionrule • It deals with basic operations on instance data, such as adding, removing and updating instances to the states. • State • It defines the state ontology used by the service together with the definition of the types of modes the concepts and relations may have

36. Choreography example Choreography_Item 1 Choreography_Item 2 Choreography_Item 3 Choreography

37. Relationships with Other Parts in MFI Metaclass from MFI-5 Metaclass from MFI-8 annotationattributes are annotated by Ontology_Atomic_Construct from MFI-3

38. Outline Motivation of this Work Definition of Service Scope of MFI-7 Metamodel for Service Registration Service Registration Example MFI-7 v.s. UDDI Summary

39. Registration example(1/4)in WSMO • Case study: Book Ticket • Description • The service can achieve the goal which specifies the intent of buying a ticket for a trip from one place to another • Service Language • WSMO

40. Registration example(2/4)in WSMO WS1 Booking WS2 Paying Reservation Book Ticket WS ReservationRequest P1 Booking P2 Paying creditCard ticket I want to book a ticket!

41. Maybe, In the above example, we should register three Web Services: Web Service1: Booking (for invoking by business process) Web Service2: Paying (for invoking by business process) Web Service3: Book Ticket WS (the whole service)

42. Registration example(2/4)in WSMO Book Ticket WS reservationRequest temporaryReservation Book Ticket WS ReservationRequest temporaryReservation Reservation creditCard ticket reservation creditCard ticket temporaryReservation What is my Goal? creditCard negative I want to book a ticket!

43. What can we find proper service by? Objective Semantic MFI-8 Functional Semantic Service Semantic Interaction Semantic MFI-7 Non Functional Semantic MFI-7 Response time <= 5 seconds Security is high … … MFI-7

44. Registration example (3/4) in WSMO

45. Registration example (3/4) in WSMO

46. Registration example (4/4) in WSMO

47. Registration example (4/4) in WSMO

48. Registration example (4/4) in WSMO

49. Registration example(1/4)in WADL • Case study: Amazon item search service • Description • The service provided by Amazon is to search items in Amazon Internet Shop. Browser will return item information after user inputs keywords or index of item • Service Language • WADL

50. Registration example(2/4)in WADL Amazon Item Search SubscriptionId name SearchIndex description KeyWord price ResponseGroup I want to search item in Amazon?