Web Services: OWL-S 2. BPEL and WSDL : Messages

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Mavis Perkins
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1 OWL-S

2 BPEL and WSDL : Messages Web s: OWL-S 2

3 Messaging and Message-Oriented Modeling Fundamental in composition: how and when the processes communicate Synchronous, asynchronous Conversations However, business processes center around activities and compositions of tasks: Control flow Data flow Messaging provides a realization of control/data flow Unclear how activities and messaging would mix Web s: OWL-S 3

4 Activity Based Models OWL-S (DAML-S) Finite state machines and statecharts Petri nets Process Specification Language (PSL) Web s: OWL-S 4

5 OWL-S/DAML-S An upper ontology for describing the properties & capabilities of agents & (Web) services in an unambiguous, computer interpretable markup language Built as an additional layer above DAML+OIL/OWL Designed to the following automated tasks Web s: OWL-S 5

6 Automation Enabled by OWL-S Web Discovery & Selection Find an airline that can fly me to New York, NY Web Invocation Book flight tickets from USAirways to arrive May 18 Web Composition & Interoperation Arrange taxis, flights and hotel for travel from Santa Barbara to Boston, MA, via New York, NY Web Execution Monitoring Has the taxi to Newark Airport been reserved yet? Web s: OWL-S 6

7 RDF Resource Description Framework Resources are related to each other by properties to form subject/predicate/object statements (triples) The triples can be used to construct a graph: subject object predicate W3C Home Page predicate object WWW Consortium Statements themselves can be resources of other statements (i.e. reified statements) Web s: OWL-S 7

8 RDF Schema RDF Schema defines new RDF vocabulary & hence definition of ontologies rdfs:class resources denoting a set of resources, by means of the property rdfs:type rdfs:subclassof Used to define class hierarchies. rdfs:domain & rdfs:range Define restrictions on the resources that have a given property (domain) and the set of valid values for that property (range) Web s: OWL-S 8

9 input types output types preconditions postconditions communication protocol (RPC, HTTP, ) port number marshalling/serialization process flow composition hierarchy process definitions Web s: OWL-S 9

10 OWL-S Upper Ontology Resource Grounding provides presents (what it does) supports (how to access) describedby (how it works) Profile input types output types preconditions effects Model communication protocol (RPC, HTTP, ) port number marshalling/serialization process flow composition hierarchy process definitions Web s: OWL-S 10

11 OWL-S Models Resource provides presents (what it does) Profile Grounding supports (how to access) describedby (how it works) Model Web s: OWL-S 11

12 Presenting Profiles Profile Presented by a service Represents what the service provides One can derive: Advertisements Requests Web s: OWL-S 12

13 Web s: OWL-S Functionality Description Non Functional Properties OWL-S Profile 13

14 Summarizes the abstract capability of a service Functional specification of what the service provides in terms of parameters, subclassed as: z preconditions z inputs z outputs z effects Web s: OWL-S Functionality Description 14

15 Functionality Description: Parameters Preconditions Set of conditions that should hold prior to service invocation Inputs Set of necessary inputs that the requester should provide to invoke the service Outputs Results that the requester should expect after interaction with the service provider is completed Effects Set of statements that should hold true if the service is invoked successfully Often refer to real-world effects Package being delivered, or Credit card being debited Web s: OWL-S 15

16 Non Functional Properties Provides supporting information about the service These include servicename textdescription has_process qualityrating serviceparameter servicecategory contactinformation Web s: OWL-S 16

17 Profile Hierarchy Sub-classing the Profile model facilitates the creation and specialisation of service categories Each subclass can: Introduce new properties Place restrictions on existing properties Sub-classing can also be used to specialise requests for service An example Profile Hierarchy is provided, but others could just as easily be defined Web s: OWL-S 17

18 Web s: OWL-S Profile Hierarchy Sample Ontology 18

19 OWL-S Models Resource provides presents (what it does) Profile Grounding supports (how to access) describedby (how it works) Model Web s: OWL-S 19

20 Describing Models Process Describes how a service works Facilitates (automated) Web service invocation composition interoperation monitoring Web s: OWL-S 20

21 The Process Ontology The basic class of the Process Ontology is the Process. Its sublcasses describe each process by: any number of (possibly, conditional) inputs; any number of (possibly, conditional) outputs; any number of preconditions, which must hold in order for the process to be invoked; any number of (possibly, conditional) side effects; any number of participants (subprocess) Web s: OWL-S 21

22 Types of the Process in OWL-S Atomic processes: directly invokable (by an agent), have no subprocesses, executed in a single step Composite processes: consist of other (non-composite or composite) processes They have a composedof property, by which the control structure of the process is indicated, using a ControlConstruct subclasses (see table ) Simple processes: abstract concepts, used to provide a view of some atomic process, or a simplified representation of some composite process (i.e., the black box view of a collapsed composite process) Web s: OWL-S 22

23 Web s: OWL-S OWL-S Model (Overview) 23

24 Control Constructs of Processes Construct Description Sequence Execute a list of processes in a sequential order Concurrent Execute elements of a bag of processes concurrently Split Invoke elements of a bag of processes Split+Join Invoke elements of a bag of processes and synchronize Unordered Execute all processes in a bag in any order Choice Choose between alternatives and execute one If-then-else If specified condition hold, execute Then, else execute Else. Repeat-Until Iterate execution of a bag of processes until a condition holds Repeat-While Iterate execution of a bag of processes while a condition holds Web s: OWL-S 24

25 Atomic Process Example Airport Flight Date departureairport_in outbounddate_in AtomicProcess GetDesired Flight Details <! Atomic Process Definition - GetDesiredFlightDetails --> <rdfs:class rdf:id= GetDesiredFlightDetails > <rdfs:subclassof rdf:resource= /> </rdfs:class> Web s: OWL-S 25

26 Atomic Process Example <! (sample) Inputs used by atomic process GetDesiredFlightDetails --> <rdf:property rdf:id="departureairport_in"> <rdfs:subpropertyof rdf:resource= " /> <rdfs:domain rdf:resource="#getdesiredflightdetails" /> <rdfs:range rdf:resource=" DAML-S/concepts.daml#Airport" /> </rdf:property> <rdf:property rdf:id="outboundate_in"> <rdfs:subpropertyof rdf:resource=" /> <rdfs:domain rdf:resource="#getdesiredflightdetails" /> <rdfs:range rdf:resource=" DAML-S/concepts.daml#FlightDate" /> </rdf:property> Web s: OWL-S 26

27 Composite Process Example <rdfs:class rdf:id="bookflight"> <rdfs:subclassof rdf:resource="#compositeprocess" /> <rdfs:subclassof rdf:resource=" /> <daml:subclassof> <daml:restriction> <daml:onproperty rdf:resource=" /> <daml:toclass> <daml:subclassof> <daml:unionof rdf:parsetype="daml:collection"> <rdfs:class rdfs:about="#getflightdetails" /> <rdfs:class rdfs:about="#getcontactdetails" /> <rdfs:class rdfs:about="#reserveflight" /> <rdfs:class rdfs:about="#confirmreservation" /> </daml:unionof> </daml:subclassof> </daml:toclass> </daml:restriction> Composite Process </daml:subclassof> BookFlight </rdfs:class> Get Flight Details Get Contact Details Reserve Flight Confirm Reservation Sequence Sequence Sequence Web s: OWL-S 27

28 OWL-S Models Resource provides presents (what it does) Profile Grounding supports (how to access) describedby (how it works) Model Web s: OWL-S 28

29 Supporting a Grounding Grounding Provides a specification of service access information Model + Grounding give everything needed for using the service Builds upon WSDL to define message structure and physical binding layer Specifies: communication protocols, transport mechanisms, agent communication languages, etc. Web s: OWL-S 29

30 OWL-S / WSDL Binding OWL-S Process Model Resources/Concepts Atomic Process Inputs / Outputs Operation Message Binding to SOAP, HTTP, etc. WSDL Web s: OWL-S 30

31 OWL-S / WSDL Mapping Web s: OWL-S 31

Limitations of the WWW

Limitations of the WWW A Semantic Web Application for the Air Tasking Order (ATO) ICCRTS Jun 13 2005 2:30-3:00 Albert Frantz, Milvio Franco In-house Program Air Force Research Laboratory AFRL/IFSA Rome NY Mentor: Prof. Bart