Tools and Technologies for Semantic Web Services - SRI's Artificial ...

Tools and Technologies for Semantic Web Services: An OWL-S Perspective Katia Sycara Agents and Web Technologies Lab Carnegie Mellon University [email protected] http://www.cs.cmu.edu/~softagents/

David Martin Artificial Intelligence Center SRI International [email protected] http://www.ai.sri.com/~martin/

Tutorial Outline The Vision Web Services Semantic Web Services Motivations Semantic Web Services Approaches OWL-S Related Work

Semantic Web Services Applications Semantic Web Services Tools Challenges and Future Directions OWL-S Tutorial

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From the Internet to the Semantic Web

Old World :

New World:

“The eye-ball Web”

“The Semantic Web”

The architecture of the Web is geared towards delivering information visually (Internet filled with human readable information)

The content of the Web becomes computer intelligible (Internet filled with machine understandable information)

Source: IBM

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From the Internet to Web Services

Old World :

New World:

“The eye-ball Web”

“The transactional Web”

The architecture of the Web is geared towards delivering information visually (Internet filled with human readable information)

The architecture of the Web geared towards exchanging information between applications (Internet filled with executables)

Source: IBM

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From the Internet to Semantic Web Services

Old World :

New World:

“The eye-ball Web”

“The Coordination Web”

The architecture of the Web is geared towards delivering information visually (Internet filled with human readable information)

The architecture of the Web geared towards applications that intelligibly coordinate information exchanges (Internet filled with machine understandable executables)

Source: IBM

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From the Internet to Autonomous Semantic Web Services

Old World :

New World:

“The eye-ball Web”

“The Agent Web”

The architecture of the Web is geared towards delivering information visually (Internet filled with human readable information)

The architecture of the Web geared towards goal directed applications that intelligibly and adaptively coordinate information and action (Internet filled with contextaware and self organizing agents)

Source: IBM

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Acknowledgments DARPA - DAML program Program managers Jim Hendler, Murray Burke, Mark Greaves

OWL-S Coalition members Evren Sirin (MINDSWAP), Katia Sycara (CMU), Massimo Paolucci (Docomo Labs), Naveen Srinivasan (WebMethods), Sheila McIlraith (U. Toronto), Terry Payne (U. Southampton)

Other researchers & users Jim Hendler (U. Maryland), Ora Lassila (Nokia), Marty Tenenbaum (CommerceNet), Carol Goble (U. Manchester), Ryu Masuoka (Fujitsu), Randy Washington (DCS Corp.), Craig Schlenoff (NIST), David Hanz, Reg Ford (SRI), E. Michael (Max) Maximilien (IBM), Jürgen Zimmer (DFKI)

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Services are Happening eBusiness need & vision, vendor investment Interoperability; virtual organizations Intranets, not just internets Market prediction: $11 Billion in 2007 (IDC study)

Standards efforts at W3C, OASIS, etc. Semantic Web community OWL-S, SWSF, WSMO, WSDL-S & other research efforts

Grid computing Ubiquitous computing (devices; smart environments) Mobile access to services

A remarkable opportunity Creating a Web with activities, computation, goals, processes as 1st-class citizens Bringing behavioral intelligence to the Web

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Web Services - A New Paradigm? Web Services heralded as: “… self-contained, self-describing, modular applications that can be published, located, and invoked across the Web…”

Which will allow… …on the fly composition of new functionality through the use of loosely coupled reusable software components …decomposition and distribution of large-scale processing tasks into component tasks executed simultaneously across many devices

“Web services are expected to revolutionize our life in much the same way as the Internet has during the past decade or so.” (Gartner)

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Web Services: The Essence “Loosely coupled software components that interact with one another dynamically via standard Internet technologies” (Gartner) Reliable, ubiquitous software interoperability Across networks Across organizations Non-proprietary standards

Focus on communications; content exchange Basic infrastructure & tools

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WS: The Broader Vision

Widely distributed, decentralized, reusable capabilities Accessible from a variety of platforms & devices The Internet as a global platform where organizations and individuals engage in cooperative activities & transactions Highly dynamic, flexible “virtual organizations”

Adaptive, composable workflows

“When new techniques improve the reaction times of organizations and people from weeks to seconds, they change the very structure of business. This is not a mere quantitative change, but a major qualitative change.” (Singh & Huhns)

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So what is new about Web Services?

Component-Based Model

Web Services Model

Tightly coupled software applications (high dependencies between systems)

Loosely coupled software applications (low dependencies between applications)

Mainly designed for processes within the enterprise

Mainly designed for processes across enterprises

Uses different protocols and technologies (e.g., Microsoft DCOM, CORBA)

Uses standard protocols and technologies (e.g., XML, SOAP, WSDL, HTTP)

Web Services do for programs what the Web did for Documents

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Machine Comprehension Current e-commerce sites that provide services traditionally have a human interface Required information is presented using forms Humans interpret labels and enter corresponding information Humans interpret resulting information

Form-based interaction ill-suited for machine comprehension Prior knowledge can be used to prime parsing of pages • E.g. screen scraping

CGI-based services can ignore presented page and submit a preformed request directly to the server

Web Services make the implicit specifications explicit! OWL-S Tutorial

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Requirements and Challenges Information and action integration across the Web (currently the user is the “glue”) System integration/interoperability Web-wide (within and across organizations) Semantic Interoperability Consistency of behavior of long running transactions (both for e-commerce and e-science) in the face of partial, distributed failures Dynamic and goal-directed discovery, interaction and composition of applications across the Web

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Human Oriented Services vs Machine Oriented Services The web is organized around URIs, HTML, and HTTP. URIs provide defined ids to refer to elements on the web, HTML provides a standardized way to describe document structures (allowing browsers to render information for the human reader), and HTTP defines a protocol to retrieve information from the web. ==> Not surprisingly, web services require a similar infrastructure around UDDI, WSDL, and SOAP.

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Source: Dieter Fensel & Christoph Bussler Sycara / Martin

Overview / Web Services

*

Web Services: Where Are We Today? ebXML Registries

UDDI OWL-S & OWL-S Service other Model SWS approaches OWL-S WSCL Service Profile OWL-S Service Grounding OWL RDF

PSL

ebXML CPA

BPEL4WS WS-AtomicTransaction and WSXLANG BusinessActivity WS-Reliable WS-Choreography Messaging WSCI WS-Security WSCL WS-Policy

WSDL SOAP

BPML BTP ebXML BPSS

Discovery Contracts and agreements Process and workflow orchestrations QoS: Transactions QoS: Choreography QoS: Conversations

ebXML QoS: Service CPP descriptions and bindings ebXML messaging Messaging

XML, DTD, and XML Schema

Encoding

HTTP, FTP, SMTP, SIP, etc.

Transport

Derived From M. Singh and M. Huhns: Service-Oriented Computing: Semantics, Processes, Agents

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SOAP (Simple Object Access Protocol) Web Services communication protocol XML extension A convention for doing Remote Procedure Calls (RPC): Request (SOAP message) Response (SOAP message)

Current Status: Developed by Microsoft, DevelopMentor, UserLand, Lotus and IBM

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SOAP Simple Object Access Protocol W3C Recommendation

XML data transport: - sender / receiver - protocol binding - communication aspects - content

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WSDL (Web Services Description Language) Structured mechanism to describe: Abstract operations that a Web Service can perform Format of messages it can process Protocols it can support Physical bindings to: • communication languages, e.g. SOAP or HTTP messages • Location of services, i.e. URI and port numbers

XML based Current Status: Working Group at W3C

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WSDL Web Service Description Language W3C effort, WSDL 2

describes interface for consuming a Web Service: - Interface: operations (in- & output) - Access (protocol binding) - Endpoint (location of service)

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UDDI (Universal Discovery, Description & Integration) Public directory for registering and looking up services A directory entry has three main parts: White pages: to describe the company offering the service Yellow pages: to categorize services by industry type (e.g. SIC) Green pages: to describe the interface to a web service

Uses Type Model or tModel documents Current Status: Industry initiative in OASIS led by Microsoft, IBM and Ariba; more than 300 companies participating

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UDDI Universal Description, Discovery, and Integration Protocol OASIS driven standardization effort

Registry for Web Services: - provider - service information - technical access

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Current State: Web Services Standards (cnt.) BPEL: Description of how Web Services are composed Flow Model describes the structure of the business process in terms of activities of process steps and data and control links Global Model • Describes interaction between provider and requester • Mappings between internal operations and WSDL port types

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Overview / Web Services

WS: Basic Building Blocks

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Overview / Web Services

Web Services Description Language I can receive a message having this form …

WSDL

And I will reply with a message having this form …

Describes Service

On port 5552, using HTTP transport, SOAP format

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Overview / Web Services

So What’s the Problem?

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Current State: Web Services Standards SOAP: XML based web services communication protocol Limitations Unbounded message format Has no communicative speech acts (cannot determine intention of actors or type of the message)

WSDL: Structured mechanism to describe a WS interface Limitations No semantics for message sequencing and correlation No semantics for message content

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Current State: Web Services Standards (cnt.) BPEL: Description of how Web Services are composed Limitations No IOPEs Allows execution of a manually constructed composition

UDDI: Directory Service for Web Services Limitations: keyword searches, limited capability search

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Overview / Web Services

Semantics Needed To use this service you must be a member of AAA.

???

If you’ve been a member for 3 or more years, you get a 15% discount.

Describes Service

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Overview / Web Services

Semantics Needed When you access this service, you may use TLS or WS-Security. WS-Security is preferred. Using TLS costs $9; using WS-Security $15.

??? Describes Service

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Overview / Web Services

Semantics Needed If I fail to deliver this item within 7 days, I will pay a 30% penalty.

??? Describes Service

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Overview / Web Services

Semantics Needed You can only access this information if you agree to make changes to it freely available.

??? Describes Service

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Overview / Web Services

Semantics Needed I will arrange for the requested book to be shipped to you

???

and

Describes Service

I will debit your credit card account for the listed price

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Tackling Semantic Interoperability… Lack of Semantic Interoperability is a major hurdle for Discovery • Different terms used for advertisements and requests

Invocation • Different specs for messages and WS interface

Understanding • Interpreting the results returned by the Web service

Composing Services • Reconciling private goals with goals of the WS

Negotiating contracts & communications • Different terminology and protocols used

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Is this a real problem? World Wide Annual Integration plus Data Quality Costs: $1 Trillion / year “The problem is not in the plumbing. It’s in the semantics” (quotation from Michael Brodie’s invited talk at ISWC 2003)

Note: some standards committees, e.g. WSDL and UDDI start realizing this truth and planning to incorporate RDF and OWL in these standards OWL-S Tutorial

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The Need for Semantics What is the Semantic Web... …and how does it relate to Services?

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Why isn‘t XML enough? Since ontologies standardize content Why can’t standardize XML schemata? Wouldn’t it be equivalent to OWL?

XML schema Good to verify syntactic compliance • But impossible to verify semantic compliance – Can verify that the value of a slot is within the length limit – But cannot verify that it is the correct word

No logics: impossible to extract implicit knowledge

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The Semantic Web “The Semantic Web is an extension of the current Web in which information is given a well-defined meaning, better enabling computers and people to work in cooperation. It is the idea of having data on the Web defined and linked in a way that it can be used for more effective discovery, automation, integration and reuse across various applications. The Web can reach its full potential if it becomes a place where data can be processed by automated tools as well as people”

From the W3C Semantic Web Activity statement “computational agents require machine-readable descriptions of the content and capabilities of web accessible resources. These descriptions must be in addition to the human-readable versions of that information. “

From the OWL Guide OWL-S Tutorial

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Overview / Semantic Web

What is the Semantic Web (cont’d)? A Vision for the Evolution of the Web An (envisioned) pervasive information infrastructure A web for machines as well as people

A Research Area A Set of Standards Activities at the W3C A Collection of Languages, Reasoners, and Tools A Growing Collection of Ontologies and Knowledge Bases (WorldWide) A Set of Shared Representations, Collaborative Activities and Communities Forming Around Them

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Overview / Semantic Web

Semantic Web Layers

Source of picture: W3C

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Semantic Web

OWL OWL is a W3C standard OWL is a Description Logic-based Language: provides the basic constructs to describe ontologies Definition of concepts Relations between concepts Special relation: subclass for generalization Effectively computable • Good optimization algorithms support inference OWL specifications W3C page on OWL • http://www.w3c.org/2001/sw/WebOnt/ OWL Guide and language reference • http://www.w3.org/TR/owl-guide/ • http://www.w3.org/TR/owl-ref/ Tutorials Costello and Jacobs’ OWL tutorial: http://www.xfront.com/owl

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OWL as Description Logics Language Subset of First Order Logics used to describe objects in a domain Allows three types of objects Concepts: describe general concepts of things in the domain Individuals: an object in the domain Properties: relations between concepts • One special relation is ISA (or subclassOf)

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Types and quantifiers on Properties Different types of properties Transitivity, Symmetry, Function, Inverse etc… Cardinality restrictions at-most, at-least, exactly, optionality (0 or more) Type restrictions Identifies subclasses that have some restriction on a property P

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Equivalence between concepts Equivalence of concepts Ont1:LiquidContainer sameAs ont2:Bottle Equivalence of individuals EveningStar sameAs MorningStar Difference of individuals and concepts Assert values that are mutually distinct.

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Using Set Theory Complex types to support set theory union, intersection and complement Enumerated Classes means to specify a class via a direct enumeration of its members, Disjoint Classes It guarantees that an individual that is a member of one class cannot simultaneously be an instance of a specified other class.

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OWL Full, OWL DL, OWL Lite Description Logics provides a careful balance between expressivity and computational complexity OWL provides sublanguages with reduced expressivity and computational complexity

OWL Full OWL DL OWL Lite

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Advantages of using OWL Benefits to application developers: Less code to write: code becomes reusable Less chance of misinterpretation

Benefits to community at large: Everyone can understand each other's data's semantics, since they are in a common language. OWL uses the XML syntax to express semantics

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Semantic WEB

Rich metadata Data harvesting & visualization

A little Semantics goes a long way Web-based social networks

Courtesy of Jim Hendler & Ora Lassila OWL-S Tutorial

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SEMANTIC Web

Digital asset management

Scientific portals

A little Web goes a long way Tools for developers OWL-S Tutorial

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Overview / Semantic Web

A Lot is Happening … Semantic (Web) technology companies starting & growing Cerebra, Siderean, SandPiper, SiberLogic, Ontology Works, Intellidimension, Intellisophic, TopQuadrant, Data Grid, …

Bigger players buying in Adobe, Cisco, HP, IBM, Nokia, Oracle, Sun, Vodaphone… announcements/use in 2005 integrator and contractor uptake: Northrop Grumman buys TKS, Lockheed-Martin uses SiberLogic in FCS, SAIC teams with ClarkParsia, WebMethods buys Cerebra.. tools being announced: AllegroGraph, TopBraid, …

Government projects in and across agencies US, EU, Japan, Korea, China, …

Life sciences/pharma an increasingly important market Health Care and Life Sciences Interest Group at W3C

Many open source tools available Kowari, RDFLib, Jena, Sesame, Protégé, SWOOP, Onto(xxx), Wilbur, …

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Tutorial Outline The Vision Web Services Semantic Web Services Motivations Semantic Web Services Approaches OWL-S Related Work

Semantic Web Services Applications Semantic Web Services Tools Challenges and Future Directions OWL-S Tutorial

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Contributors to OWL-S (partial list) BBN: Mark Burstein CMU: Katia Sycara, Massimo Paolucci (now at Docomo Labs), Naveen Srinivasan (now at WebMethods) De Montfort University: Monika Solanki Univ. of Maryland / College Park: Bijan Parsia , Evren Sirin NIST: Craig Schlenoff Nokia: Ora Lassila SRI: David Martin, Grit Denker, Daniel Elenius Stanford KSL: Deb McGuinness Univ. of Southampton: Terry Payne Univ. of Toronto: Sheila McIlraith USC-ISI: Jerry Hobbs Yale: Drew McDermott OWL-S Tutorial

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What is OWL-S? Ontology Web Language for Services An OWL ontology/language for (formally) describing properties and capabilities of Web services Accepted as a Member Submission by W3C (12/1/2004) OWL-S leverages on OWL to Support Support Support Support

capability based discovery of Web services automatic composition of Web services automatic invocation / enactment of Web services monitoring of the execution of Web services

Complete do not compete OWL-S does not aim to replace the Web services standards; rather OWL-S attempts to augment with a semantic layer OWL-S relies on WSDL for Web service invocation (see Grounding) OWL-s Expands UDDI for Web service discovery (OWL-S/UDDI mapping) Well suited for use with SAWSDL (Semantic Annotations for WSDL) OWL-S Tutorial

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Layered Approach to Language Development OWL-S: an ontology expressed in OWL and related languages OWL-S (Services) SWRL (Rules) OWL ([DLP], Light, DL, Full) RDFS (RDF Schema) RDF (Resource Description Framework) XML (Extensible Markup Language) OWL-S Tutorial

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Relation to Web Services Technology

Discovery What it does

Orchestration / Local Choreography

OWL-S

Web Services Infrastructure

Profile

UDDI API

Process Model

BPEL4WS

Grounding+ WSDL/SOAP

WSDL/SOAP

How it’s done

Invocation How to invoke OWL-S Tutorial

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Upper Ontology of Services

Ontology images compliments of Terry Payne, University of Southampton

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Upper Ontology of Services

Ontology images compliments of Terry Payne, University of Southampton

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Service Profile: “What does it do?” High-level characterization/summary of a service Used for • Populating service registries • A service can have many profiles

Automated service discovery • Service selection (matchmaking) One can derive: • Service advertisements • Service requests •

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Basic Service Profile (partial)

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Service Profile Content Capabilities description (“functional properties”) Inputs, outputs, preconditions, results May be a subset of process model IOPRs

Service descriptors (“non-functional properties”) Provenance Quality of Service • Response time, quality guarantees, etc.

Security Policy Domain-specific characteristics • E.g., geographical region, class of service OWL-S Tutorial

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Class Hierarchies of Services name provider avgResponseTime? …

ServiceProfile

ProductProviding Service InfoService

informationProduct+

physicalProduct+ manufacturer+ deliveryRegion* deliveryProvider* deliveryType

PhysicalProduct Service

FeeBased

feeBasis+ paymentMethod+

ActionService

physicalProduct+

Repair

Tie in with UNSPSC, etc. Transportation DL Basis for matchmaking Multiple profiles; multiple hierarchies

Manufacturing

physicalProduct+

transportationMode+ geographicRegion+

Service Profile: Styles of use Class hierarchical yellow pages Implicit capability characterization Arrangement of attributes on class hierarchy Can use multiple inheritance Relies primarily on “non-functional” properties

Process summaries for planning purposes More explicit Inputs, outputs, preconditions, effects Less reliance on formal hierarchical organization Summarizes process model specs Relies primarily on functional description OWL-S Tutorial

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Security and Policies No candidate standard OWL-S representation for Security and Policies has been published yet But proposals have been made (as extensions to Profile) Adoption of a solution will depend on WS security standards

Research underway on Representing security capability/requirements for discovery Representing security information in Process Model.

Policies: Experiments combining OWL-S and Rei Rei statements included in Process Model to constrain the use of a Web service (see Kagal 2004)

Recent work on Formal Verification of OWL-S Process Models provides a way to certify adherence to a policy Grit Denker, Lalana Kagal, Tim Finin, Massimo Paolucci, Naveen Srinivasan and Katia Sycara, "Security For DAML Web Services: Annotation and Matchmaking" In Proceedings of the Second International Semantic Web Conference (ISWC 2003), Sandial Island, Fl, USA, October 2003, pp 335-350. Anupriya Ankolekar, Massimo Paolucci, and Katia Sycara Spinning the OWL-S Process Model -- Toward the Verification of the OWL-S Process Models In Proceedings of Workshop on Semantic Web Services: Preparing to Meet the World of Business Applications (ISWC 2004)

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Security Ontology Security Coalition in DAML project Various members from SRI, UMBC, CMU, etc.

Ontologies and matching algorithms are documented in http://www.daml.org/services/owl-s/security.html Ontologies: Credential (Simple, Composed, Cookie, Login, Certificate, …) SecurityMechanism (Authentication, Authorization, Access Control, …) Service Security Extensions (securityRequirement, securityCapability) Agent Security Extensions (securityRequirement, securityCapability) Privacy (Policy has rules, each rule has an action and is applied on a resource; three types of rules: authorization, obligation, capability)

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Upper Ontology of Services

(Process Model)

Ontology images compliments of Terry Payne, University of Southampton

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Process Model: “How does it work?” Process Potentially interpretable description of service provider’s behavior Specifies service interaction protocol • Tells service user how and when to interact (read/write messages)

Specifies abstract messages: ontological type of information transmitted

Used for: Service invocation, planning/composition, interoperation, monitoring

All processes have Inputs, outputs, preconditions and effects

Composite processes Control flow Data flow

OWL standard serializations; presentation syntax

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Definition of Process A Process represents a transformation from an initial state to a set of possible result states Initial state defined by Inputs: the inputs that the process requires Preconditions: must be true before process execution

Result states described by Condition that specifies when a result is generated Outputs: the data produced by the process Effects: effects of the execution of the process

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Process Model (partial)

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Function/Dataflow Perspective

Output:

Input: • customer name • flight number • credit card • ...

www.acmeair.com book flight service

• confirmation no. • ... flight available ? + valid credit card

Y N

• failure notification •…

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Action/Process Perspective Output: Input: • customer name • flight number • credit card • ...

Effect: www.acmeair.com book flight service

Preconditions: • knowledge of the input •...

Output:

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• ticket purchased • credit card debited • ...

flight available ? + valid credit card

Effect: OWL-S Tutorial

• confirmation no. • ...

Y N

• failure notification •… Sycara / Martin

Composite Process Input & Preconditions • • • • • • • • • •

Output & Effects

www.acmetravel.com book travel service

• • • • • • • •

• confirmation no. • ...

• • • • • • • • • • •

• customer name • location • car type • dates • credit card no. • ...

www.acmecar.com

?

book car service

• failure notification •…

• confirmation no. • ...

• confirmation no. • ...

• customer name • flight numbers • dates • credit card no. • • ...

www.acmeair.com book flight service

?

• confirmation no. • dates • room type • credit card no. • ...

www.acmehotel.com book hotel service

? • failure notification •…

?

• • • • • • • •

• failure notification • errror information •…

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Atomic Process Example …… Airport …… DepartureAirport_In …… GetDesired Flight Details …… Flight_Out …… Flight

Composite Process Example