Service Oriented Architectures and Semantic Web Processes

Wright State University CORE Scholar

The Ohio Center of Excellence in Knowledge- Kno.e.sis Publications Enabled Computing (Kno.e.sis)

2004

Francisco Cubera

Kunal Verma

Amit P. Sheth Wright State University - Main Campus, [email protected]

Follow this and additional works at: https://corescholar.libraries.wright.edu/knoesis

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Repository Citation Cubera, F., Verma, K., & Sheth, A. P. (2004). Service Oriented Architectures and Semantic Web Processes. . https://corescholar.libraries.wright.edu/knoesis/62

This Tutorial is brought to you for free and open access by the The Ohio Center of Excellence in Knowledge-Enabled Computing (Kno.e.sis) at CORE Scholar. It has been accepted for inclusion in Kno.e.sis Publications by an authorized administrator of CORE Scholar. For more information, please contact [email protected]. Service Oriented Architectures and Semantic Web Processes

Jorge Cardoso1, Francisco Curbera2, Amit Sheth3

1University of Madeira (Portugal) 2IBM T.J. Watson Research Center (USA) 3 LSDIS Lab, University of Georgia and Semagix, Inc (USA) 2

Service Oriented Architectures and Web Services

Semantic Web Processes

2 3

Semantic Web Processes

Part

3 Service Oriented Architectures and Web Services 5 Overview

z IT for a new business model z Service Oriented Architectures (SOAs). z Web services as an XML based instantiation of SOA. z Protocols. z Metadata. z Discovery. z Composition. z Summary. 5 6 A New Business Environment

z Business outsource every non-essential function. z Concentrate on core function and values. z Vertically integrated enterprises are being broken apart z Replaced by heavily networked ones. z Applications that used to be internal are now provided by outside parties. z Corporate boundaries become fuzzier. z Does today’s IT models support the new business environment? z IT is too centered on IT! z When enterprises where islands this was sort of OK. z Today it is vital to adapt the computing model to the business interaction model.

6 7 Enterprises as IT Islands

Value added networks and proprietary protocols support most B2B interactions Ad-hoc bridges support interorganizational interactions. Most application interactions take place inside the enterprise.

Most applications belong to a single administrative domain. 7 8 Fully Networked Enterprises

Web based interactions become pervasive, based on standard protocols

The frequency of external interactions and their reach inside the Internal applications enterprise increases seamlessly reach out of dramatically. the enterprise.

Interacting applications naturally belong to multiple administrative domains. 8 Fully Networked Business 9 Interactions

The distinction between internal and external applications and providers looses importance

Many potential providers can be found for each required function.

9 10 IT for the New Enterprise: Business Components

z Need to raise the level of IT abstractions. z Concentrate on business function and requirements. z Need to encapsulate business function to make it available to partners: service components. z Different level granularity – coarse grained business services vs. fine grained objects. z Services must be defined by explicit contracts to allow independent party access. z Consequence is automatic binding. z Core concern of business is to integrate business processes and functions. z Business components are integrated creating service compositions. z New value is created through integration/composition. z New components are recursively created.

10 11 Business Interactions

z Business interact over standard protocols. z Businesses interact as peers: z Interactions are not client-server. z They are “conversational” in nature: asynchronous, stateful, bidirectional. z Business interactions are often multi-party interactions z Business process integration model is intrinsically multi-party. z Distributed multi-party interactions are a cornerstone of advanced enterprise integration: z Making distributed computing truly distributed.

11 12 What About The SOA Triangle?

z Standard protocols augment the pool of technically compatible services.

z Explicit contracts allow automatic discovery.

z Central registries build on registered contracts extend the reach of the enterprise both as provider and consumer of business services.

12 13 Traditional Middleware

z Distributed object systems z Based on client-server paradigm. z Heavily asymmetric Client interaction model. JNDI z Biased towards synchronous protocols. z Assigns public interfaces to Server network accessible objects. Name=A? A z Supports “name-oriented” object discovery. Client Client

13 14 Service Oriented Middleware

z Service interactions z Peer to peer by nature. z Symmetric interaction Service model. Registry D z Mixes synchronous and asynchronous protocols. Server z Assigns public contracts QoS=A/B? to network accessible Iface=I A etc… objects. Service Service B C z Supports capability based service discovery.

14 Coupling Between 15 Applications

z Interacting applications are bound by the set of assumptions each one Explicit contract makes about the other: z What message formats can be sent/received z Constraints on how content of these messages z Sequencing information. z Required QoS characteristics of the Implicit contract interaction.

15 16 Tight and loose binding

z Tight coupling leads to monolithic and brittle distributed applications. Explicit contract z Even trivial changes in one component lead to catastrophic breaks in function. z Small changes in one application require matching changes in partner applications. z Lack of componentization and explicit contracts. Broken implicit contract

16 17 A Plan for Building a SOA

z Requirement #1: Interaction protocols must be standardized. z Need to ensure the widest interoperability among unrelated institutions. z Requirement #2: Make all contracts explicit. z Explicit contracts define what may be changed in an application without breaking the interaction. z It is hard or impossible to make all assumptions explicit, but the more the better. z Requirement #2 : Standardize contract language(s) and formats. z Standard metadata is the basis of interoperable contract selection and execution. z Requirement #3: Allow for points of variability in the contract. z Dynamic adaptation on variability points. z Increases the number of possible interactions supported. z Requirement #4: Provide native composition models and runtimes.

17 Web Services As a SOA

SOA and Web Services Where Are We on Web 19 Services?

BPEL4WS Composition

WSDL, WS-Policy, UDDI, Inspection Description

Reliable Security Transactions Quality Messaging of Service

SOAP (Logical Messaging) Other protocols Interaction Other services Interaction XML, Encoding

19 Protocols

SOA and Web services 21 Protocols

z Provides a common set of universally supported interaction protocols.

z A basic messaging layer z SOAP z Easily extensible, allows QoS protocols to be defined on top.

z Some basic QoS protocols: z Basic requirements of business interactions. z Provide guarantees z Message Reliability, WS-ReliableMessaging z Coordination and transactional interactions. z Message integrity, confidentiality 21 22 SOAP (v1.1)

z A lightweight XML-based mechanism for exchanging structured information between peers in a distributed environment. z A transport-independent messaging model. z Transport bindings for HTTP z An encoding model for a type system, and an RPC convention: a link to “legacy middleware”. z Built around a standard message format: z Envelope z Headers z Body z Possibly attachments.

22 23 SOAP Messaging

Service Requestor Service Provider

Application Application web service 1 4 3 2

SOAP Middleware SOAP Middleware

Network Protocol Network Protocol Response

Request (service invocation)

23 24 SOAP over HTTP

POST /StockQuote HTTP/1.1 Host: www.stockquoteserver.com Content-Type: text/xml; charset="utf-8" Content-Length: nnnn SOAPAction: "Some-URI"

02/06/01 … 24 25 SOAP Headers

z Headers are managed and consumed by the Web services middleware infrastructure. z Headers support middleware protocols such as security, transactions, reliability, provisioning, etc. z Extensible nature allows message to endowed with be an extensible set of QoS protocols. z Header attributes z actor z Indicates the intended recipient of the header z http://schemas.xmlsoap.org/soap/actor/next z mustUnderstand z encodingStyle z Identifies serialization rules

25 26 SOAP Body and Attachments

z Body: belongs and is processed by the application level. z Is the only part that should be visible by the application logic. z Business modeling is the modeling deals with what goes in the body and how it is processed and exchanges. z A separation that shows up in WSDL, BPEL4WS as well. z Attachments: Not all data can be conveniently placed within an XML document z SOAP Messages with Attachments: How to carry a SOAP envelope within a MIME Multipart/Related structure z SOAP envelope must be the root part 26 z Type is text/xml z Uses href attribute to reference parts 27 SOAP Status

z SOAP 1.2/XML Protocol is now a W3C Recommendation. http://www.w3.org/TR/soap/ z SOAP 1.1 is still (and will be for a while) what is being deployed. http://www.w3.org/TR/2000/NOTE-SOAP- 20000508/

27 28 WS-Security

for: Zoe z authentication, z confidentiality, Built on top of W-Security: … z Protocols for exchanging DJbchm5gK... security tokens and establishing trust relationships built on top. and identity propagation / mapping in multi-party communication 28 29 WS Protocols - Summary

z SOAP defines a standard messaging model in which transport, service middleware and business concerns are clearly separated. z Standardized QoS protocols ensure universal “on- the-wire” interoperability among businesses, applications. z QoS Protocols build on SOAP header extensibility to augment business exchanges with QoS properties.

29 Metadata

SOA and Web services 31 Metadata

z WSDL: Functional descriptions. z WS-Policy: QoS z Points of variability: dynamic infrastructure.

31 32 What is WSDL

z An extensible, platform independent XML language for “describing” services. z Provides functional description of Web services: z IDL description z Access protocol and deployment details z All of the functional information needed to programmatically access a service, contained within a machine-readable format z Does not include z QoS z Taxonomies z Business information z WSDL is a component definition language for Web service

component 32 33 WSDL Description Structure

… … Abstract/ … Business … Deployment

33 34 WSDL Parts At a Glance

part types

abstract interface portType

(concrete) (abstract) message(abstract) operation message

concrete implementation binding

(concrete) (concrete) message(concrete) operation message

made concrete by service concrete endpoint 34 contains one or more port 35 WSDL in SOA

1. Allow industries to define standardized service interfaces. Functional contract definition.

2. As an extended IDL: base for tools generating compliant client proxy and server stub Tool level interoperability.

3. Allowing advertisement of service descriptions, enables dynamic discovery of compatible services and dynamic binding to the actual service provider Works within registries and with discovery protocols.

4. As a normalized description of internally heterogeneous services 35 36 WSDL Status

z WSDL 1.1 was submitted to the W3C on February 2001. http://www.w3.org/TR/WSDL

z WSDL 2.0 is now being defined by the WS Descriptions working group at W3C. z Last draft (June 2002) available at http://www.w3.org/2002/ws/desc/

36 37 WS-PolicyFramework

z Complements functional description of services with QoS behaviors. z General framework for declaratively asserting how a service may be accessed: z Requirements z Constraints z Capabilities z WS-Policy provides a general framework in which arbitrary domain specific “assertions” are used. z Security z Transactions z Reliable messaging 37 38 Policy Expressions

001 002 003 004 005 wsse:Kerberosv5TGT 006 007 008 017 018 019 020 38 39 Policy Expressions

z Three generic policy operators allow combining assertions into groups, options: z z z z Usage attribute allows modification of standard meaning of assertion: z Usage=“Rejected” prevents requesters from following certain behaviors (“do not log messages!”). z Policies can be names so they can be referenced from other documents and reused. z Id attribute assigns a URI to the policy. 39 z QName naming is also allowed. 40 Attaching Policies

WSDL Document references Policy

wsdl:service

references describes

Policy Attachment identifies

40 41 WSDL and WS-Policy

z Abstract and deployment policies

What is PortType PortType required Abstract policy operation(s) operation(s)

Input Message Out Message Input Message Out Message

Abstract Interface

Binding Binding (e.g. SOAP/HTTP) (e.g. IIOP) Deployment QoS QoS policy What is Port Port supported

Service

41 42 WS-Policy and SOAP

z Policies define what QoS protocols are followed. z Are reflected on what wsse:X509v3 headers appear in the SOAP envelope. z QoS policies attached to a service of service endpoint represent protocols. z QoS protocols are html

z WS-PolicyFramework z WS-PolicyAttachments

z To be submitted for standardization. 46 47 Service Metadata - Summary

z Explicit metadata is the central characteristic of SOA z Metadata must completely define the service contract, including both functional and non- functional aspects. z WSDL z Policies z Metadata can support service discovery as well as tooling. z Advanced runtimes can derive greater flexibility from contract variability points.

47 Discovery

SOA and Web services 49 Discovery Infrastructure

z Registries z Requesters search for providers in third party central directory. z Provider policies are retrieved from registry. z Requester interacts according to discovered policies. z Will not deal with here. z Metadata exchange z Requesters and providers can exchange policies directly, no third party involved. 49 50 WS-Metadata Exchange

z Goal: Allow providers to customize their policies to individual requesters and interactions. z Requesters send: z Requester’s policies can be 1 Identity,Identity, explicitly communicated. contextcontext z Requester’s execution context may be implicitly transmitted. Policy z Providers return set of 2 Policy policies to apply to oror fault fault interaction. z “Faults” should be thrown if any party finds it cannot deal with the other’s policies.

50 51 More on Metadata Exchange

z Takes place at the beginning of an interaction. z MDE model is a request-response interaction for retrieving custom policies. z Policies are set from then on. z Both parties’ middleware must be able to deal with dynamically discovered policies. z Start-time (re) configuration of component characteristics. z Component is reconfigured to deal with discovered policies that apply to the interaction. z In flight metadata exchange? z Any party can send unsolicited policies at any point in the interaction. z Applies in particular to long running transactions where changes in policies are not unlikely. z The scope of the new policies will need to be clearly defined.

51 Metadata and Channel 52 Configuration

52 53 Cooperative Middleware

z Joint work with Nirmal Mukhi and Ravi Konuru z Requesters and providers cooperate to optimize the interaction channel. z Through “cooperative” reconfiguration of their middleware. z Follows a dynamic exchange of policies and negotiation. z Distributes roles and function between the two endpoints to optimize overall interaction. z Optimal configuration is negotiated. z Must assume a trusted relationship between the parties.

53 Cooperative Specialization Use 54 cases

z Mobile clients and servers negotiate downloading of server function to clients. z Known approach, NOT metadata based. z Hardwired protocol essentially fixes the what function can be offloaded. z Metadata allows flexible reuse of a common protocol for negotiating different functions. z Example: z Schema validation offloading to client app. z Control of the application flow can be offloaded to allow disconnected operation. z Offloading takes place selectively based on client and server declared capabilities (policies).

54 55 Discovery - Summary

z Metadata-based discovery of services is a basic SOA capability. z The discovery of metadata itself, however, does not necessarily need to follow the registry pattern. z A dynamic middleware infrastructure is required to take full advantage of dynamic discovery (of both services and metadata).

55 Composition

SOA and Web services 57 Service Composition

z Service composition is the core sw. development task in SOA. z Applications are created by combining the basic building blocks provided by other services. z Service compositions may themselves become services, following a model of recursive service composition. z Composition assumes an interaction model between components: z P2P conversational interactions. z Interactions are naturally multi-party interactions. z Many composition models are possible. We know about two: z Process oriented composition – BPEL4WS z Distributed composition – WSFL Global models.

57 58 BPEL Concepts

z A BPEL process defines the structure of the interaction in terms of

z participant services (partners) z Characterize partners z Provide support partner conversation z business logic. z Data z Control flow z Error handling and recovery mechanism 58 Structure of a BPEL4WS 59 Process

... Partner ... information ... ... Business ... logic (activities)*

59 60 BPEL Partners

z Partners: z A composition defines a new service(s) which interacts with one or more partners. z Partners are characterized by a pair of abstract WSDL interfaces: z How the composition uses and is used by the partner. z Interactions between partners are thus bidirectional, conversational in nature. z May combine synchronous and asynchronous interactions z Stateful. z How is state maintained? z BPEL correlation mechanism uses business data to maintain the state of the interaction. z Other middleware mechanism are possible as well. 60 61 BPEL4WS Partners

Bidirectional, asynchronous, conversation

Multiple simultaneous Web service conversations Many partners partner Characterized by WSDL interfaces

61 62 What is Correlation?

z Correlation sets provide support for stateful interactions. z CSs represent the data that is used to maintain the state of the interaction (a “conversation”). z At the process end of the interaction, CSs allow incoming messages to reach the right process instance. z What is a correlation set? z A set of application fields that capture the state of the interaction (“correlating business data”). For example: a “purchase order number”, a “customer id”, etc. z Each set is initialized once

z Its values do not change in the course of the interaction. 62 63 Defining Correlation Sets

63 64 Business Logic in BPEL

z Workflow-like business logic is used to specify the sequencing of the interactions with partners. z Activities representing service interactions and data manipulation. z Control constructs that combine activities: links, sequences, conditionals, etc. z The asynchronous nature of interactions is supported by event handlers. z Failure conditions and recovery are supported through by fault handlers and compensatable scopes.

64 65 BPEL Basic Activities

65 66 BPEL Structured Activities

66 Nesting Structured Activities. 67 Example

Seq Flow Seq Seq ...

While

67 68 BPEL Handlers and Scopes

Scope A scope is a set of (basic or Fault Handler structured) activities.

Each scope can have two types of handlers associated: • Fault handlers. Many can be attached, for different fault types. Compensation • Compensation Handler handlers. A single compensation handler per scope.

68 69 How Handlers Work

z A compensation handler is used to reverse the work performed by an already completed scope z A compensation handler can only be invoked by the fault handler or compensation handler of its immediate enclosing scope

z A fault handler defines alternate execution paths when a fault occurs within the scope.

z Typical scenario: 1. Fault is thrown (retuned by invoke or explicitly by process) 2. Execution of scope is terminated 3. Appropriate fault handler located (with usual propagation semantics) 4. Main execution is compensated to “undo” business effects of unfinished work.

69 70 Global Models

z BPEL processes capture multi-party interactions from a single party perspective. z There isn’t a well accepted format for capturing these interactions. z Complex interactions are naturally multi-party. z Single party view does not capture the global sequence of interactions z Each party may not be involved in every relevant interaction. z Where are global models? z WSFL (a BPEL precursor) introduced global models. z WS-Choreography WG in W3C has been working on this

concept as well. 70 71 Global Models, an Example

1-send notice Customer Cable Co. 2-pay in full

Cable Co. Cable Co.

1-send notice 1-send notice

4-pay in full

Customer 5-stop collection 2-collect from Customer 5-notify&pay 2-collect from & pay customer customer 6-notify: done 6-pay in full

3-send 3-send Collections ultimatum Collections ultimatum Agency Agency 71 72 Composition - Summary

z Business integration becomes service composition in SOA. z An interaction model needs to be assumed for composition, and supported by the corresponding composition models. z BPEL composition natively supports a multi-party, conversational model. z To support the full array of distributed compositions needs a global model formalism in addition to process centric compositions (BPEL).

72 Summary

SOA and Web services Web Services as an Instantiation 74 of SOA

z SOA is more than “publish/find/bind”. z Implies a completely business re-orientation of computing. z SOA builds on: z Standard interaction protocols. z A component model, as defined by service contracts. z A conversational interaction model. z A set of service composition model. z Web services provide an XML based instantiation of SOA.

74 Service Oriented Architectures 75 and Web Services

End

75 76

Part

76 77 Semantic Web Processes Overview

z Introduction z Semantic Web Processes Life cycle z Web services Semantic Annotation z Web services Discovery z Semantic Process Composition z Web service QoS z Ontologies, Ontology Languages and Editors z Projects/approaches: OWL-S, METEOR-S z Conclusions

77 78 Our Focus (1)

z Supporting Web Processes on multi-enterprise and Web scale require addressing heterogeneity/integration, scalability, dynamic change and performance challenges

z Semantics is seen as the key enabler to address these challenges; Semantic Web Processes build upon Web Services and Semantic Web technologies

z This part of tutorial is about adding semantics to Web Services, and exploiting them in Web Process Lifecycle (Specification, Discovery, Composition, Execution)

z Functional perspective takes form of process composition involving Web Service Discovery, handling semantic heterogeneity [modeling data i/o, state (pre/post condition) and function]

z Operational perspective takes form of the research on QoS Specification for Web Services and Processes [modeling QoS and execution behavior]

78 79 Our Focus (2)

Semantics Web Processes

Web Process Composition Execution Web Process QoS

Web Services

Web Service Annotation Web Service Discovery Web Service QoS

79 80 The Basics

WhatWhat areare WebWeb Services,Services, WebWeb Processes,Processes, andand Semantics?Semantics?

80 81 Web Services: Definition Web Services

“Web services are a new breed of Web application. They are self-contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions, which can be anything from simple requests to complicated business processes. … Once a Web service is deployed, other applications (and other Web services) can discover and invoke the deployed service.”

IBM web service tutorial 81 82 Why Web Services? Web Services

UDDI SOAP WebWeb services services Jini Enterprise Java Beans WSDL RMI (Remote Method Invocation) Microsoft DCOM CORBA (Common Object Request Broker Architecture)

Open Software Foundation DCE (Distributed Computing Environment)

Sun ONC/RPC (Open Network Computing)

IP,IP, UDP, UDP, TCP TCP 82 83 Web Process An Example Web Processes

Organization B Organization A + Organization C

t1 + t t t5 t6 7 8 Setup Test Quality Get Sequences Sequence Process t2 t3 t4 Processing Report

Prepare Prepare Clones Assembly Sample and Sequence

83 84 What are Web Processes (1)? Web Processes

z 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

z encompass the ideas of both intra and inter organizational workflow. z created from the composition of Web services z can use BPEL4WS to represent composition, but how to get there?

84 85 What are Web Processes ? (2) Web Processes

z Web processes describe how Web services are connected to create reliable and dependable business solutions

z Web processes allow businesses to describe sophisticated processes that can both consume and provide Web services

z The role of Web processes within the enterprise is to simplify the integration of business and application processes across technological and corporate domains

85 86 Web Process An Example Web Processes

z Graphical example of a web process

ISBN, Email Id., ID

isbn price price, id

86 The BarnesBookPurchase process 87 Web Processes Composition Web Processes

WS WS1 9

WS2 WS3 Web Process Design

WS4 WS5

WS7 WS 8 WS6

Web services

87 88 Globalization of Processes

B2B E-Services

Workflows Distributed Web Processes Workflows

Enterprise Inter-Enterprise Global 88

Processes driving the Networked Economy 89 BIG Challenges

z Heterogeneity and Autonomy z Syntactic, semantic and pragmatic z Complex rules/regulations related to B2B and e- commerce interactions z Solution: Machine processable descriptions

z Dynamic nature of business interactions z Demands: Efficient Discovery, Composition, etc.

z Scalability (Enterprises → Web) z Needs: Automated service discovery/selection and composition Proposition: Semantics is the most important enabler to address these challenges. 89 90 Semantics, Ontologies, Semantic Web Processes

Temporal-Entity

Time-Point{absolute_time} Time Domain

{year, month, day} Date Time {hour, minute, second}

Calendar-Date Event {dayOftheWeek, monthOftheYear} Scientific-Event {millisecond} z When Web services and other descriptions that define a Web process are semantically described, we may call such process as Semantic Web Processes. z An ontology provides semantic grounding. It includes a vocabulary of terms, and some specification of their meaning. z The goal is to create an agreed-upon vocabulary and semantic structure for exchanging information about that domain. 90 91 Broad Scope of Semantic (Web) Technology Formal Degree ofAgreement Current Semantic Web Focus

Se Semi-Formal ma Lots of ntic Proc We Useful es b ses Semantic Technology (interoperability, t Integration) ou Ab how agreements are reached,

t Other dimensions: …

Informal n e Qos em re Execution Ag Scope of Agreement Function Task/ Domain Gen. Common Data/ App Industry Purpose, Sense Info. Cf: Guarino,91 Gruber Broad Based Knowledge 92 Representation and Ontologies TAMBIS KEGG BioPAX Thesauri “narrower Disjointness, Frames term” Formal Inverse, (properties) relation is-a part of… Catalog/ID DB SchemaUMLS RDF RDFS DAML CYC Wordnet OO OWL IEEE SUO Terms/ Informal Formal Value General glossary is-a instance Restriction Logical constraints GO GlycO EcoCyc Simple Expressive Taxonomies Ontologies

92 Ontology Dimensions After McGuinness and Finin 93

z Approximately 95 000 different word forms z English nouns, verbs, adjectives and adverbs are organized into synonym sets, each representing one underlying lexical concept. z Different relations link the synonym sets. z Create a lexical thesaurus (not a dictionary) which models the lexical organization used by humans. z http://www.cogsci.princeton.edu/~wn/

93 94 Using WordNet

4 senses of eagle

Sense 1 eagle, bird of Jove -- (any of various large keen-sighted diurnal birds of prey noted for their broad wings and strong soaring flight) => bird of prey, raptor, raptorial bird -- (any of numerous carnivorous birds that hunt and kill other animals) => bird -- (warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings) => vertebrate, craniate -- (animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium) => chordate -- (any animal of the phylum Chordata having a notochord or spinal column) => animal, animate being, beast, brute, creature, fauna -- (a living organism characterized by voluntary movement) => organism, being -- (a living thing that has (or can develop) the ability to act or function independently) => living thing, animate thing -- (a living (or once living) entity) => object, physical object -- (a tangible and visible entity; an entity that can cast a shadow; "it was full of rackets, balls and other objects") => entity, physical thing -- (that which is perceived or known or inferred to have its own physical existence (living or nonliving))

94 95 Using WordNet

Sense 2 eagle -- ((in golf) a score of two strokes under par on a golf hole) => score -- (a number that expresses the accomplishment of a team or an individual in a game or contest; "the score was 7 to 0") => number -- (a concept of quantity derived from zero and units; "every number has a unique position in the sequence") => definite quantity -- (a specific measure of amount) => measure, quantity, amount, quantum -- (how much there is of something that you can measure) => abstraction -- (a general concept formed by extracting common features from specific examples)

95 Semantic Web Process Life Cycle 97 Semantics for Web Processes

z Data/Information Semantics z What: Formal definition of data in input and output messages of a web service z Why: for discovery and interoperability z How: by annotating input/output data of web services using ontologies

z Functional/Operational Semantics z Formally representing capabilities of web service z for discovery and composition of Web Services z by annotating operations of Web Services as well as provide preconditions and effects; Annotating TPA/SLA (future work)

z Execution Semantics z Formally representing the execution or flow of a services in a process or operations in a service z for analysis (verification), validation (simulation) and execution (exception handling) of the process models z using State Machines, Petri nets, activity diagrams etc.

z QoS Semantics z Formally describing operational metrics of a web service/process z To select the most suitable service to carry out an activity in a process z using QoS model [Cardoso and Sheth, 2002] for web services 97 98 Data and Functional Ontology an example based on Rosettanet

Functions

Data

98 99

QoS Ontology in METEOR-S

99 100 Semantics for Web Process Life- Cycle

Development Execution / Description (Orchestration?) / Annotation WSDL, WSEL BPWS4J, Commercial BPEL OWL-S Execution Engines, Data WSDL-S Intalio n3, HP / Information eFlow METEOR-S Semantics (MWSAF)

BPEL, BPML, UDDI WSCI, WSCL, WSIL, OWL-S OWL-S, METEOR-S Composition Publication METEOR-S (MWSCF) (Choreography?) / Discovery (MWSDI)

100 101 Semantics for Web Process Life- Cycle

Development Execution / Description (Orchestration?) / Annotation BPWS4J, WSDL, Commercial BPEL WSEL Execution Engines, Data Intalio n3, HP / Information OWL-S eFlow Semantics WSDL-S METEOR- S (MWSAF) BPEL, BPML, UDDI WSCI, WSCL, WSIL, OWL-S OWL-S, METEOR-S Composition Publication METEOR-S (P2P (SCET,SPTB) (Choreography?) / Discovery model of registries)

101 102 Semantics for Web Process Life- Cycle

Development Execution / Description (Orchestration?) / Annotation WSDL, WSEL BPWS4J, Commercial BPEL OWL-S Execution Engines, WSDL-S Intalio n3, HP eFlow

Functional / Operational BPEL, BPML, Semantics UDDI WSCI, WSCL, WSIL, OWL-S OWL-S, METEOR-S Composition Publication METEOR-S (P2P (SCET,SPTB) (Choreography?) / Discovery model of registries)

102 103 Semantics for Web Process Life- Cycle

Development Execution / Description (Orchestration?) / Annotation WSDL, WSEL BPWS4J, Commercial BPEL OWL-S Execution Engines, WSDL-S Intalio n3, HP eFlow

QoS Semantics BPEL, BPML, UDDI WSCI, WSCL, WSIL, OWL-S OWL-S, METEOR-S Composition Publication METEOR-S (P2P (SCET,SPTB) (Choreography?) / Discovery model of registries)

103 104 Semantics for Web Process Life- Cycle

Development Execution / Description (Orchestration?) / Annotation WSDL, WSEL BPWS4J, Commercial BPEL OWL-S Execution Engines, WSDL-S Intalio n3, HP Execution eFlow Semantics

BPEL, BPML, UDDI WSCI, WSCL, WSIL, OWL-S OWL-S, METEOR-S Composition Publication METEOR-S (P2P (SCET,SPTB) (Choreography?) / Discovery model of registries)

104 105 Semantics for Web Process Life- Cycle

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

105 106 Semantics at Different Layers

Description Layer: Why: Flow • Unambiguously understand the functionality of the services and the semantics of the operational data

Discovery How: • Using Ontologies to semantically annotate WSDL Publication constructs (conforming to extensibility allowed in WSDL specification version 1.2/2.0) – WSDL-S : Incorporate all types of semantics in the service Description description

Messaging Present scenario: • WSDL descriptions are mainly syntactic (provides Network operational information and not functional information) • Semantic matchmaking is not possible

106 107 WSDL-S

Function from Rosetta Net Ontology

Data from

Rosetta Net Ontology 107 108 Semantics at Different Layers (contd..)

Publication and Discovery Layers: Why: • Enable scalable, efficient and dynamic publication and Flow discovery (machine processable / automation)

Discovery How: • Use of ontology to categorize registries based on domains Publication and characterize them by maintaining the 1. properties of each registry 2. relationships between the registries Description • Capturing the WSDL annotations in UDDI

Messaging Present scenario: Network • 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 108 109 MWSDI

Registry Federation belongsTo Federation belongsTo Registry supports Ontology Domain

consistsOf subDomainOf

109 110 Semantics at Different Layers (contd..) Flow Layer: Why: •Design(composition), analysis (verification), validation (simulation) and execution (exception handling) of the Flow process models • To employ mediator architectures for automated composition, control flow and data flow based on Discovery requirements • To employ user interface to capture template requirements Publication and generate template based on that How: •Using Description – Functionality/preconditions/effects of the participating services Messaging – Knowledge of conversation patterns supported by the service – Formal mathematical models like process algebra, Network 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 and110 simulation are not supported directly 111 Using Colored Petri nets

111 112

Semantics in WS stack and METEOR-S

MWSCF: Semantic Web Process Composition Flow Framework Discovery MWSDI: Scalable Infrastructure of Registries for Semantic publication and discovery of Web Publication Services

Description MWSDI: Semantic Annotation of WSDL (WSDL-S) Messaging Network

112 113

Annotation of Web Services

Web Process Composition Semantic Web Service Web Discovery Web Processes Quality of Service

113 Web Service Semantic Annotation 115 Web Service

WSDL WSDL

SOAP

XML z WSDL stands for Web Services Description Language z WSDL is an XML document z WSDL is used to describe Web services z WSDL is also used to locate Web services

115 116 Web Service

WSDL WSDL

SOAP

XML

Abstract Description

Concrete Description

116

From S. Chandrasekaran’s Talk 117 Semantic Annotation of Web Services Annotation of Web Services

z To enhance the discovery, composition, and orchestration of Web services, it is necessary to increase the description of their interfaces.

z One solution is to annotate WSDL interfaces with semantic metadata based on relevant ontologies.

An ontology is a specification of a representational vocabulary for a shared domain of discourse.

117 118 How to Annotate ?

z Map Web service’s input & output data as well as functional description using relevant data and function/operation ontologies, respectively

z How ? z Borrow from schema matching z Semantic disambiguation between terms in XML messages represented in WSDL and concepts in ontology

118 Semantic Annotation of Web Services 119 Web Services Interfaces

z A Web service (WS) invocation specifies: z The number of input parameters that must be supplied for a proper WS realization and z The number of outputs parameters to hold and transfer the results of the WS realization to other tasks. z A function to invoke

Inputs Outputs Receipt Client Itinerary Local Tourism

function_foo(x..y)

119 120 Types of Annotation

Functional Data QoS Semantics Semantics Semantics

QoS Security Inputs Outputs Price Time Receipt Duration Client Cost Itinerary Fidelity Local Tourism Reliability Repudiation Availability function_foo(x..y)

120 Adding Semantics to Web 121 Services

WSDL Ontologies Data = Time - Ontology Semantics Temporal-Entity XML Schema Web Service Data type hierarchy Time Time Time-Point {absolute_time} Interfaces Interval Domain

{year, month, day} Date Time {hour, minute, second} Inputs Outputs

Date Calendar-Date Event Name {dayOftheWeek, monthOftheYear} Duration Year City = Local ontology Scientific-Event {millisecond} Coordinates {x, y}

Get Conference Area {name} Information QoS City Forrest QoSQoS OntologyOntology Functional Semantics Semantics Quality WSDL Information Function Min Conference Information Functions 121 Get Information Get Date 122 OWL-S

z OWL-S z Formerly OWL-S z Set of markup language constructs for describing the properties and capabilities of their Web services in unambiguous, computer-intepretable form

122 123 OWL-S Introduction OWL-S

z OWL-S z DAML (DARPA Agent Markup Language) z OWL-S: Upper ontology of web services

z OWL-S provides support for the following elements: z Process description. z Advertisement and discovery of services. z Selection, composition & interoperation. z Invocation. z Execution and monitoring.

123 OWL-S project home page 124 OWL-S Ontologies

z OWL-S defines ontologies for the construction of service models: z Service Profiles z Process Models z Service Grounding provides ResourceResource ServiceService

presents supports described by

ServiceService ServiceProfileServiceProfile ServiceModelServiceModel GroundingGrounding

what the how the how to access service does service works the service 124 125 OWL-S Service Profile

The Service Profile provides details about a service.

Inputs.Inputs.InputsInputs that that Outputs.Outputs.OutputsOutputs expected expected after after shouldshould be be provided provided to to thethe interaction interaction with with the the service. service. invokeinvoke the the service. service. Receipt Client Itinerary Local Tourism

Preconditions. Set of Web Service Effects. Set of statements that conditions that should hold prior should hold true if the service is to the service being invoked. invoked successfully.

125 126 Service Profile An example of Inputs and Outputs

... ...

Addr Inputs Outputs When Addr ... ,,, ... ... When < output > ...

126 Semantic Web Service Discovery 128 UDDI Brokering Discovery

UDDI

z UDDI stands for Universal Description, Discovery and Integration

z UDDI serves as a “Business and services” registry and directory and are essential for dynamic usage of Web services

z A UDDI registry is similar to a CORBA trader, or it can be thought of as a DNS for business applications.

z Is a platform-independent framework for describing services, discovering businesses, and integrating business services by using the Internet.

128 129 How UDDI Works ?

4. 1. SW companies, standards bodies, and programmers populate the registry with descriptions of different types of services Marketplaces, search engines, and business apps query the registry to 2. discover services at other UDDI Business Registry companies

Business Service Type 5. Businesses Registrations Registrations populate the registry UBR assigns a programmatically unique with 3. identifier to each service and business Business uses this descriptions of registration data to facilitate the services easier integration they support with each other over the Web 129 Source : http://www.uddi.org/pubs/UDDI_Overview_Presentation.ppt 130 UDDI and Semantics

Marketplaces, search engines, and business apps query

Semantic UDDI Registry entry Functional Data QoS Semantics Semantics Semantics

Internet WS9 InputsQoS Outputs Security WS Price 4 Receipt Time Duration Client Cost Itinerary Local Fidelity Tourism Reliability Repudiation

Availability WS8:function_foo(x..y) WS 130 2 WS7 131 Semantic Discovery of Web Services Web Service Discovery

Web Services must be located (Discovery) that might contain the desired Brokering functionality, operational Discovery

metrics, and interfaces UDDI needed to carry out the realization of a given task.

131 Discovery 132 New Requirements Web Service Discovery Before Now

QoS B3 A1 B3 A1 B3 A1 B3 A1 A1 A1 A1 Tasks B8 A4 A1 A4 A2 A1 A4 A2 A4 A1 A2 A4 A2 A1 A2 A1 Web ServicesB3A1 A1 B3 A1 A4 A2 B3 B3 A5A1 A1 A1 B3A1 A1 A1 A1 A4 A1 A4A1 B3A1 A4 A1A1 A2 A1 A4A1 B3 A1 A1 A1 A1 A4 A1 A2 A1 A4 A6 A4 B3 A4A1 A2 B3 A1 A2 A4 A2 A2 A1 A4 A2 A1 A1 A1 A1A2 A1 A1A1A1 A1 A2 A1B3 A4 A2 A1 A1 A2 A4A4 A2A2 A1 A4 A2A4 A1B3A4 A1A1A2 A1A1 A4 A2 A4 B3 A4A1A2 A1A4 A1 A1A1 A1 A1 A4 A2 A1 A1A1 B3 A2 B3 B3A2 A1 A4A1A1A1 A4 A2 B3 A4 A1A1 A1A1A1 A1 A4A4 A2A2 A1 B3 A1B3 B3 A1 A4 A1 A1 A1 A1 A4A2 A2A4A1 A1 A1A2 A1A1 A4A1 A4A1A4A1A1A1A1A2A2 A4 B3 A1 B3 A1 B3 A1 B3 A1A1 QoS

Workflow Web Process A N1 E N2 F A N1 E N2 F

C D C D 132 133 State of the art in discovery

UDDI Business Registry Results

Keyword and attribute-based Provides non-semantic match Search retrieves lot of search services (irrelevant Selection results included)

Which service to select ? How to select? 133 134 Present Discovery Mechanism Keyword and attribute-based search Web Service Discovery z UDDI :Keyword and attribute-based search z Example: “Quote” z Microsoft UBR returned 12 services z Human reading of description (Natural Language) help me understand: z 6 Entries are to get Famous Quotes z 1 Entry for personal auto and homeowners quoting z 1 Entry for multiple supplier quotes on all building materials

z Categorization suggested for UDDI is useful but inadequate (what does the WS do?) : z 1 Entry for Automobile Manufacturing z 1 Entry for Insurance agents, brokers, & service

z Alternatively read and try to understand WSDL z 1 Entry related to security details (Human Understanding) z 1 Test Web service for Quotes (which quote?) 134 Present Discovery Mechanism 135 Search for services to book an air ticket (using categories)*

z unspsc-org: unspsc:3-1

z Travel, Food, Lodging and Entertainment Services

z Travel facilitation Travel agents Travel agencies

z Services: 3 records found. z AirFares Returns air fares from netviagens.com travel agent z Hotel reservations Reservations for hotels in Asia, Australia and New Zealand z Your Vacation Specialists Web enabled vacation information

z Providers: 2 records found.

135 * Search carried out in one of the Universal Business Registries Present Discovery Mechanism 136 Search for services to book an air ticket (using Keywords)*

z air ticket z 1 record with name air tickets booking

z airticket, ticketbooking, airtravel, air travel, travel agent, airticketbooking, air ticket booking, travel agency, travelagency z 0 records were returned

z travelagent z 1 record with name travelagent test z 4 services: BookFlight, cancelFlightBooking etc. z Descriptions say that both these services are “XML based Web services” z No URL for WSDL

z Travel z 15 records. Purpose/functionality understood from descriptions z 2 services : TravelBooks z 4 services : TravelInformation z 2 services : Reservation and cancallation of travel tickets z 1 service : Emergency Services for travellers z 1 service : Travel documentation and itinerary 136 z 5 services : Description is ambiguous/not present* Search carried out in one of the Universal Business Registries 137 The use of semantics Benefits Web Service Discovery z Search engines can better “understand” the contents of a particular page z More accurate searches z Additional information aids precision z Makes it possible to automate searches because less manual “weeding” is needed to process the search results z Facilitates the integration of several Web services

137 138 Semantic Discovery: Overview

z Annotation and Publication z WSDL file is annotated using ontologies and the annotations are captured in UDDI

z Discovery z Requirements are captured as templates that are constructed using ontologies and semantic matching is done against UDDI entries z Functionality of the template, its inputs, outputs, preconditions and effects are represented using ontologies

z Use of ontologies z brings service provider and service requestor to a common conceptual space z helps in semantic matching of requirements and specifications 138 139 Semantic Publication and Discovery

Use of ontologies enables shared understanding between the service provider and service requestor

For simplicity of depicting, the ontology is shown with classes for both operation and data 139 Adding Semantics to Web Services Standards 140 Discovery The Match Function z The Web service discovery and integration process is carried out by a key operation:

z The match function. z The matching step is dedicated to finding correspondences between a service template (ST, i.e., a query) and a service object (SO).

140 141

The Match Function

SO 0.76 SO2 SO 0.14 SOSO1 2 SO3 0.31 0.68 1 3 Match Function 0.98 0.43 0.34 0.74 0.99 Conference Registry Hotel Reservation Service f(ST, SO ) f(ST, SO ) f(ST, SO ) Service 1 ?2 3

DateDate DurationDuration CityCity Conference

Get ItineraryItinerary Conference ST B End Start A Information Travel Hotel User Name Reservation Reservation Employee ID User Name AddressAddress Get User Information Web Process 141 142 Discovery in Semantic Web Using Semantics Web Service Discovery z Functionality: What capabilities the distributor expects from the service (Functional semantics) (Functional semantics) z Inputs: What the distributor can give (Data semantics) to the to the Manufacturer’s service (QoS semantics) (Data semantics) (Syntactic description) z Outputs: What the distributor expects as outputs from the service (Data semantics) z Description: Natural z QoS: Quality of Service the language distributor expects from the service description of the (QoS semantics) service functionality (Syntactic description) 142 143 Syntactic, QoS, and Semantic (Functional & Data) Similarity Web Service Discovery Similarity ? SyntacticSyntactic Name, A Name, Name, X Name, Similarity ω Description, Description, Similarity ω Description, B Description, Y …. … ω1SynNS(ST.sn, SO.sn) +ω2SynDS(ST.sd, SO.sd) … C …. SynSimilarty(ST, SO) = ∈[0..1], 1 + 2 and ω ,ω ∈[0..1] Web Service Web Service 1 2 Similarity ? QoS QoS QoSQoS A Similarity X OpSimilarity(ST, SO) = Similarity Buy B Purchase Buy Y Purchase 3 QoSdimD(ST, SO,time) * QoSdimD(ST, SO,cost) * QoSdimD(ST, SO,reliability) C

Web Service Web Service FunctionalFunctional & & DataData Similarity ? Calendar-Date Similarity Event Similarity A1 … A2 A1 … A2 Coordinates{x, y} … Information Function Area {name} 143 Web Service Web Service Forrest Get Information Get Date 144 The Match Function Semantic Similarity z Purely syntactical methods that treat terms in isolation from their contexts.

z It is insufficient since they deal with syntactic but not with semantic correspondences

z Users may express the same concept in different ways. z Therefore, we rely on semantic information to evaluate the similarity of concepts that define ST and SO interfaces. z This evaluation will be used to calculate their degree of integration.

144 145 The Match Function Semantic Similarity z When comparing concepts two main cases can occur:

¾ The concepts are defined with the same Ontology (Ω(O) = Ω(I)) ¾ The concepts are defined in different Ontologies (Ω(O) ≠Ω(I))

145 146 The Match Function Semantic Similarity (Ω(O) = Ω(I)) z When comparing concepts defined with the same ontology four distinct scenarios need to be considered: z a) the concepts are the same (O=I) z b) the concept I subsumes concept O (O>I) z c) the concept O subsumes concept I (O

146 147 The Match Function Semantic Similarity (Ω(O) = Ω(I))

Similarity ? Calendar-Date Event … A2 A1A1 … A2 …

Web Service Web Service

ST1,2 (output) SO1,2,3,4 (input)

Time ontology b) Time ontology

Temporal-Entity Temporal-Entity

2 Time Time Time-Point {absolute_time} a) Time Time Time-Point {absolute_time} Interval Domain Interval Domain 1 1 {year, month, day} Date Time {hour, minute, second} {year, month, day} Date Time {hour, minute, second}

2 3 4 Calendar-Date Event Calendar-Date Event {dayOftheWeek, monthOftheYear} c) {dayOftheWeek, monthOftheYear}

Scientific-Event {millisecond} Scientific-Event {millisecond}

147 148 The Match Function Semantic Similarity (Ω(O) = Ω(I)) New Date Date … Similarity ? A? A1A1 … A? … Web Service Web Service

Temporal-Entity 100100 % % Temporal-Entity

2 Time Time-Point Time Time-Point Domain { absolute_time} Domain { absolute_time} 1 1 {year, month, day} Date Time {year, month, day} Date Time {hour, minute, second} {hour, minute, second} 2 3 4 Calendar-Date Event Calendar-Date Event { dayOftheWeek, monthOftheYear} dayOftheWeek, monthOftheYear}

Scientific-Event Scientific-Event {millisecond} {millisecond}

 1, O = I   1, O > I SemS'(O, I) = | p(O) |  , O < I  | p(I) | 148  Similarity'(O, I), O ≠ I 149 The Match Function Semantic Similarity (Ω(O) = Ω(I)) New CalendarDate Date … Similarity ? A? A1A1 … A? … Web Service Web Service

Temporal-Entity 100100 % % Temporal-Entity

Scientific-Event Scientific-Event {millisecond} {millisecond}

 1, O = I   1, O > I SemS'(O, I) = | p(O) |  , O < I  | p(I) | 149  Similarity'(O, I), O ≠ I 150 The Match Function Semantic Similarity (Ω(O) = Ω(I)) New Date CalendarDate … Similarity ? A? A1A1 … A? … Web Service Web Service

Temporal-Entity 4/6=0,67=>4/6=0,67=> 67% 67% Temporal-Entity

Scientific-Event Scientific-Event {millisecond} {millisecond}

 1, O = I   1, O > I SemS'(O, I) = | p(O) |  , O < I  | p(I) | 150  Similarity'(O, I), O ≠ I 151 The Match Function Semantic Similarity (Ω(O) = Ω(I)) New Date Event … Similarity ? A? A1A1 … A? … Web Service Web Service

4/9*4/7=0.5044/9*4/7=0.504 => => 50% 50% Temporal-Entity Temporal-Entity

Scientific-Event Scientific-Event {millisecond} {millisecond}

z When comparing concepts defined with different ontologies three distinct scenarios can occur:

z The ontological properties involved are associated with a primitive data type

z The properties are associated with concept classes, and

z One property is associated with a primitive data type, while the other is associated with a concept class.

152 153 The Match Function Semantic Similarity (Ω(O) <> Ω(I)) New TheDate Date … Similarity ? A? A1A1 … A? … Web Service Web Service

2.58

DateTime Temporal-Entity {TheDate, TheTime}

5 Time Time Time-Point {absolute_time} TheTime TheDate Interval Domain {gHour, gMinute, gSecond} {gYear, gMonth, gDay} 1 {year, month, day} Date Time {hour, minute, second}