Chapter 2: Basic Standards for Web Services Service-Oriented Computing: Semantics, Processes, Agents – Munindar P. Singh and Michael N. Huhns, Wiley, 2005.

Chapter 2:Basic Standards for Web Services

Service-Oriented Computing: Semantics, Processes, Agents– Munindar P. Singh and Michael N. Huhns, Wiley, 2005

Chapter 2 2Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

Michael Huhns

Highlights of this Chapter

eXtensible Markup Language (XML) Simple Object Access Protocol

(SOAP) Web Services Description

Language (WSDL) Directory Services Universal Description, Discovery,

and Integration (UDDI)

Chapter 2 3Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

Michael Huhns

Standards for Web Services

BPEL4WSOWL-S Service

Model

ebXMLCPA

Process and workfloworchestrations

QoS: Servicedescriptions and bindings

Contracts andagreements

XLANG

WSCL

WSDLebXML

CPP

ebXMLBPSS

XML, DTD, and XML Schema

HTTP, FTP, SMTP, SIP, etc.

SOAPebXML

messaging

OWL

UDDIebXML

Registries

WSCLWSCI

WS-Coordination

WS-AtomicTransaction and WS-BusinessActivity

OWL-S ServiceGrounding

OWL-S ServiceProfile

BTP

BPML

Discovery

Messaging

Transport

QoS: Conversations

QoS: Choreography

QoS: Transactions

Encoding

WS-Policy

WS-Security

WS-ReliableMessaging

PSL

RDF

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XML Web Service Foundation

Open and with broad industry support

Publish, Find, Use Services UDDI

Service Interactions SOAP

Universal Data Format XML

Description Language WSDL

Ubiquitous Communications TCP/IP, HTTP, SMTP, SIP, Reliable messaging

Security (authentication and authorization) WS-Security, SAML

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Markup History

None, as in comma separated values Ad hoc tags SGML (Standard Generalized Markup L):

complex, few reliable tools HTML (HyperText ML): simple,

unprincipled, mixes structure and display XML (eXtensible ML): simple, yet

extensible subset of SGML to capture new vocabularies Machine processible Comprehensible to people: easier debugging

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XML Basics and Namespaces

<?xml version="1.0"?> <!– not part of the document per se <arbitrary:toptag xmlns=“http://one.default.namespace/if-

needed”xmlns:arbitrary=“http://wherever.it.might.be/arbit-ns”

      xmlns:random=“http://another.one/random-ns”>

    <arbitrary:atag attr1=“v1” attr2=“v2”>Optional text also known as PCDATA

<arbitrary:btag attr1=“v1” attr2=“v2” /></arbitrary:atag><random:simple_tag/><random:atag attr3=“v3”/> <!– compare with

arbitrary:atag above </arbitrary:toptag>

Chapter 2 7Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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XML Schema A data definition language for XML: defines

a notion of schema validity; helps us define desired grammars for documents Same syntax as regular XML documents Local scoping of subelement names Incorporates namespaces Types

Primitive (built-in): string, ID, IDREF, integer, float, date,

simpleType constructors: list, union Restrictions: intervals, lengths, enumerations, regex

patterns, Flexible ordering of elements

Key and referential integrity constraints

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Web Services: Basic Architecture

ServiceBroker

ServiceProvider

ServiceRequesto

r

Bind or invoke(SOAP)

Find or discover(UDDI)

Publish or announce(WSDL)

Registry; well-known

Not well-known

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Michael Huhns

Basic Profile (BP 1.0)

The Web Services Interoperability Organization (WS-I) has specified the following Basic Profile version 1.0: SOAP 1.1 HTTP 1.1 XML 1.0 XML Schema Parts 1 and 2 UDDI Version 2 WSDL 1.1

Chapter 2 10Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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Describing a Service

Namee.g., GetTemperature

Types of Input Parameterse.g., (String, String)

Types of Output Parameterse.g., Integer

Chapter 2 11Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

Michael Huhns

Interactions

Via MethodsVia Methods Via MessagesVia Messages

Purchasing()Purchasing()

CatalogService()CatalogService()

Order()Order()

invokeinvoke

invokeinvoke

catalogcatalog

confirmation #confirmation #

Dell Purchasing Intel Sales

SubmitPO

AckPO

SubmitASN

SubmitInvoice

SubmitPayment

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SOAP (Simple Object Access Protocol)

Used to exchange messages via HTTP, SMTP, and SIP (Session Initiation Protocol for Internet telephony)

Originally designed for remote-procedure calls (RPC)

Works through firewalls on port 80 Character-based, so easy to encrypt/decrypt

and thus easy to secure Inefficient due to character, not binary, data

and large headers Does not describe bidirectional or n-party

interaction

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Michael Huhns

Ex. SOAP Request

POST /temp HTTP/1.1Host: www.socweather.comContent-Type: text/xml; charset="utf-8"Content-Length: xxxSOAPAction: "http://www.socweather.com/temp"

<!-- The above are HTTP headers --><?xml version=“1.0”?><env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" env:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/> <env:Body> <m:GetTemp xmlns:m="http://www.socweather.com/temp.xsd"> <m:City>Honolulu</m:City> <m:When>now</m:When> </m:GetTemp> </env:Body></env:Envelope>

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Ex. SOAP Response

HTTP/1.1 200 OKContent-Type: text/xml; charset="utf-8"Content-Length: xxxSOAPAction: "http://www.socweather.com/temp"

<?xml version=“1.0”?><env:Envelope

xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"

env:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>

<env:Body> <m:GetTempResponse

xmlns:m="http://www.socweather.com/temp.xsd"> <DegreesCelsius>30</DegreesCelsius> </m:GetTempResponse> </env:Body></env:Envelope>

Chapter 2 15Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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WSDL: Web Services Description Language

Describes a programmatic interface to a Web service, including Definitions of data types Input and output message formats The operations provided by the service Network addresses Protocol bindings

Chapter 2 16Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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WSDL Data Model definitions targetNamespace=thisNamespace xmins:tns=thisNamespace

types message name=in message name=out

portType name=foo operation input message=tns:in output message=tns:out

binding name=foobar type=tns:foo [binding information]

service name=foobar Service

Port name=foobarPort binding=tns:foobar [endpoint information]

Types contains data type definitionsMessages consist of one or more parts

A portType describes an abstract setof operations

A binding describes a concrete set offormats and protocols for the fooportTypes

A port describes an implementationof the foobar binding

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WSDL Example: 1

<?xml version="1.0"?><!-- the root element, wsdl:definitions, defines a set of --><!-- related services --><wsdl:definitions name="Temperature" targetNamespace="http://www.socweather.com/schema" xmlns:ts="http://www.socweather.com/TempSvc.wsdl"

xmlns:tsxsd="http://schemas.socweather.com/TempSvc.xsd"

xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/">

Chapter 2 18Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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WSDL Example: 2

<!-- wsdl:types encapsulates schema definitions of --><!-- communication types; here using xsd --> <wsdl:types><!-- all type declarations are expressed in xsd --> <xsd:schema targetNamespace="http://namespaces.socweather.com" xmlns:xsd="http://www.w3.org/1999/XMLSchema">

<!-- xsd def: GetTemp [City string, When string] --> <xsd:element name="GetTemp"> <xsd:complexType> <xsd:sequence> <xsd:element name="City" type="string"/> <xsd:element name="When" type="string"/> </xsd:sequence> </xsd:complexType> </xsd:element>

Chapter 2 19Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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WSDL Example: 3<!-- xsd def: GetTempResponse [DegreesCelsius integer] --> <xsd:element name="GetTempResponse"> <xsd:complexType> <xsd:all> <xsd:element name="DegreesCelsius" type="integer"/> </xsd:all> </xsd:complexType> </xsd:element>

<!-- xsd def: GetTempFault [errorMessage string] --> <xsd:element name="GetTempFault"> <xsd:complexType> <xsd:all> <xsd:element name="errorMessage" type="string"/> </xsd:all> </xsd:complexType> </xsd:element> </xsd:schema> </wsdl:types>

Chapter 2 20Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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WSDL Example: 4<!-- wsdl:message elements describe potential transactions --><!-- Most messages, as here, have only one part. Multiple --><!-- parts provide a way to aggregate complex messages -->

<!-- request GetTempRequest is of type GetTemp --> <wsdl:message name="GetTempRequest"> <wsdl:part name="body" element="tsxsd:GetTemp"/> </wsdl:message>

<!-- response GetTempResponse is of type GetTempResponse --> <wsdl:message name="GetTempResponse"> <wsdl:part name="body" element="tsxsd:GetTempResponse"/> </wsdl:message>

<!-- wsdl:portType describes messages in an operation --> <wsdl:portType name="GetTempPortType">

<!-- wsdl:operation describes the entire protocol from --><!-- input to output or fault --> <wsdl:operation name="GetTemp"><!-- The order of input and output is significant; input --><!-- preceding output indicates the request-response --><!-- operation type --> <wsdl:input message="ts:GetTempRequest"/> <wsdl:output message="ts:GetTempResponse"/> <wsdl:fault message="ts:GetTempFault"/> </wsdl:operation> </wsdl:portType>

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WSDL Example: 5<!-- wsdl:binding states a serialization protocol for --><!-- this service --> <wsdl:binding name="TempSvcSoapBinding" type="ts:GetTempPortType">

<!-- leverage off soap:binding document style --> <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>

<!-- semi-opaque container of network transport details --> <!-- classed by soap:binding above @@@ --> <wsdl:operation name="GetTemp"> <soap:operation soapAction="http://www.socweather.com/TempSvc"/><!-- further specify that the messages in the --><!-- wsdl:operation "GetTemp" use SOAP? @@@ --> <wsdl:input> <soap:body use="literal"

namespace="http://schemas.socweather.com/TempSvc.xsd"/> </wsdl:input> <wsdl:output> <soap:body use="literal"

namespace="http://schemas.socweather.com/TempSvc.xsd"/> </wsdl:output> <wsdl:fault> <soap:body use="literal"

namespace="http://schemas.socweather.com/TempSvc.xsd"/> </wsdl:fault> </wsdl:operation> </wsdl:binding>

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WSDL Example: 6

<!-- wsdl:service names a new service "TemperatureService" -->

<wsdl:service name="TemperatureService"> <wsdl:documentation>socweather.com temperature service </wsdl:documentation>

<!-- connect it to the binding "TempSvcSoapBinding" above --> <wsdl:port name="GetTempPort"

binding="ts:TempSvcSoapBinding">

<!-- give the binding a network address --> <soap:address

location="http://www.socweather.com/TempSvc"/> </wsdl:port> </wsdl:service></wsdl:definitions>

Chapter 2 23Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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Directory Services Support discovery: enable applications,

agents, Web service providers, Web service requestors, people, objects, and procedures to locate each other White pages – entries found by name Yellow pages – entries found by characteristics

and capabilities A basic directory might be a simple

database (passive) or a broker/facilitator (active, that provides alerts and recruits participants)

UDDI – both white pages and yellow pages, but passive

Chapter 2 24Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and

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UDDI: Universal Description, Discovery, and Integration

UDDI is a Web service that is based on SOAP and XML

UDDI registers1. tModels: technical descriptions of a

service’s behavior2. businessEntities: describes the

specifications of multiple tModels

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Yellow, Green, and White Pages in UDDI

-businessKey : string(idl)-name : string(idl)-description : string(idl)-URL : string(idl)-contacts : contact-businessServices : businessService-identifierBag : keyedReference-categoryBag : keyedReference

businessEntity

1

*

-tModelKey : string(idl)-keyName : string(idl)-keyValue : string(idl)

keyedReference

-serviceKey : string(idl)-tModelKey : string(idl)-name : string(idl)-description : string(idl)-bindingTemplates

businessService

-phone : string(idl)-address : string(idl)

contact

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UML Model for Business Entity in a UDDI Registry

-businessKey-name-description-businessServices-categoryBag-identifierBag

businessEntity

-serviceKey-businessKey-name-description-bindingTemplates-categoryBag

businessService

-bindingKey-serviceKey-description-accessPoint

bindingTemplate

-name-description-overviewDoc-categoryBag-identifierBag

tModel

identifierBag

categoryBag

-keyName-keyValue

keyedReference

-description-overviewDoc

tModelInstanceInfo

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Michael Huhns

Core Data Structures for UDDI

businessEntity: Information about theparty who publishes information about

a service

businessService: Descriptiveinformation about a particular family of

technical services

bindingTemplate: Technicalinformation about a service entry point

and implementation specs

tModel: Descriptions of specificationsfor services or value sets. Basis for

technical fingerprints

businessEntities containbusinessServices

businessServices containbindingTemplates

bindingTemplates contain referencesto tModels. These references

designate the interface specificationsfor a service

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Michael Huhns

WSDL UDDI Correspondence

<import>

<port>

<port>

BusinessEntity

BusinessService

BindingTemplate

BindingTemplate

Service Implementation

UDDI

<service>

Service Interface

<types>

<message>

<portType>

<binding>

tModel

WSDL

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Michael Huhns

An Inquiry to a UDDI Registry

A UDDI registry acts as a service in its own right

<?xml version="1.0" encoding="UTF-8"?><find_business xmlns="urn:uddi-org:api_v3"> <findQualifiers> <findQualifier> uddi:uddi.org:findqualifier:exactmatch </findQualifier> </findQualifiers> <!--find information about all businesses with the exact name "WeatherService Inc." --> <name>WeatherService Inc.</name></find_business>

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Michael Huhns

Response from a UDDI Registry

<?xml version="1.0" encoding="UTF-8"?><businessList> <businessInfos> <businessInfo businessKey="...KO..."> <name>WeatherService, Inc.</name> <serviceInfos> <serviceInfo serviceKey="...KN..." businessKey="...K1..."> <name>Temperature Service</name> </serviceInfo> </serviceInfos> </businessInfo> </businessInfos></businessList>

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Chapter 2 Summary

The main triad of Web services standards Bring together well-known ideas Provide necessary functionality for

interoperation Are complicated in their details Meant for tool vendors rather than

programmers Increasingly hidden by tools