11

Review

V. “Juggy” JagannathanAssociate Professor of Computer Science

West Virginia University

22

Focus of Global Knowledge Focus of Global Knowledge NetworksNetworks

Enterprise Application DevelopmentEnterprise Application Development Distributed Systems DevelopmentDistributed Systems Development Component-based Solution Component-based Solution

DevelopmentDevelopment Knowledge-based Solution Knowledge-based Solution

DevelopmentDevelopment

33

ASP & Enterprise ApplicationsASP & Enterprise Applications

Application Service Provider (ASP) provides Application Service Provider (ASP) provides applications to customers on a applications to customers on a subscription basis. ASPs provide for all the subscription basis. ASPs provide for all the infrastructure needs to host the application infrastructure needs to host the application and rely on Internet or Intranets to deliver and rely on Internet or Intranets to deliver the applications to customers. the applications to customers.

ASPs are Enterprise Applications and need ASPs are Enterprise Applications and need to satisfy a wide range of stringent to satisfy a wide range of stringent requirements.requirements.

44

Enterprise Application Enterprise Application RequirementsRequirements

FlexibilityFlexibility SecuritySecurity ReliabilityReliability AvailabilityAvailability ScalabilityScalability EvolvabilityEvolvability PerformancePerformance SupportabilitySupportability MaintainabilityMaintainability InteroperabilityInteroperability

Platform IndependencePlatform Independence Location IndependenceLocation Independence Open Standards and SystemsOpen Standards and Systems Architectural ChoicesArchitectural Choices

55

Platform ChoicesPlatform Choices

Platform StandardsPlatform Standards– Object Management Group (OMG) Object Management Group (OMG)

CORBA Infrastructure and approach CORBA Infrastructure and approach – Web services – the new kid on the blockWeb services – the new kid on the block

Other Popular PlatformsOther Popular Platforms– Sun J2EE PlatformSun J2EE Platform– Windows .NETWindows .NET

Host of other vendor platformsHost of other vendor platforms– OracleOracle– IBMIBM– IonaIona

66

CORBA Architecture – CORBA Architecture – Simple viewSimple view

ServersServers

ORB

C++JavaAda otherC C++JavaAda otherC

ClientsClients ServerServer

Client RequestsClient RequestsIDL-based

ServiceServiceIDL-based

77

Java and J2EE Java and J2EE PlatformPlatform

OverviewOverview

88

J2EEApplication

Server

J2EE ArchitectureJ2EE Architecture

JAF

JavaMail

JMS

JDB

C

JTA

JND

I

RM

I/IIOP

Servlets JSPsTag

Library

Web Container

JAF

JavaMail

JMS

JDB

C

JTA

JND

I

RM

I/IIOP

EJB Container

SessionBeans

EntityBeans

RDBMS Mail ServerJava App.

CORBA Server

DirectoryService

Message Queue

XHTMLXML

Applet

ClientApp.

HTTP(S)

Reproduced with Permission from Java Server Programming J2EE Edition – Wrox Press, Ltd, 2000

99

J2EE Platform ComponentsJ2EE Platform Components

JAXP 1.0 – Java API for JAXP 1.0 – Java API for XML ProcessingXML Processing

JDBC 3.0 – Java Data JDBC 3.0 – Java Data Base ConnectivityBase Connectivity

RMI over IIOPRMI over IIOP EJB 2.1 – Enterprise EJB 2.1 – Enterprise

Java BeansJava Beans Java Servlets 2.4Java Servlets 2.4 Java Server Pages 2.0Java Server Pages 2.0

Java Message Service 1.0Java Message Service 1.0 Java Naming and Java Naming and

Directory Interface (JNDI) Directory Interface (JNDI) 1.21.2

Java Transaction API 1.0Java Transaction API 1.0 JavaMail 1.1 J2EE JavaMail 1.1 J2EE

Connector Architecture Connector Architecture 1.01.0

Java Authentication and Java Authentication and Authorization Service 1.0Authorization Service 1.0

1010

J2EE PlatformJ2EE Platform

Strong and proven platformStrong and proven platform Evolving constantlyEvolving constantly Already supports various APIs Already supports various APIs

to develop and deploy web to develop and deploy web servicesservices

1111

.NET Platform.NET PlatformClient App. Users

Web Services

WebForms

.NET Framework

HT

TP

SO

AP

UD

DI

OD

BC

DC

OM

.NE

T

Web serversWeb serversWeb serversWeb serversWeb servers.NET servers

1212

.NET Components.NET Components .NET framework.NET framework

– Common Language Runtime (CLR) Common Language Runtime (CLR) librarylibrary

– ActiveX Data Objects - (ADO.NET)ActiveX Data Objects - (ADO.NET)– Active Server Pages – (ASP.NET) and Active Server Pages – (ASP.NET) and

supports Web Services (UDDI, WSDL & supports Web Services (UDDI, WSDL & SOAP)SOAP)

– .NET Compact framework for PDAs.NET Compact framework for PDAs– .NET Remoting (RPC support).NET Remoting (RPC support)

Visual Studio .NETVisual Studio .NET– VB, C++, C#, Jscript… all compile to VB, C++, C#, Jscript… all compile to

MSIL (Microsoft Intermediate Language) MSIL (Microsoft Intermediate Language) and utilize CLR. and utilize CLR.

1313

.NET Framework.NET Framework

Microsoft’s big push to open Microsoft’s big push to open standards and support for XML-standards and support for XML-based solutionsbased solutions

Fully supports web services Fully supports web services approachapproach

Microsoft is an active participant in Microsoft is an active participant in W3C efforts and is a strong W3C efforts and is a strong proponent of standardization of web proponent of standardization of web services and related technologies. services and related technologies.

1414

XML Technology XML Technology OverviewOverview

1515

Emerging Importance of XMLEmerging Importance of XML

HTML-tagging is display oriented.HTML-tagging is display oriented. XML-based content tagging has important uses:XML-based content tagging has important uses:

– data miningdata mining– role-oriented display customizationrole-oriented display customization– intelligent searching and other value added intelligent searching and other value added

elementselements Wide spread industry support for this new open Wide spread industry support for this new open

standardstandard– MicrosoftMicrosoft– NetscapeNetscape– W3C is pushing the standardization effortsW3C is pushing the standardization efforts

Complementary technology to HTML-based web Complementary technology to HTML-based web browsersbrowsers

Why do we care about XML?

1616

Requirements best addressed by XML ?Requirements best addressed by XML ?

Customizing front-end applications - Customizing front-end applications - easy presentation of what users want easy presentation of what users want to seeto see

Data miningData mining Synthesis type applications - Synthesis type applications -

combining multiple information combining multiple information sourcessources

Electronic commerce-type Electronic commerce-type applicationsapplications

Structured Data ExchangeStructured Data Exchange

1717

XML MarkupXML Markup

Elements and attributesElements and attributes Entity ReferencesEntity References CommentsComments Processing InstructionsProcessing Instructions Marked SectionsMarked Sections Document Type Definitions Document Type Definitions

(DTDs)(DTDs) Now, XML SchemasNow, XML Schemas

1818

ElementsElements

Bounded by start and end tagsBounded by start and end tags Sample markupSample markup

<Patient> <Patient> <FirstName> Frank</FirstName> <FirstName> Frank</FirstName> <LastName> Foster</LastName> <LastName> Foster</LastName>

</Patient></Patient> Patient, LastName, FirstName Patient, LastName, FirstName

are all entity tags.are all entity tags.

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AttributesAttributes

Name-value pairs included as part of Name-value pairs included as part of start tags.start tags.

Sample markupSample markup<APatient patientID=“123” FirstName=“Frank” <APatient patientID=“123” FirstName=“Frank”

LastName=“Foster”>LastName=“Foster”>

<Insurance> Blue Cross </Insurance><Insurance> Blue Cross </Insurance>

<Insurance> HMO </Insurance> <Insurance> HMO </Insurance>

</APatient></APatient>

FirstName and LastName in the example FirstName and LastName in the example above are attribute declarations.above are attribute declarations.

2020

Document Type DefinitionsDocument Type Definitions

Allows the expression of Allows the expression of constraints on tagsconstraints on tags

Defines sequencing and nesting Defines sequencing and nesting of tagsof tags

Defines attributes and values Defines attributes and values and defaultsand defaults

Allows specification of external Allows specification of external file referencesfile references

2121

XML SchemasXML Schemas

Replaces DTDsReplaces DTDs Is in XML format (DTD’s are Is in XML format (DTD’s are

not)not) Supports data typing (DTD’s Supports data typing (DTD’s

didn't)didn't) Schemas are extensibleSchemas are extensible XML Schemas – next XML Schemas – next

generation of DTDs.generation of DTDs. Wide industry supportWide industry support

2222

XML’s evolving family of standardsXML’s evolving family of standards

XML Linking Specification (XLL)XML Linking Specification (XLL) Resource Directory Framework (RDF)Resource Directory Framework (RDF) Style sheetsStyle sheets

– CSS Cascading Style sheetsCSS Cascading Style sheets– XSL - XML Style sheet Specification XSL - XML Style sheet Specification

LanguageLanguage Document Object Model (DOM)Document Object Model (DOM) XML SchemasXML Schemas Provides the basis for Web Services Provides the basis for Web Services

and Simple Object Access Protocol and Simple Object Access Protocol (SOAP)(SOAP)

2323

Web ServicesWeb Services

2424

Web Service DefinitionWeb Service Definition

A Web service is a software system designed A Web service is a software system designed to support interoperable machine-to-to support interoperable machine-to-machine interaction over a network. It has machine interaction over a network. It has an interface described in a machine- an interface described in a machine- processable format (specifically WSDL). processable format (specifically WSDL). Other systems interact with the Web Other systems interact with the Web service in a manner prescribed by its service in a manner prescribed by its description using SOAP messages, description using SOAP messages, typically conveyed using HTTP with an typically conveyed using HTTP with an XML serialization in conjunction with other XML serialization in conjunction with other Web-related standards.Web-related standards.

Source: W3C definition: http://www.w3.org/TR/2004/NOTE-ws-arch-20040211/

2525

What are XML Web Services?What are XML Web Services?

Interaction using standard Interaction using standard internet protocolsinternet protocols

A vehicle used to integrate A vehicle used to integrate other applicationsother applications

Expose functionality through Expose functionality through well-defined interfaceswell-defined interfaces

Can be advertised in a Can be advertised in a registry/directory.registry/directory.

2626

Web Services ArchitectureWeb Services Architecture

http://www.w3.org/TR/2004/NOTE-http://www.w3.org/TR/2004/NOTE-ws-arch-20040211/ws-arch-20040211/

2727

Different Models supported by Web Different Models supported by Web ServicesServices

Message Oriented ModelMessage Oriented Model Service Oriented ModelService Oriented Model Resource Oriented ModelResource Oriented Model Policy ModelPolicy Model

2828

Example XML Web Services?Example XML Web Services?

Information servicesInformation services Centralization servicesCentralization services Data Integration, Data Integration,

Aggregation and AnalysisAggregation and Analysis Extending and Integrating Extending and Integrating

ApplicationsApplications Peer-and-Push-based Peer-and-Push-based

systemssystems

2929

Benefits of Web Services?Benefits of Web Services?

Standards basedStandards based Vendor neutralVendor neutral SimplicitySimplicity Language and Platform Language and Platform

IndependenceIndependence Functional AbstractionFunctional Abstraction DiscoverableDiscoverable Reduced Development timeReduced Development time

3030

When not to use Web When not to use Web Services?Services?

Closed systemsClosed systems Critical Performance Critical Performance

requirementsrequirements Technical limitations – like Technical limitations – like

transaction support and transaction support and security elements have not security elements have not been standardizedbeen standardized

3131

Web Services EnsembleWeb Services EnsembleDiscovery

UDDI

DescriptionWSDL

MessagingSOAP

EncodingXML

TransportHTTP

3232

Web Services Web Services Definition Definition LanguageLanguage

WSDLWSDL

3333

What is WSDL?What is WSDL? Web Services Definition LanguageWeb Services Definition Language It is equivalent of IDL for Web ServicesIt is equivalent of IDL for Web Services It is in XML Schema formatIt is in XML Schema format It defines an EXTENSIBLE framework for It defines an EXTENSIBLE framework for

specifying web services interfacesspecifying web services interfaces Developed originally by Microsoft and IBM Developed originally by Microsoft and IBM

and now being put through its paces in and now being put through its paces in W3C.W3C.

W3C working on Version 1.2 of WSDL right W3C working on Version 1.2 of WSDL right now (Fall 2003).now (Fall 2003).

3434

WSDL: What does it support?WSDL: What does it support?

Data type definitionsData type definitions Messages supportedMessages supported Operations supportedOperations supported Port type (an aggregation of Port type (an aggregation of

messages and operations)messages and operations) Binding (what protocol supports the Binding (what protocol supports the

service – ala SOAP)service – ala SOAP) Port – target address where service Port – target address where service

is availableis available Service – aggregation of port typesService – aggregation of port types

3535

WSDL ServiceWSDL Service

WSDL WSDL specifications are specifications are published in a published in a URL.URL.

Clients download Clients download this specification, this specification, pick a particular pick a particular protocol to protocol to communicate communicate with the service with the service (binding) and use (binding) and use that protocol.that protocol.

OperationOperation

Operation

BindingBindingBinding

Port Type

OperationOperation

Operation

BindingBindingBinding

Port Type

OperationOperation

Operation

BindingBindingBinding

Port Type

Web Service

3636

SOAP...SOAP...

It is a It is a SSimple imple PProtocol that allows rotocol that allows you to you to AAccess an ccess an OObject through bject through

the net.the net.Courtesy: Yan Liu, my student.

3737

SOAP MotivationsSOAP Motivations

Heterogeneous systems Heterogeneous systems mustmust be able be able to communicateto communicate

Binary protocols don’t always workBinary protocols don’t always work– CORBA, DCOM, etc. don’t work well through CORBA, DCOM, etc. don’t work well through

firewallsfirewalls– Nobody can agree on a standard binary format Nobody can agree on a standard binary format

(usually due to platform-related issues)(usually due to platform-related issues)– We’re dealing with many heterogeneous We’re dealing with many heterogeneous

environments (MVS, Unix, Windows NT, Linux, environments (MVS, Unix, Windows NT, Linux, PalmOS, etc.)PalmOS, etc.)

– Component runtimes differComponent runtimes differ– Security models differ (Kerberos, NTLM, OSF-DCE)Security models differ (Kerberos, NTLM, OSF-DCE)

Courtesy: Yan Liu, my student.

3838

What SOAP is...What SOAP is...

SOAP is a specification for defining...SOAP is a specification for defining...– an encoding style that uses XML to an encoding style that uses XML to

represent information graphsrepresent information graphs– a standard way to move XML with HTTPa standard way to move XML with HTTP– rules for passing messagesrules for passing messages– error (fault) definitionerror (fault) definition– a medium for performing Remote a medium for performing Remote

Procedure Calls (RPC)Procedure Calls (RPC)– one layer in a multi-layer architectureone layer in a multi-layer architecture

Courtesy: Yan Liu, my student.

3939

Courtesy: Yan Liu, my student.

SOAP Contains Four Parts:SOAP Contains Four Parts:

An extensible envelope expressing An extensible envelope expressing (mandatory)(mandatory)– whatwhat features and services are represented in a features and services are represented in a

message;message;– whowho should deal with them, should deal with them,– whetherwhether they are optional or mandatory. they are optional or mandatory.

A set of encoding rules for data A set of encoding rules for data (optional)(optional)– Exchange instances of application-defined data types Exchange instances of application-defined data types

and directed graphsand directed graphs– Uniform model for serializing abstract data models Uniform model for serializing abstract data models

that can not directly be expressed in XML schemathat can not directly be expressed in XML schema A Convention for representation RPC A Convention for representation RPC (optional)(optional)

– How to make calls and responsesHow to make calls and responses A protocol binding to A protocol binding to HTTPHTTP and and HTTP-EFHTTP-EF (optional)(optional)

4040

<Envelope>

<Header>

<transId>1234</transId>

</Header>

<Body>

<Add>

<a>3</a>

<b>4</b>

</Add>

</Body>

</Envelope>

c = Add(a, b)

Courtesy: Yan Liu, my student.

SOAP - Simple ExampleSOAP - Simple Example

4141

<<Envelope>Envelope> <Header><Header> <transId>1234</transId><transId>1234</transId> </Header></Header> <Body><Body> <Add><Add> <a>3</a><a>3</a> <b>4</b><b>4</b> </Add></Add> </Body></Body></Envelope></Envelope>

<<Envelope>Envelope> <Header><Header> <transId>1234</transId><transId>1234</transId> </Header></Header> <Body><Body> <AddResponse><AddResponse> <c>7</c><c>7</c> </AddResponse></AddResponse> </Body></Body></Envelope></Envelope>

Courtesy: Yan Liu, my student.

System Flow (HTTP)System Flow (HTTP)

4242

SOAP – Example from SOAP – Example from healthcarehealthcare

Example RequestExample Request

<soap:Envelope> <soap:Envelope>

<header> …. </header><header> …. </header>

<soap:Body> <soap:Body>

<GetName> <GetName>

<MR#>123456</MR#> <MR#>123456</MR#>

</GetName> </GetName>

</soap:Body> </soap:Body>

</soap:Envelope></soap:Envelope>

Example Example ResponseResponse

<soap:Envelope> <soap:Envelope> <header> …. </header><header> …. </header> <soap:Body> <soap:Body> <GetNameResponse> <GetNameResponse> <Name>John <Name>John

Doe</Name> Doe</Name> </GetNameResponse> </GetNameResponse> </soap:Body> </soap:Body> </soap:Envelope></soap:Envelope>

4343

Transport (e.g. HTTP)

Application

Envelope/Header/Body

TCP/IP

Message Encoding

Transport (e.g. HTTP)

Web Service

Envelope/Header/Body

TCP/IP

Message Encoding

Interface Semantics Interface Semantics

SOAP ExecutionSOAP Execution

Courtesy: Yan Liu, my student.

4444

SOAP – ConclusionsSOAP – Conclusions

Basis for Web servicesBasis for Web services Significant component of Significant component of

Microsoft’s .NET platformMicrosoft’s .NET platform Supported by everyoneSupported by everyone Has a strong futureHas a strong future

4545

Universal Universal Description, Description,

Discovery and Discovery and IntegrationIntegration

(UDDI)(UDDI)

4646

UDDI – What is it?UDDI – What is it?

A vehicle to locate operational A vehicle to locate operational web servicesweb services

Similar to Domain Name Similar to Domain Name Service (DNS) lookupService (DNS) lookup

Embodies the concepts of Embodies the concepts of “White Pages and Yellow “White Pages and Yellow Pages”.Pages”.

4747

UDDI ElementsUDDI Elements

White Pages: Business Name, White Pages: Business Name, Contact Info, DUNS etcContact Info, DUNS etc

Yellow Pages: Business Yellow Pages: Business categories, key-value pairs of categories, key-value pairs of relevant informationrelevant information

Green Pages: Technical Green Pages: Technical information on how to connect information on how to connect to web servicesto web services

4848

UDDI Process SupportedUDDI Process Supported

Business registers its web service Business registers its web service (information that put in white, yellow (information that put in white, yellow and green pages).and green pages).

The information gets propagated to The information gets propagated to all UDDI servers (replicated)all UDDI servers (replicated)

Customers contact known registriesCustomers contact known registries Locate appropriate service and Locate appropriate service and

invoke them.invoke them. Main protocol supported is SOAP.Main protocol supported is SOAP.

4949

Web Services Current StatusWeb Services Current Status

Evolving rapidly – strong support for Evolving rapidly – strong support for SOAP and WSDL has decent support.SOAP and WSDL has decent support.

UDDI is little further away.UDDI is little further away. All vendors are incorporating various All vendors are incorporating various

components of Web servicescomponents of Web services Web services is the future – right Web services is the future – right

now people have to deal with other now people have to deal with other component technologiescomponent technologies