Web Services Overview

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Web Services Overview

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Sang Shin sang.shin_at_sun.com Java Technology
Evangelist Sun Microsystems, Inc. www.javapassion.
com/webservices
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Disclaimer

• Even though Sang Shin is a full-time employee of
  Sun Microsystems, the contents here are created
  as his own personal endeavor and thus does not
  reflect any official stance of Sun Microsystems.
• Sun Microsystems is not responsible for any
  inaccuracies in the contents.

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Agenda

• Evolution of network computing
• What is Web Services?
• Why Web Services?
• Where is Web Services?
• Web Services Architecture
• Web Services Standards
• Java APIs for Web Services
• J2EE as platform of choice for Web Services
• Web Services Tools
• Roadmap and Summary

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Evolution of Network Computing

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What is Web Services?

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The New Software
Payment
Developer
X1
Locater
X106
NewService
UsersDevice
X106
Calendar
Authentication
Software-as-a-Service
Shrink Wrap
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Simple WS Metaphors

• A WS is text-messaging between systems instead of
  humans
• Systems cant understand free-form text messages
  like humans can
• So, all WS messages must conform to a defined
  structure (protocol)

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Simple WS Metaphors

• Other distributed protocols are typically binary
  (RMI-IIOP), this severely complicates
  interoperability
• How can a COBOL program talk to a Java program
• The simplest protocol is text-based
  (ASCII/Unicode)
• XML is the ideal choice for specifying text-based
  WS protocols

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Simple WS Metaphors

• How do WS clients google WS providers?
• How does a WS client surf to a WS server of
  interest?

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(Simplified) Web Service Architecture
Registry
Service Client
Web Service
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Web Services Definition by W3C

• A Web service is a software application
• identified by a URI,
• whose interfaces and binding are capable of being
  defined, described and discovered by XML
  artifacts and
• supports direct interactions with other software
  applications
• using XML based messages
• via internet-based protocols

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Distributed Computing Evolution
Servers
Servers
Cell Phone
Clients
PDA
Internet
Client-Server(C/S) silos
Server
Clients
Workstation
Web-based computing
Laptop
Kiosk
Web Services/Peer-to-Peer
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Traditional C/S vs. Web Services
Web Service
Traditional C/S

• Within enterprise
• Tied to a set of programming languages
• Procedural
• Usually bound to a particular transport
• Tightly-coupled
• Efficient processing (space/time)

• Between enterprises
• Program language independent
• Message-driven
• Easily bound to different transports
• Loosely-coupled
• Relatively not efficient processing

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Web Application vs. Web Services
Web Service
Web Application

• User-to-program interaction
• Static integration of components
• Monolithic service

• Program-to-program interaction
• Possibility of dynamic integration of components
  (in the future)
• Possibility of service aggregation (in the future)

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Characteristics of Web Services

• XML based everywhere
• Message-based
• Programming language independent
• Could be dynamically located
• Could be dynamically assembled or aggregated
• Accessed over the internet
• Loosely coupled
• Based on industry standards

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Web Services
Service registration
Service Registry
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Service Aggregation
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Why Web Services?
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Why Web Services?

• Web Services
• Are platform neutral
• Are accessible in a standard way
• Are accessible in an interoperable way
• Use simple and ubiquitous plumbing
• Are relatively cheap
• Simplify enterprise integration

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Why Web Services?

• Interoperable Connect across heterogeneous
  networks using ubiquitous web-based standards
• Economical Recycle components, no installation
  and tight integration of software
• Automatic No human intervention required even
  for highly complex transactions
• Accessible Legacy assets internal apps are
  exposed and accessible on the web
• Available Services on any device, anywhere,
  anytime
• Scalable No limits on scope of applications and
  amount of heterogeneous applications

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Web Services Usage Example
Internet
Growing need for a standard lightweight
infrastructure for data exchange in e-business
applications.
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Impact of Web Services on SoftwareApplication
Dis-Integration
Web Services
Monolithic Software
The Network
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Macro web services Virtual Systems
Web Services

• A web service is accessed programmatically by
  applications or otherweb services

Bank Balance
Stock Position
Insurance Cash Value
Biz News
Portfolio can be an application, a portal
channel, or a web service itself
World News
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Micro web services Virtual Apps

• A web service is accessed programmatically by
  applications or otherweb services

Web Services
Spell Check
Dictionary
Thesaurus
c\...
Word processing can be an application, a
capability, or a web service itself
http//...
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Three Laws of Computing

• Moore's Law
• Computing power doubles every 18 months
• Gilder's Law
• Network bandwidth capacity doubles every 12
  months
• Metcalfe's Law (Net Effect)
• Value of network increases exponentially as
  number of participants increases

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Impact on IntegrationTrigger the Network Effect
CustomIntegration
Web Services
Metcalfes Law The value of the network is
proportional to the square of the number of
participants
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Myth Web Services is a New Concept

• Web services is distributed computing all over
  again only now it is based on the web

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Other Popular Myths Surrounding Web Services

• Web services require only SOAP, WSDL, UDDI We
  need more high-level semantics
• Web services are based on the RPC paradigm
  Document-driven model would be more popular
  communication model
• Web services must be based on HTTP Other
  transports such as SMTP can be also used

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Where is Where is Web Services going?

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Myths about Web Services

• Web Services cure cancer Not for a very very
  long time!
• Web Services are something completely new Not
  True!
• You have to write Web Services from scratch Not
  True!
• J2EE Platform does not support web services Not
  True!

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State of Web Services

• Technology/Standards are still evolving
• SOAP, WSDL, UDDI are not enough
• Business web services is the next big thing, but
  more works are needed in
• Quality of Service, management
• Security, transaction, state and user context
• Work flow, Identity management,
• Provisioning, Accounting
• Will be adopted in phases

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Web Services Adoption Phases

• 1st phase (current state)
• Concerted deployment internally within an
  organization mainly for interoperability
• SOAP over HTTP/S
• 2nd phase (1 to 2 years)
• Selective and non-aggregate deployment with
  trusted outside business partners
• Private registry deployment
• 3rd phase (at least 3 to 4 years away)
• Wider, more dynamic and aggregate deployment with
  outside business partners
• Public registry deployment

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Business Web Services (B2B) Architectural
Components (ebXML)

• B2B collaboration
• Secure and reliable message delivery
• Non-repudiation
• Partner profile
• Repository for business data objects

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B2B Collaboration
Simple Web Services
B2B Collaboration

• Complex interaction
• Business oriented
• Long-running process
• Supports business collaboration
• Supports partner profile
• Secure and reliable and non-repudiation
  
• Supports non-repudiation
• Registry and repository
• Supports legal binding

• Simple interaction
• Consumer oriented
• Short-living process
• No business collaboration
• No partner profile
• Not secure, not reliable
• Does not support non-repudiation
• No repository support
• No legal binding

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Trends Towards Service Orientation

• Evolution of EAI to web service standards
• XML RPC gt Asynchronous XML Messaging
• Towards de-centralization
• Componentized services
• Composable and composite services
• Data encapsulated within component
• Data ownership follows component ownership
• Brokered web services
• Flexible relationships gt Adaptive businesses

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Simple Web Services Architectural Components (WUS)

• Service Description
• Service Registration (Publication) and Discovery
• Service Invocation

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Core Web Services Standards

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(Simplified) Web Service Architecture
Registry
Service Client
Web Service
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SOAP (Simple Object Access Protocol)
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SOAP

• Simple Object Access Protocol
• Wire protocol similar to
• IIOP for CORBA
• JRMP for RMI
• XML is used for data encoding
• text based protocol vs. binary protocol
• Supports XML-based RPC

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What SOAP is Not

• Not a component model
• So it will not replace objects and components,
  i.e. EJB, JavaBeans
• Not a programming language
• So it will not replace Java
• Not a solution for all
• So it will not replace other distributed
  computing technologies such as RMI

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What does SOAP Define?

• Message Envelope
• Encoding Rules
• RPC Convention
• Binding with underlying protocols

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SOAP Message Format
SOAP Envelope
SOAP Message
SOAP Header
Primary MIME part (text/xml)
Header Entry
Header Entry
Attachment
SOAP Body
Attachment
Body Entry
Body Entry
Attachment
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SOAP Message Envelope

• Encoding information
• Header
• Optional
• Could contain context knowledge
• Security
• Transaction
• Body
• RPC methods and parameters
• Contains application data

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SOAP Encoding

• Rules of expressing application-defined data
  types in XML
• Based on W3C XML Schema
• Simple values
• Built-in types from XML Schema, Part 2 (simple
  types, enumerations, arrays of bytes)
• Compound values
• Structs, arrays, complex types

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SOAP RPC Request Example

• ltSOAP-ENVEnvelope xmlnsSOAP-ENV""
  SOAP-ENVencodingStyle""gt
• ltSOAP-ENVHeadergt
• lt!-- Optional context information --gt
• lt/SOAP-ENVHeadergt
• ltSOAP-ENVBodygt   ltmGetLastTradePrice
  xmlnsmsome_URI"gt     lttickerSymbolgtSUNWlt/t
  ickerSymbolgt   lt/mGetLastTradePricegtlt/SOAP-ENV
  Bodygt
• lt/SOAP-ENVEnvelopegt

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SOAP RPC Response Example

• ltSOAP-ENVEnvelope xmlnsSOAP-ENV""
  SOAP-ENVencodingStyle""gt
• ltSOAP-ENVHeadergt
• lt!-- Optional context information --gt
• lt/SOAP-ENVHeadergt
• ltSOAP-ENVBodygt  ltmGetLastTradePriceResponse
  xmlnsmsome_URI"gt     ltpricegt30.5lt/pricegt 
   lt/mGetLastTradePriceResponsegtlt/SOAP-ENVBodygt
• lt/SOAP-ENVEnvelopegt

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SOAP RPC

• Information needed for a method call
• The URI of the target object
• ltSOAP-ENVBodygt
• ltmGetLastTradePrice
• xmlnsmhttp//stocks.com/StockQuotes
  "gt
• lttickerSymbolgtSUNWlt/tickerSymbol
  gt
• lt/mGetLastTradePricegt
• lt/SOAP-ENVBodygt

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SOAP RPC

• Information needed for a method call
• The URI of the target object
• Method name
• ltSOAP-ENVBodygt
• ltmGetLastTradePrice
• xmlnsmhttp//stocks.com/StockQuotes
  "gt
• lttickerSymbolgtSUNWlt/tickerSymbol
  gt
• lt/mGetLastTradePricegt
• lt/SOAP-ENVBodygt

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SOAP RPC

• Information needed for a method call
• The URI of the target object
• Method name
• Parameters
• ltSOAP-ENVBodygt
• ltmGetLastTradePrice
• xmlnsmhttp//stocks.com/StockQuotes
  "gt
• lttickerSymbolgtSUNWlt/tickerSymbol
  gt
• lt/mGetLastTradePricegt
• lt/SOAP-ENVBodygt

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Quick WSDL Tutorial
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What is WSDL?

• XML language for describing web services
• Web service is described as
• A set of communication endpoints (ports)
• Endpoint is made of two parts
• Abstract definitions of operations and messages
• Concrete binding to networking protocol (and
  corresponding endpoint address) and message
  format
• Why this separation?
• Enhance reusability (as we will see in UDDI
  reference to WSDL document)

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Why WSDL?

• Enables automation of communication details
  between communicating partners
• Machines can read WSDL
• Machines can invoke a service defined in WSDL
• Discoverable through registry
• Arbitration
• 3rd party can verify if communication conforms to
  WSDL

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WSDL Document Example

• Simple service providing stock quotes
• A single operation called GetLastTradePrice
• Deployed using SOAP 1.1 over HTTP
• Request takes a ticker symbol of type string
• Response returns price as a float

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WSDL Elements

• Types
• Message
• Operation
• Port Type
• Binding
• Port
• Service

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WSDL Elements

• Types
• Data type definitions
• Used to describe exchanged messages
• Uses W3C XML Schema as canonical type system

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WSDL Example Types

• ltdefinitions name"StockQuote"
• targetNamespace"http//example.com/stockquote.
  wsdl"
• xmlnstns"http//example.com/stockqu
  ote.wsdl"
• xmlnsxsd1"http//example.com/stockq
  uote.xsd"
• xmlnssoap"http//schemas.xmlsoap.or
  g/wsdl/soap/"
• xmlns"http//schemas.xmlsoap.org/wsd
  l/gt
• lttypesgt
• ltschema targetNamespace"http//example.com
  /stockquote.xsd"
• xmlns"http//www.w3.org/2000/10/XML
  Schema"gt
• ltelement name"TradePriceRequest"gt
• ltcomplexTypegt
• ltallgt
• ltelement nametickerSymbol"
  type"string"/gt
• lt/allgt
• lt/complexTypegt
• lt/elementgt
• ltelement name"TradePrice"gt
• ltcomplexTypegt
• ltallgt

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WSDL Elements

• Messages
• Abstract, typed definitions of data being
  exchanged
• Operations
• Abstract description of an action
• Refers to an input and/or output messages
• Port type
• Collection of operations
• Abstract definition of a service

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Example Messages, Operation, Port type

• ltmessage name"GetLastTradePriceInput"gt
• ltpart name"body" element"xsd1TradePriceRequ
  est"/gt
• lt/messagegt
• ltmessage name"GetLastTradePriceOutput"gt
• ltpart name"body" element"xsd1TradePrice"/gt
• lt/messagegt
• ltportType name"StockQuotePortType"gt
• ltoperation name"GetLastTradePrice"gt
• ltinput message"tnsGetLastTradePriceInput"
  /gt
• ltoutput message"tnsGetLastTradePriceOutpu
  t"/gt
• lt/operationgt
• lt!-- More operations --gt
• lt/portTypegt

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WSDL Elements

• Binding
• Concrete protocol and data format for a
  particular Port type
• Protocol example SOAP 1.1 over HTTP or SOAP 1.1
  over SMTP
• Port
• Defines a single communication endpoint
• Endpoint address for binding
• URL for HTTP, email address for SMTP
• Service
• Aggregate set of related ports

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Example Binding, Port, Service

• ltbinding name"StockQuoteSoapBinding"
  type"tnsStockQuotePortType"gt
• ltsoapbinding style"document"
• transport"http//schemas.xmlsoap.org/soa
  p/http"/gt
• ltoperation name"GetLastTradePrice"gt
• ltsoapoperation
• soapAction"http//example.com/GetLast
  TradePrice"/gt
• ltinputgt ltsoapbody use"literal" /gt
• lt/inputgt
• ltoutputgt ltsoapbody use"literal" /gt
• lt/outputgt
• lt/operationgt
• lt/bindinggt
• ltservice name"StockQuoteService"gt
• ltdocumentationgtMy first servicelt/documentationgt
  
• ltport name"StockQuotePort" binding"tnsStockQ
  uoteBinding"gt
• ltsoapaddress location"http//example.com/
  stockquote"/gt
• lt/portgt
• lt/servicegt

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UDDI
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Service Architecture
UDDI Registry
Service Client
Web Service
UDDI defines a way to publish and find
information about Web services.
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UDDI (Universal Description, Discovery and
Integration)

• White pages
• address, contact, and known identifiers
• Yellow pages
• industrial categorizations
• Industry NAICS (Industry codes - US Govt.)
• Product/Services UN/SPSC (ECMA)
• Location Geographical taxonomy
• Green pages
• technical information about services

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Other Web Services Standards
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ebXML

• A global electronic market place where
  enterprises of any size, anywhere can
• Find each other electronically
• Conduct business through exchange of XML based
  business messages

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More Web Services Standards

• Security
• XML Signature, XML Encryption, XKMS, XACML, SAML,
  Liberty, WS-Security
• Transaction
• BTP, WS-Transaction
• Business collaboration and choreography
• ebXML BPSS, ebXML CPP/CPA, BPML, WSFL, XLANG,
  WSCI, BPEL4WS

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More Web Services Standards

• Business Language
• UBL (Universal Business Language)
• Component model
• WSIA (Web Services for Interactive Application)
• Portal
• WSRP (Web Services for Remote Portals)

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Java APIs for Web Services
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Java APIs for SOAP, WSDL, UDDI

• SOAP Messaging
• JAXM (JSR 67), SAAJ, JAX-RPC (JSR 101), JMS
• WSDL
• Java API for WSDL (JSR 110)
• JAX-RPC (JSR 101)
• UDDI
• JAXR (JSR 67)

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Java APIs for ebXML

• ebXML Message Service (TRP)
• JAXM (JSR 67) with ebXML Message Service profile
• ebXML Registry/Repository
• JAXR (JSR 93)
• CPP/CPA
• Java API for ebXML CPP/CPA (JSR 157)

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J2EE Web Services Framework

• J2EE 1.4 (JSR 151)
• Web services for J2EE (JSR 109)
• JAX-RPC (JSR 101)
• JAXR
• SAAJ
• EJB 2.1

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Java APIs for XML Document Management

• JAXP (Java API for XML processing, JSR 05)
• Assembly language for XML document processing
• JAXB (Java API for XML data-binding, JSR 31)
• Higher level language for XML document processing
• Streaming API for XML (JSR 173)
• Pull-parsing API based on Iterator
• Gives parsing control to programmers

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Java APIs for XML Security

• XML Digital Signature (JSR 105)
• XML Encryption (JSR 106)
• XML Trust Service (JSR 104)
• Secure Assertion Markup Language (SAML, JSR 155)
• WS-Security (JSR 183)

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More Java APIs for Web Services

• XML Transactioning API for Java (JSR 156)
• Java API for OASIS BTP
• Web Services for J2ME (JSR 172)
• SOAP messaging for J2ME devices
• Web Services Metadata for J2EE (JSR 181)
• Metadata based Web services

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Web Services Framework for J2EE

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J2EE Platform Web Services
B2B Applications
Existing Applications
B2C Applications
WebServices
Application Server
EnterpriseInformationSystems
Wireless Applications
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Why J2EE for Web Services?

• Web services is just one of many service delivery
  channels of J2EE
• No architectural change is needed
• Existing J2EE components can be easily exposed as
  Web services
• Many benefits of J2EE are preserved for Web
  services
• Portability, Scalability, Reliability
• No single-vendor lock-in

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Where Are We Now?

• Java APIs for Web Services are being developed
  very rapidly
• Tools are available now for exposing existing
  J2EE components as Web services
• J2EE community has defined overall framework for
  Web Services (J2EE 1.4, JSR 109)

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Design Goals J2EE Web Services Framework

• Portability of Web services component
• Over different vendor platform
• Over different operational environment
• Leveraging existing J2EE programming models for
  service implementation
• Easy to program and deploy
• High-level Java APIs
• Use existing deployment model

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J2EE Web Services Framework

• J2EE 1.4
• Umbrella framework for Web services
• JSR 109, JAX-RPC, JAXR, EJB 2.1, Servlet 2.4,
• JAX-RPC
• Defines client programming model
• Defines Servlet-based Web services endpoint model

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J2EE Web Services Framework

• EJB 2.1
• Defines Stateless Session Bean-based Web services
  endpoint model
• Servlet 2.4
• Will be aligned with JAX-RPC
• JSR 109
• Defines standard Web services packaging and
  deployment model

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Web Services Architecture over J2EE
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What Is a Web Service?

• A set of endpoints (ports) operating on messages
• Ports are operating within a container
• Container provides runtime environment
• Contract for runtime environment are specified in
  JAX-RPC, EJB 2.1, JSR 109
• Service is described in WSDL document and
  published to a registry
• WSDL specifies a contract between service
  provider and client

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Web Service Component and Container

• Container vs. Component model
• Web services components get executed within a
  container
• Components are portable (under J2EE 1.4)
• Web service components
• Web-tier (Servlet-based endpoint)
• EJB-tier (Stateless session bean-based endpoint)

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Web Service Components
Web services components
Source Web Services for J2EE (JSR 109), V1.0
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Java Technology-based Web Services Tools

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Web Services Tools for Java Platform

• Web Services Tools (Available Now!)
• Tools that come with reference implementations of
  Java APIs for Web services (JAX-RPC RI)
• Systinet (Idoox), Iopsys, Cape Clear, Apach SOAP
• IDE's (Now!)
• Sun Java Enterprise Studio 7
• JBuilder from Borland
• JDeveloper from Oracle
• WebGain from WebGain

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J2EE 1.4

• Focus is Web services
• Umbrella JSR for all Java APIs for Web services
• JSR 109, JAX-RPC, JAXR, EJB 2.1
• Web services framework for J2EE
• J2EE component model, deployment, packaging, and
  container requirements
• Released in Nov. 2003
• http//java.sun.com/j2ee/1.4/download-dr.html

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J2EE 1.4 SDK

• Web services APIs are well integrated
• Contains
• JAXP, SAAJ, JAX-RPC, JAXR
• Sun Java App Server PE 8
• Extensive tutorial

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Summary

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Summary

• Web services provides a new paradigm for program
  to program communication
• Comprehensive set of Java APIs for Web Services
  are now available!
• J2EE is the platform of choice for Web services

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Passion!