CS/INFO 330: Web Driven Web Applications Web Services Definition: - - PowerPoint PPT Presentation

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CS/INFO 330: Web Driven Web Applications Web Services Definition: - - PowerPoint PPT Presentation

May 29, 2023 37 likes •288 views

CS/INFO 330: Web Driven Web Applications Web Services Definition: Web Services A standardized way of integrating Web- based applications, using XML to tag data SOAP to transport data Simple Object Access Protocol WSDL to

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CS/INFO 330: Web Driven Web Applications

Web Services

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Definition: Web Services

  • A standardized way of integrating Web-

based applications, using

  • XML to tag data
  • SOAP to transport data
  • Simple Object Access Protocol
  • WSDL to describe available services
  • Web Services Description Language
  • An Interface Description Language

(IDL)

  • UDDI to list available services
  • Universal Description, Discovery and

Integration

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Goals for B2B Integration

  • Service-Oriented Architecture
  • Redesign of middleware protocols
  • Standardization
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Service-Oriented

  • Service: procedure, method, or object

with stable published interface

  • Functionality always exposed as

services

  • Loosely coupled
  • Invoked by programs as well as users
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Middleware Redesign

  • Peer-to-Peer
  • No central coordinator
  • Between trust domains
  • Compatibility with Internet
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Web Services Integrating Between Companies

internal infrastructure

supplier customer warehouse

internal infrastructure internal infrastructure internal procurement requests internal functionality made available as a service Web service Web service Web service interactions based on protocols redesigned for peer to peer and B2B settings languages and protocols standardized, eliminating need for many different middleware infrastructures (need only the Web services middleware)

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Basic Web Services

  • Components:
  • communicate (SOAP)
  • describe services - IDL (WSDL)
  • directory service (UDDI)
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Minimalist Infrastructure ...

service provider service requestor

application object (client) application object (service provider) SOAP-based middleware SOAP-based middleware SOAP messages exchanged on top of, HTTP, SMTP, or other transport converts procedure calls to/ from XML messages sent through HTTP or other protocols.

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Using WSDL Specification

service provider service requestor

application object (client) application object (service provider) stub skeleton WSDL of service provider WSDL compiler (server side) WSDL compiler (client side) <operation name="orderGoods"> <input message = "OrderMsg"/ > </ operation> SOAP-based middleware SOAP-based middleware SOAP messages

Note all WSDL “processing” happens at development time.

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Using UDDI Registry

service descriptions

SOAP-based middleware

UDDI registry service provider service requestor

application object (client) application object (service provider) stub skeleton SOAP-based middleware SOAP-based middleware SOAP messages SOAP messages (to look for services) SOAP messages (to publish service description)

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Simple Object Access Protocol

  • Specifies:
  • message format for one-way comms
  • specification for SOAP RPC
  • rules for processing SOAP messages
  • rules for transport - HTTP and SMTP
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A SOAP Message

SOAP envelope SOAP header header block SOAP body body block

Header: info for intermediate nodes Body: actual message

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SOAP Message Example

<?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Header> <m:reservation xmlns:m="http://travelcompany.example.org/reservation" env:role="http://www.w3.org/2003/05/soap-envelope/role/next" env:mustUnderstand="true"> <m:reference>uuid:093a2da1-q345-739r-ba5d-pqff98fe8j7d</m:reference> <m:dateAndTime>2001-11-29T13:20:00.000-05:00</m:dateAndTime> </m:reservation> <n:passenger xmlns:n="http://mycompany.example.com/employees" env:role="http://www.w3.org/2003/05/soap-envelope/role/next" env:mustUnderstand="true"> <n:name>Åke Jógvan Øyvind</n:name> </n:passenger> </env:Header> <env:Body> <p:itinerary xmlns:p="http://travelcompany.example.org/reservation/travel"> <p:departure> <p:departing>New York</p:departing> <p:arriving>Los Angeles</p:arriving> <p:departureDate>2001-12-14</p:departureDate> <p:departureTime>late afternoon</p:departureTime> <p:seatPreference>aisle</p:seatPreference> </p:departure> <p:return> <p:departing>Los Angeles</p:departing> <p:arriving>New York</p:arriving> <p:departureDate>2001-12-20</p:departureDate> <p:departureTime>mid-morning</p:departureTime> <p:seatPreference/> </p:return> </p:itinerary> <q:lodging xmlns:q="http://travelcompany.example.org/reservation/hotels"> <q:preference>none</q:preference> </q:lodging> </env:Body> </env:Envelope>

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SOAP over HTTP

service provider

SOAP engine service implementation (other tiers) HTTP engine

service requestor

HTTP engine client implementation (other tiers) SOAP engine

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Simple Implementation

service requestor

client implementation HTTP engine client stub SOAP engine

invokes the service as a local call invoke SOAP engine to prepare SOAP message packages SOAP into HTTP and passes it to an HTTP client that sends it to the provider

service provider

service implementation HTTP server server stub SOAP router

invokes the local procedure of the service implementation the router parses the message, identifies the appropriate stub, and delivers the parsed message passes the content of the HTTP message to the router

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WSDL Specifications

  • Abstract part
  • signatures,
  • perations
  • like traditional IDL
  • Concrete part
  • bindings / services

/ ports

WSDL specification abstract part

types messages

  • perations

port types

concrete part

bindings services and ports

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Concrete Part

  • Interface Bindings
  • message encoding and protocol

bindings (e.g., RPC-style operation, communication via SOAP over HTTP)

  • Ports
  • interface binding + network address

where port type implementation can be accessed

  • Services
  • logical groupings of ports
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Automatic Generation of WSDL

service provider service requestor

application object (client) application object (service provider) stub skeleton WSDL of service provider WSDL compiler (server side) WSDL compiler (client side) SOAP-based middleware SOAP-based middleware SOAP messages WSDL generator

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WSDL Example: GreatH Hotel Reservation Service

<?xml version="1.0" encoding="utf-8" ?> <description xmlns="http://www.w3.org/@@@@/@@/wsdl" targetNamespace= "http://greath.example.com/2004/wsdl/resSvc" xmlns:tns= "http://greath.example.com/2004/wsdl/resSvc" . . . > . . . </description>

WSDL 2.0 empty shell (Example taken from W3C’s WSDL primer)

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Message Types

<?xml version="1.0" encoding="utf-8" ?> <description xmlns="http://www.w3.org/@@@@/@@/wsdl" targetNamespace= "http://greath.example.com/2004/wsdl/resSvc" xmlns:tns= "http://greath.example.com/2004/wsdl/resSvc" xmlns:ghns = "http://greath.example.com/2004/schemas/resSvc" . . . > ... <types> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://greath.example.com/2004/schemas/resSvc" xmlns="http://greath.example.com/2004/schemas/resSvc"> <xs:element name="checkAvailability" type="tCheckAvailability"/> <xs:complexType name="tCheckAvailability"> <xs:sequence> <xs:element name="checkInDate" type="xs:date"/> <xs:element name="checkOutDate" type="xs:date"/> <xs:element name="roomType" type="xs:string"/> </xs:sequence> </xs:complexType> <xs:element name="checkAvailabilityResponse" type="xs:double"/> <xs:element name="invalidDataError" type="xs:string"/> </xs:schema> </types> . . . </description>

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Interface Definition

<?xml version="1.0" encoding="utf-8" ?> <description xmlns="http://www.w3.org/@@@@/@@/wsdl" targetNamespace= "http://greath.example.com/2004/wsdl/resSvc" xmlns:tns= "http://greath.example.com/2004/wsdl/resSvc" xmlns:ghns = "http://greath.example.com/2004/schemas/resSvc" . . . xmlns:wsdlx="http://www.w3.org/@@@@/@@/wsdl-extensions"> . . . <types> ... </types> <interface name = "reservationInterface" > <fault name = "invalidDataFault" element = "ghns:invalidDataError"/> <operation name="opCheckAvailability" pattern="http://www.w3.org/@@@@/@@/wsdl/in-out" style="http://www.w3.org/@@@@/@@/wsdl/style/iri" wsdlx:safe = "true"> <input messageLabel="In" element="ghns:checkAvailability" /> <output messageLabel="Out" element="ghns:checkAvailabilityResponse" /> <outfault ref="tns:invalidDataFault" messageLabel="Out"/> </operation> </interface> . . . </description>

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Bindings

Specifies how messages can be exchanged

<?xml version="1.0" encoding="utf-8" ?> <description xmlns="http://www.w3.org/@@@@/@@/wsdl" targetNamespace= "http://greath.example.com/2004/wsdl/resSvc" xmlns:tns= "http://greath.example.com/2004/wsdl/resSvc" xmlns:ghns = "http://greath.example.com/2004/schemas/resSvc" xmlns:wsoap= "http://www.w3.org/@@@@/@@/wsdl/soap" xmlns:soap="http://www.w3.org/2003/05/soap-envelope"> . . . <types> . . . </types> <interface name = "reservationInterface" > ... </interface> <binding name="reservationSOAPBinding" interface="tns:reservationInterface" type="http://www.w3.org/@@@@/@@/wsdl/soap" wsoap:protocol="http://www.w3.org/2003/05/soap/bindings/HTTP"> <operation ref="tns:opCheckAvailability" wsoap:mep="http://www.w3.org/2003/05/soap/mep/soap-response"/> <fault ref="tns:invalidDataFault" wsoap:code="soap:Sender"/> </binding> . . . </description>

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Service Definition

Where can the service be accessed

<?xml version="1.0" encoding="utf-8" ?> <description xmlns="http://www.w3.org/@@@@/@@/wsdl" targetNamespace= "http://greath.example.com/2004/wsdl/resSvc" xmlns:tns= "http://greath.example.com/2004/wsdl/resSvc" xmlns:ghns = "http://greath.example.com/2004/schemas/resSvc" xmlns:wsoap= "http://www.w3.org/@@@@/@@/wsdl/soap" xmlns:soap="http://www.w3.org/2003/05/soap-envelope"> . . . <types> . . . </types> <interface name = "reservationInterface" > . . . </interface> <binding name="reservationSOAPBinding" interface="tns:reservationInterface" . . . > . . . </binding> <service name="reservationService" interface="tns:reservationInterface"> <endpoint name="reservationEndpoint" binding="tns:reservationSOAPBinding" address ="http://greath.example.com/2004/reservation"/> </service> </description>

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Documenting the Service

<?xml version="1.0" encoding="utf-8" ?> <description . . . > <documentation> This document describes the GreatH Web service. Additional application-level requirements for use of this service -- beyond what WSDL 2.0 is able to describe -- are available at http://greath.example.com/2004/reservation-documentation.html </documentation> . . . </description>

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The Whole Picture

<?xml version="1.0" encoding="utf-8" ?> <description xmlns="http://www.w3.org/@@@@/@@/wsdl" targetNamespace= "http://greath.example.com/2004/wsdl/resSvc" xmlns:tns= "http://greath.example.com/2004/wsdl/resSvc" xmlns:ghns = "http://greath.example.com/2004/schemas/resSvc" xmlns:wsoap= "http://www.w3.org/@@@@/@@/wsdl/soap" xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:wsdlx= "http://www.w3.org/@@@@/@@/wsdl-extensions"> <documentation> This document describes the GreatH Web service. Additional application-level requirements for use of this service -- beyond what WSDL 2.0 is able to describe -- are available at http://greath.example.com/2004/reservation-documentation.html </documentation> <types> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://greath.example.com/2004/schemas/resSvc" xmlns="http://greath.example.com/2004/schemas/resSvc"> <xs:element name="checkAvailability" type="tCheckAvailability"/> <xs:complexType name="tCheckAvailability"> <xs:sequence> <xs:element name="checkInDate" type="xs:date"/> <xs:element name="checkOutDate" type="xs:date"/> <xs:element name="roomType" type="xs:string"/> </xs:sequence> </xs:complexType> <xs:element name="checkAvailabilityResponse" type="xs:double"/> <xs:element name="invalidDataError" type="xs:string"/> </xs:schema> </types> <interface name = "reservationInterface" > <fault name = "invalidDataFault" element = "ghns:invalidDataError"/> <operation name="opCheckAvailability" pattern="http://www.w3.org/@@@@/@@/wsdl/in-out" style="http://www.w3.org/@@@@/@@/wsdl/style/iri" wsdlx:safe = "true"> <input messageLabel="In" element="ghns:checkAvailability" /> <output messageLabel="Out" element="ghns:checkAvailabilityResponse" /> <outfault ref="tns:invalidDataFault" messageLabel="Out"/> </operation> </interface> <binding name="reservationSOAPBinding" interface="tns:reservationInterface" type="http://www.w3.org/@@@@/@@/wsdl/soap" wsoap:protocol="http://www.w3.org/2003/05/soap/bindings/HTTP"> <fault ref="tns:invalidDataFault" wsoap:code="soap:Sender"/> <operation ref="tns:opCheckAvailability" wsoap:mep="http://www.w3.org/2003/05/soap/mep/soap-response"/> </binding> <service name="reservationService" interface="tns:reservationInterface"> <endpoint name="reservationEndpoint" binding="tns:reservationSOAPBinding" address ="http://greath.example.com/2004/reservation"/> </service> </description>