Web Services Distributed computing framework Similar to CORBA or - - PowerPoint PPT Presentation

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Web Services Distributed computing framework Similar to CORBA or - - PowerPoint PPT Presentation

Web Services Distributed computing framework Similar to CORBA or EJBs Designed to make software components available for remote execution Features (from IBM tutorial): Self-contained, self-describing, modular


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SLIDE 1
  • Dec. 7. 2005

CS 440 Lecture Notes 1

Web Services

  • Distributed computing framework

– Similar to CORBA or EJBs – Designed to make software components available for remote execution

  • Features (from IBM tutorial):

– Self-contained, self-describing, modular – Published, located, and invoked across the Web – Functions range from simple requests to complicated business processes

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SLIDE 2
  • Dec. 7. 2005

CS 440 Lecture Notes 2

Advantages of Web Services

  • Web Services advantages over CORBA,

RMI, etc.

– Based on standard Web technologies – Provide simple, easy to access interface

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SLIDE 3
  • Dec. 7. 2005

CS 440 Lecture Notes 3

Web Services Foundations

  • Basic platform is XML and HTTP
  • Additional layers to actually provide RPC

functionality

– SOAP (Simple Object Access Protocol) – WSDL (Web Services Definition Language) – UDDI (Universal Description, Discovery, and Integration Service)

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SLIDE 4
  • Dec. 7. 2005

CS 440 Lecture Notes 4

SOAP

  • Protocol for passing XML-encoded data
  • Defines mechanism for performing remote

procedure calls using HTTP

– HTTP is everywhere, and is easy to access

  • ver WAN

– XML is very interoperable, easy to debug

  • Overseen by W2C’s XML Protocols

Working Group

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SLIDE 5
  • Dec. 7. 2005

CS 440 Lecture Notes 5

WSDL

  • Describes a web services

– What the service does – Where the service is located – How the service is invoked

  • Similar to CORBA IDL
  • Written in XML
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SLIDE 6
  • Dec. 7. 2005

CS 440 Lecture Notes 6

WSDL (cont.)

  • Elements

– Types (typically XML Schema types – XSD) – Message – typed definition of data exchanged – Operation – description of action provided – Port Type – set of operations supported by one or more endpoints – Binding – protocol and data format specification for port type – Port – single endpoint (binding + address) – Service – collection of related endpoints

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SLIDE 7
  • Dec. 7. 2005

CS 440 Lecture Notes 7

UDDI

  • Mechanism to dynamically find web

services

– Similar to DNS server or CORBA trader

  • Layered over SOAP

– Use SOAP to access UDDI services – Everything is XML and HTTP

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SLIDE 8
  • Dec. 7. 2005

CS 440 Lecture Notes 8

UDDI Services

  • White Pages

– Publish operation to allow Web service to register itself

  • Yellow Pages

– Find operation to look up particular service

  • Green Pages

– Bind operation to describe how client app connects to service