Web%20Services

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Web Services

• By Ethan
• Justin
• Yuli

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Web Services in Action
What do Web Services offer developers, businesses
and consumers?

• Information through Integration
• (Google Example)

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Web Services in Action (continued)

• Google.com
• Google Web APIs service gives you query access to
  Google's web search, giving developers access to
  billions of web documents that are constantly
  refreshed
• Developers receive results as structured data,
  can access information in the Google cache, and
  check the spelling of words
• Examples of use
• Issuing regularly scheduled search requests to
  monitor the web for new information on a subject
• Performing market research by analyzing
  differences in the amount of information
  available on different subjects over time
• Searching via non-HTML interfaces, such as the
  command line, pagers, or visualization
  applications
• Creating innovative games that play with
  information on the web

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Web Services in Action (continued)

• Amazon.com
• Add thousands of products available through
  Amazon.com to your own website and earn referral
  commissions for sales
• List hundreds of thousands of products on your
  site available through Amazon.com affiliates and
  customize the content so products match the theme
  of your web site
• Dynamically maintain product listings to give
  visitors current information

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Presentation-Outline

• Topics
• SOAP and REST
• WSDL
• UDDI
• Summary
• Questions

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Web Service-Overview

• Web services facilitate the automated transfer of
  information from Computer A to Computer B using
  the XML language.
• This can be accomplished in a number of ways, but
  for today were focused on Standards based
  approaches

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Web Services- Two Approaches

• There is a division in the web community about
  the best method for accessing resources over the
  internet.
• The two leading methods are SOAP, a
  standards-based approach, and REST

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Web Services-SOAPStandards Based Approach

• Definition Simple Object Access Protocol
• Function SOAP is an envelope that a request for
  resources is packaged in. It includes a header
  and body.
• The header can include information about
  security, recipients, handling, routing, etc.
• The body includes a standard XML request

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Web Services-RESTNon-Standards Based Approach

• Definition Representation State Transfer
• Function REST is an architectural style for
  accessing distributed media or resources.

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Summary of REST and SOAP

• REST
• Messages are represented in plain XML
• HTTP is used for the transfer protocol
• HTTP verbs are used for access/manipulation
  commands
• URIs are used to uniquely identify resources in
  message
• HTTP authentication provides security
• There is no formal method for expressing the
  interface contract

• SOAP
• Messages are represented in a standardized XML
  SOAP "envelope"
• Can be bound to various protocols including HTTP
  and SMTP
• Access to and manipulation of data are
  application specific
• Security is not described by SOAP and is to be
  provided by the developer
• XML schemas or DTD are used to define the
  contract between client and service

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Web Services Description Language (WSDL)

• WSDL is a language for describing the
  capabilities of Web services
• In order for computer A to request information
  from computer B it must know the appropriate
  method for asking the question
• Essentially, a WSDL document describes how to
  invoke a service and provides information on the
  data being exchanged, the sequence of messages
  for an operation, protocol bindings, and the
  location of the service.
• WSDL is an integral part of UDDI, an XML-based
  worldwide business registry

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Web Services-UDDI(Yellow Pages for Web Services)

• Definition Universal Description Discovery and
  Integration
• Function The UDDI specifications define a
  registry service for Web services and for other
  electronic and non-electronic services. A UDDI
  registry service is a Web service that manages
  information about service providers, service
  implementations, and service metadata.
• Service providers can use UDDI to advertise the
  services they offer.
• Service consumers can use UDDI to discover
  services that suit their requirements and to
  obtain the service metadata needed to consume
  those services.

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Key Topics to Remember

• Summary
• WSDL Standards-Based Description language for
  making resource requests
• SOAP Standards-Based Envelope for delivering the
  request
• REST Messages are represented in plain (pure)
  XML only
• UDDI Voluntary registry for listing and finding
  web services (Yellow Pages)

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Questions??