Simple Object Access Protocol (SOAP)

1
Simple Object Access Protocol(SOAP)

• Mark H Needleman
• Data Research Associates, Inc.
• ZIG Meeting
• December 2000

2
Background

• Developed by IBM, Microsoft, Lotus, and others
• Submitted to W3C - Became W3C Note in May 1998
• Current Version is 1.1 See
• http//www.w3.org/TR/SOAP
• Input Document to New W3C XML Protocol Working
  Group

3
Design Goals

• Simplicity
• Extensibility
• Not Exclusive to HTTP - HTTP Binding defined in
  Specification
• Need to expose more of what is being run on top
  of HTTP to help Fireall Administrators do better
  filtering

4
SOAP Design

• Lightweight Information Exchange in a
  Decentralized Environment
• XML Based
• Envelope/Body Framework for defining whats in a
  message and how to process it
• Encoding Rules
• Convention for expressing RPC calls and responses

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Sample Soap Message

• POST /StockQuote HTTP/1.1Host
  www.stockquoteserver.comContent-Type text/xml
  charset"utf-8"Content-Length nnnnSOAPAction
  "Some-URI"ltSOAP-ENVEnvelopexmlnsSOAP-ENV"htt
  p//schemas.xmlsoap.org/soap/envelope/"SOAP-ENVe
  ncodingStyle"http//schemas.xmlsoap.org/soap/enco
  ding/"gtltSOAP-ENVBodygtltmGetLastTradePrice
  xmlnsm"Some-URI"gtltsymbolgtDISlt/symbolgtlt/mGetLa
  stTradePricegtlt/SOAP-ENVBodygtlt/SOAP-ENVEnvelope
  gt

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SOAP Message Embedded in HTTP Response

• HTTP/1.1 200 OKContent-Type text/xml
  charset"utf-8"Content-Length
  nnnnltSOAP-ENVEnvelopexmlnsSOAP-ENV"http//sc
  hemas.xmlsoap.org/soap/envelope/"SOAP-ENVencodin
  gStyle"http//schemas.xmlsoap.org/soap/encoding/"
  /gtltSOAP-ENVBodygtltmGetLastTradePriceResponse
  xmlnsm"Some-URI"gtltPricegt34.5lt/Pricegtlt/mGetLas
  tTradePriceResponsegtlt/SOAP-ENVBodygtlt/SOAP-ENVE
  nvelopegt

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SOAP Messaging Models

• Request/Response
• One way
• Multicast

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Why NCIP Did Not Use SOAP

• Not an Official Standard
• Uncertainty about support
• Lack of Deployment
• Some Ignorance about SOAP Itself
• Didnt want to add one more level of complexity
  into the mix
• No good sense of what it would do for us or what
  problems it might solve

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W3C XML Protocol WG

• Developing an Envelope for encapsulating XML -
  must support distributed extensibility,
  evolvability, and intermediaries
• A convention for the content of the envelope when
  used for RPC
• A mechanism for serializing data
• A convention for the use of HTTP

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XML Protocol WG (2)

• Currently defining requirements - expect to
  publish initial draft soon
• Will be coordinating with other activities like
  IETF work
• Doing much of its work publicly - discussions
  happen on public mailing list
• xml-dist-app_at_w3.org