Simple Object Access Protocol (SOAP)

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Simple Object Access Protocol (SOAP)

• by Kazi Huque

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Presentation Outline

• Definition
• Motivation
• Characteristics
• SOAP message format
• SOAP in code
• SOAP Security
• SOAP in action

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What is SOAP?

• SOAP is a lightweight protocol intended for
  exchanging structured information in a
  decentralized, distributed environment. SOAP uses
  XML technologies to define an extensible
  messaging framework, which provides a message
  construct that can be exchanged over a variety of
  underlying protocols. The framework has been
  designed to be independent of any particular
  programming model and other implementation-specifi
  c semantics.

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SOAP is the Foundation
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Simply Put...

• SOAP is a way for a program running in one
  operating system to communicate with a program
  running in either the same or a different
  operating system, using HTTP (or any other
  transport protocol) and XML.

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SOAP Messaging Framework

• XML-based messaging framework that is
• 1) extensible
• 2) interoperable
• 3) independent
• Next we discuss these three characteristics in
  more detail

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Extensible

• Simplicity remains one of SOAP's primary design
  goals
• SOAP defines a communication framework that
  allows for features such as security, routing,
  and reliability to be added later as layered
  extensions

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Interoperable

• SOAP can be used over any transport protocol such
  as TCP, HTTP, SMTP
• SOAP provides an explicit binding today for HTTP

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Interoperable Cont
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Independent

• SOAP allows for any programming model and is not
  tied to RPC
• SOAP defines a model for processing individual,
  one-way messages
• SOAP also allows for any number of message
  exchange patterns (MEPs)

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One-Way Message
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Request/Response
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SOAP Message Format

• SOAP message consists of three parts
• SOAP Envelope
• SOAP Header (optional)
• SOAP Body
• From the http//schemas.xmlsoap.org/soap/envelope/
  namespace

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SOAP Envelope

• The SOAP Envelope construct defines an overall
  framework for expressing what is in a message and
  who should deal with it.

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SOAP Envelope Cont

• The Envelope is the top element of the XML
  document representing the message.
• The Envelope element is always the root element
  of a SOAP message.
• The Envelope element contains an optional Header
  element followed by a mandatory Body element.

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SOAP Envelope Code

• ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
  org/soap/envelope/"gt ltsoapHeadergt lt!-- optional
  --gt
• lt!-- header blocks go here... --gt
• lt/soapHeadergt
• ltsoapBodygt
• lt!-- payload or Fault element goes here... --gt
  lt/soapBodygt
• lt/soapEnvelopegt

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SOAP Header

• The Header element is a generic container for
  control information
• It may contain any number of elements from any
  namespace
• Header blocks should contain information that
  influences payload processing
• Header is optional

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SOAP Header Code

• ltsoapHeadergt
• lt!-- security credentials --gt
• ltscredentials xmlnss"urnexamples-orgsecurity
  "gt ltusernamegtdavelt/usernamegt ltpasswordgtevadlt/pas
  swordgt
• lt/scredentialsgt
• lt/soapHeadergt

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SOAP Body

• The Body element represents the message payload

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SOAP Body Code

• ltsoapBodygt
• ltxTransferFunds xmlnsx"urnexamples-orgbankin
  g"gt ltfromgt22-342439lt/fromgt
• lttogt98-283843lt/togt
• ltamountgt100.00lt/amountgt
• lt/xTransferFundsgt
• lt/soapBodygt

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SOAP in Code

• SOAP Message Embedded in HTTP Request
• ltSOAP-ENVEnvelope xmlnsSOAP-ENV"http//schema
  s.xmlsoap.org/soap/envelope/"  SOAPENVencodingSt
  yle"http//schemas.xmlsoap.org/soap/encoding/"gt
  ltSOAP-ENVBodygt       ltmGetLastTradePrice
  xmlnsm"Some-URI"gt           ltsymbolgtDISlt/symbol
  gt       lt/mGetLastTradePricegt   lt/SOAP-ENVBody
  gt
• lt/SOAP-ENVEnvelopegt

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SOAP in Code Cont

• SOAP Message Embedded in HTTP Response
• ltSOAP-ENVEnvelope  xmlnsSOAP-ENV"http//schema
  s.xmlsoap.org/soap/envelope/"  SOAP-ENVencodingS
  tyle"http//schemas.xmlsoap.org/soap/encoding/"/gt
     ltSOAP-ENVBodygt       ltmGetLastTradePriceRes
  ponse xmlnsm"Some-URI"gt           ltPricegt34.5lt/
  Pricegt       lt/mGetLastTradePriceResponsegt   lt/
  SOAP-ENVBodygt
• lt/SOAP-ENVEnvelopegt

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SOAP Security

• The SOAP specification does not define encryption
  for XML Web Services.
• This is left up to the implementer of the SOAP
  protocol.

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Issues About Security

• Encryption places a dependency on the transport
  protocol
• Does the transport protocol support secure
  communication?
• What is the cost of encrypting all the data
  versus part of the data?

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SOAP Code with Encryption

• lt_at_ WebService Language"C" Class"CreditCardServ
  ice" gt
• using System.Web.Services
• public class CreditCardService
• WebMethod
• EncryptionExtension(EncryptEncryptMode.Respons
  e)
• public string GetCreditCardNumber()
• return "MC 4111-1111-1111-1111"

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Request Encrypted

• lt?xml version"1.0" encoding"utf-8"?gt
• ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
  org/soap/envelope/"
  xmlnsxsi"http//www.w3.org/2001/XMLSchema-instan
  ce" xmlnsxsd"http//www.w3.org/200
  1/XMLSchema"gt
• ltsoapBodygt
• ltGetCreditCardNumber xmlns"http//tempuri.org/"
  /gt
• lt/soapBodygt
• lt/soapEnvelopegt

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Response Encrypted

• ltsoapBodygt
• ltGetCreditCardNumber xmlns"http//tempuri.org/"gt
  
• ltGetCreditCardNumberResultgt83 151 243 32 53 95
  86 13 190 134 188 241 198 209 72 114 122 38 180
  34 194 138 16 97 221 195 239 86 26 152 94 27
• lt/GetCreditCardNumberResultgt
• lt/GetCreditCardNumbergt
• lt/soapBodygt

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SOAP in Action

• Demo

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References

• Understanding SOAP
• Overall explanation of what SOAP is, and what it
  can do.
• http//msdn.microsoft.com/webservices/understand
  ing/webservicebasics/default.aspx?pull/library/en
  -us//dnsoap/html/understandsoap.asp
• W3C Note
• Explains how SOAP exchanges messages. Code level
  details.
• http//www.w3.org/TR/2000/NOTE-SOAP-20000508/