Chapter 6

Simple Object Access Protocol (SOAP)

• An infrastructure for developers to build, expose, and consume web services.

• A lightweight, XML-based protocol for exchanging information in a decentralized, distributed environment

• Based primarily on Remote Procedure Calls (RPC)

• Defines an envelope formatting and processing mechanism for arbitrarily complex message structures

• Submitted to the W3C for consideration

• Supported by Microsoft (Develop a Web Service) and others

• Sample XML data used by SOAP: (from MS's USStateRates.xml)

  <?xml version='1.0' ?> <serviceDescription name='SalesTaxRates' xmlns='urn:schemas-xmlsoap-org:servicedesc/2000-1-17' xmlns:dt='http://www.w3.org/1999/XMLSchema' xmlns:USStateRates='USStateRates' > <import namespace='USStateRates' location='#USStateRates'/> <soap xmlns='urn:schemas-xmlsoap-org:soap-sdl-2000-01-25'> <interface name='USStateRates'> <requestResponse name='GetStateTaxRates'> <request ref='USStateRates:GetStateTaxRates'/> <response ref='USStateRates:GetStateTaxRatesResponse'/> </requestResponse> <requestResponse name='GetTaxRateForState'> <request ref='USStateRates:GetTaxRateForState'/> <response ref='USStateRates:GetTaxRateForStateResponse'/> </requestResponse> <requestResponse name='GetStateTaxAmt'> <request ref='USStateRates:GetStateTaxAmt'/> <response ref='USStateRates:GetStateTaxAmtResponse'/> </requestResponse> </interface> <service> <addresses> <location url='http://hacek/soaplisten/USStateRates.asp'/> </addresses> <implements name='USStateRates'/> </service> </soap> <USStateRates:schema id='USStateRates' targetNamespace='USStateRates' xmlns='http://www.w3.org/1999/XMLSchema'> <element name='GetStateTaxRates'> </element> <element name='GetStateTaxRatesResponse'> <type> <element name='return' type='dt:string'/> </type> </element> <element name='GetTaxRateForState'> <type> <element name='StateAbbrev' type='dt:string'/> </type> </element> <element name='GetTaxRateForStateResponse'> <type> <element name='return' type='dt:single'/> </type> </element> <element name='GetStateTaxAmt'> <type> <element name='StateAbbrev' type='dt:string'/> <element name='TaxableTotal' type='dt:string'/> </type> </element> <element name='GetStateTaxAmtResponse'> <type> <element name='return' type='dt:string'/> </type> </element> </USStateRates:schema> </serviceDescription>