XMLRPC and SOAP

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XML-RPC and SOAP
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XMLExtensible Markup Language

• Markup Language.
• HTML is also a markup language (but it's not
  extensible!).
• XML allows you to make up your own tags.
• Document Type Definition
• Schema

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Sample XML

• lt?xml version"1.0"?gt
• ltstudentgt
• ltridgt660012345lt/ridgt
• ltfirstgtJoelt/firstgt
• ltmiddlegtX.lt/middlegt
• ltlastgtSmithlt/lastgt
• ltcourses semester"fall02"gt
• ltcoursegt
• ltnamegtExploiting the Information
  Worldlt/namegt
• ltcrngt12345lt/crngt
• ltnumgtITEC-2110lt/numgt
• lt/coursegt
• lt/coursesgt
• ltaddressgt123 main streetlt/addressgt
• ltphonegt555-2929lt/phonegt
• lt/studentgt

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So What ?

• XML generation is simple
• XML Parsing is also pretty simple
• there are lots of parsers available!
• Browsers understand XML (somewhat).
• CSS style sheets
• XSL Extensible Stylesheet Language
• XML can be used for document storage and
  transfer.

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XML messaging

• RPC XML is used to encode procedure calls and
  responses.
• EDI Electronic Document Interchange
• transfer documents between applications across a
  network
• purchase orders, financial transactions, etc.

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XML-RPC

• Use XML to encode requests
• procedure name
• parameter values
• Response is also an XML document
• return value(s)
• errors (faults)
• Both are well defined document types
• tag names are defined in the XML-RPC
  specification document.

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Uses HTTP POST

• Use existing protocol (and software!).
• Avoid firewall issues (everyone allows HTTP
  traffic).
• XML-RPC Request is the body of an HTTP POST.
• XML-RPC Response is the body (content) of the
  HTTP response.

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Example Request(swiped from xml-rpc.com)

• POST /RPC2 HTTP/1.0
• Host betty.userland.com
• User-Agent Frontier/5.1.2 (WinNT)
• Content-Type text/xml
• Content-length 181
• lt?xml version"1.0"?gt
• ltmethodCallgt ltmethodNamegtexamples.getStateNamelt/me
  thodNamegt ltparamsgt
• ltparamgt
• ltvaluegtlti4gt41lt/i4gtlt/valuegt
• lt/paramgt
• lt/paramsgt
• lt/methodCallgt

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Sample Response

• HTTP/1.1 200 OK
• Connection close
• Content-Length 158
• Content-Type text/xml
• Date Fri, 17 Jul 1998 195508 GMT
• Server UserLand Frontier/5.1.2-WinNTltpgt
• ltxml version"1.0"?gt
• ltmethodResponsegt
• ltparamsgt
• ltparamgt
• ltvaluegt
• ltstringgtSouth Dakotalt/stringgt
• lt/valuegt
• lt/paramgt
• lt/paramsgt
• lt/methodResponsegt

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XML-RPC Data Types

• ltintgt or lti4gt
• ltbooleangt
• ltstringgt
• ltdoublegt
• ltdateTime.iso8601gt
• ltstructgt
• ltarraygt

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XML-RPC struct

• ltstructgt
• ltmembergt
• ltnamegtHostnamelt/namegt
• ltvaluegt
• ltstringgtmonte.cs.rpi.edult/stringgt
• lt/valuegt
• lt/membergt
• ltmembergt
• ltnamegtIPAddresslt/namegt
• ltvaluegt
• ltstringgt128.213.7.32lt/stringgt
• lt/valuegt
• lt/membergt
• lt/structgt

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XML-RPC array
ltarraygt ltdatagt ltvaluegtlti4gt12lt/i4gtlt/valuegt
ltvaluegtltstringgtEgyptlt/stringgtlt/valuegt
ltvaluegtltbooleangt0lt/booleangtlt/valuegt
ltvaluegtlti4gt-31lt/i4gtlt/valuegt lt/datagt lt/arraygt
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XML-RPC Programming

• Need to be able to generate HTTP requests
  (client) and responses(server).
• Need to generate XML documents.
• Need to parse XML documents and extract specific
  items.
• Need to handle faults (errors).

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SOAPSimple Object Access Protocol

• Same general idea as XML-RPC, but more features
• enumerations
• Polymorphism (type determined at run time)
• user defined data types

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SOAP

• XML Documents are more complex
• use namespaces
• formal "envelope"
• Soap Header
• Soap Body

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SOAP Request Example

• POST /StockQuote HTTP/1.1
• Host www.stockquoteserver.com
• Content-Type text/xml charset"utf-8"
• Content-Length nnnn
• SOAPAction "Some-URI"
• ltSOAP-ENVEnvelope
• xmlnsSOAP-ENVhttp//schemas.xmlsoap.org/soap/e
  nvelope/
• SOAP-ENVencodingStyle"http//schemas.xmlsoap.o
  rg/soap/encoding/"gt
• ltSOAP-ENVBodygt ltmGetLastTradePrice
  xmlnsm"Some-URI"gt      ltsymbolgtDISlt/symbolgt  lt
  /mGetLastTradePricegtlt/SOAP-ENVBodygt
• lt/SOAP-ENVEnvelopegt

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XML-RPC vs. SOAP

• XML-RPC is much simpler
• There are lots of web services based on XML-RPC.
• SOAP makes it easier to exchange more complex
  documents.
• SOAP runs over many protocols
• HTTP, SMTP, FTP,

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SOAP is an integral part of .NET

• Programmer Transparency
• Multiple Languages

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Resources

• xml-rpc.com (userland)
• specification, info, tutorials, code resources
• www.soapware.org
• tutorials, code resources
• www.w3.org
• SOAP specification