SOAP Version 1.2

• Simple Object Access Protocol — W3C Recommendation 2007
• Part 0: Primer
• Part 1: Messaging Framework (SOAP envelope)
• Part 2: Adjuncts (SOAP data model and binding to HTTP)
• Stateless, one-way messaging; but more sophisticated protocols typically encoded
• Processing model
• roles = handlers of header data: initial sender, intermediaries, ultimate receiver
• any node may detect a fault (e.g., message not understood) and use protocol to report it
• independent of underlying communications mechanism (e.g., http, email)
• Envelope = Header? Body
• Header includes meta information directed at processors (including recipient and intermediary nodes)
• Body contains the message itself (e.g., request or response)
• Example (from SOAP Primer)

<?xml version='1.0' ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> 
 <env:Header>
  <m:reservation xmlns:m="http://travelcompany.example.org/reservation" 
           env:role="http://www.w3.org/2003/05/soap-envelope/role/next"
           env:mustUnderstand="true">
   <m:reference>uuid:093a2da1-q345-739r-ba5d-pqff98fe8j7d</m:reference>
   <m:dateAndTime>2001-11-29T13:20:00.000-05:00</m:dateAndTime>
  </m:reservation>
  <n:passenger xmlns:n="http://mycompany.example.com/employees"
           env:role="http://www.w3.org/2003/05/soap-envelope/role/next"
           env:mustUnderstand="true">
   <n:name>Eke Jsgvan Xyvind</n:name>
  </n:passenger>
 </env:Header>
 <env:Body>
  <p:itinerary xmlns:p="http://travelcompany.example.org/reservation/travel">
   <p:departure>
     <p:departing>New York</p:departing>
     <p:arriving>Los Angeles</p:arriving>
     <p:departureDate>2001-12-14</p:departureDate>
     <p:departureTime>late afternoon</p:departureTime>
     <p:seatPreference>aisle</p:seatPreference>
   </p:departure>
   <p:return>
     <p:departing>Los Angeles</p:departing>
     <p:arriving>New York</p:arriving>
     <p:departureDate>2001-12-20</p:departureDate>
     <p:departureTime>mid-morning</p:departureTime>
     <p:seatPreference/>
   </p:return>
  </p:itinerary>
  <q:lodging xmlns:q="http://travelcompany.example.org/reservation/hotels">
   <q:preference>none</q:preference>
  </q:lodging>
 </env:Body>
</env:Envelope>

• Often used for remote procedure calls:
• address of target SOAP node
• method name
• list of arguments
• Example (request and response):

<?xml version='1.0' ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope" >
 <env:Header>
   <t:transaction
           xmlns:t="http://thirdparty.example.org/transaction"
           env:encodingStyle="http://example.com/encoding"
           env:mustUnderstand="true" >5</t:transaction>
 </env:Header>  
 <env:Body>
  <m:chargeReservation 
         env:encodingStyle="http://www.w3.org/2003/05/soap-encoding"
         xmlns:m="http://travelcompany.example.org/">
   <m:reservation xmlns:m="http://travelcompany.example.org/reservation">
    <m:code>FT35ZBQ</m:code>
   </m:reservation>   
   <o:creditCard xmlns:o="http://mycompany.example.com/financial">
    <n:name xmlns:n="http://mycompany.example.com/employees">
           Eke Jsgvan Xyvind
    </n:name>     
    <o:number>123456789099999</o:number>
    <o:expiration>2005-02</o:expiration>
   </o:creditCard>
  </m:chargeReservation>
 </env:Body>
</env:Envelope>


<?xml version='1.0' ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope" >
 <env:Header>
    <t:transaction
          xmlns:t="http://thirdparty.example.org/transaction"
          env:encodingStyle="http://example.com/encoding"
          env:mustUnderstand="true">5</t:transaction>
 </env:Header>  
 <env:Body>
    <m:chargeReservationResponse 
             env:encodingStyle="http://www.w3.org/2003/05/soap-encoding"
             xmlns:rpc="http://www.w3.org/2003/05/soap-rpc"
             xmlns:m="http://travelcompany.example.org/">
       <rpc:result>m:status</rpc:result>
       <m:status>confirmed</m:status>
       <m:code>FT35ZBQ</m:code>
       <m:viewAt>
        http://travelcompany.example.org/reservations?code=FT35ZBQ
       </m:viewAt>
    </m:chargeReservationResponse>
 </env:Body>
</env:Envelope>

WSDL 2.0

• Web Services Description Language — W3C Recommendation 2007
• Part 0: Primer
• Part 1: Core Language
• Part 2: Message Patterns
• Part 3: Bindings
• Server-client architecture, but "one person's server is another person's client"
• Machine readable description of services offered and protocol(s) understood — including syntax and semantics
• Abstract interfaces
• Definition of data and messages exchanged
• built on XML Schema types

<types>   
   <xs:schema elementFormDefault="qualified" 
        targetNamespace="http://www.w3.org/wsd12/PrimerExamples/example0">    
     <xs:element name="eReserveRoom" type="tReserveRoom"/>    
        <xs:complexType name="tReserveRoom">     
        <xs:sequence>      
          <xs:element name="customerName" type="xs:string"/>      
          <xs:element  name="checkInDate" type="xs:date"/>      
          <xs:element  name="checkOutDate" type="xs:date"/>      
          <xs:element  name="roomType" type="xs:string"/>      
          <xs:element  name="comments" element="xs:string"/>      
          <xs:element  name="agentID" type="xs:string"/>     
        </xs:sequence>     
        <xs:attribute name="mustUnderstand" type="xs:boolean" 
                        default="false"/>     
        <xs:attribute name="actor" type="xs:anyURI"/>    
    </xs:complexType>   
   </xs:schema>  
</types>    

<message name="inReserveRoom">   
    <part name="ReserveRoom" type="tns:eReserveRoom"/>  
</message>  

• Operations
• packaging of messages (e.g., as request-reply pairs)
• Bindings to concrete protocol

<env:Envelope xmlns:env=http://www.w3.org/2003/05/soap-envelope>
    <env:Body>
        <ReserveRoom actor=http://travelcompany.example.org>
            <customerName>J. Smith</customerName>
            <checkInDate> ...
            ...
        </ReserveRoom>
    </env:Body>
</env:Envelope>

UDDI Version 3.0

• Universal Description, Discovery, and Integration — OASIS Specification 2005
• "... creates a platform-independent, open framework for describing services, discovering businesses, and integrating business services using the Internet, as well as an operational registry that is available today." [http://xml.coverpages.org/uddi.html]
• Possible sitting on top of WSDL
Figure from UDDI specification

References and related reading

Querying XML, Chapters 17-18

W3C SOAP

W3C SOAP Scenarios

W3C WSDL

OASIS UDDI