[References to http://www.w3school.com, http://www.w3.org/TR/wsdl]

What are Web Services?

  • Web services are application components
  • Web services communicate using open protocols
  • Web services are self-contained and self-describing
  • Web services can be discovered using UDDI
  • Web services can be used by other applications
  • XML is the basis for Web services

Web services platform elements

  • SOAP (Simple Object Access Protocol)
  • UDDI (Universal Description, Discovery and Integration)
  • WSDL (Web Services Description Language)

The body of the http:
Example 1 SOAP 1.1 Request/Response via HTTP

<?xml version="1.0"?>
<definitions name="StockQuote"

targetNamespace="http://example.com/stockquote.wsdl"
          xmlns:tns="http://example.com/stockquote.wsdl"
          xmlns:xsd1="http://example.com/stockquote.xsd"
          xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
          xmlns="http://schemas.xmlsoap.org/wsdl/">

    <types>
       <schema targetNamespace="http://example.com/stockquote.xsd"
              xmlns="http://www.w3.org/2000/10/XMLSchema">
           <element name="TradePriceRequest">
              <complexType>
                  <all>
                      <element name="tickerSymbol" type="string"/>
                  </all>
              </complexType>
           </element>
           <element name="TradePrice">
              <complexType>
                  <all>
                      <element name="price" type="float"/>
                  </all>
              </complexType>
           </element>
       </schema>
    </types>

    <message name="GetLastTradePriceInput">
        <part name="body" element="xsd1:TradePriceRequest"/>
    </message>

    <message name="GetLastTradePriceOutput">
        <part name="body" element="xsd1:TradePrice"/>
    </message>

    <portType name="StockQuotePortType">
        <operation name="GetLastTradePrice">
           <input message="tns:GetLastTradePriceInput"/>
           <output message="tns:GetLastTradePriceOutput"/>
        </operation>
    </portType>

    <binding name="StockQuoteSoapBinding" type="tns:StockQuotePortType">
        <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>
        <operation name="GetLastTradePrice">
           <soap:operation soapAction="http://example.com/GetLastTradePrice"/>
           <input>
               <soap:body use="literal"/>
           </input>
           <output>
               <soap:body use="literal"/>
           </output>
        </operation>
    </binding>

    <service name="StockQuoteService">
        <documentation>My first service</documentation>
        <port name="StockQuotePort" binding="tns:StockQuoteBinding">
           <soap:address location="http://example.com/stockquote"/>
        </port>
    </service>

</definitions>


WSDL:
A WSDL document is simply a set of definitions. There is a definitions element at the root, and definitions inside. The grammar is as follows:

<wsdl:definitions name="nmtoken"? targetNamespace="uri"?>

    <import namespace="uri" location="uri"/>*

    <wsdl:documentation . /> ?

    <wsdl:types> ?
        <wsdl:documentation . />?
        <xsd:schema . />*
        <-- extensibility element --> *
    </wsdl:types>

    <wsdl:message name="nmtoken"> *
        <wsdl:documentation . />?
        <part name="nmtoken" element="qname"? type="qname"?/> *
    </wsdl:message>

    <wsdl:portType name="nmtoken">*
        <wsdl:documentation . />?
        <wsdl:operation name="nmtoken">*
           <wsdl:documentation . /> ?
           <wsdl:input name="nmtoken"? message="qname">?
               <wsdl:documentation . /> ?
           </wsdl:input>
           <wsdl:output name="nmtoken"? message="qname">?
               <wsdl:documentation . /> ?
           </wsdl:output>
           <wsdl:fault name="nmtoken" message="qname"> *
               <wsdl:documentation . /> ?
           </wsdl:fault>
        </wsdl:operation>
    </wsdl:portType>

    <wsdl:binding name="nmtoken" type="qname">*
        <wsdl:documentation . />?
        <-- extensibility element --> *
        <wsdl:operation name="nmtoken">*
           <wsdl:documentation . /> ?
           <-- extensibility element --> *
           <wsdl:input> ?
               <wsdl:documentation . /> ?
               <-- extensibility element -->
           </wsdl:input>
           <wsdl:output> ?
               <wsdl:documentation . /> ?
               <-- extensibility element --> *
           </wsdl:output>
           <wsdl:fault name="nmtoken"> *
               <wsdl:documentation . /> ?
               <-- extensibility element --> *
           </wsdl:fault>
        </wsdl:operation>
    </wsdl:binding>

    <wsdl:service name="nmtoken"> *
        <wsdl:documentation . />?
        <wsdl:port name="nmtoken" binding="qname"> *
           <wsdl:documentation . /> ?
           <-- extensibility element -->
        </wsdl:port>
        <-- extensibility element -->
    </wsdl:service>

    <-- extensibility element --> *

</wsdl:definitions>

Services are defined using six major elements:

  • types, which provides data type definitions used to describe the messages exchanged.
  • message, which represents an abstract definition of the data being transmitted. A message consists of logical parts, each of which is associated with a definition within some type system.
  • portType, which is a set of abstract operations. Each operation refers to an input message and output messages.
  • binding, which specifies concrete protocol and data format specifications for the operations and messages defined by a particular portType.
  • port, which specifies an address for a binding, thus defining a single communication endpoint.
  • service, which is used to aggregate a set of related ports.

You can put the Web Service on your site.

<form target="_blank" action='http://www.w3schools.com
/webservices/tempconvert.asmx/FahrenheitToCelsius' 
method="POST"> 
<table>
    <tr>
        <td>Fahrenheit to Celsius:</td>
        <td><input class="frmInput" type="text" 
        size="30" name="Fahrenheit"></td>
    </tr>
    <tr>
        <td></td>
        <td align="right"> <input type="submit" 
        value="Submit" class="button"></td>
    </tr>
</table>
</form>