Developing ColdFusion MX Applications with CFML
Using Web Services

Working with WSDL files

WSDL files define the interface to a web service. To consume a web service, you access the service's WSDL file to determine information about it. If you publish your application logic as a web service, you must create a WSDL file for it.

WSDL is a draft standard supported by the World Wide Web Consortium. You can access the specification at the following URL:

http://www.w3.org/TR/wsdl

Creating a WSDL file

To publish a web service, you construct the service's functionality and then create the WSDL file defining the service. In ColdFusion, you use components to create web services. ColdFusion automatically generates the WSDL file for a component that you use to produce a web service. For more information on creating web services, see "Publishing web services".

For more information on components, see Chapter 11, "Building and Using ColdFusion Components".

Viewing a WSDL file using Dreamweaver MX

Dreamweaver MX contains a utility to view web services, including operation names, parameter names, and parameter data types. The following figure shows a WSDL file for the BabelFish web service:

This figure shows that the web service method babelFish returns a string, and that it takes string parameters named sourcedata and translationmode as input.

To open the Components tab in the Dreamweaver MX and add a web service:

1. Choose Window > Components, or use Ctrl-F7, to open the Components panel.
2. In the Components panel, choose Web Services from the dropdown list in the upper-left of the panel.
3. Click the Plus (+) button.

   The Add Using WSDL dialog box appears.

4. Specify the URL of the WSDL file.

For more information on using Dreamweaver MX, see its online Help system.

Reading a WSDL file

A WSDL file takes practice to read. You can view the WSDL file in a browser, or you can use a tool such as Dreamweaver MX, which contains a built-in utility for displaying WSDL files in an easy-to-read format.

The following example shows a WSDL file for the BabelFish web service:

<?xml version="1.0" ?> 

  <definitions name="BabelFishService" 
xmlns:tns="http://www.xmethods.net/sd/BabelFishService.wsdl" 
targetNamespace="http://www.xmethods.net/sd/BabelFishService.wsdl" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" 
xmlns="http://schemas.xmlsoap.org/wsdl/"> 
    <message name="BabelFishRequest"> 
      <part name="translationmode" type="xsd:string" /> 
      <part name="sourcedata" type="xsd:string" /> 
    </message> 
    <message name="BabelFishResponse"> 
      <part name="return" type="xsd:string" /> 
    </message> 
    <portType name="BabelFishPortType"> 
      <operation name="BabelFish"> 
        <input message="tns:BabelFishRequest" /> 
        <output message="tns:BabelFishResponse" /> 
      </operation> 
    </portType> 
    <binding name="BabelFishBinding" type="tns:BabelFishPortType"> 
      <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" /> 
      <operation name="BabelFish"> 
        <soap:operation soapAction="urn:xmethodsBabelFish#BabelFish" /> 
        <input> 
          <soap:body use="encoded" namespace="urn:xmethodsBabelFish" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" /> 
        </input> 
        <output> 
          <soap:body use="encoded" namespace="urn:xmethodsBabelFish" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" /> 
        </output> 
      </operation> 
    </binding> 
  <service name="BabelFishService"> 
    <documentation>Translates text of up to 5k in length, between a variety of languages.</documentation> 
    <port name="BabelFishPort" binding="tns:BabelFishBinding"> 
      <soap:address location="http://services.xmethods.net:80/perl/soaplite.cgi" /> 
    </port> 
  </service> 
</definitions>

The following are the major components of the WSDL file:

Component	Definition
definitions	The root element of the WSDL file. This area contains namespace definitions that you use to avoid naming conflicts between multiple web services.
types	(not shown) Defines data types used by the service's messages.
message	Defines the data transferred by a web service operation, typically the name and data type of input parameters and return values.
port type	Defines one or more operations provided by the web service.
operation	Defines an operation that can be remotely invoked.
input	Specifies an input parameter to the operation using a previously defined message.
output	Specifies the return values from the operation using a previously defined message.
fault	(not shown) Optionally specifies an error message returned from the operation.
binding	Specifies the protocol used to access a web service including SOAP, HTTP GET and POST, and MIME.
service	Defines a group of related operations.
port	Defines an operation and its associated inputs and outputs.

For additional descriptions of the contents of this WSDL file, see "Consuming web services".

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