Consider 'idWebService' as the identifier of the 'WebService' instance and that in the WSDL document is defined an operation like this:

<wsdl:operation name="getNamesArray">
    <wsdlsoap:operation soapAction="" />
    <wsdl:input name="getNamesArrayRequest">
        <wsdlsoap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" namespace="http://services" use="encoded" />
    </wsdl:input>
    <wsdl:output name="getNamesArrayResponse">
        <wsdlsoap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" namespace="http://lucabonacorsi.org/exampleWebService" use="encoded" /> 
    </wsdl:output>
</wsdl:operation>

then the ActionScript code to use is 'idWebService.getNamesArray();'.

For example, if we wanted to call such a method soon after the WSDL document has been loaded, we could exploit the 'load' event of the 'WebService' class this way:

<mx:WebService
    id="idWebService"
    wsdl="http://lucabonacorsi.org/exampleWebService?wsdl"
    load="idWebService.getNamesArray();" />

If we were interested in calling that method in response to a button 'click', we could take advantage of the following MXML code:

<mx:Button
    label="get all names"
    click="idWebService.getNamesArray();" />

The 'getNamesArray' operation, set here as an example, is supposed to return a data 'array'.
This data structure in Flex/ActionScript is represented trough an 'ArrayCollection' object.

We will focus on this aspect in another article.