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SOAP Toolkit FAQ - What is WSDL?
SOAP Interview Questions and Answers
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SOAP Toolkit FAQ - What is WSDL?
The Web Services Description Language (WSDL) currently represents the service description layer within the Web service protocol stack.
In a nutshell, WSDL is an XML grammar for specifying a public interface for a Web service. This public interface can include the following:
Information on all publicly available functions.
Data type information for all XML messages.
Binding information about the specific transport protocol to be used.
Address information for locating the specified service.
WSDL is not necessarily tied to a specific XML messaging system, but it does include built-in extensions for describing SOAP services.
Below is a sample WSDL file. This file describes the public interface for the weather service used in the SOAP example above. Obviously, there are many details to understanding the example. For now, just consider two points.
First, the elements specify the individual XML messages that are transferred between computers. In this case, we have a getWeatherRequest and a getWeatherResponse. Second, the element specifies that the service is available via SOAP and is available at a specific URL.
WSDL is a standard, structured way of describing Soap messages and Web Services. The Soap Toolkit is dependent upon WSDL to create and interpret Soap Messages, so a WSDL file is required for any Soap Toolkit 2.0 client or server. If you want a Soap Toolkit 2.0 client to communicate with a Soap Server that doesn't supply a WSDL, you must create a WSDL file that describes the messages the Soap Services expects. I find the easiest way to do this is to create a dummy interface in Microsoft® Visual Basic® that matches what the server expects and use WSDLGen on the VB dll to create the WSDL file. You may also create the WSDL file by hand. If you want a non-WSDL enabled Soap client to talk to a Soap Toolkit 2.0 Service, just use the WSDL file as a description of what the Soap message needs to look like and translate this to whatever mechanism the client uses to create Soap messages.
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