Definition and Ownership of Web Service Interfaces: WSDL or XSD?
Web services are a preferred way to expose business modules. But the decision to use web servicesor any other distributed technologyshould be independent of the interface definition or development of the business module. The business module should be developed first, and then the decision can be made to use a suitable distributed technology. This strategy implies that WSDL may not be the appropriate choice for defining the interface, as it's part of a specific distributed technology specification. If you already have XML-based messages as an interface to your module, the XSD for the messages could also be the web service interface for the module.
Our previous article discussed the practice of separating the business module from the web services infrastructure, using web services as a "packaging strategy" for an application. This technique gives the company the flexibility to have separate development teamsone to build the business module and another to develop the web services layer to expose that module. In that article, we also introduced the gist of this articledetermining the appropriate technology to expose the web service interface. In this article, we explore the use of XSD Schema as a web service message interface and identify the appropriate group in the enterprise to take ownership of that interface.