Current Web services are able to interoperate successfully with most basic data types. However, due to the limited functionality of existing data binding tools, they still experiment difficulties manipulating more complex XML data types, forcing programmers to work at the XML level. In this paper we propose a business model for web services where data binding tools not only generate the WSDL, but also provide portable binding extensions for manipulating theXSD types. These binding extensions can be integrated into any other binding tool, overcoming their limitations. Because these extensions are written in XML, this model conforms to the principle of platform independence. In addition, this model does not suppose any extra programming effort to neither service providers or clients. The approach has been validated with the creation of several extensions, which has been ported into Java and PHP clients. Our preliminary results show no performance penalty.