Web Services (WSs) are the W3C-endorsed realization of the Service-Oriented Architecture (SOA). Since they are supposed to be implementation-neutral, WSs are typically tested black-box at their interface. Such an interface is generally specified in an XML-based notation called the WS Description Language (WSDL). Conceptually, these WSDL documents are eligible for fully automated WS test generation using syntax-based testing approaches. Towards such goal, we introduce the WS-TAXI framework, in which we combine the coverage of WS operations with data-driven test generation. In this paper we present an early-stage implementation of WS-TAXI, obtained by the integration of two existing softwares: soapUI, a popular tool for WS testing, and TAXI, an application we have previously developed for the automated derivation of XML instances from a XML schema. WS-TAXI delivers a complete suite of test messages ready for execution. Test generation is driven by basic coverage criteria and by the application of some heuristics. The application of WS-TAXI to a real case study gave encouraging results.