A technique is described in which a web service provider is able to specify that messages related to business transactions with the web service includes trading partner information. For example, a provider may specify such requirements in a WSDL description of the relevant web service and may register the description with a UDDI registry. The trading partner information is regarding business transactions between the requesting party and the provider and is related to pre-established trading partner relationships and associated agreements and processes. Such trading partner information typically includes information that identifies, for example, the requesting party and the type of transaction. Consequently, the provider can determine whether the received request originates from an established trading partner and whether the requesting party is entitled to conduct the requested business transaction. Hence, application-level security is provided to electronic business transactions. Furthermore, enhanced processing of the business transaction results from being able to access, based on the received trading partner information, more elaborate data models associated with electronic transaction processes established between the trading partners.