Web-services are broadly considered as an effective means to achieve interoperability between heterogeneous parties of a business process and offer an open platform for developing new composite web-services out of existing ones. In the literature many approaches have been proposed with the aim to automatically compose web-services. All of them assume that, along with the webservice signature, some information is provided about how clients interacting with the web-service should behave when invoking it. We call this piece of information the web-service behavior protocol. Unfortunately, in the practice this assumption turns out to be unfounded. To address this need, in this paper we propose a method to automatically derive from the web-service signature an automaton modeling its behavior protocol. The method, called StrawBerry, combines synthesis and testing techniques. In particular, synthesis is based on data type analysis. The conformance between the synthesized automaton and the implementation of the corresponding web-service is checked by means of testing. The application of StrawBerry to the Amazon E-Commerce Service shows that it is practical and realistic.