“At their core, Web services define a mechanism for machine-to-machine interaction using a network and XML. A key component of a Web service is a formal description with Web Services Description Language (WSDL). Until recently there was no formal language to describe Representational State Transfer (REST) Web services-now there’s WSDL 2.0. This article introduces you to REST and WSDL 2.0, and walks you through creating a WSDL 2.0 REST description of a Web service. “