Used for describing interfaces for Web Services. It is a general specification independent of SOAP (i.e. WSDL for REST services) and defines data types, interface definitions, transport bindings, and service descriptions. WSDL makes creating SOAP proxies simpler (either dynamic or static), it can also be used for interface documentation, and can be integrated into development systems (code editors, class generators, etc.). Defines a system for automated publishing and discovery of Web Services, allowing registries to be maintained for different purposes and contexts. UDDI defines an API specification for publish and inquire for businesses and web services, a data structure, and several XML Schemas for custody, subscription policy, replication, etc.