WSDLn

WSDLn is a proposed specification for describing network services that extends the Web Services Description Language (WSDL). It targets both SOAP and REST-based services, providing a unified contract language for service interfaces, data types, endpoints, and bindings. WSDLn seeks to address modularity and evolution by allowing service descriptions to be composed from reusable modules and by supporting formal versioning and compatibility rules.

The design emphasizes strong tooling support, enabling automatic code generation, service discovery, and testing, as well as interoperability across languages and platforms. Core concepts mirror WSDL: services, interfaces (port types), operations, messages, and data types, but WSDLn introduces modular components, policy annotations, and semantic metadata to enhance interoperability and verifiability.

Syntax and notation: the primary representation is an XML-based schema, with proposals for JSON or YAML encodings in certain ecosystems; descriptions use namespaces, modules, interfaces, operations, and bindings, plus optional policy and capability declarations.

Adoption and status: WSDLn remains exploratory and unofficial, without an accepted standard status. It has been discussed in community forums and used in demonstrations and educational materials; a few open-source projects provide experimental tooling for editing, validating, and transforming WSDLn documents.

See also: WSDL, Web Services Description Language, SOAP, REST, XML-based service descriptions.