The Web Application Description Language (WADL) is a machine-readable
XML
Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...
description of
HTTP
The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, ...
-based web services. WADL models the resources provided by a service and the relationships between them. WADL is intended to simplify the reuse of web services that are based on the existing HTTP architecture of the Web. It is platform and language independent and aims to promote reuse of applications beyond the basic use in a web browser.
WADL was submitted to the
World Wide Web Consortium
The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 and led by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working to ...
by
Sun Microsystems
Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, the ...
on 31 August 2009, but the consortium has no current plans to standardize it. WADL is the
REST
Rest or REST may refer to:
Relief from activity
* Sleep
** Bed rest
* Kneeling
* Lying (position)
* Sitting
* Squatting position
Structural support
* Structural support
** Rest (cue sports)
** Armrest
** Headrest
** Footrest
Arts and entert ...
equivalent of
SOAP
Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...
's
Web Services Description Language
The Web Services Description Language (WSDL ) is an XML-based interface description language that is used for describing the functionality offered by a web service. The acronym is also used for any specific WSDL description of a web service (also ...
(WSDL), which can also be used to describe
REST
Rest or REST may refer to:
Relief from activity
* Sleep
** Bed rest
* Kneeling
* Lying (position)
* Sitting
* Squatting position
Structural support
* Structural support
** Rest (cue sports)
** Armrest
** Headrest
** Footrest
Arts and entert ...
web services.
Format
The service is described using a set of ''
resource
Resource refers to all the materials available in our environment which are technologically accessible, economically feasible and culturally sustainable and help us to satisfy our needs and wants. Resources can broadly be classified upon their ...
'' elements. Each resource contains ''param'' elements to describe the inputs, and ''method'' elements which describe the ''request'' and ''response'' of a resource. The ''request'' element specifies how to represent the input, what types are required and any specific HTTP headers that are required. The ''response'' describes the representation of the service's response, as well as any fault information, to deal with errors.
Example
The following listing shows an example of a WADL description for the Yahoo News Search application.
Generate WADL or generate code from WADL
Java
There are multiple tools to generate java code from an existing WADL:Apache CXF /ref>
*
Apache CXF
Apache CXF is an open source software project developing a Web services framework. It originated as the combination of Celtix developed by IONA Technologies and XFire developed by a team hosted at Codehaus in 2006. These two projects were combin ...
*
Java API for RESTful Web Services
Jakarta RESTful Web Services, (JAX-RS; formerly Java API for RESTful Web Services) is a Jakarta EE API specification that provides support in creating web services according to the Representational State Transfer (REST) architectural pattern. ...
, and its reference implementation, Jersey
Example WADL Generated by CXF
See also
*
Overview of RESTful API Description Languages RESTful (representational state transfer) API (application programming interface) DLs (description languages) are formal languages designed to provide a structured description of a RESTful web API that is useful both to a human and for automated mac ...
*
OpenAPI Specification
The OpenAPI Specification, previously known as the Swagger Specification, is a specification for a machine-readable interface definition language for describing, producing, consuming and visualizing RESTful web services. Previously part of the S ...