Java Reference
In-Depth Information
Web Service Description Language (WSDL) specifies the service interface and the rules
for binding the service consumer and the provider. According to the specification of WSDL
1.1, WSDL is defined as “an XML format for describing network services as a set of en-
dpoints operating on messages containing either document-oriented or procedure-oriented
information” (
http://www.w3.org/TR/wsdl
). WSDL defines how a consumer can interact
with a service via a concrete network protocol and message format using eXtended Markup
Language (XML).
XML is a profile (subset) of Standard Generalized Markup Language (SGML). SGML is a
metalanguage, i.e., a language that describes other languages. Unlike HyperText Markup
Language (HTML), which is used to serve static webpages, XML allows the author to create
his or her own tags. Thus, XML facilitates the data and document processing functions.
Web Service relies on Simple Object Application Protocol (SOAP) as its transport. As
its name implies, SOAP is a lightweight protocol that can be used to exchange structured
messages (i.e., XML). SOAP 1.2 is the latest version. WSDL 1.1 supports SOAP 1.1,
HTTP GET/POST, and MIME.
A service can be defined, published and discovered using some type of service registry. Cur-
rent supporting service registries include electronic business XML (ebXML), Universal
Discovery, Description and Integration (UDDI), and Metadata Registry (MDR). UDDI is
usually a good idea; however, it is not widely used except in a private network of services.
