The W3C Web Services Description Working Group has released two revised Working Draft specifications for WSDL 2.0.

Web Services Description Language (WSDL) Version 2.0 Part 2: Message Exchange Patterns defines patterns that are intended for use with the Web Services Description Language (WSDL). "WSDL message exchange patterns define the sequence and cardinality of abstract messages listed in an operation. Message exchange patterns also define which other nodes send messages to, and receive messages from, the service implementing the operation. WSDL patterns are described in terms of the WSDL component model, specifically the Label and Fault Reference components."

Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language "describes the Web Services Description Language (WSDL) Version 2.0, an XML language for describing Web services. It defines the core language which can be used to describe Web services based on an abstract model of what the service offers. It also defines criteria for a conformant processor of this language."

Bibliographic Information

• Web Services Description Language (WSDL) Version 2.0 Part 2: Message Exchange Patterns. W3C Working Draft 26-March-2004. Edited by Martin Gudgin (Microsoft), Amy Lewis (TIBCO), and Jeffrey Schlimmer (Microsoft). Produced by members of the W3C Web Services Description Working Group. Version URL: http://www.w3.org/TR/2004/WD-wsdl20-patterns-20040326. Latest version URL: http://www.w3.org/TR/wsdl20-patterns. Previous version URL: http://www.w3.org/TR/2003/WD-wsdl20-patterns-20031110. Also available in PDF format and in a 2004-03-26 diff-marked version.

• Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language. W3C Working Draft 26-March-2004. Edited by Roberto Chinnici (Sun Microsystems), Martin Gudgin (Microsoft), Jean-Jacques Moreau (Canon), Jeffrey Schlimmer (Microsoft), and Sanjiva Weerawarana (IBM Research). Produced by members of the W3C Web Services Description Working Group. Version URL: http://www.w3.org/TR/2004/WD-wsdl20-20040326. Latest version URL: http://www.w3.org/TR/wsdl20. Previous version URL: http://www.w3.org/TR/2003/WD-wsdl20-20031110. Also available in PDF format and in a diff-marked version.

From WSDL Version 2.0 Core Language

Web Services Description Language (WSDL) provides a model and an XML format for describing Web services. WSDL enables one to separate the description of the abstract functionality offered by a service from concrete details of a service description such as 'how' and 'where' that functionality is offered.

This specification defines a language for describing the abstract functionality of a service as well as a framework for describing the concrete details of a service description. It also defines criteria for a conformant processor of this language. The WSDL Version 2.0 Part 2: Message Exchange Patterns specification defines the sequence and cardinality of abstract messages sent or received by an operation. The WSDL Version 2.0 Part 3: Bindings specification [WSDL 2.0 Bindings] defines a language for describing such concrete details for SOAP 1.2, HTTP, and MIME.

Web Service: WSDL describes a Web service in two fundamental stages: one abstract and one concrete. Within each stage, the description uses a number of constructs to promote reusability of the description and separate independent design concerns.

At an abstract level, WSDL describes a Web service in terms of the messages it sends and receives; messages are described independent of a specific wire format using a type system, typically XML Schema.

An operation associates a message exchange pattern with one or more messages. A message exchange pattern identifies the sequence and cardinality of messages sent and/or received as well as who they are logically sent to and/or received from. An interface groups together operations without any commitment to transport or wire format.

At a concrete level, a binding specifies transport and wire format details for one or more interfaces. An endpoint associates a network address with a binding. And finally, a service groups together endpoints that implement a common interface. [from WD spec Section 1]