The W3C Web Services Addressing Working Group has released its first three Working Drafts for the Web Services Addressing specification, which provides transport-neutral mechanisms to address Web services and messages.

W3C chartered the new Web Services Addressing Working Group in October 2004 as part of the W3C Web Services Activity, under the W3C Architecture Domain. In August 2004 a revised Web Services Addressing (WS-Addressing) specification was presented to W3C as a Member Submission by BEA, IBM, Microsoft, SAP AG, and Sun Microsystems. WS-Addressing "defines XML elements to identify Web service endpoints and to secure end-to-end endpoint identification in messages. The specification enables messaging systems to support message transmission through networks that include processing nodes such as endpoint managers, firewalls, and gateways in a transport-neutral manner."

In keeping with terms of the WG Charter, the Member Submission document has been separated into three separate specifications: Core, SOAP Binding, and WSDL Binding. The new Web Services Addressing Core "defines a set of abstract properties and an XML Infoset representation thereof to identify Web service endpoints and to secure end-to-end identification of endpoints in messages." In this version the dependency upon on WS-Policy has been removed, along with references to WS-Trust and WS-SecurityPolicy. The Web Services Addressing - WSDL Binding specification "defines how the abstract properties defined in Web Services Addressing Core are described using WSDL."

Part 3, the Web Services Addressing SOAP Binding, defines the binding of the abstract properties defined in Web Services Addressing Core to SOAP Messages. "When a message needs to be addressed to the endpoint, the information contained in the endpoint reference is mapped to the message according to a transformation that is dependent on the protocol and data representation used to send the message. Protocol-specific mappings (or bindings) will define how the information in the endpoint reference is copied to message and protocol fields. This specification defines the SOAP binding for endpoint references. This mapping may be explicitly replaced by other bindings (defined as WSDL bindings or as policies); however, in the absence of an applicable policy stating that a different mapping must be used, the SOAP binding defined here is assumed to apply. To ensure interoperability with a broad range of devices, all conformant implementations must support the SOAP binding."

A note in the Working Drafts reports that the Web Services Addressing WG has decided to use XML Schema, where appropriate, to describe constructs defined in this specification; this restricts use of Web Services Addressing to XML Version 1.0.

The Web Services Addressing First Public Working Drafts have been produced under the 5-February-2004 W3C Patent Policy. This W3C Patent Policy "governs the handling of patents in the process of producing Web standards, and its goal is to assure that Recommendations produced under the policy can be implemented on a Royalty-Free (RF) basis."

W3C Member Organizations represented as participants on the Web Services Addressing Working Group include Arjuna Technologies Ltd; BEA Systems, Inc; BT; Computer Associates; DataPower Technology, Inc; Fujitsu Limited; Hewlett Packard Company; Hitachi, Ltd; IBM Corporation; IONA Technologies, Inc; Microsoft Corp; Nokia Corporation; Novell, Inc; Oracle Corporation; SAIC - Telcordia Technologies; SAP AG; SeeBeyond Technology Corporation; Sonic Software; Sun Microsystems, Inc; Systinet, Inc; and webMethods, Inc.

Bibliographic Information

• Web Services Addressing — Core Edited by Martin Gudgin (Microsoft Corp) and Marc Hadley (Sun Microsystems, Inc). W3C Working Draft. 8-December-2004. Version URL: http://www.w3.org/TR/2004/WD-ws-addr-core-20041208. Latest version URL: http://www.w3.org/TR/ws-addr-core. Also in PDF and XML formats.

• Web Services Addressing — WSDL Binding. Edited by Martin Gudgin (Microsoft Corp) and Marc Hadley (Sun Microsystems, Inc). W3C Working Draft. 8-December-2004. Version URL: http://www.w3.org/TR/2004/WD-ws-addr-wsdl-20041208. Latest version URL: http://www.w3.org/TR/ws-addr-wsdl. Also in PDF and XML formats.

• Web Services Addressing — SOAP Binding. Edited by Martin Gudgin (Microsoft Corp) and Marc Hadley (Sun Microsystems, Inc). W3C Working Draft. 8-December-2004. Version URL: http://www.w3.org/TR/2004/WD-ws-addr-soap-20041208. Latest version URL: http://www.w3.org/TR/ws-addr-soap. Also in PDF and XML formats.

Web Services Addressing Overview

"Web Services Addressing (WS-Addressing) defines two constructs that convey information that is typically provided by transport protocols and messaging systems: endpoint references and message addressing properties. These constructs normalize this underlying information into a uniform format that can be processed independently of transport or application.

Web service endpoint is a (referenceable) entity, processor, or resource to which Web service messages can be targeted. Endpoint references convey the information needed to identify/reference a Web service endpoint, and may be used in several different ways:

• To convey the information needed to access a Web service endpoint
• To provide addresses for individual messages sent to and from Web services

To deal with this last usage case this specification defines a family of message addressing properties that allows uniform addressing of messages independent of underlying transport. These message addressing properties convey end-to-end message characteristics including addressing for source and destination endpoints as well as message identity.

Both of these constructs are designed to be extensible and re-usable so that other specifications can build on and leverage endpoint references and message information headers..." [from the 'Introduction']

W3C Web Services Addressing Working Group Outline of Work

The new W3C Web Services Addressing Working Group has been chartered to "standardize the mechanisms for referencing and addressing Web services by refining WS-Addressing, which includes four principal components of the W3C's Web Services Architecture specification. These referencing and addressing mechanisms are (1) a means by which message headers are used to direct messages to a Web service or agent; (2) abstract message properties (message identifier; a URI for the destination address; a URI designating the action to be taken at the destination; correlation with other message[s]; the nature of the relationship with those messages) (3) an appropriate XML Infoset definition; (4) abstract properties to identify subsequent destinations in the message exchange, including the reply destination and the fault destination."

The XML Infoset required for "communicating the information necessary to generate appropriate headers to direct messages to a service or an agent includes a URI designating the destination address; service specific message headers; interaction specific message headers; WSDL definitions relevant to this service; additional metadata as required."

According to the WG Charter, these components "must be extensible to enable other mechanisms such as new kinds of relationships between correlated messages, policies, or service semantics to be built upon Web Services Addressing. The components must also be usable independently of the SOAP or WSDL version in use."

Additionally, the WG will define SOAP 1.1 and WSDL 1.1 bindings (defined for backward compatibility only). It will define (1) a binding of all abstract message properties to SOAP 1.1 and SOAP 1.2 headers, (2) the use of these abstract message properties in the context of all WSDL 1.1 or WSDL 2.0 Message Exchange Patterns, including the asynchronous use of these MEPs; in particular, the relationship between message properties and WSDL 1.1 and WSDL 2.0 service descriptions will be provided if applicable, and (3) a security model for using and communicating these abstract properties."

The specified deliverables of the Working Group include a W3C Recommendation for the Web Services Addressing specification; a W3C Recommendation for the Web Services Addressing SOAP 1.1 and SOAP 1.2 Binding specification, mapping Web Services Addressing message properties to SOAP 1. 1 and SOAP 1.2 headers; a W3C Recommendation for the Web Services Addressing WSDL 1.1 and WSDL 2.0 Binding specification, defining the use of Web Services Addressing components in WSDL 1.1 and WSDL 2.0 message exchange patterns and providing the mechanisms for defining Web Services Addressing property values in WSDL 1.1 and WSDL 2.0 service descriptions; a test suite intended to promote implementation of the Candidate Recommendation and to assess interoperability between four interoperable implementations.

The W3C Web Services Addressing Working Group will coordinate with other W3C Groups, especially with those Working Groups involved in the Web Services Activity: XML Protocol Working Group, Web Services Description Working Group, Web Services Choreography Working Group, and Web Services Coordination Group. The specification defined by the Web Services Addressing Working Group will also "be aligned with the World Wide Web architecture as defined by the Technical Architecture Group (TAG), e.g., for mapping qnames to URIs. The WG will coordinate with relevant OASIS TCs and with the Web Services Interoperability Organization (WS-I).