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SSDL: SOAP Service Description Language

From: Savas Parastatidis <Savas.Parastatidis@newcastle.ac.uk>
Date: Tue, 15 Feb 2005 00:32:14 -0000
Message-ID: <37E80E80B681A24B8F768D607373CA8001CA746D@largo.campus.ncl.ac.uk>
To: "ww" <xml-dist-app@w3.org>, <www-ws-desc@w3.org>, <public-ws-addressing@w3.org>, <www-ws@w3.org>

Dear all,

[Appologies for cross-posting but we thought that this work may be of
interest to the members of all these groups]

We would like to announce the release of the SOAP Service Description
Language, or SSDL. SSDL is a SOAP-centric description language for Web
Services which promotes a message-oriented view of a Service-Oriented
application and works harmoniously with the underlying SOAP processing
model. SSDL enables developers to publish and share descriptions of the
messages and message exchange patterns that a Web Service supports. The
SSDL work was developed as a vehicle for exploring ideas in the areas of
contract and protocol description, and is being released to the Web
Services community for feedback and to encourage further exploration of
this area.

The SSDL specifications are the result of an effort by an international
team of practitioners and researchers in the Web Services area. The SSDL
authors created a base framework to manage the abstractions common to
contracts: messages, protocols, and endpoints. These features are
defined by the core SSDL specification and facilitate the description of
messages and service endpoints (using WS-Addressing) that a Web Service

The basic SSDL contract has a placeholder which houses protocol
descriptions (sets of message exchanges) and means for those protocol
descriptions to reference the declared messages in a standard way. While
this aspect of SSDL is completely extensible by third-parties, the SSDL
team have provided four different protocol frameworks for immediate use:

 * MEP - The Message Exchange Patterns (MEP) Framework provides a
superset of the message exchange patterns supported by the latest draft
of the WSDL 2.0 specification.
 * CSP - The CSP Protocol Framework supports the design of protocols
using basic Communicating Sequential Processes (CSP) semantics. The
protocols captured using the CSP SSDL protocol framework can be
validated for correctness, liveness, and other properties.
 * Rules - The Rules-based SSDL Protocol Framework can be used to
describe a multi-message exchange protocol using conditions on incoming
or outgoing messages. The protocols captured using the Rules-based SSDL
protocol framework can be validated for correctness, liveness, and other
 * The Sequencing Constraints (SC) Protocol Framework is used to
describe a multi-party, multi-message exchange protocol using notations
based on the pi-calculus. The protocols captured using the SC SSDL
protocol framework can be validated for correctness, liveness, and other

The focus of each of these protocol frameworks is different, and
end-users are free to choose one which most closely matches their needs,
or are free to implement their own protocol framework.

In addition to the SSDL documentation, the SSDL team have prototypical
software tools to automate the consumption of SSDL contracts in
application code. These tools are currently in alpha testing and will be
made available for users on the .Net 2.0 platform with Web Services
Enhancements (WSE) 2.0 in due course.  There is also a mailing list
being run from the SSDL web site to which users and potential users are
encouraged to subscribe. The main contact point for the SSDL team is the
SSDL Web site at http://www.ssdl.org. The SSDL framework documents,
mailing list, tool support, and other information are all available via
the site.

Best regards,
Savas Parastatidis (http://savas.parastatidis.name)


Jim Webber (http://jim.webber.name)
Received on Tuesday, 15 February 2005 00:32:36 GMT

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