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The W3C framework for Web services consists of a foundation built on top of three core XML specifications: WSDL, SOAP, and UDDI. These technology standards, coupled with service-oriented design principles, form a basic XML-driven SOA.
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This first-generation Web services architecture allows for the creation of independent Web services capable of encapsulating isolated units of business functionality. It also has a number of limitations, which have been addressed in a second generation of specifications.
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Below are resources for each of the first-generation Web services specifications referenced in the books.
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Web Services Description Language (WSDL)
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Web services need to be defined in a consistent manner so that they can be discovered by and interfaced with other services and applications. The Web Services Description Language is a W3C specification providing the foremost language for the description of Web service definitions.
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WSDL 1.1
Status: Working Group Note
Location: W3C (html)
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WSDL 2.0 Part 1 (core language)
Status: Recommendation
Location: W3C (html)
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WSDL 2.0 Part 2 (message patterns)
Status: Recommendation
Location: W3C (html)
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Simple Object Access Protocol (SOAP)
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Although originally conceived as a technology to bridge the gap between disparate RPC-based communication platforms, SOAP has evolved into the most widely supported messaging format and protocol for use with XML Web services.
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The SOAP specification establishes a standard message format that consists of an XML document capable of hosting RPC and document-centric data. This facilitates synchronous (request and response) as well as asynchronous (process-driven) data exchange models. With WSDL establishing a standard endpoint description format for applications, the document-centric message format is much more common.
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SOAP 1.1
Status: W3C Note
Location: W3C (html)
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SOAP 1.2 Part 0 (primer)
Status: Recommendation
Location: W3C (html)
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SOAP 1.2 Part 1 (messaging framework)
Status: Recommendation
Location: W3C (html)
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SOAP 1.2 Part 2 (adjuncts)
Status: Recommendation
Location: W3C (html)
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SOAP 1.2 (assertions and test collection)
Status: Recommendation
Location: W3C (html)
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SOAP Message Transmission Optimization Mechanism (MTOM)
Status: Recommendation
Location: W3C (html)
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XML-binary Optimized Packaging (XOP)
Status: Recommendation
Location: W3C (html)
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Universal Description, Discovery, and Integration (UDDI)
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One of the fundamental components of a service-oriented architecture is a mechanism for Web service descriptions to be discovered by potential requestors. To establish this part of a Web services framework, a central directory to host service descriptions is required. Such a directory can become an integral part of an organization or an Internet community, so much so, it is considered an extension to infrastructure.
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This is why the Universal Description, Discovery, and Integration specification has become increasingly important. A key part of UDDI is the standardization of profile records stored within such a directory, also known as a registry. Depending on who the registry is intended for, different implementations can be created.
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UDDI 2.0 Specifications
Status: Standard
Location: OASIS (html)
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UDDI 3.0 Specifications
Status: Standard
Location: OASIS (html)
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WS-I Profiles and Web Services Architecture
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To promote the evolution of industry standard, interoperable Web services platforms, architecture and technology profile specifications have been developed by the WS-I and the W3C, respectively.
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WS-I Basic Profile 1.0a
Status: Final Material
Location: WS-I (html)
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WS-I Basic Profile 1.1
Status: Working Group Draft
Location: WS-I (html)
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WS-I Basic Profile 1.2
Status: Board Approval Draft
Location: WS-I (html)
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WS-I Basic Security Profile 1.0
Status: Final Material
Location: WS-I (html)
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WS-I Basic Security Profile 1.1
Status: Working Group Approval Draft
Location: WS-I (html)
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WS-I Simple SOAP Binding Profile 1.0
Status: Working Group Draft
Location: WS-I (html)
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WS-I Attachments Profile 1.0
Status: Final Material
Location: WS-I (html)
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Web Services Architecture
Status: Working Group Note
Location: W3C (html)
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SOA: Principles
of Service Design
by Thomas Erl
An in-depth guide dedicated to service engineering with a thorough exploration of the design principles that comprise the service-orientation design paradigm (including a comparison with object-orientation).
Service-Oriented Architecture:
Concepts, Technology, and Design
by Thomas Erl
The first "how-to" guide to building SOA, providing coverage of WS-* specifications, .NET and J2EE platforms, and step-by-step processes for service-oriented analysis and design.
Service-Oriented Architecture:
A Field Guide
to Integrating
XML and Web Services
by Thomas Erl
The best-selling guide to service-oriented integration, providing hundreds of integration strategies and over sixty best practices.
For more information about either book, visit: www.soabooks.com
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More Resources
• www.whatissoa.com
• www.soaprinciples.com
• www.soamagazine.com
• www.soamethodology.com
• www.ws-standards.com
• www.xmlenterprise.com
• www.soaglossary.com
About SOA Systems
SOA Systems Inc. provides strategic SOA consulting services and offers a comprehensive SOA training program.
For more information see:
• www.soasystems.com
• www.soatraining.com
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