Service-Oriented Computing in the Real World - About Web Services (Part I)

SOA Service Oriented Architecture

Service-Oriented Computing in the Real World - About Web Services (Part I)

The Web services platform is defined through a number of industry standards that are supported throughout the vendor community. This platform can be partitioned into two clearly identifiable generations, each associated with a collection of standards and specifications:

First-Generation Web Services Platform

The original Web services technology platform is comprised of the following core open technologies and specifications:

- Web Services Description Language (WSDL)
- XML Schema Definition Language (XSD)
- SOAP (formerly the Simple Object Access Protocol)
- UDDI (Universal Description, Discovery, and Integration)
- WS-I Basic Profile

These specifications have been around for some time and have been adopted across the IT industry. However, the platform they collectively represent seriously lacks several of the quality of service features required to deliver mission critical, enterprise-level production functionality.

Second-Generation Web Services Platform (WS-* extensions)

Some of the greatest quality of service-related gaps in the first-generation platform lie in the areas of message-level security, cross-service transactions, and reliable messaging. These, along with many other extensions, are being provided by the second-generation Web services platform.

Consisting of numerous specifications that build upon the fundamental first-generation messaging framework, this set of Web services technologies (generally labeled as "WS-* extensions") provides a rich feature-set far more complex both in technology and in design.

Some of the notable WS-* specifications include:

- WS-Security (and WS-SX)
- WS-Coordination, WS-AtomicTransaction, WS-BusinessActivity (and WS-TX)
- WS-ReliableMessaging (and WS-RX)
- WS-Policy
- WS-Addressing

For an introduction to first and second-generation Web services technologies, read the short tutorials located at www.ws-standards.com. To view the actual specifications, visit www.soaspecs.com.