|
Context and Transaction Management
|
|
The initial set of Web services technologies lacked the ability to support the structured maintenance of context throughout a service activity. Without an active, stateful context, Web services act independently and cannot support distributed transactions.
|
|
The WS-Coordination specification provides a context management system, which is applied to support atomic and long-running transactions, using protocols described in the WS-Transaction specification.
|
|
The atomic transaction part of the WS-Transaction specification is superseded by a separate specification titled WS-AtomicTransaction. Similarly, the WS-BusinessActivity specification replaces the corresponding coordination type definition within WS-Transaction.
|
Referenced Specifications:
 WS-Coordination
WS-Transaction (and the WS-TX TC)
WS-AtomicTransaction
WS-BusinessActivity
|
Locations:
IBM
Microsoft
OASIS (WS-TX TC)
|
|
Business Process Definition and Execution
|
|
In order to compose Web services into a structured workflow, a standard vocabulary is required. The Business Process Execution Language for Web Services provides a process description vocabulary that can be compiled into runtime scripts, executable by middleware products that support orchestration. BPEL4WS (and its successor, WS-BPEL) brings Web services into the realm of enterprise integration.
|
Referenced Specifications:
WS-BPEL
BPEL4WS
|
Locations:
IBM (BPEL4WS)
Microsoft (BPEL4WS)
OASIS (WS-BPEL)
|
|
Probably the largest gap in the first-generation Web services platform was an absence of any real security standards. Consequently, organizations were reluctant to expose business processes over the Internet.
|
|
The WS-Security framework institutes a thorough security model consisting of a stack of complementary specifications. It establishes security measures to protect SOAP messages throughout a message path, and supports the creation of policies and the unification of trust boundaries. The core WS-Security specifications are further supplemented by a series of established XML security specifications.
|
Referenced Specifications:
WS-Security (and the WS-SX TC)
WS-Federation
WS-SecureConversation
WS-Trust
XML Encryption
XML Signature
XKMS
XACML
SAML
WS-I Basic Security Profile
|
Locations:
Microsoft (WS-Security)
IBM (WS-Security)
W3C (XML Encryption, XML Signature, XKMS)
OASIS (WS-Security, SAML)
OASIS (WS-SX TC)
|
|
Reliability, Routing, and Attachments
|
|
In order for a solution to be capable of enterprise-level automation, its communications framework must be failsafe, flexible, and efficient. The following WS-* specifications propose critical features that deal with reliabile delivery, self-governing messaging, and message attachments.
|
Referenced Specifications:
WS-ReliableMessaging (and the WS-RX TC)
WS-Addressing
WS-Attachments
SwA
DIME
|
Locations:
Microsoft (WS-ReliableMessaging)
Microsoft (WS-Addressing, SwA, DIME)
IBM (WS-ReliableMessaging)
IBM (WS-Attachments)
OASIS (WS-RX TC)
W3C (WS-Addressing)
|
|
Within a service-oriented enterprise, it would be useful to be able to abstract high-level business rules, security rules, and descriptive properties so that they can be applied to groups of services as policies.
|
|
The WS-Policy framework consists of a set of specifications that allow for the description of such policies, as well as a standard means of attaching them to Web services. WS-MetadataExchange complements WS-Policy (and WSDL) by providing a standardized means of querying Web services for metadata.
|
Referenced Specifications:
WS-Policy
WS-PolicyAssertions
WS-PolicyAttachments
WS-MetadataExchange
|
Locations:
Microsoft
IBM (WS-Policy)
IBM (WS-MetadataExchange)
W3C (WS-Policy)
|
|
Other Referenced Specifications
|
Referenced Specifications:
Plain Old XML (POX)
Representational State Transfer (REST)
WS-CDL (Choreography Description Language)
WS-Eventing
WS-Notification
WS-RF (Resource Framework)
|
Locations:
WP (POX)
WP (REST)
W3C (WS-CDL)
Microsoft (WS-Eventing)
IBM (WS-Notification)
OASIS (WS-RF)
|
|
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
|
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
|
|
