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

Organizations:

• IBM (Location: BPEL4WS)
• Microsoft (Location: BPEL4WS)
• OASIS WS-BPEL)

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The atomic transaction part of the WS-Transaction specification is superseded by a separate specification titled WS-AtomicTransaction.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

Organizations:

• IBM (Location: WS-TX)
• Microsoft
• OASIS (Location: WS-TX TC)

Referenced Specifications:

• WS-CDL (Choreography Description Language)
• WS-Eventing
• WS-Notification
• WS-RF (Resource Framework)

Organizations:

• W3C (Location: WS-CDL)
• W3C (Location: WS-Eventing)
• IBM (Location: WS-Notification)
• OASIS (WS-RF)

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

Organizations:

• Microsoft
• IBM (Location: WS-Policy)
• IBM (Location: WS-MetadataExchange)
• W3C (Location: WS-Policy)

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-Attachments
• SwA
• DIME

Organizations:

• Microsoft (Location: WS-ReliableMessaging)
• IBM (Location: WS-ReliableMessaging)
• IBM (Location: WS-Attachments)
• OASIS (Location: WS-RX TC)
• W3C (Location: WS-Addressing)

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)M
• WS-Federation
• WS-SecureConversation
• WS-Trust
• XML Encryption
• XML Signature
• XKMS
• XACML
• SAML
• WS-I Basic Security Profile

Organizations:

• Microsoft (Location: WS-Security)
• IBM (Location: WS-Security)
• W3C (Location: XML Encryption, XML Signature, XKMS)
• OASIS (Location: WS-Security, SAML)
• OASIS (Location: WS-SX TC)

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.

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.

Location: SOAP 1.1
Organization: W3C
Location: SOAP 1.2 Part 0 (primer)
Organization: W3C
Location: SOAP 1.2 Part 1 (messaging framework)
Organization: W3C
Location: SOAP 1.2 Part 2 (adjuncts)
Organization: W3C
Location: SOAP 1.2 (assertions and test collection)
Organization: W3C
Location: SOAP Message Transmission Optimization Mechanism (MTOM)C
Organization: W3C
Location: XML-binary Optimized Packaging (XOP)
Organization: W3C

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.

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.

Location: UDDI 2.0 Specifications
Organization: OASIS
Location: UDDI 3.0 Specifications
Organization: OASIS

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.

Location: WSDL 1.1
Organization: W3C
Location: WSDL 2.0 Part 1 (core language)
Organization: W3C
Location: WSDL 2.0 Part 2 (message patterns)
Organization: W3C

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.

Location: WS-I Basic Profile 1.0a
Organization: WS-I
Location: WS-I Basic Profile 1.1
Organization: WS-I
Location: WS-I Basic Profile 1.2
Organization: WS-I
Location: WS-I Basic Security Profile 1.0
Organization: WS-I
Location: WS-I Basic Security Profile 1.1
Organization: WS-I
Location: WS-I Simple SOAP Binding Profile 1.0
Organization: WS-I
Location: WS-I Attachments Profile 1.0
Organization: WS-I
Location: Web Services Architecture
Organization: W3C