Newsletter sign-up
View all newsletters

Enterprise Java Newsletter
Stay up to date on the latest tutorials and Java community news posted on JavaWorld

Sponsored Links

Optimize with a SATA RAID Storage Solution
Range of capacities as low as $1250 per TB. Ideal if you currently rely on servers/disks/JBODs

What is service-oriented architecture?

An introduction to SOA

  • Print
  • Feedback

Page 3 of 4

Quality of services

Existing mission-critical systems in enterprises address advanced requirements such as security, reliability, and transactions. As enterprises start adopting service architecture as a vehicle for developing and deploying applications, basic Web services specifications like WSDL, SOAP, and UDDI aren't going to fulfill these advanced requirements. As mentioned previously, these requirements are also known as quality of services. Numerous specifications related to QoS are being worked out in standards bodies like the World Wide Web Consortium (W3C) and the Organization for the Advancement of Structured Information Standards (OASIS). Sections below discuss some of the QoS artifacts and related standards.

Security
The Web Services Security specification addresses message security. This specification focuses on credential exchange, message integrity, and message confidentiality. The attractive thing about this specification is it leverages existing security standards, such as Security Assertion Markup Language (SAML), and allows the usage of these standards to secure Web services messages. Web Services Security is an ongoing OASIS effort.

Reliability
In a typical SOA environment, several documents are exchanged between service consumers and service providers. Delivery of messages with characteristics like once-and-only-once delivery, at-most-once delivery, duplicate message elimination, guaranteed message delivery, and acknowledgment become important in mission-critical systems using service architecture. WS-Reliability and WS-ReliableMessaging are two standards that address the issues of reliable messaging. Both these standards are now part of OASIS.

Policy
Service providers sometimes require service consumers to communicate with certain policies. As an example, a service provider may require a Kerberos security token for accessing the service. These requirements are defined as policy assertions. A policy may consist of multiple assertions. WS-Policy standardizes how policies are to be communicated between service consumers and service providers.

Orchestration
As enterprises embark on service architecture, services can be used to integrate silos of data, applications, and components. Integrating applications means that the process requirements, such as asynchronous communication, parallel processing, data transformation, and compensation, must be standardized. BPEL4WS or WSBPEL (Web Services Business Process Execution Language) is an OASIS specification that addresses service orchestration, where business processes are created using a set of discrete services. WSBPEL is now part of OASIS.

Management
As the number of services and business processes exposed as services grow in the enterprise, a management infrastructure that lets the system administrators manage the services running in a heterogeneous environment becomes important. Web Services for Distributed Management (WSDM) will specify that any service implemented according to WSDM will be manageable by a WSDM-compliant management solution.

  • Print
  • Feedback

Resources