SOA – Service Oriented Architecture - Cloud Computing

SOA – Service Oriented Architecture

• The service provider publishes a service description (WSDL), e.g. on a service broker
• Service Requester finds service (on service broker) and dynamically binds to service
• Enables ad-hoc collaboration and Enterprise Application Integration (EAI) within web- based information systems
• SOA is about how to design a software system that makes use of services of new or legacy applications through their published or discoverable interfaces.
• These applications are often distributed over the networks.
• SOA also aims to make service interoperability extensible and effective.
• It prompts architecture styles such as loose coupling, published interfaces and a standard communication model in order to support this goal.

Properties of SOA

• Logical view
• Message orientation
• Description orientation

Logical view

• The SOA is an abstracted, logical view of actual programs, databases, and business processes.
• Defined in terms of what it does, typically carrying out a business-level operation.
• The service is formally defined in terms of the messages exchanged between provider agents and requester agents.

Message Orientation

• The internal structure of providers and requesters includes the implementation language, process structure, and even database structure.
• These features are deliberately abstracted away in the SOA
• Using the SOA discipline one does not and should not need to know how an agent implementing a service is constructed.
• The key benefit of this concerns legacy systems.
• By avoiding any knowledge of the internal structure of an agent, one can incorporate any software component or application to adhere to the formal service definition.

Description orientation

• A service is described by machine-executable metadata.
• The description supports the public nature of the SOA.
• Only those details that are exposed to the public and are important for the use of the service should be included in the description.
• The semantics of service should be documented, either directly or indirectly, by its description.