What is SoA
A service-oriented architecture is essentially a collection of services and these services are communicated with each other.

An architecture principle for structuring systems into coarse-grained services enables the technology neutral and platform interoperability emphasizes the loosely coupling of services. It also promotes loose coupling between components for their reuse.

Applications build using SOA style deliver functionally as service that can be used or reused when building applications or integrating with in the enterprise.In Large term, SOA will describe the four aspects of services; Services are composable, Re-usable, Loosely coupled and Interoperable

QoS

Service
A service is a unit of work done by a service provider to achieve desired end results for a service consumer. Both provider and consumer are roles played by software agents on behalf of their owners

Services can be published into service directory and Consumers can dynamically discover services from service directory via the well defined service contract

Types of Services
Simple
Basic services that have a simple interfaces and when invoked perform a business function
Building block of any SOA solution

Composite
Aggregate services, which when invoked perform a sequential set of business functions

Conversational
Long latencies
Conversational in-nature
Ex:SCM (Supply chain automation)

Types of Message Communication
Synchronous
In Sync Mode, the sender waits till the receiving program has received the messaged, processed it and respond backed to the sender

Asynchronus
In Async Mode, the sender sends the messages and continues its processing regardless of when the receiving program receives and process the messages

About Author / Additional Info:
Arivuvel Ramu
Technical Architect (SOA)
galaxE Solutions, Bangalore, India