What is a Service?

This is a questions I hear very often - not only from the Management but also from Architects and Developers.
Let's try to find an answer....

First, you should understand the Term 'Service' because this is the most important part of any Service Oriented Architecture.

The term 'Service' indicates that IT is moving towards the Business Layers and therefore offering its functions as Services.

A Service has the following characteristics:

• a Service is, from a business perspective, a reusable component
• a Service has a standardized interface that abstracts the implementation details and technology of the underlying system. It is therefore loosly coupled.
• a Service always has a contracts that specifies the terms of use and the policies applied.

To make it more clear what Services are we can differentiate between three types of Services:

• Business Services; offer a Business Functionality that is needed in a certain Business Process Step.
• Intermediary Services; handle technology gaps, offer routing, transformation and security capabilities.
• Basic Services; implement the needed Business Logic and handle the data.