Book Image

SOA Made Simple

Book Image

SOA Made Simple

Overview of this book

SOA is an industry term which is often preached like a religion rather than taught like a technology, and over time, grasping the concept has become unnecessarily difficult. Many companies proclaim that they don't know where to begin with SOA, while others have begun their SOA effort but haven't reaped the benefits they were convinced it would bring. "SOA Made Simple"ù unveils the true meaning of Service Oriented Architecture and how to make it successful so that you can confidently explain SOA to anyone! "SOA Made Simple"ù explains exactly what SOA is in simple terminology and by using real-life examples. Once a simple definition is clear in your mind, you'll be guided through what SOA solves, when and why you should use it, and how to set up, design and categorize your SOA landscape. With this book in hand you'll learn to keep your SOA strategy successful as you expand on it. "SOA Made Simple"ù demystifies SOA, simply. It is not difficult to grasp, but for various reasons SOA is often made unnecessarily complex. Service-orientation is already a very natural way of thinking for business stakeholders that want to realize and sell services to potential clients, and this book helps you to realize that concept both in theory and practice. You'll begin with a clear and simple explanation of what SOA is and why we need it. You'll then be presented with plain facts about the key ingredients of a service, and along the way learn about service design, layering and categorizing, some major SOA platform offerings as well as governance and successful implementation. After reading "SOA Made Simple"ù you will have a clear understanding of what SOA is so you can implement and govern SOA in your own organization.
Table of Contents (17 chapters)
SOA Made Simple
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Isolation and composition – a contradiction?


The design principle isolation that was introduced in the previous chapter and composability that is introduced in this chapter might seem to contradict each other. How can you have autonomous services if you compose larger services out of smaller ones? Wouldn't that mean that the composed service is dependent on the smaller services?

The answer is that service composition promotes isolation of services. Isolation is viewed from the perspective of consumers, a consumer should be able to invoke a service independently without needing to know if other services need to be invoked before or afterwards. Service composition wraps such dependencies and knowledge of how to combine them into a separate service, thereby hiding this from the consumer and offering a new autonomous service.

Isolation is also known as loose-coupling, too many dependencies between services make them tightly coupled and therefore harder to change. As you know from the previous...