Chapter 1. From Objects to Web Services

Web services have been put into practical use for many years. In this time, developers and architects have encountered a number of recurring design challenges related to their usage. We have also learned that certain design approaches work better than others to solve certain problems. This book is for software developers and architects who are currently using web services or are thinking about using them. The goal is to acquaint you with some of the most common and fundamental web service design solutions and to help you determine when to use them. All of the concepts discussed here are derived from real-life lessons. Proven design solutions will also be demonstrated through code examples.

Service developers are confronted with a long list of questions.

• How do you create a service API, what are the common API styles, and when should a particular style be used?

• How can clients and services communicate, and what are the foundations for creating complex conversations in which multiple parties exchange data over extended periods of time?

• What are the options for implementing service logic, and when should a particular approach be used?

• How can clients become less coupled to the underlying systems used by a service?

• How can information about a service be discovered?

• How can generic functions like authentication, validation, caching, and logging be supported on the client or service?

• What changes to a service cause clients to break?

• What are the common ways to version a service?

• How can services be designed to support the continuing evolution of business logic without forcing clients to constantly upgrade?

These are just a few of the questions that must be answered. This book will help you find solutions that are appropriate for your situation.

In this chapter, you’ll learn what services are and how web services address the shortcomings of their predecessors.