A web service is a software service or a software functionality provided by one set of computing devices to another set of computing devices. These devices communicate using established or standardized communication protocols through the World Wide Web (WWW).

This chapter intends to refresh your understanding of a few fundamental concepts of the web and its architecture, and the way it is evolving, hoping to lay a firm foundation for RESTful service designs and applications. The following topics are covered in this chapter:

• A brief history of the WWW and its evolution
• WWW layers and architecture
• Web API development models and REST-based service communication
• A brief introduction to service-oriented architecture
• Resource-oriented architecture principles and characteristics
• Introduction to REST
• REST constraints
• RESTful qualifiers
• REST architecture goals