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REST in Practice

Cover of REST in Practice by Ian Robinson... Published by O'Reilly Media, Inc.
  1. REST in Practice
    1. SPECIAL OFFER: Upgrade this ebook with O’Reilly
    2. Foreword
    3. Preface
      1. Should I Read This Book?
      2. Should I Skip This Book?
      3. Resources
      4. What Did You Think About the Book?
      5. Errata
      6. Conventions Used in This Book
      7. Using Code Examples
      8. How to Contact Us
      9. Safari® Books Online
      10. Acknowledgments
    4. 1. The Web As a Platform for Building Distributed Systems
      1. Architecture of the Web
      2. Thinking in Resources
      3. From the Web Architecture to the REST Architectural Style
      4. The Web As an Application Platform
      5. Web Friendliness and the Richardson Maturity Model
      6. GET on Board
    5. 2. Introducing Restbucks: How to GET a Coffee, Web Style
      1. Restbucks: A Little Coffee Shop with Global Ambitions
      2. Toolbox
      3. Here Comes the Web
    6. 3. Basic Web Integration
      1. Lose Weight, Feel Great!
      2. A Simple Coffee Ordering System
      3. URI Templates
      4. URI Tunneling
      5. POX: Plain Old XML over HTTP
      6. We Are Just Getting Started
    7. 4. CRUD Web Services
      1. Modeling Orders As Resources
      2. Building CRUD Services
      3. Aligning Resource State
      4. Consuming CRUD Services
      5. Consuming Services Automatically with WADL
      6. CRUD Is Good, but It’s Not Great
    8. 5. Hypermedia Services
      1. The Hypermedia Tenet
      2. Hypermedia Formats
      3. Contracts
      4. Hypermedia Protocols
      5. Implementing a Hypermedia Service
      6. Building the Ordering Service in Java
      7. Building the Ordering Service in .NET
      8. Ready, Set, Action
    9. 6. Scaling Out
      1. GET Back to Basics
      2. Caching
      3. Making Content Cacheable
      4. Implementing Caching in .NET
      5. Consistency
      6. Extending Freshness
      7. Stay Fresh
    10. 7. The Atom Syndication Format
      1. The Format
      2. Common Uses for Atom
      3. Using Atom for Event-Driven Systems
      4. Building an Atom Service in Java
      5. Building an Atom Service in .NET
      6. Atom Everywhere?
      7. After the Event
    11. 8. Atom Publishing Protocol
      1. Atom Publishing Protocol
      2. Implementing Order Fulfillment Using AtomPub
      3. Implementing AtomPub in .NET
      4. A Versatile Protocol
    12. 9. Web Security
      1. HTTP Security Essentials
      2. Identity and the OpenID Protocol
      3. The OAuth Protocol
      4. Service Hacks and Defenses
      5. Final Thoughts
    13. 10. Semantics
      1. Syntax Versus Semantics
      2. Structure and Representation of Information
      3. The Semantic Web
      4. Microformats
      5. Linked Data and the Web
      6. Guidance
    14. 11. The Web and WS-*
      1. Are Web Services Evil?
      2. SOAP: The Whole Truth
      3. WSDL: Just Another Object IDL
      4. Two Wrongs Don’t Make a Right
      5. Secure, Reliable, Transacted
      6. A Requiem for Web Services?
    15. 12. Building the Case for the Web
      1. No More Silver Bullets
      2. Building and Running Web-Based Services
      3. No Architecture Without Measurement
      4. Selling the Web
      5. Go Forth and Build
    16. Index
    17. About the Authors
    18. Colophon
    19. SPECIAL OFFER: Upgrade this ebook with O’Reilly
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Chapter 5. Hypermedia Services

EMBRACING HTTP AS AN APPLICATION PROTOCOL puts the Web at the heart of distributed systems development. But that’s just a start. In this chapter, we will go further, building RESTful services that use hypermedia to model state transitions and describe business protocols.

The Hypermedia Tenet

When browsing the Web, we’re used to navigating between pages by clicking links or completing and submitting forms. Although we may not realize it, these interlinked pages describe a protocol—a series of steps we take to achieve a goal, whether that’s buying books, searching for information, creating a blog post, or even ordering a coffee. This is the very essence of hypermedia: by transiting links between resources, we change the state of an application.

Hypermedia is an everyday part of our online activities, but despite this familiarity, it’s rarely used in computer-to-computer interactions. Although Fielding’s thesis on REST highlighted its role in networked systems, hypermedia has yet to figure significantly in contemporary enterprise solutions.

Hypermedia As the Engine of Application State

The phrase hypermedia as the engine of application state, sometimes abbreviated to HATEOAS, was coined to describe a core tenet of the REST architectural style. In this book, we tend to refer to the hypermedia tenet or just hypermedia. Put simply, the tenet says that hypermedia systems transform application state.

Note

What is application state? If we think of an application as ...

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