6. Implementing HATEOAS
by Geoffroy Warin, Alex Bretet, Hamidreza Sattari, Shameer Kunjumohamed
Spring MVC: Designing Real-World Web Applications
- Spring MVC: Designing Real-World Web Applications
- Table of Contents
- Spring MVC: Designing Real-World Web Applications
- Spring MVC: Designing Real-World Web Applications
- Credits
- Preface
- I. Module 1
- 1. Getting Started with Spring Core
- The Spring landscape
- Design concepts behind Spring Framework
- Setting up the development environment
- Your first Spring application
- Dependency Injection
- Beans in detail
- Bean definition
- Instantiating beans
- Injecting bean dependencies
- Constructor-based or setter-based DI – which is better?
- Cleaner bean definitions with namespace shortcuts
- Wiring a List as a dependency
- Wiring a Map as a dependency
- Autowiring dependencies
- Bean scoping
- Dependency Injection with scoped beans
- Creating a custom scope
- Hooking to bean life cycles
- Container-level default-init-method and default-destroy-method
- Working with bean definition profiles
- Injecting properties into the Spring environment
- Externalizing properties with PropertyPlaceholderConfigurer
- Handling resources
- Spring Expression Language
- Aspect Oriented Programming
- Testing with Spring
- Summary
- 2. Building the Web Layer with Spring Web MVC
- Features of Spring MVC
- The Model-View-Controller pattern
- Your first Spring MVC application
- Setting up a Spring MVC application
- The architecture and components of Spring MVC
- DispatcherServlet explained
- Controllers in detail
- Mapping request URLs with @RequestMapping
- URI template patterns with the @PathVariable annotation
- Binding parameters with the @RequestParam annotation
- Request handler method arguments
- Request handler method return types
- Setting Model attributes
- Building RESTful services for JSON and XML media
- Building a RESTful service with RestController
- Asynchronous request processing in Spring MVC
- Working with views
- Spring and Spring form tag libraries
- Composing a form in JSP
- Validating forms
- Handling file uploads
- Resolving Thymeleaf views
- More view technologies
- Summary
- 3. Accessing Data with Spring
- Configuring DataSource
- Using embedded databases
- Handling exceptions in the Spring Data layer
- DAO support and @Repository annotation
- Spring JDBC abstraction
- Spring Data
- Spring Transaction support
- Relevance of Spring Transaction
- Summary
- 4. Understanding WebSocket
- 5. Securing Your Applications
- 6. Building a Single-Page Spring Application
- The motivations behind SPAs
- SPAs explained
- Introducing Ember.js
- The anatomy of an Ember application
- Working with Ember CLI
- Understanding the Ember object model
- Working with collections
- Building UI templates using Handlebars
- Handling routes
- Handling UI behavior using components
- Persisting data with Ember Data
- Building a Taskify application
- Building the API server app
- Building the Taskify Ember app
- Summary
- 7. Integrating with Other Web Frameworks
- 1. Getting Started with Spring Core
- II. Module 2
- 1. Setup Routine for an Enterprise Spring Application
- Introduction
- Installing Eclipse for JEE Developers and Java SE 8
- Configuring Eclipse for Java 8, Maven 3, and Tomcat 8
- Defining the project structure with Maven
- Installing Spring, Spring MVC, and a web structure
- 2. Designing a Microservice Architecture with Spring MVC
- Introduction
- Configuring a controller with simple URL mapping
- Configuring a fallback controller using ViewResolver
- Setting up and customizing a responsive single page webdesign with Bootstrap
- Displaying a model in the View, using the JSTL
- Defining a common WebContentInterceptor
- Designing a client-side MVC pattern with AngularJS
- 3. Working with Java Persistence and Entities
- 4. Building a REST API for a Stateless Architecture
- Introduction
- Binding requests and marshalling responses
- Configuring content-negotiation (JSON, XML, and so on)
- Adding pagination, filters, and sorting capabilities
- Handling exceptions globally
- Documenting and exposing an API with Swagger
- 5. Authenticating with Spring MVC
- Introduction
- Configuring Apache HTTP to proxy your Tomcat(s)
- Adapting users and roles to Spring Security
- Authenticating over a BASIC scheme
- Authenticating with a third-party OAuth2 scheme
- Storing credentials in a REST environment
- Authorizing on services and controllers
- 6. Implementing HATEOAS
- 7. Developing CRUD Operations and Validations
- Introduction
- Extending REST handlers to all HTTP methods
- Validating resources using bean validation support
- Internationalizing messages and contents for REST
- Validating client-side forms with HTML5 AngularJS
- 8. Communicating Through WebSockets and STOMP
- Introduction
- Streaming social events with STOMP over SockJS
- Using RabbitMQ as a multiprotocol message broker
- Stacking and consuming tasks with RabbitMQ and AMQP
- Securing messages with Spring Session and Redis
- Getting ready
- How to do it…
- How it works...
- There's more…
- See also
- 9. Testing and Troubleshooting
- Introduction
- Automating Database Migrations with FlyWay
- Unit testing with Mockito and Maven Surefire
- Integration testing with Cargo, Rest-assured, and Maven failsafe
- Injecting Spring Beans into integration tests
- Modern application Logging with Log4j2
- Getting ready
- How to do it…
- How it works...
- There is more…
- Automatic configuration
- Official documentation
- Interesting Redis Appender implementation
- III. Module 3
- 1. Mastering the MVC Architecture
- 2. Handling Forms and Complex URL Mapping
- 3. File Upload and Error Handling
- 4. Crafting a RESTful Application
- 5. Securing Your Application
- 6. Leaving Nothing to Luck – Unit Tests and Acceptance Tests
- 7. Optimizing Your Requests
- 8. Deploying Your Web Application to the Cloud
- 9. Beyond Spring Web
- A. Bibliography
- Index
- 1. Setup Routine for an Enterprise Spring Application
This chapter contains the following recipes:
- Turning DTOs into Spring HATEOAS resources
- Building links for a Hypermedia-driven API
- Choosing a strategy to expose JPA entities
- Retrieving data from a third-party API with OAuth
What is HATEOAS? If you have never seen this word before, it can appear to be difficult to pronounce. Some pronounce it hate-ee-os; others say hate O-A-S. The important point is to remember that this abbreviation stands for Hypermedia as the Engine of Application State (HATEOAS). At the very least, you should remember Hypermedia. Hypermedia as a resource's capability to embed nodes that target external resources. Being connected to other resources, a hypermedia resource is also constrained to its domain, as it can't technically develop (as part of itself) other resources' domains.
Think of it as Wikipedia. If we create a page whose sections are not self contained in the page title (domain), and if one of these sections is already covered in an external page, there are few chances that this situation will be raised by an administrator.
HATEOAS is a constraint applicable to a REST architecture. It imposes on its resources a domain consistency, and at the same time, it imposes an explicit self documentation that the owner has to maintained for the sake of the whole cohesion.
The Richardson Maturity Model (by Leonard Richardson) provides a way to grade and qualify a REST API by its level of REST constraints:
The more REST-compliant an API is, the higher its grade.
The initial state in this model is Level 0: The Swamp of POX. Here, the protocol (usually HTTP) is only used for its transport capabilities (not for its state description features). Also, there are no resource-specific URIs here, just one endpoint is used for one method (normally, POST in HTTP).
Level 1: Resources is characterized by the implementation of resource-specific URIs. The resource identifiers can be found in URIs. However, still, only one method of the protocol is used (POST for HTTP again).
Level 2: HTTP Verbs reflects an improved use of the protocol properties. For HTTP, this actually means that the API is making use of the HTTP methods for their purpose (GET to read, POST to create, PUT to edit, DELETE to delete, and so on). Also, the API provides response codes that reliably inform the user about the operation state.
Level 3: Hypermedia Controls is the highest level in this model. It indicates the use of HATEOAS, which provides API-discovery features to the client.
You can read more on the Richardson Maturity Model on Martin Fowler's blog at:
http://martinfowler.com/articles/richardsonMaturityModel.html
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