Richardson Maturity Model

Richardson Maturity Model – Level 0, Level 1, and Level 2 (HATEOAS) are explained

Level 0

Level 1

  • Expose Resources with proper URI’s (using nouns).
  • http://server/accounts, http://server/accounts/10.
  • HTTP Methods are not used.
  • POST – Create a new resource
  • GET – Read a resource
  • PUT – Update an existing resource (complete replacement)
  • PATCH – Partial update
  • DELETE – Delete a resource

Level 2

  • Resources use proper URI’s + HTTP Methods.
  • For example, to update an account, you do a PUT to .
  • The create an account, you do a POST to .
  • Uri’s look like posts/1/comments/5 and accounts/1/friends/1.

Level 3

  • HATEOAS (Hypermedia as the engine of application state).
  • You will tell not only about the information being requested but also about the next possible actions that the service consumer can do.
  • When requesting information about a facebook user, a REST service can return user details along with information about how to get his recent posts, how to get his recent comments and how to retrieve his friend’s list.

Configuration

   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-hateoas</artifactId>
    </dependency>

@GetMapping("/students/{id}")
public Resource<Student> retrieveStudent(@PathVariable long id) {
  Optional<Student> student = studentRepository.findById(id);

  if (!student.isPresent())
    throw new StudentNotFoundException("id-" + id);

  Resource<Student> resource = new Resource<Student>(student.get());

  ControllerLinkBuilder linkTo = linkTo(methodOn(this.getClass()).retrieveAllStudents());

  resource.add(linkTo.withRel("all-students"));

  return resource;
}

JSON response

{
  "id": 10001,
  "name": "Ranga",
  "passportNumber": "E1234567",
  "_links": {
    "all-students": {
      "href": "http://localhost:8080/students"
    }
  }

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