REST API

What is REST API?

• REST stands for Representational State Transfer
• Uses HTTP and HTTP Standard request types to perform operations  on resource exposed by server
  • GET
  • PUT
  • POST
  • DELETE

What is a Resource?

Resource is a Domain Object around which API are exposed.

Resource Examples Consider you are creating School Management Application, here resources will be:

• Student
• Teacher
• ReportCard
• School
• Subject

Which HTTP request type is used for what kind of operation on resource in REST API?

• GET
  • Query specific resource
  • Query collection of resources
• PUT
  • Updating a resource
• POST
  • Creating a resource
• DELETE
  • Deleting a resource

REST stands for: Representational State Transfer, what do you mean by Representational State Transfer?

As per REST standards, Client and Server exchange Representation of Resource

• When creating a new resource, client sends representation of new resource and server saves it.
• When client wants its existing resource, it asks server for it and server sends representation of existing state of resource.
• When client wants to update state of resource on server side, it sends updated representation of resource.

Representation types

• XML
• JSON
• ProtoBuf

Representation being transferred contains:

• Data
• Metadata
• hypermedia links to transition to more information

Example

Create: Client sends data to Server

{
    name: Rakesh Kalra,
    age: 14
    course: science,
}

Get

{
    id: 1211
    name: Rakesh Kalra,
    age: 14
    course: science,
    createTime: 12-05-2020
}

Get All

[
    {
        id: 1211
        name: Rakesh Kalra,
        age: 14
        course: science,
        createTime: 12-05-2020
    },
    {
        id: 1222
        name: Harish Singh,
        age: 17
        course: commerce,
        createTime: 19-05-2020
    }
    ....
]

How updation of information works?

• Client ask server for current state of resource
• Client sends server updated state of resource

Can you give example of REST API with say example of Student URLs?

Operation	Request Type	URI	Request Body
Get all Students	GET	/api/students
Get specific Student	GET	/api/students/123
Create new Student	POST	/api/students	Request body will contain representation of new student
Update specific Student	PUT	/api/students/123	Request body will contain updated representation of specific student
Delete a Student	DELETE	/api/students/123