Tech

Intro of API, REST, and RESTful API

Wen-Yu Lee

16 Feb 2024 • 4 min read

REST & RESTFUL API are often asked in my interviews recently, so I decided to briefly record it.

What is API?

API(Application Programming Interface) is a way for applications, systems or components to communicate with each other.

What is REST?

REST is the abbreviation of Representational State Transfer. It is a software architecture and a design style for CRUD between the server and the client.
- CRUD represents CREATE/READ/UPDATE/DELETE
Some REST principles
- Unified interface: Abstract the details of operations and provide unified operation methods and specifications.
- Stateless: Stateless means that the server is independent of all previous requests, so the client can request resources in any order.
- Layered system: The client does not know how many layers the server has, and the server can even request resources from other servers.
- Cacheability: The client caches some information after getting the first response, and then directly uses the cache to obtain information later. (For example: header, footer, LOGO, etc. of each page in the website)
- Coding on demand: 1. Code on demand: Server can expand its functions at any time to meet the immediate needs of Client.

RESTful API

An API that conforms to the REST design style is called RESTful API
Advantages include :
- Scalability
  - Because REST optimizes client-server interaction, systems implementing REST APIs scale efficiently.
  - Statelessness eliminates server load since the server does not have to retain information about past client requests. Well-managed caches partially or completely eliminate some client-server interactions. All of these features support scalability without causing communication bottlenecks that reduce performance.
- Flexibility
  - RESTful web services support complete client-server separation.
  - Platform or technology changes to server applications will not affect client applications.
  - Layered application functionality further increases flexibility. For example, developers can make changes to the database layer without rewriting application logic.
- Independence
  - REST API is independent of the technology used
    - Client and server applications can be written in a variety of programming languages without affecting API design.
    - You can also change the underlying technology on either end without affecting communication

Implement the RESTful API

Unique resource identifier
The server uses a unique resource identifier to identify each resource.
- For REST services, servers typically use Uniform Resource Locators (URLs) to perform resource identification.
- URL specifies the path to the resource. A URL is similar to the website address you enter into your browser to view any web page. A URL, also called a request endpoint, clearly specifies to the server what the client needs.
Common Http methods include
- GET
- POST
- PUT
- DELETE
- PATCH
  - differences between POST and PATCH
    - PATCH : Partial update to a resource
    - POST : Replace the entire resource with a new representation
HTTP header: Relay data between Client and Server, including required parameters (path parameters, Cookie parameters, etc.)

Examples

index | /comments | GET | all information

new | /comments | GET | Form to display new information

create | /comments/new | POST | New information

show | /comments/:id | GET | Show information

edit | /comments/:id/edit | GET | show information

update | /comments/:id | PATCH | Edit information

delete | /comments/:id/edit | DELETE | Edit information