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3 min readOctober 19, 2023

🍉 HTTP

http
networks

What is The Hypertext Transfer Protocol (HTTP)

It is an application protocol for distributed, collaborative, hypermedia information systems.

  • responsible for communication between web servers and clients

HTTP request methods

HTTP defines a set of request methods (HTTP verbs) to indicate the desired action to be performed for a given resource.

Each of them implements a different semantic, but some common features are shared by a group of them: e.g. a request method can be safe, idempotent, or cacheable.

  • GET
    • retrieves data from the server
    • The GET method requests a representation of the specified resource. Requests using GET should only retrieve data.
  • POST
    • submits data to the server
    • The POST method submits an entity to the specified resource, often causing a change in state or side effects on the server.
  • PUT
    • update data already on the server
    • The PUT method replaces all current representations of the target resource with the request payload.
  • DELETE
    • delete data from the server
    • The DELETE method deletes the specified resource.
  • CONNECT The CONNECT method establishes a tunnel to the server identified by the target resource.
  • OPTIONS The OPTIONS method describes the communication options for the target resource.
  • TRACE The TRACE method performs a message loop-back test along the path to the target resource.
  • PATCH The PATCH method applies partial modifications to a resource.
  • HEAD The HEAD method asks for a response identical to a GET request, but without the response body.

HTTP header fields

General Header Fields:

  • Cache-Control
  • Connection
  • Date
  • Pragma
  • Trailer
  • Transfer-Encoding
  • Upgrade
  • Via

Response-Specific Header Fields:

  • Accept-Ranges
  • Age
  • Content-Encoding
  • Content-Language
  • Content-Length
  • Content-Location
  • Content-Type
  • Expires
  • Last-Modified
  • Server
  • Set-Cookie

Request-Specific Header Fields:

  • Accept
  • Accept-Encoding
  • Accept-Language
  • Authorization
  • Content-Length
  • Content-Type
  • Cookie
  • Host
  • Referer
  • User-Agent

HTTP status code

General

  • 1xx: informational
  • 2xx: success
  • 3xx: redirect
  • 4xx: client error
  • 5xx: server error
  • 200: ok
  • 201: ok created
  • 301: moved to new url
  • 304: not modified (cached version)
  • 400: bad request
  • 401: unauthorized
  • 404: not found
  • 500: internal server error

RESTful APIs Routes

  • Index Route: GET /books
    • return all the items of a database table
  • Show Route: GET /books:id
    • returns a single item
  • Create Route: POST /books
    • returns the newly created item
  • Edit/Update Route: PUT /books:id or PATCH /books:id
    • returns the updated item
  • Delete Route: DELETE /books:id
    • returns the deleted item

Why REST is useful

For providing a predictable, industry standard, well-organized way to structure API endpoints.

Notes

  • every request is independent
  • http is stateless
  • each request consist of a header and a body

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