HTTP

• HTTP stands for Hyper Text Transfer Protocol, a stateless request-response application layer protocol

  • Applications built using HTTP subscribe to the client-server computing model

  • server: host designed to provide a service
  • client: hosts that make requests to the service

HTTP Requests

• The first line of a request contains a method, URL, and HTTP version. Following lines are request headers.

Key Terms regarding Methods:

safe: does not change the state of the server - should only be used for information retrieval

idempotent: identical requests of this type will get identical responses, no matter how many times they are called. All safe methods are also idempotent

cacheable: the client is able to cache the response

HTTP Method	Request has Body	Response has Body	Safe	Idempotent	Cachable
GET	no	yes	yes	yes	yes
HEAD	no	no	yes	yes	yes
POST	yes	yes	no	no	yes
PUT	yes	yes	no	yes	no
DELETE	no	yes	no	yes	no
CONNECT	yes	yes	no	no	no
OPTIONS	optional	yes	yes	yes	no
TRACE	no	yes	yes	yes	no
PATCH	yes	yes	no	no	no

HTTP Response

• The first line of a response contains an HTTP version, status code and status message. Following lines are request headers.

REST

• Acronym for REpresentational State Transfer - a means by which we can reference, manipulate and transfer state.

REST Method	CRUD Operation	Function
GET	READ	Retrieve 1+ Records
POST	CREATE	Create a New Record
PUT	UPDATE	Replace Record with an updated version
PATCH	UPDATE	Replace the updated portion of the Record
DESTROY	DELETE	Remove a Record

What Is A RESTful API? Explanation of REST & HTTP

API: Application Program Interface - a contract provided by one piece of software to another (request & response)

Video uses the GitHub API as an example of a RESTful API and demonstrates accessing data from the GitHub API using Postman

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