02. Introduction to HTTP

Introduction to HTTP

Introduction to HTTP

FSND C2 L2 A02 Introduction To HTTP

Hypertext Transfer Protocol (HTTP) is a protocol that provides a standardized way for computers to communicate with each other. It has been the foundation for data communication over the internet since 1990 and is integral to understanding how client-server communication functions.

In this lesson, we'll discuss key features and elements of HTTP.

Features:

  • Connectionless: When a request is sent, the client opens the connection; once a response is received, the client closes the connection. The client and server only maintain a connection during the response and request. Future responses are made on a new connection.
  • Stateless: There is no dependency between successive requests.
  • Not Sessionless: Utilizing headers and cookies, sessions can be created to allow each HTTP request to share the same context.
  • Media Independent: Any type of data can be sent over HTTP as long as both the client and server know how to handle the data format. In our case, we'll use JSON.

Elements:

  • Universal Resource Identifiers (URIs): An example URI is http://www.example.com/tasks/term=homework . It has certain components:
    • Scheme: specifies the protocol used to access the resource, HTTP or HTTPS. In our example http .
    • Host: specifies the host that holds the resources. In our example www.example.com .
    • Path: specifies the specific resource being requested. In our example, /tasks .
    • Query: an optional component, the query string provides information the resource can use for some purpose such as a search parameter. In our example, /term=homework .

Side Note: URI vs URL

You may be unsure what the difference is between a URI ( Universal Resource Identifier ) and a URL ( Universal Resource Locator ). These terms tend to get confused a lot, and are even frequently used interchangeably—but there is a distinction.

The term URI can refer to any identifier for a resource—for example, it could be either the name of a resource or the address of a resource (since both the name and address are identifiers of that resource). In contrast, URL only refers to the location of a resource—in other words, it only ever refers to an address .

So, "URI" could refer to a name or an address, while "URL" only refers to an address. Thus, URLs are a specific type of URI that is used to locate a resource on the internet when a client makes a request to a server.

And if you really want to dive into the topic, here are some further readings (with examples and Venn diagrams):

What is the entire URL of the resource being requested based on the following HTTP request? 

POST /stores/1/pastries HTTP/2.0
Host: http://www.coffee-example.com
Accept-Language: en
Body: { 'name': 'croissant', 'price':3.99 }
SOLUTION: `http://www.coffee-example.com/stores/1/pastries`

QUIZ QUESTION: :

Match the features of HTTP communication to their descriptions.

ANSWER CHOICES:



HTTP Features

Descriptions

NOT Sessionless

Stateless

Connectionless

Media Independent

SOLUTION:

HTTP Features

Descriptions

NOT Sessionless

Stateless

Connectionless

Media Independent

Which of these are features of HTTP?
(Select all that apply.)

Note: Read the options carefully!

SOLUTION:
  • Stateless
  • Connectionless

Which feature of HTTP solves for the following problem?

The client makes a request and opens a connection over port 3000 to the server. When they receive the response, that port doesn't close. When a new request is sent, it fails because the port is occupied.

SOLUTION: Connectionless

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