HTTP

What is HTTP? #

• HTTP is the Hypertext Transfer Protocol.

• HTTP was invented between 1989 and 1991.

• HTTP is the protocol inherent to the World Wide Web (WWW).

• HTTP is a protocol that allows data to be exchanged over the internet.

• Every time you visit a web page, your computer uses HTTP to download that page from another computer somewhere on the internet.

  http:// ......

What is a Protocol? #

• A protocol means a rule (or agreement).
• In computer networks, when exchanging data, developing according to these rules enables information exchange.
• Protocols were created based on the nature of sending and receiving data in computer networks.
• When exchanging web documents, HTTP must be used; for files, FTP; for mail, SMTP, POP, etc. Various protocols are created depending on the transport layer and type.

Why HTTP is Important in Web Development #

• Both clients and servers communicate using HTTP, so web developers must have a good understanding of HTTP.
• HTTP knowledge is also crucial for resolving errors.

The Invention of WWW (World Wide Web) #

• WWW refers to a structure for using web pages over a network.
• WWW was invented between 1989 and 1991 for exchanging files in a laboratory.
• In WWW, data exchange is carried out based on the communication method (protocol) called HTTP.
• WWW consists of four components.
  1. HTML, a text-based language and file format for expressing hypertext documents
  2. HTTP, a protocol for exchanging documents and other data over the internet
  3. Early versions of HTTPD that allowed access to documents, i.e., servers that support HTTP (building a web server is equivalent to running HTTPD).

Characteristics of HTTP #

1. Client-Server Architecture
2. Stateless Protocol
3. Connectionless
4. HTTP Messages
5. Simplicity, Extensibility

HTTP Connection-Oriented vs. Connectionless #

Connection-Oriented - A Model That Maintains Connections #

• In the case of TCP/IP, connections are fundamentally maintained.
• In a connection-oriented model, the connection must be maintained even if the client does not send a request.
• In such cases, server resources used to maintain the connection are continuously consumed.

Connectionless - A Model That Does Not Maintain Connections #

• In connectionless HTTP, a connection is maintained only when requests are actually exchanged, and the TCP/IP connection is terminated after the response is sent.
• This allows the server to be maintained with minimal resources.

Limitations and Overcoming Connectionlessness #

• Connectionlessness has the following limitations:

  • A new TCP/IP connection must be established.
  • When a website is requested via a web browser, numerous resources such as JavaScript, CSS, and additional images are downloaded along with the HTML.

• Repeatedly disconnecting and reconnecting for each of these resources is inefficient, so this problem is now solved with HTTP persistent connections.

• Further optimizations in HTTP/2, HTTP/3

Overcoming Connectionlessness - HTTP Persistent Connections #

• Early HTTP - Wasted connections and disconnections

  • In early HTTP, connections and disconnections had to be repeated to download each resource.

• HTTP Persistent Connections

  • In HTTP persistent connections, after a connection is established, resources are requested, and the connection is terminated only after responses for all resources have been received.