What is the HTTP protocol? Explanation of core concepts and working principles

in the current high-speed operation of the Internet, every total page browsing, file download or data interaction is supported by a set of invisible rules, and the HTTP protocol is the core existence. It is the "common language" of communication between the client side and the server, which determines how data is requested, transmitted and parsed. This article will dismantle the whole picture of the HTTP protocol for your system from the basic concepts, core features, workflow and other dimensions, and help you sort out the underlying logic of network communication.

What is the basic definition of the HTTP protocol?

to understand the role of the HTTP protocol, we must first clarify its essential positioning, which is the basis for mastering subsequent content.

1, the core essence of HTTP protocol

HTTP protocol is an application layer communication protocol based on TCP/IP protocol suite, which is specially used for hypertext data transmission between client side and server. Its core function is to standardize the format and flow of data interaction, so that different systems and different devices can smoothly complete data requests and responses, which is the underlying basis for the normal operation of the World Wide Web.

2, the application scenario of HTTP protocol

from daily web page visits, online video playback, to commodity inquiries and payment requests on e-commerce platforms, almost all web application interactions rely on HTTP protocol. In addition, the interface calls of mobile end APP, API data transmission and other scenarios are mostly based on HTTP protocol as a communication standard, which has penetrated into every corner of Internet applications.

What are the core features of the HTTP protocol?

HTTP protocol can become the mainstream standard of network communication, inseparable from its unique core characteristics, which determine its ease of use and adaptability.

1, stateless characteristics

The stateless nature of the

HTTP protocol means that the server does not record the historical request information of the client, and each request is an independent and brand-new interaction. This feature simplifies the design of the server and reduces resource consumption, but also leads to the inability to directly maintain the session state. Later, cookies, sessions and other technologies make up for this deficiency.

2, request-responsive architecture

HTTP protocol adopts a typical request-response mode, the communication is initiated by the client side actively, and the server passively receives the request and returns the response result. This architecture has clear logic, the client side can precisely control the request content, and the server focuses on processing and returning the corresponding data, ensuring the orderliness of the communication flow.

3, scalability features

HTTP protocol supports function expansion through custom header fields, request methods, etc., such as the later addition of PUT, DELETE request methods, and header fields for authentication and cache control, which are the embodiment of its scalability.

What is the request response process of HTTP protocol?

The core value of the

HTTP protocol is reflected in the specific communication process, which is also a key part of understanding its operation logic.

1, establishing a TCP connection

before initiating the HTTP protocol request, the client side will first establish a TCP connection with the server, which is the basis for reliable data transmission. Usually a three-way handshake is used to complete the connection establishment to ensure the smooth communication channel between the two parties. Only after the connection is established successfully can the subsequent HTTP protocol data exchange begin.

2, sending request and receiving response

connection is established, the client side will construct the request message according to the HTTP protocol specification, including the request method, request URL, request header and request body, etc., and send it to the server. After the server receives the request, it will parse the message content, process the corresponding business logic, and then construct a response message to return to the client side. The response message contains the status code, response header and response body.

3, close the TCP connection

when the client side receives the complete response data, the two sides will close the TCP connection by waving four times. However, in HTTP/1.1 and later, the persistent connection function is supported, which allows multiple HTTP protocol request responses to be completed in a TCP connection, effectively reducing the overhead of connection establishment and closure.

What are the major versions of the HTTP protocol?

with the development of Internet technology, HTTP protocol is also constantly iterative optimization, different versions of the characteristics of the difference directly affects the efficiency of communication.

1, HTTP/1.0 and HTTP/1.1 versions

HTTP/1.0 is the early mainstream version, but there is a problem that each request needs to establish a new TCP connection, and the communication efficiency is low. HTTP/1.1 introduces the characteristics of persistent connection and request pipeline, which greatly reduces the connection overhead. At the same time, OPTIONS, PUT and other request methods are added, which improves the function of the protocol and becomes the dominant version for a long time.

2, HTTP/2 and HTTP/3 versions

HTTP/2 adopts binary framing transmission, multiplexing and other technologies, which can simultaneously transmit multiple request responses in a TCP connection, further improving communication efficiency, and also supports server push function, which can actively send resources to the client side. HTTP/3 is based on QUIC protocol and uses UDP as the transport layer protocol, which solves the problem of TCP connection handshake delay and queue head blocking, and performs better in weak connection environment.

To sum up, HTTP protocol is the core foundation supporting Internet communication. From basic definition, core features to request response process, and then to version evolution, each part bears the key role of standardizing data interaction. Through the analysis of this article, I believe you have a systematic understanding of the whole picture of HTTP protocol. Its stateless nature, request response architecture and continuously optimized version jointly promote the efficient operation of Internet applications. It is the core knowledge that every Internet practitioner and enthusiast needs to master.