What does HTTP protocol stateless mean? What is the mechanism for making a web application stateful?

Generally, it needs to be normalized (minus the mean, dividing the variance). The benefit can reduce the variance and make different variables intersect at the same scale. Its economic implication is the additional explanatory power of union.

HTTP stateless protocol means that the protocol does not have the ability to remember transactions. The lack of state means that if the previous information is needed for subsequent processing, it must be retransmitted, which can result in an increased amount of data being transferred per connection. On the other hand, it responds faster when the server does not need previous information.

After the emergence of web applications that dynamically interact with the server, the stateless nature of HTTP has seriously hindered the implementation of these applications, after all, the interaction needs to be carried forward, and a simple shopping cart program needs to know what the user has chosen before. As a result, two technologies for maintaining HTTP connection state have emerged, one is a cookie, and the other is a stateless connection protocol itself, in order to support the interaction between the client and the server, we need to store state for the interaction through different technologies, and these different technologies are cookies and sessions.

Cookies are a solution that keeps state through the client. By definition, a cookie is a piece of information that is sent by the server to the client, which is stored on the client as a text file, and then the client carries this special information with it every time the client sends a request to the server. Let's be a little more specific:

When a user accesses a cookie-enabled device using a browser, the user provides personal information, including a username, and submits it to the server; Then, when the server sends back the corresponding hypertext to the client, it will also send back this personal information, of course, this information is not stored in the HTTP response body, but in the HTTP response header; When the client browser receives a response from the server, the browser stores this information in a unified location, and for Windows operating systems, we can find the stored cookies from the [system disk]: documents and settings [username] cookies directory; From then on, when the client sends a request to the server, it sends the corresponding cookie back to the server again.

This time, the cookie information is stored in the HTTP request header.

The HTTP protocol is stateless.

This refers to the HTTP version. It's all stateful at first.

Stateless means that when the browser sends a request to the server, the server responds, but when the same browser sends a request to the server to sell Jane, it will respond, but he doesn't know that you are matched with the browser just now, in short, the server will not remember you.

The core content of the HTTP protocol.

Don't know which part of the content you want.

Let's talk about the format of the HTTP protocol.

The format of the HTTP protocol is as follows.

headmethod method (get or post, etc.) filepath The path to request the file.

version http (or so on).

parameter (the list of parameters passed to the server by the post method).

Connectionless means limiting each connection to only one request per connection. Once the server has processed the customer's request and received a response from the customer, it disconnects. In this way, you can save transfer time.

Stateless means that the protocol does not have the ability to remember transactions, and the server does not know what state the client is. That is, after we send an HTTP request to the server, the server will send us data according to the request, but after sending, no information will be recorded.