What are HTTP functions?

We all know that HTTP is the core of WWW. However, the specific HTTP protocol features may not be fully described by many friends. Now, let's explain this question in detail. To sum up what HTTP functions are available. Now, let's take a look at the basic concepts of HTTP.

The development of HTTP is the result of cooperation between World Wide Web Consortium and Internet team Internet Engineering Task Force. They) finally released a series of RFC, the most famous one is RFC 2616. RFC 2616 defines a common version of the HTTP protocol-HTTP 1.1.

HTTP is the standard TCP for client and server requests and responses ). The client is an end user and the server is a website. By using a Web browser, Web crawler, or other tools, the client initiates an HTTP request to the server with the default port 80. This client is called the user agent ). The response server stores some) resources, such as HTML files and images. We call it) The response server is the origin server of the source server ). There may be multiple middle layers between the user proxy and the source server, such as the proxy, gateway, or tunnels ). Although TCP/IP is the most popular application on the internet, HTTP does not stipulate that it must be used and based on) the layer it supports. In fact, HTTP can be implemented on any other Internet protocol or on another network. HTTP only assumes that its lower-layer protocol provides reliable transmission. Any protocol that can provide this guarantee can be used by it.

Generally, an HTTP client initiates a request to establish a TCP connection to the specified port on the server, which defaults to port 80. The HTTP server listens to the requests sent from the client on that port. Once a request is received, the server sends a status line, such as "HTTP/1.1 200 OK" and the Response) message to the client, the message body may be the requested file, error message, or other information.
The reason why HTTP uses TCP instead of UDP is to open a webpage) a webpage must transmit a lot of data, while TCP provides transmission control, organizes data in order, and corrects errors.

Resources requested through HTTP or HTTPS are identified by the Uniform Resource Identifier Uniform Resource Identifiers) or, more accurately, URLs.

HTTP Functions

HTTP is a hypertext transfer protocol and an application-layer communication protocol between a client browser or other programs and a Web server. The Web server on the Internet stores hypertext information. The client needs to transmit the hypertext information to be accessed through HTTP. HTTP contains commands and transmission information, which can be used not only for Web access, but also for communication between other Internet/Intranet application systems, so as to integrate various application resources with hypermedia access.

When we want to browse a website, just enter the address of the website in the address bar of the browser, for example, www.abc.com, but in the address bar of the browser appears is: http://www.abc.com, do you know why there is an additional "http? The website address we enter in the address bar of the browser is called URL (Uniform Resource Locator, unified Resource Locator ). Just as each household has a home address, each webpage also has an Internet address. When you enter a URL in the address box of the http function browser or click a hyperlink, the URL determines the address to be browsed. The browser extracts the website code on the Web server through the Hypertext Transfer Protocol (HTTP) and translates it into beautiful Web pages. Therefore, before we understand HTTP, it is necessary to clarify the URL composition, for example, http://www.abc.com/china/index.htm.

Its meaning is as follows:

1. http: //: indicates the hypertext transfer protocol, which notifies the abc.com server to display a Web page. Generally, no input is required;

2. www: represents a Web world wide Web server;

3. abc.com/:this is the domain name of the server with web pages or the name of the site server;

4. China/: The subdirectory on the server, just like our folder;

5. Index.htm: index.htm is an HTML file webpage in the folder ).

We know that the basic protocol of the Internet is the TCP/IP protocol, but the upper layer of the TCP/IP model is the Application layer. It contains all high-level protocols. High-level protocols include file transfer protocol FTP, email transmission protocol SMTP, Domain Name System Service DNS, network news transmission protocol NNTP and HTTP.

HTTP HyperText Transfer Protocol (HyperText Transfer Protocol) is a Transfer Protocol used to Transfer HyperText from a WWW server to a local browser. HTTP has many functions, which can make the browser more efficient and reduce network transmission. It not only ensures that the computer transfers hypertext documents correctly and quickly, but also determines which part of the transmitted documents and which part of the content is first displayed (such as text before graphics. This is why all the web addresses you see in your browser start with http.

Since the birth of WWW, a colorful information and virtual world have appeared in front of us, but how can we find the information we need more easily? After deciding to use hypertext as the standard format for WWW documents, in 1990, scientists immediately developed a protocol to quickly search for these hypertext documents, namely HTTP. After several years of use and development, it has been continuously improved and expanded. Currently, the sixth version of HTTP/1.0 is used in WWW.