Getting started with the HTTP protocol (i)-Historical evolution

When we enter a URL in the address bar of the browser, the message is sent to the Web server, the server responds, and the data is transferred back to the Web page, where the transmission method is the HTTP protocol.

One, HTTP 0.9

• Released in 1991, it is the first HTTP version and is simple to function.

1. Only the GET request method is supported, the server responds with a data format that is formatted as an HTML string;

   GET / index.html

2. The request header is not supported, so the content format can only be plain text;

3. Stateless, the request is closed after the response, if there is an error, do not return the error code;

Second, HTTP 1.0

• Released in May 1996, the second version of the HTTP protocol, the first HTTP protocol version that specifies the version number in the communication, is still widely used today. The following main features are added relative to HTTP 0.9:

1. Content in any format can be sent. This allows the Internet not only to transfer text, but also to transfer images, video, binary files. This laid the foundation for the great development of the Internet.
2. In addition to the GET command, the post command and Head command are introduced to enrich the browser's interaction with the server.

3. The format of the HTTP request and response has changed. In addition to the data section, each communication must include the header information (HTTP header), which is used to describe some meta-data.

4. Supports long connections (but with short connections by default), caching mechanisms, and authentication.

5. Other new features include status code, multi-character set support, multipart send (multi-part type), permissions (authorization), caching (cache), content encoding (contents encoding), and more.

   GET / HTTP/1.0User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5)Accept: */*

Third, HTTP 1.1

• In January 1997, the http/1.1 version was released only half a year later than the 1.0 version. It further improved the HTTP protocol, which has been used 20 years later today, and is still the most popular version.

1. Persistent connection.
2. Pipeline mechanism, with multiple requests simultaneously.
3. Content-length field, declaring the data length.
4. Block transfer coding for improved efficiency.
5. Added a number of verb methods: PUT, PATCH, HEAD, OPTIONS, DELETE.
6. The client header information is incremented by the host field, which represents the requested principal domain name.

Iv. HTTP 2

• 2015, HTTP/2 released. It is not called http/2.0, because the standard Committee does not intend to release the child version again, the next new version will be HTTP/3.

1. Binary protocol
2. Data flow, you can cancel the request to continue to be used by other requests without interrupting the TCP connection.
3. Header information Compression
4. Websoket Full duplex Communication, can implement server push and so on.

Reference links

1. Getting Started with HTTP protocol-Nanyi
2. HTTP protocol in the past life--versions of HTTP protocol comparison
3. [Graphic HTTP protocol-Ueno Xuan]

Getting started with the HTTP protocol (i)-Historical evolution