Brief introduction
HTTP protocol is widely used at present, whether it is Internet browser, APP listen to music or play games, whether it is Android, Linux or Windows, are behind the HTTP protocol as a support, silent service. So shows the importance of the HTTP protocol, this section introduces the history of the development of HTTP.
HTTP/0.9
The early 1990s, the Internet world is very simple, low computer processing power, storage capacity is small, Suman, or an "information desert."
The vast majority of resources on the network are plain text, many communication protocols also use plain text, so the design of HTTP inevitably limited time.
This period HTTP version 0.9 is defined as a relatively simple structure, in order to facilitate the processing server and the client, it uses the plain text. Tim Berners - Lee envisioned a system early in the document are read-only, so only allows "GET" action to get the HTML document from the server, and close the connection immediately after the response to the request, which is very limited.
HTTP/1.0
In 1993, NCSA (National Center for Supercomputing Applications) developed Mosaic, the first browser can be photo-text, and subsequently developed the Apache server software in 1995, simplifies the construction work of the HTTP server.
During the same period, computer multimedia technology has also been a new development: in 1992, invented the JPEG image format, in 1995 invented the MP3 music format.
These new software new technology as soon as immediately attracted the enthusiasm of Internet users, but the more people begin to use the Internet, research HTTP and suggest improvements, even experimentally to agreement in adding various characteristics, promote from the perspective of user needs the development of HTTP.
So on the basis of these existing practice, through a series of draft, HTTP / 1.0 version released in 1996. It is in many ways enhanced version 0.9, and we now have the form of HTTP is not very different, for example:
- Added new method HEAD, POST, etc.
- Increase the response status code, markup possible causes of errors
- It introduces the concept of protocol version number
- Introduces the concept of HTTP Header (head), so that HTTP request and response more flexible
- Data transmission is no longer limited to text
However, HTTP / 1.0 is not a standard, is only a prototype, the Internet was the intention of the parties or their own subject.
HTTP/1.1
In 1995, Netscape's Netscape Navigator and Microsoft Internet Explorer to start the famous "browser wars", we want to dominate on the Internet. The war has greatly promoted the development of the Web, HTTP / 1.0 also in the process withstood the test of practice. So in 1999, after the "browser wars" ended, HTTP / 1.1 RFC documents issued, numbered 2616, different from the HTTP / 1.0, HTTP / 1.1 became the official standard of the Internet, until now continued to widely used.
HTTP / 1.1 compared to HTTP / 1.0, not a lot of change, after years of practice, the main changes are as follows:
- Adds new methods PUT, DELETE, etc.
- Increased cache management and control
- Support long connection (but still using the default short connections)
- Allowing response data block (chunked), facilitate the transmission of large files
- Mandatory Host header so that the Internet hosting possible
HTTP/2
After the HTTP / 1.1 release, the entire Internet world has shown a explosive growth, the emergence of a Taobao, FaceBook, Jingdong and other Internet giants.
With the rapid development of the Internet, HTTP / 1.1, there have been some drawbacks, the connection speed is slow, can not keep up with the rapid development of the Internet. So there have been many optimization methods, such as the common cut plan, JS merger and other means. And after all these palliatives, Google finally launched a new SPDY protocol, and Chrome was used in its own server, HTTP started a new round of reform.
Internet-based standardization organizations SPDY begun to develop a new version of the HTTP protocol, and finally released the HTTP / 2 in 2015, RFC number 7540.
Development of HTTP / 2 full account of the current status of the Internet: broadband, mobile, secure, highly compatible in HTTP / 1.1 at the same time made great efforts in improving performance, the main features are:
- Binary protocol, is no longer plain text
- You may initiate multiple requests, in the abandoned pipeline 1.1
- Dedicated header compression algorithm to reduce the amount of data transmission
- It allows the server to take the initiative to push data to the client
- Enhanced security, "de facto" require encryption communication
HTTP / 2.0 has now been launched for four years, but is still widely used HTTP / 1.1, 2.0 transition was thinking.
HTTP/3
In HTTP / 2 is still in the draft of, Google has invented a new protocol, called QUIC, continue to apply in Chrome and home server where relying on its massive amount of users and amount of data, continue to promote QUIC protocol to be on the Internet standard.
In 2018, the Internet standardization organization IETF proposed "HTTP over QUIC" was renamed "HTTP / 3" and approved, HTTP / 3 has officially entered the standardized formulation stage, perhaps after 2023 will be officially released, then we are may be skipped HTTP / 2 directly to HTTP / 3.
to sum up
- HTTP protocol began thirty years ago, Tim Berners - Lee's paper
- HTTP / 0.9 is a simple text-based protocol, you can only get the text resources
- HTTP / 1.0 established most of the technology currently in use, but it is not an official standard
- HTTP / 1.1 is currently used widely on the Internet protocol, functions very well
- HTTP / 2 based on Google's SPDY protocol, focus on improving performance, but not yet universal
- HTTP / 3 based on Google's QUIC protocol, is the future direction of development