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HTTP protocol version of the HTTPD protocol
1. Structure overview
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in the HTTP protocol chapter, I will introduce six parts, this article first describes the protocol version of HTTP.
2.http Protocol version
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The history of the HTTP protocol is not long, from 1991 of the 0.9 version to now (2017) only more than 20 years, calculated that the HTTP is still in the youth, it is a good time to develop. Though less than 27, it has changed the way human beings know the world. Here, we must bow to the great sages and salute them.
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The 0.9 version feature is very simple, just a get function, get translation came to be obtained, here refers to the acquisition of resources. The new version 1.0 was released five years later because of the poor functionality and nature of the application.
The 1.0 version is rich in content and adds a lot of functionality. Get resource, Post send resource, head holds the header information of the resource. The Multipurpose Internet Mail Extension (mime,multipurpose) is an Internet standard that extends e-mail standards, supports multimedia data transfer, and greatly enriches the HTTP protocol.
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The http1.0 version request format is as follows:
get/http/1.0
user-agent:mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5)
Accept: */*
The response format is like this:
http/1.0 OK
Content-type:text/plain
content-length:137582
Expires:thu, Dec 1997 16:00:00 GMT
Last-modified:wed, 5 August 1996 15:55:28 GMT
Server:apache 0.84
<body>hello world</body>
Although the http1.0 function is already very powerful, there are still drawbacks. Each TCP connection can send only one request, so the new TCP connection is expensive and inefficient, so the keep-alive mechanism, the persistent connection, was later introduced. Simple to understand, that is, long-time connection uninterrupted.
http1.0 function is very powerful, therefore increased the people's dependence on the HTTP protocol, with a wide range of applications and audience applause, the developers of the HTTP protocol like the chicken Blood, only a half-yearly release of http1.1. People often say slow work out deliberately, sorry, it doesn't apply. It's more like the condensed product of time here is the essence. http1.1 is more powerful, so it's still in use today.
The advantages of the http1.1 protocol are as follows:
1. Enhanced cache function, currently popular version
2. The introduction of a persistent connection (persistent connection)
3. The pipeline mechanism (pipelining) is introduced, and the client can send multiple requests at the same time.
4. Introduce the Content-length field to mark the content length
5. The introduction of chunked transmission coding, greatly increased the speed of transmission
6. Richer Method:get, POST, Head,put, Delete,trace, Options,host
http1.1 data in order to communicate, there is a team head jam problem. There are two common ways to unblock nature and dredge it:
1. Reduce the number of requests
2. Simultaneously open persistent connections more
Reduce the number of requests very well understood, no longer verbose. Multiple open persistent connections, essentially also reduce the number of requests, avoid unnecessary to frequent disconnects. Because of these two ways, there are a lot of solving techniques, and the techniques are as follows:
1. Merge scripts and style sheets,
2. Embed the image in the CSS code
3. Domain name Shard (sharding)
Based on efficiency and safety considerations, HTTP2 a strong debut. HTTP2 's predecessor is Google's Spdy agreement, Spdy protocol is very powerful, HTTP research engineer, self-inductance Alexander, so too hectic to research and development in addition to HTTP2 protocol. HTTP2 has the following features:
1. Predecessor: SPDY Agreement (Google)
2. Complete binary protocol, header information and data body are binary, improve efficiency, increase security
3. Multiplexing (multiplexing), which is connection sharing, avoids block head blockage
4. Data stream transmission, increase transmission efficiency
5. Header information compression, reducing the size of the transmission
6. Server Push
At this point, the HTTP protocol version is complete, thanks for viewing, the next section describes a complete HTTP request process.
Resources:
Http://www.ruanyifeng.com/blog/2016/08/http.html
http://www.alloyteam.com/2016/07/httphttp2-0spdyhttps-reading-this-is-enough/
This article is from the "complete more important than perfect" blog, please be sure to keep this source http://powermichael.blog.51cto.com/12450987/1931998
Mind Mapping Analysis HTTP version of HTTP protocol
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