# 6、gRPC组件Http 2.0

* [HTTP 2.0](/golang/grpc/http2.md#HTTP-20)
  * [尝鲜一下](https://www.selinux.tech/golang/grpc/pages/-LhJ-YQaMc8FzG5wi0Ap#尝鲜一下)
  * [HTTP 1.1 VS HTTP 2.0](/golang/grpc/http2.md#HTTP-11-VS-HTTP-20)
  * [gRPC基于HTTP/2的优缺点](https://www.selinux.tech/golang/grpc/pages/-LhJ-YQaMc8FzG5wi0Ap#gRPC基于HTTP2的优缺点)

关于 HTTP 2.0 具体有哪些新的内容，标准发生了什么变化，或许不是一篇文章就能够说明白的。或许，我们自己瞎解释一通，不如将一些有用的资料列举出来更有意义。

## 尝鲜一下

首先，我们来直观的体验一下HTTP2.0 。 [HTTP/2 is the future of the Web, and it is here!](https://http2.akamai.com/demo) Akamai 公司 建立了一个在线的演示，可以直观的感受HTTP1.1与HTTP2.0的差距。

![HTTP/2 is the future of the Web, and it is here!](/files/-LhKPhIf-IA72hr-j2FR)

如果我们打开chrome的调试工具，切换到network选项，可以看到，同样是对390张图片的传输，HTTP 1.1 与 HTTP 2.0 有着明显的区别。

![HTTP 1.1](/files/-LhKPhIh6C9e7VycLWV1)

![HTTP 2.0](/files/-LhKPhIjK5G604jifknn)

## HTTP 1.1 VS HTTP 2.0

下面是查阅的一些资料，获取能让我们明白具体什么是HTTP2.0,以及它与HTTP1.1的区别。

* [HTTP/2](https://http2.github.io/)
* [Hypertext Transfer Protocol Version 2 (HTTP/2)(rfc7540)](https://httpwg.org/specs/rfc7540.html)
* [HTTP/2 简介](https://developers.google.com/web/fundamentals/performance/http2/?hl=zh-cn)
* \[http2讲解]<https://ye11ow.gitbooks.io/http2-explained/content/>
* [gRPC over HTTP2](https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md)

## gRPC基于HTTP/2的优缺点

**优点**

* HTTP/2是一个经过实践检验的公开的标准
* 天然支持手机、物联网、浏览器
* 多语言实现容易，每种流行的编程语言都有自己的HTTP/2 Client
* HTTP/2支持Stream和流控
* 基于HTTP/2 在Gateway/Proxy很容易支持
* HTTP/2 安全性有保证
* HTTP/2 鉴权成熟

**缺点**

* rpc的元数据的传输不够高效
* HTTP/2 里一次gRPC调用需要解码两次,一次是HEADERS frame，一次是DATA frame
* HTTP/2 标准本身是只有一个TCP连接，但是实际在gRPC里是会有多个TCP连接，使用时需要注意

参考 [思考gRPC ：为什么是HTTP/2](https://blog.csdn.net/hengyunabc/article/details/81120904)


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