iOS HTTP/2 Server Push 探索

作者: 李剑飞的简书 | 来源:发表于2017-04-11 18:09 被阅读1135次

    本文首发地址为-iOS HTTP/2 Server Push 探索 | 李剑飞的博客


    HTTP/2

    HTTP/2 Server Push 是什么

    当用户的浏览器和服务器在建立链接后,服务器主动将一些资源推送给浏览器并缓存起来,这样当浏览器接下来请求这些资源时就直接从缓存中读取,不会在从服务器上拉了,提升了速率。举一个例子就是:

    假如一个页面有3个资源文件index.html,index.css,index.js,当浏览器请求index.html的时候,服务器不仅返回index.html的内容,同时将index.css和index.js的内容push给浏览器,当浏览器下次请求这2两个文件时就可以直接从缓存中读取了。

    如下图所示:


    Apple-http2ServerPush

    HTTP/2 Server Push 原理是什么

    要想了解server push原理,首先要理解一些概念。我们知道HTTP/2传输的格式并不像HTTP1使用文本来传输,而是启用了二进制帧(Frames)格式来传输,和server push相关的帧主要分成这几种类型:

    1. HEADERS frame(请求返回头帧):这种帧主要携带的http请求头信息,和HTTP1的header类似。
    2. DATA frames(数据帧) :这种帧存放真正的数据content,用来传输。
    3. PUSH_PROMISE frame(推送帧):这种帧是由server端发送给client的帧,用来表示server push的帧,这种帧是实现server push的主要帧类型。
    4. RST_STREAM(取消推送帧):这种帧表示请求关闭帧,简单讲就是当client不想接受某些资源或者接受timeout时会向发送方发送此帧,和PUSH_PROMISE frame一起使用时表示拒绝或者关闭server push。

    (PS:HTTP/2相关的帧其实包括10种帧,正是因为底层数据格式的改变,才为HTTP/2带来许多的特性,帧的引入不仅有利于压缩数据,也有利于数据的安全性和可靠传输性。)

    了解了相关的帧类型,下面就是具体server push的实现过程了:

    1. 由多路复用我们可以知道HTTP/2中对于同一个域名的请求会使用一条tcp链接而用不同的stream ID来区分各自的请求。
    2. 当client使用stream 1请求index.html时,server正常处理index.html的请求,并可以得知index.html页面还将要会请求index.css和index.js。
    3. server使用stream 1发送PUSH_PROMISE frame给client告诉client我这边可以使用stream 2来推送index.js和stream 3来推送index.css资源。
    4. server使用stream 1正常的发送HEADERS frame和DATA frames将index.html的内容返回给client。
    5. client接收到PUSH_PROMISE frame得知stream 2和stream 3来接收推送资源。
    6. server拿到index.css和index.js便会发送HEADERS frame和DATA frames将资源发送给client。
    7. client拿到push的资源后会缓存起来当请求这个资源时会从直接从从缓存中读取。

    Server Push 怎么用

    使用 nghttp2 调试 HTTP/2 流量

    查看 HTTP/2 流量的几种方式

    • 在 Chrome 地址栏输入 chrome://net-internals/#http2,使用 Chrome 自带的 HTTP/2 调试工具;
      使用方便,但受限于 Chrome 浏览器,对于 Chrome 不支持的 h2c(HTTP/2 Cleartext,没有部署 TLS 的 HTTP/2)协议无能为力。同时,这个工具显示的信息经过了解析和筛选,不够全面。
    • 使用 Wireshark 调试 HTTP/2 流量;
      Wireshark 位于服务端和浏览器之间,充当的是中间人角色,用它查看 HTTP/2 over HTTPS 流量时,必须拥有网站私钥或者借助浏览器共享对称密钥,才能解密 TLS 流量,配置起来比较麻烦。

    nghttp2,是一个用 C 实现的 HTTP/2 库,支持 h2c。它可以做为其它软件的一部分,为其提供 HTTP/2 相关功能(例如 curl 的 HTTP/2 功能就是用的 nghttp2)。除此之外,它还提供了四个有用的 HTTP/2 工具:

    • nghttp:HTTP/2 客户端;
    • nghttpd:HTTP/2 服务端;
    • nghttpx:HTTP/2 代理,提供 HTTP/1、HTTP/2 等协议之间的转换;
    • h2load:HTTP/2 性能测试工具;

    nghttp2 安装

    先来用 brew 看一下有没有 nghttp 相关的库:

    ~ brew search nghttp
    nghttp2
    

    看来是有 nghttp2 的,再用 brew 看下需要安装哪些环境:

    ~ brew info nghttp2
    nghttp2: stable 1.21.0 (bottled), HEAD
    HTTP/2 C Library
    https://nghttp2.org/
    Not installed
    From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/nghttp2.rb
    ==> Dependencies
    Build: sphinx-doc ✘, pkg-config ✔, cunit ✘
    Required: c-ares ✘, libev ✘, openssl ✔, libevent ✘, jansson ✘, boost ✘, spdylay ✘
    Recommended: jemalloc ✘
    ==> Requirements
    Optional: python3 ✔
    ==> Options
    --with-examples
        Compile and install example programs
    --with-python3
        Build python3 bindings
    --without-docs
        Don't build man pages
    --without-jemalloc
        Build without jemalloc support
    --HEAD
        Install HEAD version
    

    看来需要的依赖还挺多。

    使用 brew 安装 nghttp2 :

    brew install nghttp2
    

    一切妥当后,nghttp2 提供的几个工具就可以直接用了。

    nghttp

    nghttp 做为一个功能完整的 HTTP/2 客户端,非常适合用来查看和调试 HTTP/2 流量。它支持的参数很多,通过官方文档或者 nghttp -h 都能查看。最常用几个参数如下:

    • -v, --verbose,输出完整的 debug 信息;
    • -n, --null-out,丢弃下载的数据;
    • -a, --get-assets,下载 html 中的 css、js、image 等外链资源;
    • -H, --header = < HEADER >,添加请求头部字段,如 -H':method: PUT';
    • -u, --upgrade,使用 HTTP 的 Upgrade 机制来协商 HTTP/2 协议,用于 h2c,详见下面的例子;

    以下是使用 nghttp 访问 https://h2o.examp1e.net 的结果。从调试信息中可以清晰看到 h2c 协商以及 Server Push 的整个过程:

    nghttp -nv 'https://h2o.examp1e.net'
    [  0.201] Connected
    The negotiated protocol: h2
    [  1.180] send SETTINGS frame <length=12, flags=0x00, stream_id=0>
              (niv=2)
              [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
              [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
    [  1.180] send PRIORITY frame <length=5, flags=0x00, stream_id=3>
              (dep_stream_id=0, weight=201, exclusive=0)
    [  1.180] send PRIORITY frame <length=5, flags=0x00, stream_id=5>
              (dep_stream_id=0, weight=101, exclusive=0)
    [  1.180] send PRIORITY frame <length=5, flags=0x00, stream_id=7>
              (dep_stream_id=0, weight=1, exclusive=0)
    [  1.180] send PRIORITY frame <length=5, flags=0x00, stream_id=9>
              (dep_stream_id=7, weight=1, exclusive=0)
    [  1.180] send PRIORITY frame <length=5, flags=0x00, stream_id=11>
              (dep_stream_id=3, weight=1, exclusive=0)
    [  1.180] send HEADERS frame <length=39, flags=0x25, stream_id=13>
              ; END_STREAM | END_HEADERS | PRIORITY
              (padlen=0, dep_stream_id=11, weight=16, exclusive=0)
              ; Open new stream
              :method: GET
              :path: /
              :scheme: https
              :authority: h2o.examp1e.net
              accept: */*
              accept-encoding: gzip, deflate
              user-agent: nghttp2/1.21.1
    [  1.373] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>
              (niv=2)
              [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
              [SETTINGS_INITIAL_WINDOW_SIZE(0x04):16777216]
    [  1.373] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
              ; ACK
              (niv=0)
    [  1.373] recv (stream_id=13) :method: GET
    [  1.373] recv (stream_id=13) :scheme: https
    [  1.373] recv (stream_id=13) :authority: h2o.examp1e.net
    [  1.373] recv (stream_id=13) :path: /search/jquery-1.9.1.min.js
    [  1.373] recv (stream_id=13) accept: */*
    [  1.373] recv (stream_id=13) accept-encoding: gzip, deflate
    [  1.373] recv (stream_id=13) user-agent: nghttp2/1.21.1
    [  1.373] recv PUSH_PROMISE frame <length=59, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0, promised_stream_id=2)
    [  1.373] recv (stream_id=2) :status: 200
    [  1.373] recv (stream_id=2) server: h2o/2.2.0-beta2
    [  1.373] recv (stream_id=2) date: Mon, 10 Apr 2017 06:30:29 GMT
    [  1.373] recv (stream_id=2) content-type: application/javascript
    [  1.373] recv (stream_id=2) last-modified: Thu, 14 May 2015 04:10:14 GMT
    [  1.373] recv (stream_id=2) etag: "55542026-169d5"
    [  1.373] recv (stream_id=2) accept-ranges: bytes
    [  1.373] recv (stream_id=2) x-http2-push: pushed
    [  1.373] recv (stream_id=2) content-length: 92629
    [  1.373] recv HEADERS frame <length=126, flags=0x04, stream_id=2>
              ; END_HEADERS
              (padlen=0)
              ; First push response header
    [  1.373] recv (stream_id=13) :method: GET
    [  1.373] recv (stream_id=13) :scheme: https
    [  1.373] recv (stream_id=13) :authority: h2o.examp1e.net
    [  1.373] recv (stream_id=13) :path: /search/oktavia-jquery-ui.js
    [  1.373] recv (stream_id=13) accept: */*
    [  1.373] recv (stream_id=13) accept-encoding: gzip, deflate
    [  1.373] recv (stream_id=13) user-agent: nghttp2/1.21.1
    [  1.373] recv PUSH_PROMISE frame <length=33, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0, promised_stream_id=4)
    [  1.373] recv (stream_id=4) :status: 200
    [  1.373] recv (stream_id=4) server: h2o/2.2.0-beta2
    [  1.373] recv (stream_id=4) date: Mon, 10 Apr 2017 06:30:29 GMT
    [  1.373] recv (stream_id=4) content-type: application/javascript
    [  1.373] recv (stream_id=4) last-modified: Thu, 14 May 2015 04:10:14 GMT
    [  1.373] recv (stream_id=4) etag: "55542026-1388"
    [  1.373] recv (stream_id=4) accept-ranges: bytes
    [  1.374] recv (stream_id=4) x-http2-push: pushed
    [  1.374] recv (stream_id=4) content-length: 5000
    [  1.374] recv HEADERS frame <length=28, flags=0x04, stream_id=4>
              ; END_HEADERS
              (padlen=0)
              ; First push response header
    [  1.374] recv (stream_id=13) :method: GET
    [  1.374] recv (stream_id=13) :scheme: https
    [  1.374] recv (stream_id=13) :authority: h2o.examp1e.net
    [  1.374] recv (stream_id=13) :path: /search/oktavia-english-search.js
    [  1.374] recv (stream_id=13) accept: */*
    [  1.374] recv (stream_id=13) accept-encoding: gzip, deflate
    [  1.374] recv (stream_id=13) user-agent: nghttp2/1.21.1
    [  1.374] recv PUSH_PROMISE frame <length=35, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0, promised_stream_id=6)
    [  1.374] recv (stream_id=6) :status: 200
    [  1.374] recv (stream_id=6) server: h2o/2.2.0-beta2
    [  1.374] recv (stream_id=6) date: Mon, 10 Apr 2017 06:30:29 GMT
    [  1.374] recv (stream_id=6) content-type: application/javascript
    [  1.374] recv (stream_id=6) last-modified: Thu, 14 May 2015 04:10:14 GMT
    [  1.374] recv (stream_id=6) etag: "55542026-34dd6"
    [  1.374] recv (stream_id=6) accept-ranges: bytes
    [  1.374] recv (stream_id=6) x-http2-push: pushed
    [  1.374] recv (stream_id=6) content-length: 216534
    [  1.374] recv HEADERS frame <length=31, flags=0x04, stream_id=6>
              ; END_HEADERS
              (padlen=0)
              ; First push response header
    [  1.374] recv (stream_id=13) :method: GET
    [  1.374] recv (stream_id=13) :scheme: https
    [  1.374] recv (stream_id=13) :authority: h2o.examp1e.net
    [  1.374] recv (stream_id=13) :path: /assets/style.css
    [  1.374] recv (stream_id=13) accept: */*
    [  1.374] recv (stream_id=13) accept-encoding: gzip, deflate
    [  1.374] recv (stream_id=13) user-agent: nghttp2/1.21.1
    [  1.374] recv PUSH_PROMISE frame <length=24, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0, promised_stream_id=8)
    [  1.374] recv (stream_id=8) :status: 200
    [  1.374] recv (stream_id=8) server: h2o/2.2.0-beta2
    [  1.374] recv (stream_id=8) date: Mon, 10 Apr 2017 06:30:29 GMT
    [  1.374] recv (stream_id=8) content-type: text/css
    [  1.374] recv (stream_id=8) last-modified: Tue, 20 Sep 2016 05:27:06 GMT
    [  1.374] recv (stream_id=8) etag: "57e0c8aa-1586"
    [  1.374] recv (stream_id=8) accept-ranges: bytes
    [  1.374] recv (stream_id=8) x-http2-push: pushed
    [  1.374] recv (stream_id=8) content-length: 5510
    [  1.374] recv HEADERS frame <length=58, flags=0x04, stream_id=8>
              ; END_HEADERS
              (padlen=0)
              ; First push response header
    [  1.374] recv (stream_id=13) :method: GET
    [  1.374] recv (stream_id=13) :scheme: https
    [  1.374] recv (stream_id=13) :authority: h2o.examp1e.net
    [  1.374] recv (stream_id=13) :path: /assets/searchstyle.css
    [  1.374] recv (stream_id=13) accept: */*
    [  1.374] recv (stream_id=13) accept-encoding: gzip, deflate
    [  1.374] recv (stream_id=13) user-agent: nghttp2/1.21.1
    [  1.374] recv PUSH_PROMISE frame <length=28, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0, promised_stream_id=10)
    [  1.374] recv (stream_id=10) :status: 200
    [  1.374] recv (stream_id=10) server: h2o/2.2.0-beta2
    [  1.374] recv (stream_id=10) date: Mon, 10 Apr 2017 06:30:29 GMT
    [  1.374] recv (stream_id=10) content-type: text/css
    [  1.374] recv (stream_id=10) last-modified: Tue, 20 Sep 2016 05:27:06 GMT
    [  1.374] recv (stream_id=10) etag: "57e0c8aa-8dd"
    [  1.374] recv (stream_id=10) accept-ranges: bytes
    [  1.374] recv (stream_id=10) x-http2-push: pushed
    [  1.374] recv (stream_id=10) content-length: 2269
    [  1.374] recv HEADERS frame <length=27, flags=0x04, stream_id=10>
              ; END_HEADERS
              (padlen=0)
              ; First push response header
    [  1.374] recv (stream_id=13) :status: 200
    [  1.374] recv (stream_id=13) server: h2o/2.2.0-beta2
    [  1.374] recv (stream_id=13) date: Mon, 10 Apr 2017 06:30:29 GMT
    [  1.374] recv (stream_id=13) link: </search/jquery-1.9.1.min.js>; rel=preload
    [  1.374] recv (stream_id=13) link: </search/oktavia-jquery-ui.js>; rel=preload
    [  1.374] recv (stream_id=13) link: </search/oktavia-english-search.js>; rel=preload
    [  1.374] recv (stream_id=13) link: </assets/style.css>; rel=preload
    [  1.374] recv (stream_id=13) link: </assets/searchstyle.css>; rel=preload
    [  1.374] recv (stream_id=13) cache-control: no-cache
    [  1.374] recv (stream_id=13) content-type: text/html
    [  1.374] recv (stream_id=13) last-modified: Wed, 05 Apr 2017 06:55:14 GMT
    [  1.374] recv (stream_id=13) etag: "58e494d2-1665"
    [  1.374] recv (stream_id=13) accept-ranges: bytes
    [  1.374] recv (stream_id=13) set-cookie: h2o_casper=AmgAAAAAAAAAAAAYxfEYAAABSA; Path=/; Expires=Tue, 01 Jan 2030 00:00:00 GMT; Secure
    [  1.374] recv (stream_id=13) content-length: 5733
    [  1.374] recv HEADERS frame <length=304, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0)
              ; First response header
    [  1.375] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
              ; ACK
              (niv=0)
    [  1.566] recv DATA frame <length=16137, flags=0x00, stream_id=2>
    [  1.567] recv DATA frame <length=5000, flags=0x01, stream_id=4>
              ; END_STREAM
    [  1.567] recv DATA frame <length=4915, flags=0x00, stream_id=6>
    [  1.766] recv DATA frame <length=2829, flags=0x00, stream_id=8>
    [  1.766] recv DATA frame <length=2269, flags=0x01, stream_id=10>
              ; END_STREAM
    [  1.766] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=33120)
    [  1.767] recv DATA frame <length=9065, flags=0x00, stream_id=2>
    [  1.970] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  1.970] recv DATA frame <length=2681, flags=0x01, stream_id=8>
              ; END_STREAM
    [  1.971] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=2>
              (window_size_increment=33855)
    [  1.971] recv DATA frame <length=10072, flags=0x00, stream_id=2>
    [  2.172] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  2.172] recv DATA frame <length=4248, flags=0x00, stream_id=2>
    [  2.173] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  2.173] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=34002)
    [  2.173] recv DATA frame <length=4248, flags=0x00, stream_id=2>
    [  2.577] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  2.578] recv DATA frame <length=2829, flags=0x00, stream_id=2>
    [  2.579] recv DATA frame <length=12762, flags=0x00, stream_id=6>
    [  2.777] recv DATA frame <length=2829, flags=0x00, stream_id=2>
    [  2.777] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=6>
              (window_size_increment=33241)
    [  2.778] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  3.177] recv DATA frame <length=8505, flags=0x00, stream_id=2>
    [  3.177] recv DATA frame <length=5667, flags=0x00, stream_id=6>
    [  3.177] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=33993)
    [  3.177] recv DATA frame <length=2829, flags=0x00, stream_id=2>
    [  3.177] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  3.378] recv DATA frame <length=2829, flags=0x00, stream_id=2>
    [  3.579] recv DATA frame <length=11343, flags=0x00, stream_id=6>
    [  3.580] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=34002)
    [  3.580] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=2>
              (window_size_increment=33984)
    [  3.583] recv DATA frame <length=7086, flags=0x00, stream_id=2>
    [  3.779] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  4.186] recv DATA frame <length=7086, flags=0x00, stream_id=2>
    [  4.186] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  4.186] recv DATA frame <length=2829, flags=0x00, stream_id=2>
    [  4.395] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  4.396] recv DATA frame <length=2829, flags=0x00, stream_id=2>
    [  4.602] recv DATA frame <length=5667, flags=0x00, stream_id=6>
    [  4.602] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=6>
              (window_size_increment=33993)
    [  4.602] recv DATA frame <length=2829, flags=0x00, stream_id=2>
    [  4.602] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=33975)
    [  4.808] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  4.809] recv DATA frame <length=6379, flags=0x01, stream_id=2>
              ; END_STREAM
    [  5.010] recv DATA frame <length=3536, flags=0x00, stream_id=6>
    [  5.420] recv DATA frame <length=8505, flags=0x00, stream_id=6>
    [  5.420] recv DATA frame <length=5667, flags=0x00, stream_id=6>
    [  5.628] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  5.842] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  5.842] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  5.842] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=34002)
    [  5.842] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=6>
              (window_size_increment=33281)
    [  6.057] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  6.273] recv DATA frame <length=8505, flags=0x00, stream_id=6>
    [  6.490] recv DATA frame <length=9924, flags=0x00, stream_id=6>
    [  6.490] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  6.706] recv DATA frame <length=4248, flags=0x00, stream_id=6>
    [  6.706] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=34002)
    [  6.706] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=6>
              (window_size_increment=34002)
    [  6.924] recv DATA frame <length=8505, flags=0x00, stream_id=6>
    [  7.141] recv DATA frame <length=8505, flags=0x00, stream_id=6>
    [  7.361] recv DATA frame <length=8505, flags=0x00, stream_id=6>
    [  7.361] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=34020)
    [  7.574] recv DATA frame <length=9924, flags=0x00, stream_id=6>
    [  7.574] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=6>
              (window_size_increment=34029)
    [  7.787] recv DATA frame <length=9924, flags=0x00, stream_id=6>
    [  7.787] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  7.998] recv DATA frame <length=7086, flags=0x00, stream_id=6>
    [  8.210] recv DATA frame <length=9924, flags=0x00, stream_id=6>
    [  8.210] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
              (window_size_increment=34011)
    [  8.210] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=6>
              (window_size_increment=34011)
    [  8.425] recv DATA frame <length=11343, flags=0x00, stream_id=6>
    [  8.426] recv DATA frame <length=2829, flags=0x00, stream_id=6>
    [  8.426] recv DATA frame <length=4053, flags=0x01, stream_id=6>
              ; END_STREAM
    [  8.631] recv DATA frame <length=4443, flags=0x00, stream_id=13>
    [  8.633] recv DATA frame <length=1290, flags=0x01, stream_id=13>
              ; END_STREAM
    [  8.633] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
              (last_stream_id=10, error_code=NO_ERROR(0x00), opaque_data(0)=[])
    

    当然,我们也可以使用 grep 搜索出来 server push 的相关 stream:

    nghttp -nv 'https://h2o.examp1e.net' | grep 'PUSH_PROMISE'
    [  1.582] recv PUSH_PROMISE frame <length=59, flags=0x04, stream_id=13>
    [  1.582] recv PUSH_PROMISE frame <length=33, flags=0x04, stream_id=13>
    [  1.582] recv PUSH_PROMISE frame <length=35, flags=0x04, stream_id=13>
    [  1.582] recv PUSH_PROMISE frame <length=24, flags=0x04, stream_id=13>
    [  1.582] recv PUSH_PROMISE frame <length=28, flags=0x04, stream_id=13>
    

    使用 NodeJS 搭建 HTTP/2 服务器

    在大前端的时代背景下,客户端开发不会点 JavaScript 都快混不下去了,笔者前段时间在我司前端轮岗了两周,再加上之前也写过 ReactNative,但还是感觉前端变化之快领人咋舌,革命尚未结束,同志仍需努力啊。

    咱们直接上代码:

    var http2 = require('http2');// http2
    var url=require('url'); // https://www.npmjs.com/package/url
    var fs=require('fs'); // https://www.npmjs.com/package/fs
    var mine=require('mine');
    var path=require('path'); // 路径
     
    var server = http2.createServer({
      key: fs.readFileSync('./localhost.key'),
      cert: fs.readFileSync('./localhost.crt')
    }, function(request, response) {
    
        // var pathname = url.parse(request.url).pathname;
        var realPath = './push.json' ;//path.join(pathname,"push.json");    //这里设置自己的文件路径,这是该次response返回的内容;
     
        var pushArray = [];
        var ext = path.extname(realPath);
        ext = ext ? ext.slice(1) : 'unknown';
        var contentType = mine[ext] || "text/plain";
     
        if (fs.existsSync(realPath)) {
            
            console.log('success')
            response.writeHead(200, {
                'Content-Type': contentType
            });
            
            response.write(fs.readFileSync(realPath,'binary'));
    
            // 注意 push 路径必须是绝对路径,这是该次 server push 返回的内容
            var pushItem = response.push('/Users/f.li/Desktop/http2-nodeServer/newpush.json', {
                    response: {
                      'content-type': contentType
                    }    
            });
            pushItem.end(fs.readFileSync('/Users/f.li/Desktop/http2-nodeServer/newpush.json','binary'),()=>{
              console.log('newpush end')
            });
    
            response.end();
     
        } else {
          response.writeHead(404, {
              'Content-Type': 'text/plain'
          });
    
          response.write("This request URL " + realPath + " was not found on this server.");
          response.end();
        }
     
    });
     
    server.listen(3000, function() {
      console.log('listen on 3000');
    });
    

    这里需要注意几点:

    • 创建http2的nodejs服务必须时基于https的,因为现在主流的浏览器都要支持SSL/TLS的http2,证书和私钥可以自己通过OPENSSL生成。
    • node http2的相关api和正常的node httpserver相同,可以直接使用。

    使用 nghttp 测试一下我们的代码有没有进行 server push:

    ~ nghttp -nv 'https://localhost:3000/'
    [  0.007] Connected
    The negotiated protocol: h2
    [  0.029] recv SETTINGS frame <length=0, flags=0x00, stream_id=0>
              (niv=0)
    [  0.029] send SETTINGS frame <length=12, flags=0x00, stream_id=0>
              (niv=2)
              [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
              [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
    [  0.029] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
              ; ACK
              (niv=0)
    [  0.029] send PRIORITY frame <length=5, flags=0x00, stream_id=3>
              (dep_stream_id=0, weight=201, exclusive=0)
    [  0.029] send PRIORITY frame <length=5, flags=0x00, stream_id=5>
              (dep_stream_id=0, weight=101, exclusive=0)
    [  0.029] send PRIORITY frame <length=5, flags=0x00, stream_id=7>
              (dep_stream_id=0, weight=1, exclusive=0)
    [  0.029] send PRIORITY frame <length=5, flags=0x00, stream_id=9>
              (dep_stream_id=7, weight=1, exclusive=0)
    [  0.029] send PRIORITY frame <length=5, flags=0x00, stream_id=11>
              (dep_stream_id=3, weight=1, exclusive=0)
    [  0.029] send HEADERS frame <length=38, flags=0x25, stream_id=13>
              ; END_STREAM | END_HEADERS | PRIORITY
              (padlen=0, dep_stream_id=11, weight=16, exclusive=0)
              ; Open new stream
              :method: GET
              :path: /
              :scheme: https
              :authority: localhost:3000
              accept: */*
              accept-encoding: gzip, deflate
              user-agent: nghttp2/1.21.1
    [  0.043] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
              ; ACK
              (niv=0)
    [  0.049] recv (stream_id=13) :status: 200
    [  0.049] recv (stream_id=13) content-type: text/plain
    [  0.049] recv (stream_id=13) date: Tue, 11 Apr 2017 08:34:46 GMT
    [  0.049] recv HEADERS frame <length=34, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0)
              ; First response header
    [  0.049] recv DATA frame <length=35, flags=0x00, stream_id=13>
    [  0.049] recv (stream_id=13) :method: GET
    [  0.049] recv (stream_id=13) :scheme: https
    [  0.050] recv (stream_id=13) :authority: localhost:3000
    [  0.050] recv (stream_id=13) :path: /Users/f.li/Desktop/http2-nodeServer/newpush.json
    [  0.050] recv PUSH_PROMISE frame <length=56, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0, promised_stream_id=2)
    [  0.050] recv DATA frame <length=0, flags=0x01, stream_id=13>
              ; END_STREAM
    [  0.050] recv (stream_id=2) :status: 200
    [  0.050] recv (stream_id=2) date: Tue, 11 Apr 2017 08:34:46 GMT
    [  0.050] recv HEADERS frame <length=2, flags=0x04, stream_id=2>
              ; END_HEADERS
              (padlen=0)
              ; First push response header
    [  0.050] recv DATA frame <length=21, flags=0x00, stream_id=2>
    [  0.050] recv DATA frame <length=0, flags=0x01, stream_id=2>
              ; END_STREAM
    [  0.050] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
              (last_stream_id=2, error_code=NO_ERROR(0x00), opaque_data(0)=[])
    

    看到了 PUSH_PROMISE 的帧,说明进行了 server push。

    同样也可以使用chrome查看 server push,如下图所示:


    chrome 查看 http2 server push

    服务端介绍基本完毕。下面我们来介绍一些 iOS 客户端对 Server Push 的使用。

    iOS 使用 HTTP/2 Server Push

    Apple 在这方面做的很好,基本实现了客户端无感调用http/2 server push。但是笔者查看了些许资料,现在只有iOS 10 支持 http/2。

    直接上代码吧:

    #import "ViewController.h"
    
    @interface ViewController ()<NSURLSessionDelegate>
    
    @property(nonatomic,strong)NSURLSession *session;
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad
    {
        [super viewDidLoad];
        // Do any additional setup after loading the view, typically from a nib.
        
    }
    #pragma mark - Touch
    - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
    {
        [self urlSession];
    }
    #pragma mark - 发送请求
    - (void)urlSession
    {
        NSURL *url = [NSURL URLWithString:@"https://localhost:3000"];
        
        //发送HTTPS请求是需要对网络会话设置代理的
        _session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];
        
        NSURLSessionDataTask *dataTask = [_session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
            NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
            // 收到该次请求后,立即请求下次的内容
            [self urlSessionPush];
            
        }];
        
        [dataTask resume];
    }
    
    - (void)urlSessionPush
    {
        NSURL *url = [NSURL URLWithString:@"https://localhost:3000/Users/f.li/Desktop/http2-nodeServer/newpush.json"];
        NSURLSessionDataTask *dataTask = [_session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
            NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
        }];
        [dataTask resume];
    }
    
    #pragma mark - URLSession Delegate
    - (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential * _Nullable))completionHandler
    {
        // 这里还要设置下 plist 中设置 ATS
        if (![challenge.protectionSpace.authenticationMethod isEqualToString:@"NSURLAuthenticationMethodServerTrust"])
        {
            return;
        }
        NSURLCredential *credential = [[NSURLCredential alloc] initWithTrust:challenge.protectionSpace.serverTrust];
        completionHandler(NSURLSessionAuthChallengeUseCredential,credential);
    }
    
    
    - (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didFinishCollectingMetrics:(NSURLSessionTaskMetrics *)metrics
    {
        NSArray *fetchTypes = @[ @"Unknown", @"Network Load", @"Server Push", @"Local Cache"];
        
        for(NSURLSessionTaskTransactionMetrics *transactionMetrics in [metrics transactionMetrics])
        {
            
            NSLog(@"protocol[%@] reuse[%d] fetch:%@ - %@", [transactionMetrics networkProtocolName], [transactionMetrics isReusedConnection], fetchTypes[[transactionMetrics resourceFetchType]], [[transactionMetrics request] URL]);
            
            if([transactionMetrics resourceFetchType] == NSURLSessionTaskMetricsResourceFetchTypeServerPush)
            {
                NSLog(@"Asset was server pushed");
            }
        }
    }
    
    - (void)didReceiveMemoryWarning
    {
        [super didReceiveMemoryWarning];
        // Dispose of any resources that can be recreated.
    }
    
    @end
    
    

    分别看下服务端和客户端的Log:
    客户端:

    Http2ServerPush[2525:274943] protocol[h2] reuse[0] fetch:Network Load - https://localhost:3000/
    Http2ServerPush[2525:274943] {"message":" http2.0 server is ok"}
    Http2ServerPush[2525:274943] protocol[h2] reuse[1] fetch:Server Push - https://localhost:3000/Users/f.li/Desktop/http2-nodeServer/newpush.json
    Http2ServerPush[2525:274943] Asset was server pushed
    Http2ServerPush[2525:274943] {"message":"newPush"}
    

    服务端:

    http2-nodeServer npm start
    
    > http2-nodeServer@1.0.0 start /Users/f.li/Desktop/http2-nodeServer
    > node index.js
    
    listen on 3000
    success
    newpush end
    

    看来确实是客户端发出了两次请求,但是服务端只响应了一次(该次响应+ server push)

    本文相关Demo

    参考文献

    相关文章

      网友评论

        本文标题:iOS HTTP/2 Server Push 探索

        本文链接:https://www.haomeiwen.com/subject/mauuattx.html