在IIS7/8/8.5中指定多个(gzip + brotli)httpCompression方案并优先化brotli [英] Specify multiple (gzip + brotli) httpCompression schemes in IIS7/8/8.5 and prioritise brotli

问题描述

我正在尝试使用" Brotli 压缩方案. ="https://www.iispeed.com/pagespeed/products/iisbrotli" rel ="noreferrer">用于Microsoft IIS的Brotli压缩模块"通过 iisspeed.com .

I'm trying to get the new Brotli compression scheme working in IIS using "Brotli compression module for Microsoft IIS" by iisspeed.com.

如果我将applicationHost.config中的<httpCompression>配置部分更改为仅具有Brotli模块，则Brotli压缩模块本身可以正常工作.

The Brotli compression module itself works fine if I change the <httpCompression> config section in applicationHost.config to only have the Brotli module.

iisspeed.com上的文档说要这样做:

The documentation on iisspeed.com says to do this:

<httpCompression directory="path\to\temp\folder" minFileSizeForComp="50">
        <scheme name="br" dll="path\to\iisbrotli.dll" />
        <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" />
        ...
</httpCompression>

但是我发现这行不通.

浏览器(在此示例中为Chrome)发送以下accept-encoding标头:

The browser (Chrome in this example) sends the following accept-encoding header:

accept-encoding: gzip, deflate, sdch, br

这意味着浏览器可以接受Brotli编码br和gzip. 我希望IIS比gzip更喜欢br，但是似乎没有一种方法可以对配置中的每个<scheme>元素进行优先级排序.我尝试更改.config文件中的顺序，但没有效果.

This means the browser can accept Brotli encoding br as well as gzip. I want IIS to prefer br over gzip but there doesn't appear to be a way to prioritise each <scheme> element in the config. I've tried changing the order in the .config file but it has no effect.

即使支持br，IIS仍始终使用gzip，因此它是首选文件，因为它的文件大小较小.

IIS always uses gzip even though br is supported and would be preferred because it's a smaller file size.

我曾搜寻过Google，以发现IIS 6中曾经为每个压缩方案设置了优先级设置，但在IIS7 +中似乎已将其删除.

I have scoured Google to find that there used to be a priority setting for each compression scheme in IIS 6 but it seems to have been removed in IIS7+.

它称为HcPriority，并进入IIS6元数据库XML文件.

It's called HcPriority and went into the IIS6 metabase XML file.

请参阅以下链接:

https://msdn.microsoft.com /en-us/library/ms525366(v=vs.90).aspx

https://blogs.iis.net/ksingla/changes- to-compression-in-iis7

https://forums.iis.net/t/1150520.aspx

推荐答案

您所引用的Brotli模块似乎需要付费许可证，因此我没有尝试过，但是我自己的用于IIS的开源Brotli插件.

It appears the Brotli module you referenced requires a paid license, so I haven't tried it, but I encountered a similar issue with my own open source Brotli plugin for IIS.

正如您所指出的那样，当前的浏览器在Accept-Encoding标头中的gzip和deflate之后宣传Brotli支持.

As you pointed out, current browsers advertise Brotli support after gzip and deflate in the Accept-Encoding header.

HTTP RFC 没有提供有关如何选择的具体指导许多具有相同优先级的Accept-Encoding值，因此可以将br内容返回给那些客户端是可以接受的.但是，IIS似乎总是选择与其配置的压缩方案之一匹配的第一个(从左到右).

The HTTP RFC gives no specific guidance on how to choose from many Accept-Encoding values with the same priority, so it would be acceptable to return br content to those clients. However, it appears IIS always chooses the first one (left to right) that matches one of its configured compression schemes.

如果希望两个方案都保持启用状态，则可以在请求进入IIS管道时修改请求的Accept-Encoding标头值. IIS URL重写模块可以通过简单的规则来做到这一点.

If you wish to leave both schemes enabled, you can modify the Accept-Encoding header value on requests as they enter your IIS pipeline. The IIS URL Rewrite Module can do this with a simple rule.

Accept-Encoding标头由IIS管道中的HTTP_ACCEPT_ENCODING服务器变量表示，可以在到达压缩模块之前对其进行修改.这是一个示例配置:

The Accept-Encoding header is represented by the HTTP_ACCEPT_ENCODING Server Variable in the IIS pipeline, and you can modify it before it reaches the Compression Module(s). Here is a sample configuration:

<rewrite>
    <allowedServerVariables>
        <add name="HTTP_ACCEPT_ENCODING" />
    </allowedServerVariables>
    <rules>
        <rule name="Prioritize Brotli">
            <match url=".*" />
            <conditions>
                <add input="{HTTP_ACCEPT_ENCODING}" pattern="\bbr(?!;q=0)\b" />
            </conditions>
            <serverVariables>
                <set name="HTTP_ACCEPT_ENCODING" value="br" />
            </serverVariables>
        </rule>
    </rules>
</rewrite>

上面的规则在Accept-Encoding标头中查找字符串br(由单词边界包围-而不是紧跟在;q=0之后)，并将其重新编写为纯文本br，从而得到IIS只有一种选择.

The rule above looks for the string br (surrounded by word boundaries -- and not immediately followed by ;q=0) in the Accept-Encoding header and re-writes it to be just plain br, giving IIS only one choice.

请注意，默认的URL重写配置不允许修改HTTP_ACCEPT_ENCODING变量. allowedServerVariables元素将覆盖该限制，并且必须在applicationHost.config中进行配置.可以在配置层次结构的任何级别上定义重写规则，尽管将其设置为全局可能很有意义.

Note that the default URL Rewrite configuration does not allow modification of the HTTP_ACCEPT_ENCODING variable. The allowedServerVariables element overrides that restriction and must be configured in applicationHost.config. The rewrite rule can then be defined at any level in the config hierarchy, although it probably makes sense to make it global.

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