Sitecore Implementation - HTML Cache Control Setting options

Question

We are building a very transnational membership portal on sitecore platform. So Rendering output caching is not a good option for us.

Per this htm-caching guideline (https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching), we would like all the static contents such as JS, CSS, Images etc to be cached by both user browser as well as CDN. This means setting the cache-control as public, max-age: 1 week and appropriate ETAG).

At the same time there will be static user specific PDF files which should be set as Private ,max-age:0,no-store).

Is there a best way to configure above using sitecore (configuration or custom code or module)?

Answer 1

Sitecore comes with out of the box possibilities to configure media caching.
Have a look at the Sitecore.config:

<!--  MEDIA RESPONSE - CACHEABILITY
        The <see cref="HttpCacheability">cacheability</see> to use in media response headers.
        Possible values: NoCache, Private, Public, Server, ServerAndNoCache, ServerAndPrivate
        Default value: private
  -->
<setting name="MediaResponse.Cacheability" value="private"/>
<!--  MEDIA RESPONSE - CacheExtensions
        The <see cref="HttpCachePolicy.AppendCacheExtension">cache extension(s)</see> to use in media response headers.
        Default value: ""
  -->
<setting name="MediaResponse.CacheExtensions" value=""/>
<!--  MEDIA RESPONSE - MAX AGE
        The <see cref="HttpCachePolicy.SetMaxAge">max age</see> to use in media response headers.
        Set it to "00:00:00" to omit this header.
        Default value: 7.00:00:00 (seven days)
  -->
<setting name="MediaResponse.MaxAge" value="7.00:00:00"/>
<!--  MEDIA RESPONSE - SLIDING EXPIRATION
        The <see cref="HttpCachePolicy.SetSlidingExpiration">sliding expiration</see> to use in media response headers.
        Set it to "" to omit this header. To include it, use "true" or "false".
        Default value: ""
  -->
<setting name="MediaResponse.SlidingExpiration" value=""/>
<!--  MEDIA RESPONSE - VARY HEADER
        Specifies the value for the Vary HTTP header to use in media response headers.
        Set it to "" to omit this header.
        Default value: ""
  -->
<setting name="MediaResponse.VaryHeader" value=""/>

These are used in the MediaRequestHandler. Check the handlers section of your Web.config file.

<add verb="*" path="sitecore_media.ashx" type="Sitecore.Resources.Media.MediaRequestHandler, Sitecore.Kernel" name="Sitecore.MediaRequestHandler"/>

If you want the static user specific PDF files set up correctly, you would need to:

• Not change the MediaResponse.Cacheability since it is already set to private
• Set the MediaResponse.MaxAge to 00:00:00.
• No-store should also already be present due to the setting DisableBrowserCaching.

---

<!--  DISABLE BROWSER CACHING
      If true, all pages will have:
        Cache-Control: no-cache, no-store
        Pragma: no-cache
      in the http header
-->
<setting name="DisableBrowserCaching" value="true"/>

---

You can modify the MediaRequestHandler to tailor it more to your needs. For example: only logged in users to a specific domain can download media files. Read this blog for some more information: http://www.doodle.co.uk/blogs/2015/03/03/restricting-access-to-sitecore-media-items