HTTP Caching & Cache-Busting
for Content Publishers

Publishers must think about caching

HTTP Review

HTTP Review (cont’d)

HTTP Example

Browsers use private caches

Revalidation (Conditional GET)

Non-Caching Proxy

Proxy Cache Miss

Proxy Cache Hit

Proxy Cache Revalidation Hit

Assumptions about content types

Top 5 techniques for publishers

1. Use “Cache-Control: private”
for personalized content

Bad caching of personalized content

Bad caching of personalized content

Bad caching of personalized content

What’s cacheable?

Cache-Control: private

2. “Images Never Expire” policy

The “Images Never Expire” Policy

Images Never Expire (mod_expires)

Images Never Expire (mod_headers)

mod_images_never_expire

3. Cookie-free TLD for static content

Cookie-free TLD for static content

Typical GET request w/Cookies

Same request, no Cookies

4. Apache defaults for static, occasionally-changing content

Revalidation works pretty well

Techniques to encourage caching

5. Random URL strings for accurate hit metering or very sensitive content

Accurate advertising statistics

Hit-metering for advertisements (1)

Hit-metering for advertisements (2)

Hit-metering for advertisements (3)

Turning proxies into private caches

Breaking the Back button

Review: Top 5 techniques

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