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Caching secrets of the HTTP elders, part 1
ETags - an elegant weapon, for a more civilised age
This was essential because, back in the day, the repeated re-downloading of unchanged files was a real headache. One of the cool new features in HTTP/1.1 (implemented in Netscape Navigator 4.0, available from all reputable software stockists) is the ETag header. That key represents both the version of the file plus what page is being looked it (the JSON and HTML formats are paginated).
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