Will nginx support HTTP Etag ?

Anton Yuzhaninov citrin at citrin.ru
Tue Apr 14 14:04:27 MSD 2009

Xia Qingran wrote:
> After reading http://wiki.nginx.org, I find out that nginx has not the
> offical support for the HTTP Etag,
> http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19 . I
> want to know whether the future version of nginx will add this
> feature.
> My website is taking use of nginx to run static files server including
> lots of Javascipt and CSS files modified frequently. Now I set a very
> short expires time like, expires 1h, to renew the client cache as soon
> as possible.
> But I think it is not a good solution. It wastes my network bandwidth
> if I do not modify the static files.

If last-modifed date of file is not changed, bandwidth saved:

client send in request

header If-Modified-Since:

and if time in request same as time of file modification on disk nginx send reply
HTTP/1.x 304 Not Modified

In general Etag for static files is not better than Last-Modified header.

Etag is useful for dynamic content, when modify time is not known. In this case Etage can be 
generated from hash (md5/sha) of content.

  Anton Yuzhaninov

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