使用e-tag来加快页面加载速度和提高用户体验

I use the Firefox plugin Tamper Data 10.0.1 to trace the http

If we open the website http://10.242.224.69:8080/estore/ and activate the tamper data plugin.
We can see that:





We can see that If-None-Match=02e81f8533137e20549e917d7122ec ,which means that If the etag equals to this one ,then the server will think that “the client has cached the resource ,so it returns 304
See from the right column . In http protocol : 304 means that

If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server SHOULD respond with this status code. The 304 response MUST NOT contain a message-body, and thus is always terminated by the first empty line after the header fields.

The response MUST include the following header fields:

- Date, unless its omission is required by section 14.18.1
If a clockless origin server obeys these rules, and proxies and clients add their own Date to any response received without one (as already specified by [RFC 2068], section 14.19), caches will operate correctly.

- ETag and/or Content-Location, if the header would have been sent
in a 200 response to the same request
- Expires, Cache-Control, and/or Vary, if the field-value might
differ from that sent in any previous response for the same
variant
If the conditional GET used a strong cache validator (see section 13.3.3), the response SHOULD NOT include other entity-headers. Otherwise (i.e., the conditional GET used a weak validator), the response MUST NOT include other entity-headers; this prevents inconsistencies between cached entity-bodies and updated headers.

If a 304 response indicates an entity not currently cached, then the cache MUST disregard the response and repeat the request without the conditional.

If a cache uses a received 304 response to update a cache entry, the cache MUST update the entry to reflect any new field values given in the response.

So ,since the server returns 304 ,then the server will not contains any response content ,which reduces the bandwidth.. ->see from the right column ,the response is “Not Modified-304”

That’s why I suggest that we can add e-tag to most elements to accelerate the loading speed and enhance the user experience.