Daren Matthews

Browsers can setup two or more TCP connections to an HTTP server to facilitate parallel downloads. As the browser parses the Web page it is aware of which objects it needs to download.

Rather than send the requests in series over a single connection, the requests are sent over parallel connections to enable faster downloading of the Web page. Another technique used by browsers to improve the performance is “HTTP pipelining”. Read more…

HTTP and ETag

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With caching enabled, a web server does not need to send a full response if content has not changed.

• If-Modified-Since is an HTTP request header that the client sends to your browser along with a request for content.
• Last-Modified is an HTTP response header that the server returns along with the requested content.

If-Modified-Since Allows a 304 Not Modified to be returned if content is unchanged
If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMT

If-None-Match Allows a 304 Not Modified to be returned if content is unchanged,
If-None-Match: "737060cd8c082f209582d" Read more…